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* [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely
@ 2014-11-15  4:58 Steven Rostedt
  2014-11-15  4:58 ` [PATCH 01/26 v5] tracing: Fix trace_seq_bitmask() to start at current position Steven Rostedt
                   ` (27 more replies)
  0 siblings, 28 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

Version 5!

Full diff between v4 and v5 will be replied to this email.

Here's the summary of the differences since version 4:

 . Various clean ups

 . Added trace_seq_used() to be used instead of s->seq.len

 . Used seq_buf_used() instead of s->len

 . Fixed output of ftrace_raw_output_prep() as well as caller code

 . Fixed up tracing_fill_pipe_page() The logic was a bit whacky
   and this was needed when introducing trace_seq_used()

 . Rebased on latest ftrace/core code

 . Fixed uprobe to be like probe code in print_uprobe_event()

 . Introduced new seq_buf_can_fit() to remove the likelyhood of
   screwing up the s->len + * < s->size code. Now it's just
   seq_buf_can_fit(s, len) which will tell us if the len can still
   fit in the buffer.

Enjoy,

-- Steve


Steven Rostedt (Red Hat) (26):
      tracing: Fix trace_seq_bitmask() to start at current position
      tracing: Add trace_seq_has_overflowed() and trace_handle_return()
      blktrace/tracing: Use trace_seq_has_overflowed() helper function
      ring-buffer: Remove check of trace_seq_{puts,printf}() return values
      tracing: Have branch tracer use trace_handle_return() helper function
      tracing: Have function_graph use trace_seq_has_overflowed()
      kprobes/tracing: Use trace_seq_has_overflowed() for overflow checks
      tracing: Do not check return values of trace_seq_p*() for mmio tracer
      tracing/probes: Do not use return value of trace_seq_printf()
      tracing/uprobes: Do not use return values of trace_seq_printf()
      tracing: Do not use return values of trace_seq_printf() in syscall tracing
      tracing: Remove return values of most trace_seq_*() functions
      tracing: Fix return value of ftrace_raw_output_prep()
      tracing: Create seq_buf layer in trace_seq
      tracing: Convert seq_buf_path() to be like seq_path()
      tracing: Convert seq_buf fields to be like seq_file fields
      tracing: Add a seq_buf_clear() helper and clear len and readpos in init
      seq_buf: Create seq_buf_used() to find out how much was written
      tracing: Use trace_seq_used() and seq_buf_used() instead of len
      seq_buf: Add seq_buf_can_fit() helper function
      tracing: Have seq_buf use full buffer
      tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions
      seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF
      seq_buf: Move the seq_buf code to lib/
      printk: Add per_cpu printk func to allow printk to be diverted
      x86/nmi: Perform a safe NMI stack trace on all CPUs

----
 arch/x86/kernel/apic/hw_nmi.c        |  91 +++++++-
 include/linux/ftrace_event.h         |  11 +
 include/linux/percpu.h               |   3 +
 include/linux/printk.h               |   2 +
 include/linux/seq_buf.h              | 136 ++++++++++++
 include/linux/trace_seq.h            |  77 ++++---
 include/trace/ftrace.h               |   8 +-
 kernel/printk/printk.c               |  38 +++-
 kernel/trace/blktrace.c              | 148 ++++++-------
 kernel/trace/ring_buffer.c           |  75 +++----
 kernel/trace/trace.c                 | 126 ++++++-----
 kernel/trace/trace.h                 |   3 +-
 kernel/trace/trace_branch.c          |  15 +-
 kernel/trace/trace_events.c          |   9 +-
 kernel/trace/trace_functions_graph.c | 393 +++++++++++----------------------
 kernel/trace/trace_kprobe.c          |  42 ++--
 kernel/trace/trace_mmiotrace.c       |  52 ++---
 kernel/trace/trace_output.c          | 417 ++++++++++++++---------------------
 kernel/trace/trace_output.h          |  16 +-
 kernel/trace/trace_probe.c           |  10 +-
 kernel/trace/trace_seq.c             | 253 +++++++++------------
 kernel/trace/trace_syscalls.c        |  43 ++--
 kernel/trace/trace_uprobe.c          |  23 +-
 lib/Makefile                         |   2 +-
 lib/seq_buf.c                        | 351 +++++++++++++++++++++++++++++
 25 files changed, 1323 insertions(+), 1021 deletions(-)

^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 01/26 v5] tracing: Fix trace_seq_bitmask() to start at current position
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-15  4:58 ` [PATCH 02/26 v5] tracing: Add trace_seq_has_overflowed() and trace_handle_return() Steven Rostedt
                   ` (26 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0001-tracing-Fix-trace_seq_bitmask-to-start-at-current-po.patch --]
[-- Type: text/plain, Size: 1111 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

In trace_seq_bitmask() it calls bitmap_scnprintf() not from the current
position of the trace_seq buffer (s->buffer + s->len), but instead from
the beginning of the buffer (s->buffer).

Luckily, the only user of this "ipi_raise tracepoint" uses it as the
first parameter, and as such, the start of the temp buffer in
include/trace/ftrace.h (see __get_bitmask()).

Reported-by: Petr Mladek <pmladek@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_seq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index 1f24ed99dca2..b100994a17fe 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -122,7 +122,7 @@ int trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 	if (s->full || !len)
 		return 0;
 
-	ret = bitmap_scnprintf(s->buffer, len, maskp, nmaskbits);
+	ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
 	s->len += ret;
 
 	return 1;
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 02/26 v5] tracing: Add trace_seq_has_overflowed() and trace_handle_return()
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
  2014-11-15  4:58 ` [PATCH 01/26 v5] tracing: Fix trace_seq_bitmask() to start at current position Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-15  4:58 ` [PATCH 03/26 v5] blktrace/tracing: Use trace_seq_has_overflowed() helper function Steven Rostedt
                   ` (25 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0002-tracing-Add-trace_seq_has_overflowed-and-trace_handl.patch --]
[-- Type: text/plain, Size: 29495 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Adding a trace_seq_has_overflowed() which returns true if the trace_seq
had too much written into it allows us to simplify the code.

Instead of checking the return value of every call to trace_seq_printf()
and friends, they can all be called normally, and at the end we can
return !trace_seq_has_overflowed() instead.

Several functions also return TRACE_TYPE_PARTIAL_LINE when the trace_seq
overflowed and TRACE_TYPE_HANDLED otherwise. Another helper function
was created called trace_handle_return() which takes a trace_seq and
returns these enums. Using this helper function also simplifies the
code.

This change also makes it possible to remove the return values of
trace_seq_printf() and friends. They should instead just be
void functions.

Link: http://lkml.kernel.org/r/20141114011410.365183157@goodmis.org

Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ftrace_event.h |  11 ++
 include/linux/trace_seq.h    |  12 ++
 include/trace/ftrace.h       |   6 +-
 kernel/trace/trace.c         |  69 +++----
 kernel/trace/trace.h         |   1 +
 kernel/trace/trace_output.c  | 416 +++++++++++++++++--------------------------
 kernel/trace/trace_output.h  |  16 +-
 7 files changed, 231 insertions(+), 300 deletions(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 28672e87e910..0bebb5c348b8 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -138,6 +138,17 @@ enum print_line_t {
 	TRACE_TYPE_NO_CONSUME	= 3	/* Handled but ask to not consume */
 };
 
+/*
+ * Several functions return TRACE_TYPE_PARTIAL_LINE if the trace_seq
+ * overflowed, and TRACE_TYPE_HANDLED otherwise. This helper function
+ * simplifies those functions and keeps them in sync.
+ */
+static inline enum print_line_t trace_handle_return(struct trace_seq *s)
+{
+	return trace_seq_has_overflowed(s) ?
+		TRACE_TYPE_PARTIAL_LINE : TRACE_TYPE_HANDLED;
+}
+
 void tracing_generic_entry_update(struct trace_entry *entry,
 				  unsigned long flags,
 				  int pc);
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index ea6c9dea79e3..07eda413dfcf 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -40,6 +40,18 @@ trace_seq_buffer_ptr(struct trace_seq *s)
 	return s->buffer + s->len;
 }
 
+/**
+ * trace_seq_has_overflowed - return true if the trace_seq took too much
+ * @s: trace sequence descriptor
+ *
+ * Returns true if too much data was added to the trace_seq and it is
+ * now full and will not take anymore.
+ */
+static inline bool trace_seq_has_overflowed(struct trace_seq *s)
+{
+	return s->full || s->len > PAGE_SIZE - 1;
+}
+
 /*
  * Currently only defined when tracing is enabled.
  */
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 26b4f2e13275..f13471b5d27a 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -280,11 +280,9 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags,	\
 	if (ret)							\
 		return ret;						\
 									\
-	ret = trace_seq_printf(s, print);				\
-	if (!ret)							\
-		return TRACE_TYPE_PARTIAL_LINE;				\
+	trace_seq_printf(s, print);					\
 									\
-	return TRACE_TYPE_HANDLED;					\
+	return trace_handle_return(s);					\
 }									\
 static struct trace_event_functions ftrace_event_type_funcs_##call = {	\
 	.trace			= ftrace_raw_output_##call,		\
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 44d561426700..3ce3c4ccfc94 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2649,24 +2649,21 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
 	event = ftrace_find_event(entry->type);
 
 	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
-		if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
-			if (!trace_print_lat_context(iter))
-				goto partial;
-		} else {
-			if (!trace_print_context(iter))
-				goto partial;
-		}
+		if (iter->iter_flags & TRACE_FILE_LAT_FMT)
+			trace_print_lat_context(iter);
+		else
+			trace_print_context(iter);
 	}
 
+	if (trace_seq_has_overflowed(s))
+		return TRACE_TYPE_PARTIAL_LINE;
+
 	if (event)
 		return event->funcs->trace(iter, sym_flags, event);
 
-	if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
-		goto partial;
+	trace_seq_printf(s, "Unknown type %d\n", entry->type);
 
-	return TRACE_TYPE_HANDLED;
-partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
@@ -2677,22 +2674,20 @@ static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
 
 	entry = iter->ent;
 
-	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
-		if (!trace_seq_printf(s, "%d %d %llu ",
-				      entry->pid, iter->cpu, iter->ts))
-			goto partial;
-	}
+	if (trace_flags & TRACE_ITER_CONTEXT_INFO)
+		trace_seq_printf(s, "%d %d %llu ",
+				 entry->pid, iter->cpu, iter->ts);
+
+	if (trace_seq_has_overflowed(s))
+		return TRACE_TYPE_PARTIAL_LINE;
 
 	event = ftrace_find_event(entry->type);
 	if (event)
 		return event->funcs->raw(iter, 0, event);
 
-	if (!trace_seq_printf(s, "%d ?\n", entry->type))
-		goto partial;
+	trace_seq_printf(s, "%d ?\n", entry->type);
 
-	return TRACE_TYPE_HANDLED;
-partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
@@ -2705,9 +2700,11 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
 	entry = iter->ent;
 
 	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
-		SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
-		SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
-		SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
+		SEQ_PUT_HEX_FIELD(s, entry->pid);
+		SEQ_PUT_HEX_FIELD(s, iter->cpu);
+		SEQ_PUT_HEX_FIELD(s, iter->ts);
+		if (trace_seq_has_overflowed(s))
+			return TRACE_TYPE_PARTIAL_LINE;
 	}
 
 	event = ftrace_find_event(entry->type);
@@ -2717,9 +2714,9 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
 			return ret;
 	}
 
-	SEQ_PUT_FIELD_RET(s, newline);
+	SEQ_PUT_FIELD(s, newline);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
@@ -2731,9 +2728,11 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
 	entry = iter->ent;
 
 	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
-		SEQ_PUT_FIELD_RET(s, entry->pid);
-		SEQ_PUT_FIELD_RET(s, iter->cpu);
-		SEQ_PUT_FIELD_RET(s, iter->ts);
+		SEQ_PUT_FIELD(s, entry->pid);
+		SEQ_PUT_FIELD(s, iter->cpu);
+		SEQ_PUT_FIELD(s, iter->ts);
+		if (trace_seq_has_overflowed(s))
+			return TRACE_TYPE_PARTIAL_LINE;
 	}
 
 	event = ftrace_find_event(entry->type);
@@ -2779,10 +2778,12 @@ enum print_line_t print_trace_line(struct trace_iterator *iter)
 {
 	enum print_line_t ret;
 
-	if (iter->lost_events &&
-	    !trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
-				 iter->cpu, iter->lost_events))
-		return TRACE_TYPE_PARTIAL_LINE;
+	if (iter->lost_events) {
+		trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
+				 iter->cpu, iter->lost_events);
+		if (trace_seq_has_overflowed(&iter->seq))
+			return TRACE_TYPE_PARTIAL_LINE;
+	}
 
 	if (iter->trace && iter->trace->print_line) {
 		ret = iter->trace->print_line(iter);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3376de623ea0..19418221b302 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -14,6 +14,7 @@
 #include <linux/trace_seq.h>
 #include <linux/ftrace_event.h>
 #include <linux/compiler.h>
+#include <linux/trace_seq.h>
 
 #ifdef CONFIG_FTRACE_SYSCALLS
 #include <asm/unistd.h>		/* For NR_SYSCALLS	     */
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index cfa91de22e27..163c11b6b8ff 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -25,15 +25,12 @@ enum print_line_t trace_print_bputs_msg_only(struct trace_iterator *iter)
 	struct trace_seq *s = &iter->seq;
 	struct trace_entry *entry = iter->ent;
 	struct bputs_entry *field;
-	int ret;
 
 	trace_assign_type(field, entry);
 
-	ret = trace_seq_puts(s, field->str);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_puts(s, field->str);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 enum print_line_t trace_print_bprintk_msg_only(struct trace_iterator *iter)
@@ -41,15 +38,12 @@ enum print_line_t trace_print_bprintk_msg_only(struct trace_iterator *iter)
 	struct trace_seq *s = &iter->seq;
 	struct trace_entry *entry = iter->ent;
 	struct bprint_entry *field;
-	int ret;
 
 	trace_assign_type(field, entry);
 
-	ret = trace_seq_bprintf(s, field->fmt, field->buf);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_bprintf(s, field->fmt, field->buf);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 enum print_line_t trace_print_printk_msg_only(struct trace_iterator *iter)
@@ -57,15 +51,12 @@ enum print_line_t trace_print_printk_msg_only(struct trace_iterator *iter)
 	struct trace_seq *s = &iter->seq;
 	struct trace_entry *entry = iter->ent;
 	struct print_entry *field;
-	int ret;
 
 	trace_assign_type(field, entry);
 
-	ret = trace_seq_puts(s, field->buf);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_puts(s, field->buf);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 const char *
@@ -193,7 +184,6 @@ int ftrace_raw_output_prep(struct trace_iterator *iter,
 	struct trace_seq *s = &iter->seq;
 	struct trace_seq *p = &iter->tmp_seq;
 	struct trace_entry *entry;
-	int ret;
 
 	event = container_of(trace_event, struct ftrace_event_call, event);
 	entry = iter->ent;
@@ -204,8 +194,9 @@ int ftrace_raw_output_prep(struct trace_iterator *iter,
 	}
 
 	trace_seq_init(p);
-	ret = trace_seq_printf(s, "%s: ", ftrace_event_name(event));
-	if (!ret)
+	trace_seq_printf(s, "%s: ", ftrace_event_name(event));
+
+	if (trace_seq_has_overflowed(s))
 		return TRACE_TYPE_PARTIAL_LINE;
 
 	return 0;
@@ -216,18 +207,11 @@ static int ftrace_output_raw(struct trace_iterator *iter, char *name,
 			     char *fmt, va_list ap)
 {
 	struct trace_seq *s = &iter->seq;
-	int ret;
 
-	ret = trace_seq_printf(s, "%s: ", name);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	ret = trace_seq_vprintf(s, fmt, ap);
+	trace_seq_printf(s, "%s: ", name);
+	trace_seq_vprintf(s, fmt, ap);
 
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 int ftrace_output_call(struct trace_iterator *iter, char *name, char *fmt, ...)
@@ -260,7 +244,7 @@ static inline const char *kretprobed(const char *name)
 }
 #endif /* CONFIG_KRETPROBES */
 
-static int
+static void
 seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
 {
 #ifdef CONFIG_KALLSYMS
@@ -271,12 +255,11 @@ seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
 
 	name = kretprobed(str);
 
-	return trace_seq_printf(s, fmt, name);
+	trace_seq_printf(s, fmt, name);
 #endif
-	return 1;
 }
 
-static int
+static void
 seq_print_sym_offset(struct trace_seq *s, const char *fmt,
 		     unsigned long address)
 {
@@ -287,9 +270,8 @@ seq_print_sym_offset(struct trace_seq *s, const char *fmt,
 	sprint_symbol(str, address);
 	name = kretprobed(str);
 
-	return trace_seq_printf(s, fmt, name);
+	trace_seq_printf(s, fmt, name);
 #endif
-	return 1;
 }
 
 #ifndef CONFIG_64BIT
@@ -320,14 +302,14 @@ int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
 		if (file) {
 			ret = trace_seq_path(s, &file->f_path);
 			if (ret)
-				ret = trace_seq_printf(s, "[+0x%lx]",
-						       ip - vmstart);
+				trace_seq_printf(s, "[+0x%lx]",
+						 ip - vmstart);
 		}
 		up_read(&mm->mmap_sem);
 	}
 	if (ret && ((sym_flags & TRACE_ITER_SYM_ADDR) || !file))
-		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
-	return ret;
+		trace_seq_printf(s, " <" IP_FMT ">", ip);
+	return !trace_seq_has_overflowed(s);
 }
 
 int
@@ -335,7 +317,6 @@ seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
 		      unsigned long sym_flags)
 {
 	struct mm_struct *mm = NULL;
-	int ret = 1;
 	unsigned int i;
 
 	if (trace_flags & TRACE_ITER_SYM_USEROBJ) {
@@ -354,48 +335,45 @@ seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
 	for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
 		unsigned long ip = entry->caller[i];
 
-		if (ip == ULONG_MAX || !ret)
+		if (ip == ULONG_MAX || trace_seq_has_overflowed(s))
 			break;
-		if (ret)
-			ret = trace_seq_puts(s, " => ");
+
+		trace_seq_puts(s, " => ");
+
 		if (!ip) {
-			if (ret)
-				ret = trace_seq_puts(s, "??");
-			if (ret)
-				ret = trace_seq_putc(s, '\n');
+			trace_seq_puts(s, "??");
+			trace_seq_putc(s, '\n');
 			continue;
 		}
-		if (!ret)
-			break;
-		if (ret)
-			ret = seq_print_user_ip(s, mm, ip, sym_flags);
-		ret = trace_seq_putc(s, '\n');
+
+		seq_print_user_ip(s, mm, ip, sym_flags);
+		trace_seq_putc(s, '\n');
 	}
 
 	if (mm)
 		mmput(mm);
-	return ret;
+
+	return !trace_seq_has_overflowed(s);
 }
 
 int
 seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
 {
-	int ret;
-
-	if (!ip)
-		return trace_seq_putc(s, '0');
+	if (!ip) {
+		trace_seq_putc(s, '0');
+		goto out;
+	}
 
 	if (sym_flags & TRACE_ITER_SYM_OFFSET)
-		ret = seq_print_sym_offset(s, "%s", ip);
+		seq_print_sym_offset(s, "%s", ip);
 	else
-		ret = seq_print_sym_short(s, "%s", ip);
-
-	if (!ret)
-		return 0;
+		seq_print_sym_short(s, "%s", ip);
 
 	if (sym_flags & TRACE_ITER_SYM_ADDR)
-		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
-	return ret;
+		trace_seq_printf(s, " <" IP_FMT ">", ip);
+
+ out:
+	return !trace_seq_has_overflowed(s);
 }
 
 /**
@@ -413,7 +391,6 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
 	char irqs_off;
 	int hardirq;
 	int softirq;
-	int ret;
 
 	hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
 	softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
@@ -445,16 +422,15 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
 		softirq ? 's' :
 		'.';
 
-	if (!trace_seq_printf(s, "%c%c%c",
-			      irqs_off, need_resched, hardsoft_irq))
-		return 0;
+	trace_seq_printf(s, "%c%c%c",
+			 irqs_off, need_resched, hardsoft_irq);
 
 	if (entry->preempt_count)
-		ret = trace_seq_printf(s, "%x", entry->preempt_count);
+		trace_seq_printf(s, "%x", entry->preempt_count);
 	else
-		ret = trace_seq_putc(s, '.');
+		trace_seq_putc(s, '.');
 
-	return ret;
+	return !trace_seq_has_overflowed(s);
 }
 
 static int
@@ -464,9 +440,8 @@ lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
 
 	trace_find_cmdline(entry->pid, comm);
 
-	if (!trace_seq_printf(s, "%8.8s-%-5d %3d",
-			      comm, entry->pid, cpu))
-		return 0;
+	trace_seq_printf(s, "%8.8s-%-5d %3d",
+			 comm, entry->pid, cpu);
 
 	return trace_print_lat_fmt(s, entry);
 }
@@ -493,24 +468,29 @@ lat_print_timestamp(struct trace_iterator *iter, u64 next_ts)
 		unsigned long rel_usec = do_div(rel_ts, USEC_PER_MSEC);
 		unsigned long rel_msec = (unsigned long)rel_ts;
 
-		return trace_seq_printf(
-				s, "[%08llx] %ld.%03ldms (+%ld.%03ldms): ",
-				ns2usecs(iter->ts),
-				abs_msec, abs_usec,
-				rel_msec, rel_usec);
+		trace_seq_printf(
+			s, "[%08llx] %ld.%03ldms (+%ld.%03ldms): ",
+			ns2usecs(iter->ts),
+			abs_msec, abs_usec,
+			rel_msec, rel_usec);
+
 	} else if (verbose && !in_ns) {
-		return trace_seq_printf(
-				s, "[%016llx] %lld (+%lld): ",
-				iter->ts, abs_ts, rel_ts);
+		trace_seq_printf(
+			s, "[%016llx] %lld (+%lld): ",
+			iter->ts, abs_ts, rel_ts);
+
 	} else if (!verbose && in_ns) {
-		return trace_seq_printf(
-				s, " %4lldus%c: ",
-				abs_ts,
-				rel_ts > preempt_mark_thresh_us ? '!' :
-				  rel_ts > 1 ? '+' : ' ');
+		trace_seq_printf(
+			s, " %4lldus%c: ",
+			abs_ts,
+			rel_ts > preempt_mark_thresh_us ? '!' :
+			rel_ts > 1 ? '+' : ' ');
+
 	} else { /* !verbose && !in_ns */
-		return trace_seq_printf(s, " %4lld: ", abs_ts);
+		trace_seq_printf(s, " %4lld: ", abs_ts);
 	}
+
+	return !trace_seq_has_overflowed(s);
 }
 
 int trace_print_context(struct trace_iterator *iter)
@@ -520,34 +500,29 @@ int trace_print_context(struct trace_iterator *iter)
 	unsigned long long t;
 	unsigned long secs, usec_rem;
 	char comm[TASK_COMM_LEN];
-	int ret;
 
 	trace_find_cmdline(entry->pid, comm);
 
-	ret = trace_seq_printf(s, "%16s-%-5d [%03d] ",
+	trace_seq_printf(s, "%16s-%-5d [%03d] ",
 			       comm, entry->pid, iter->cpu);
-	if (!ret)
-		return 0;
 
-	if (trace_flags & TRACE_ITER_IRQ_INFO) {
-		ret = trace_print_lat_fmt(s, entry);
-		if (!ret)
-			return 0;
-	}
+	if (trace_flags & TRACE_ITER_IRQ_INFO)
+		trace_print_lat_fmt(s, entry);
 
 	if (iter->iter_flags & TRACE_FILE_TIME_IN_NS) {
 		t = ns2usecs(iter->ts);
 		usec_rem = do_div(t, USEC_PER_SEC);
 		secs = (unsigned long)t;
-		return trace_seq_printf(s, " %5lu.%06lu: ", secs, usec_rem);
+		trace_seq_printf(s, " %5lu.%06lu: ", secs, usec_rem);
 	} else
-		return trace_seq_printf(s, " %12llu: ", iter->ts);
+		trace_seq_printf(s, " %12llu: ", iter->ts);
+
+	return !trace_seq_has_overflowed(s);
 }
 
 int trace_print_lat_context(struct trace_iterator *iter)
 {
 	u64 next_ts;
-	int ret;
 	/* trace_find_next_entry will reset ent_size */
 	int ent_size = iter->ent_size;
 	struct trace_seq *s = &iter->seq;
@@ -567,18 +542,17 @@ int trace_print_lat_context(struct trace_iterator *iter)
 
 		trace_find_cmdline(entry->pid, comm);
 
-		ret = trace_seq_printf(
-				s, "%16s %5d %3d %d %08x %08lx ",
-				comm, entry->pid, iter->cpu, entry->flags,
-				entry->preempt_count, iter->idx);
+		trace_seq_printf(
+			s, "%16s %5d %3d %d %08x %08lx ",
+			comm, entry->pid, iter->cpu, entry->flags,
+			entry->preempt_count, iter->idx);
 	} else {
-		ret = lat_print_generic(s, entry, iter->cpu);
+		lat_print_generic(s, entry, iter->cpu);
 	}
 
-	if (ret)
-		ret = lat_print_timestamp(iter, next_ts);
+	lat_print_timestamp(iter, next_ts);
 
-	return ret;
+	return !trace_seq_has_overflowed(s);
 }
 
 static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;
@@ -764,10 +738,9 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_event);
 enum print_line_t trace_nop_print(struct trace_iterator *iter, int flags,
 				  struct trace_event *event)
 {
-	if (!trace_seq_printf(&iter->seq, "type: %d\n", iter->ent->type))
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_printf(&iter->seq, "type: %d\n", iter->ent->type);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(&iter->seq);
 }
 
 /* TRACE_FN */
@@ -779,24 +752,16 @@ static enum print_line_t trace_fn_trace(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, iter->ent);
 
-	if (!seq_print_ip_sym(s, field->ip, flags))
-		goto partial;
+	seq_print_ip_sym(s, field->ip, flags);
 
 	if ((flags & TRACE_ITER_PRINT_PARENT) && field->parent_ip) {
-		if (!trace_seq_puts(s, " <-"))
-			goto partial;
-		if (!seq_print_ip_sym(s,
-				      field->parent_ip,
-				      flags))
-			goto partial;
+		trace_seq_puts(s, " <-");
+		seq_print_ip_sym(s, field->parent_ip, flags);
 	}
-	if (!trace_seq_putc(s, '\n'))
-		goto partial;
 
-	return TRACE_TYPE_HANDLED;
+	trace_seq_putc(s, '\n');
 
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t trace_fn_raw(struct trace_iterator *iter, int flags,
@@ -806,12 +771,11 @@ static enum print_line_t trace_fn_raw(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, iter->ent);
 
-	if (!trace_seq_printf(&iter->seq, "%lx %lx\n",
-			      field->ip,
-			      field->parent_ip))
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_printf(&iter->seq, "%lx %lx\n",
+			 field->ip,
+			 field->parent_ip);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(&iter->seq);
 }
 
 static enum print_line_t trace_fn_hex(struct trace_iterator *iter, int flags,
@@ -822,10 +786,10 @@ static enum print_line_t trace_fn_hex(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, iter->ent);
 
-	SEQ_PUT_HEX_FIELD_RET(s, field->ip);
-	SEQ_PUT_HEX_FIELD_RET(s, field->parent_ip);
+	SEQ_PUT_HEX_FIELD(s, field->ip);
+	SEQ_PUT_HEX_FIELD(s, field->parent_ip);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t trace_fn_bin(struct trace_iterator *iter, int flags,
@@ -836,10 +800,10 @@ static enum print_line_t trace_fn_bin(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, iter->ent);
 
-	SEQ_PUT_FIELD_RET(s, field->ip);
-	SEQ_PUT_FIELD_RET(s, field->parent_ip);
+	SEQ_PUT_FIELD(s, field->ip);
+	SEQ_PUT_FIELD(s, field->parent_ip);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static struct trace_event_functions trace_fn_funcs = {
@@ -868,18 +832,17 @@ static enum print_line_t trace_ctxwake_print(struct trace_iterator *iter,
 	T = task_state_char(field->next_state);
 	S = task_state_char(field->prev_state);
 	trace_find_cmdline(field->next_pid, comm);
-	if (!trace_seq_printf(&iter->seq,
-			      " %5d:%3d:%c %s [%03d] %5d:%3d:%c %s\n",
-			      field->prev_pid,
-			      field->prev_prio,
-			      S, delim,
-			      field->next_cpu,
-			      field->next_pid,
-			      field->next_prio,
-			      T, comm))
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return TRACE_TYPE_HANDLED;
+	trace_seq_printf(&iter->seq,
+			 " %5d:%3d:%c %s [%03d] %5d:%3d:%c %s\n",
+			 field->prev_pid,
+			 field->prev_prio,
+			 S, delim,
+			 field->next_cpu,
+			 field->next_pid,
+			 field->next_prio,
+			 T, comm);
+
+	return trace_handle_return(&iter->seq);
 }
 
 static enum print_line_t trace_ctx_print(struct trace_iterator *iter, int flags,
@@ -904,17 +867,16 @@ static int trace_ctxwake_raw(struct trace_iterator *iter, char S)
 	if (!S)
 		S = task_state_char(field->prev_state);
 	T = task_state_char(field->next_state);
-	if (!trace_seq_printf(&iter->seq, "%d %d %c %d %d %d %c\n",
-			      field->prev_pid,
-			      field->prev_prio,
-			      S,
-			      field->next_cpu,
-			      field->next_pid,
-			      field->next_prio,
-			      T))
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return TRACE_TYPE_HANDLED;
+	trace_seq_printf(&iter->seq, "%d %d %c %d %d %d %c\n",
+			 field->prev_pid,
+			 field->prev_prio,
+			 S,
+			 field->next_cpu,
+			 field->next_pid,
+			 field->next_prio,
+			 T);
+
+	return trace_handle_return(&iter->seq);
 }
 
 static enum print_line_t trace_ctx_raw(struct trace_iterator *iter, int flags,
@@ -942,15 +904,15 @@ static int trace_ctxwake_hex(struct trace_iterator *iter, char S)
 		S = task_state_char(field->prev_state);
 	T = task_state_char(field->next_state);
 
-	SEQ_PUT_HEX_FIELD_RET(s, field->prev_pid);
-	SEQ_PUT_HEX_FIELD_RET(s, field->prev_prio);
-	SEQ_PUT_HEX_FIELD_RET(s, S);
-	SEQ_PUT_HEX_FIELD_RET(s, field->next_cpu);
-	SEQ_PUT_HEX_FIELD_RET(s, field->next_pid);
-	SEQ_PUT_HEX_FIELD_RET(s, field->next_prio);
-	SEQ_PUT_HEX_FIELD_RET(s, T);
+	SEQ_PUT_HEX_FIELD(s, field->prev_pid);
+	SEQ_PUT_HEX_FIELD(s, field->prev_prio);
+	SEQ_PUT_HEX_FIELD(s, S);
+	SEQ_PUT_HEX_FIELD(s, field->next_cpu);
+	SEQ_PUT_HEX_FIELD(s, field->next_pid);
+	SEQ_PUT_HEX_FIELD(s, field->next_prio);
+	SEQ_PUT_HEX_FIELD(s, T);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t trace_ctx_hex(struct trace_iterator *iter, int flags,
@@ -973,15 +935,15 @@ static enum print_line_t trace_ctxwake_bin(struct trace_iterator *iter,
 
 	trace_assign_type(field, iter->ent);
 
-	SEQ_PUT_FIELD_RET(s, field->prev_pid);
-	SEQ_PUT_FIELD_RET(s, field->prev_prio);
-	SEQ_PUT_FIELD_RET(s, field->prev_state);
-	SEQ_PUT_FIELD_RET(s, field->next_cpu);
-	SEQ_PUT_FIELD_RET(s, field->next_pid);
-	SEQ_PUT_FIELD_RET(s, field->next_prio);
-	SEQ_PUT_FIELD_RET(s, field->next_state);
+	SEQ_PUT_FIELD(s, field->prev_pid);
+	SEQ_PUT_FIELD(s, field->prev_prio);
+	SEQ_PUT_FIELD(s, field->prev_state);
+	SEQ_PUT_FIELD(s, field->next_cpu);
+	SEQ_PUT_FIELD(s, field->next_pid);
+	SEQ_PUT_FIELD(s, field->next_prio);
+	SEQ_PUT_FIELD(s, field->next_state);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static struct trace_event_functions trace_ctx_funcs = {
@@ -1021,23 +983,19 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter,
 	trace_assign_type(field, iter->ent);
 	end = (unsigned long *)((long)iter->ent + iter->ent_size);
 
-	if (!trace_seq_puts(s, "<stack trace>\n"))
-		goto partial;
+	trace_seq_puts(s, "<stack trace>\n");
 
 	for (p = field->caller; p && *p != ULONG_MAX && p < end; p++) {
-		if (!trace_seq_puts(s, " => "))
-			goto partial;
 
-		if (!seq_print_ip_sym(s, *p, flags))
-			goto partial;
-		if (!trace_seq_putc(s, '\n'))
-			goto partial;
-	}
+		if (trace_seq_has_overflowed(s))
+			break;
 
-	return TRACE_TYPE_HANDLED;
+		trace_seq_puts(s, " => ");
+		seq_print_ip_sym(s, *p, flags);
+		trace_seq_putc(s, '\n');
+	}
 
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 static struct trace_event_functions trace_stack_funcs = {
@@ -1058,16 +1016,10 @@ static enum print_line_t trace_user_stack_print(struct trace_iterator *iter,
 
 	trace_assign_type(field, iter->ent);
 
-	if (!trace_seq_puts(s, "<user stack trace>\n"))
-		goto partial;
-
-	if (!seq_print_userip_objs(field, s, flags))
-		goto partial;
-
-	return TRACE_TYPE_HANDLED;
+	trace_seq_puts(s, "<user stack trace>\n");
+	seq_print_userip_objs(field, s, flags);
 
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 static struct trace_event_functions trace_user_stack_funcs = {
@@ -1090,19 +1042,11 @@ trace_bputs_print(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, entry);
 
-	if (!seq_print_ip_sym(s, field->ip, flags))
-		goto partial;
+	seq_print_ip_sym(s, field->ip, flags);
+	trace_seq_puts(s, ": ");
+	trace_seq_puts(s, field->str);
 
-	if (!trace_seq_puts(s, ": "))
-		goto partial;
-
-	if (!trace_seq_puts(s, field->str))
-		goto partial;
-
-	return TRACE_TYPE_HANDLED;
-
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 
@@ -1115,16 +1059,10 @@ trace_bputs_raw(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, iter->ent);
 
-	if (!trace_seq_printf(s, ": %lx : ", field->ip))
-		goto partial;
-
-	if (!trace_seq_puts(s, field->str))
-		goto partial;
+	trace_seq_printf(s, ": %lx : ", field->ip);
+	trace_seq_puts(s, field->str);
 
-	return TRACE_TYPE_HANDLED;
-
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 static struct trace_event_functions trace_bputs_funcs = {
@@ -1148,19 +1086,11 @@ trace_bprint_print(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, entry);
 
-	if (!seq_print_ip_sym(s, field->ip, flags))
-		goto partial;
-
-	if (!trace_seq_puts(s, ": "))
-		goto partial;
-
-	if (!trace_seq_bprintf(s, field->fmt, field->buf))
-		goto partial;
+	seq_print_ip_sym(s, field->ip, flags);
+	trace_seq_puts(s, ": ");
+	trace_seq_bprintf(s, field->fmt, field->buf);
 
-	return TRACE_TYPE_HANDLED;
-
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 
@@ -1173,16 +1103,10 @@ trace_bprint_raw(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, iter->ent);
 
-	if (!trace_seq_printf(s, ": %lx : ", field->ip))
-		goto partial;
-
-	if (!trace_seq_bprintf(s, field->fmt, field->buf))
-		goto partial;
+	trace_seq_printf(s, ": %lx : ", field->ip);
+	trace_seq_bprintf(s, field->fmt, field->buf);
 
-	return TRACE_TYPE_HANDLED;
-
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 static struct trace_event_functions trace_bprint_funcs = {
@@ -1204,16 +1128,10 @@ static enum print_line_t trace_print_print(struct trace_iterator *iter,
 
 	trace_assign_type(field, iter->ent);
 
-	if (!seq_print_ip_sym(s, field->ip, flags))
-		goto partial;
-
-	if (!trace_seq_printf(s, ": %s", field->buf))
-		goto partial;
+	seq_print_ip_sym(s, field->ip, flags);
+	trace_seq_printf(s, ": %s", field->buf);
 
-	return TRACE_TYPE_HANDLED;
-
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t trace_print_raw(struct trace_iterator *iter, int flags,
@@ -1223,13 +1141,9 @@ static enum print_line_t trace_print_raw(struct trace_iterator *iter, int flags,
 
 	trace_assign_type(field, iter->ent);
 
-	if (!trace_seq_printf(&iter->seq, "# %lx %s", field->ip, field->buf))
-		goto partial;
-
-	return TRACE_TYPE_HANDLED;
+	trace_seq_printf(&iter->seq, "# %lx %s", field->ip, field->buf);
 
- partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	return trace_handle_return(&iter->seq);
 }
 
 static struct trace_event_functions trace_print_funcs = {
diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h
index 80b25b585a70..8ef2c40efb3c 100644
--- a/kernel/trace/trace_output.h
+++ b/kernel/trace/trace_output.h
@@ -35,17 +35,11 @@ trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry);
 extern int __unregister_ftrace_event(struct trace_event *event);
 extern struct rw_semaphore trace_event_sem;
 
-#define SEQ_PUT_FIELD_RET(s, x)				\
-do {							\
-	if (!trace_seq_putmem(s, &(x), sizeof(x)))	\
-		return TRACE_TYPE_PARTIAL_LINE;		\
-} while (0)
-
-#define SEQ_PUT_HEX_FIELD_RET(s, x)			\
-do {							\
-	if (!trace_seq_putmem_hex(s, &(x), sizeof(x)))	\
-		return TRACE_TYPE_PARTIAL_LINE;		\
-} while (0)
+#define SEQ_PUT_FIELD(s, x)				\
+	trace_seq_putmem(s, &(x), sizeof(x))
+
+#define SEQ_PUT_HEX_FIELD(s, x)				\
+	trace_seq_putmem_hex(s, &(x), sizeof(x))
 
 #endif
 
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 03/26 v5] blktrace/tracing: Use trace_seq_has_overflowed() helper function
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
  2014-11-15  4:58 ` [PATCH 01/26 v5] tracing: Fix trace_seq_bitmask() to start at current position Steven Rostedt
  2014-11-15  4:58 ` [PATCH 02/26 v5] tracing: Add trace_seq_has_overflowed() and trace_handle_return() Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-15  4:58 ` [PATCH 04/26 v5] ring-buffer: Remove check of trace_seq_{puts,printf}() return values Steven Rostedt
                   ` (24 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel
  Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek, Jens Axboe

[-- Attachment #1: 0003-blktrace-tracing-Use-trace_seq_has_overflowed-helper.patch --]
[-- Type: text/plain, Size: 10222 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Checking the return code of every trace_seq_printf() operation and having
to return early if it overflowed makes the code messy.

Using the new trace_seq_has_overflowed() and trace_handle_return() functions
allows us to clean up the code.

In the future, trace_seq_printf() and friends will be turning into void
functions and not returning a value. The trace_seq_has_overflowed() is to
be used instead. This cleanup allows that change to take place.

Cc: Jens Axboe <axboe@fb.com>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/blktrace.c | 148 +++++++++++++++++++++---------------------------
 1 file changed, 66 insertions(+), 82 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index c1bd4ada2a04..11b9cb36092b 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1142,9 +1142,9 @@ static void get_pdu_remap(const struct trace_entry *ent,
 	r->sector_from = be64_to_cpu(sector_from);
 }
 
-typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
+typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act);
 
-static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
+static void blk_log_action_classic(struct trace_iterator *iter, const char *act)
 {
 	char rwbs[RWBS_LEN];
 	unsigned long long ts  = iter->ts;
@@ -1154,33 +1154,33 @@ static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
 
 	fill_rwbs(rwbs, t);
 
-	return trace_seq_printf(&iter->seq,
-				"%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
-				MAJOR(t->device), MINOR(t->device), iter->cpu,
-				secs, nsec_rem, iter->ent->pid, act, rwbs);
+	trace_seq_printf(&iter->seq,
+			 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
+			 MAJOR(t->device), MINOR(t->device), iter->cpu,
+			 secs, nsec_rem, iter->ent->pid, act, rwbs);
 }
 
-static int blk_log_action(struct trace_iterator *iter, const char *act)
+static void blk_log_action(struct trace_iterator *iter, const char *act)
 {
 	char rwbs[RWBS_LEN];
 	const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
 
 	fill_rwbs(rwbs, t);
-	return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
-				MAJOR(t->device), MINOR(t->device), act, rwbs);
+	trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
+			 MAJOR(t->device), MINOR(t->device), act, rwbs);
 }
 
-static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
 {
 	const unsigned char *pdu_buf;
 	int pdu_len;
-	int i, end, ret;
+	int i, end;
 
 	pdu_buf = pdu_start(ent);
 	pdu_len = te_blk_io_trace(ent)->pdu_len;
 
 	if (!pdu_len)
-		return 1;
+		return;
 
 	/* find the last zero that needs to be printed */
 	for (end = pdu_len - 1; end >= 0; end--)
@@ -1188,119 +1188,107 @@ static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
 			break;
 	end++;
 
-	if (!trace_seq_putc(s, '('))
-		return 0;
+	trace_seq_putc(s, '(');
 
 	for (i = 0; i < pdu_len; i++) {
 
-		ret = trace_seq_printf(s, "%s%02x",
-				       i == 0 ? "" : " ", pdu_buf[i]);
-		if (!ret)
-			return ret;
+		trace_seq_printf(s, "%s%02x",
+				 i == 0 ? "" : " ", pdu_buf[i]);
 
 		/*
 		 * stop when the rest is just zeroes and indicate so
 		 * with a ".." appended
 		 */
-		if (i == end && end != pdu_len - 1)
-			return trace_seq_puts(s, " ..) ");
+		if (i == end && end != pdu_len - 1) {
+			trace_seq_puts(s, " ..) ");
+			return;
+		}
 	}
 
-	return trace_seq_puts(s, ") ");
+	trace_seq_puts(s, ") ");
 }
 
-static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
 {
 	char cmd[TASK_COMM_LEN];
 
 	trace_find_cmdline(ent->pid, cmd);
 
 	if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
-		int ret;
-
-		ret = trace_seq_printf(s, "%u ", t_bytes(ent));
-		if (!ret)
-			return 0;
-		ret = blk_log_dump_pdu(s, ent);
-		if (!ret)
-			return 0;
-		return trace_seq_printf(s, "[%s]\n", cmd);
+		trace_seq_printf(s, "%u ", t_bytes(ent));
+		blk_log_dump_pdu(s, ent);
+		trace_seq_printf(s, "[%s]\n", cmd);
 	} else {
 		if (t_sec(ent))
-			return trace_seq_printf(s, "%llu + %u [%s]\n",
+			trace_seq_printf(s, "%llu + %u [%s]\n",
 						t_sector(ent), t_sec(ent), cmd);
-		return trace_seq_printf(s, "[%s]\n", cmd);
+		else
+			trace_seq_printf(s, "[%s]\n", cmd);
 	}
 }
 
-static int blk_log_with_error(struct trace_seq *s,
+static void blk_log_with_error(struct trace_seq *s,
 			      const struct trace_entry *ent)
 {
 	if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
-		int ret;
-
-		ret = blk_log_dump_pdu(s, ent);
-		if (ret)
-			return trace_seq_printf(s, "[%d]\n", t_error(ent));
-		return 0;
+		blk_log_dump_pdu(s, ent);
+		trace_seq_printf(s, "[%d]\n", t_error(ent));
 	} else {
 		if (t_sec(ent))
-			return trace_seq_printf(s, "%llu + %u [%d]\n",
-						t_sector(ent),
-						t_sec(ent), t_error(ent));
-		return trace_seq_printf(s, "%llu [%d]\n",
-					t_sector(ent), t_error(ent));
+			trace_seq_printf(s, "%llu + %u [%d]\n",
+					 t_sector(ent),
+					 t_sec(ent), t_error(ent));
+		else
+			trace_seq_printf(s, "%llu [%d]\n",
+					 t_sector(ent), t_error(ent));
 	}
 }
 
-static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
 {
 	struct blk_io_trace_remap r = { .device_from = 0, };
 
 	get_pdu_remap(ent, &r);
-	return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
-				t_sector(ent), t_sec(ent),
-				MAJOR(r.device_from), MINOR(r.device_from),
-				(unsigned long long)r.sector_from);
+	trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
+			 t_sector(ent), t_sec(ent),
+			 MAJOR(r.device_from), MINOR(r.device_from),
+			 (unsigned long long)r.sector_from);
 }
 
-static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
 {
 	char cmd[TASK_COMM_LEN];
 
 	trace_find_cmdline(ent->pid, cmd);
 
-	return trace_seq_printf(s, "[%s]\n", cmd);
+	trace_seq_printf(s, "[%s]\n", cmd);
 }
 
-static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
 {
 	char cmd[TASK_COMM_LEN];
 
 	trace_find_cmdline(ent->pid, cmd);
 
-	return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
+	trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
 }
 
-static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
 {
 	char cmd[TASK_COMM_LEN];
 
 	trace_find_cmdline(ent->pid, cmd);
 
-	return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
-				get_pdu_int(ent), cmd);
+	trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
+			 get_pdu_int(ent), cmd);
 }
 
-static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
+static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
 {
-	int ret;
 	const struct blk_io_trace *t = te_blk_io_trace(ent);
 
-	ret = trace_seq_putmem(s, t + 1, t->pdu_len);
-	if (ret)
-		return trace_seq_putc(s, '\n');
-	return ret;
+	trace_seq_putmem(s, t + 1, t->pdu_len);
+	trace_seq_putc(s, '\n');
 }
 
 /*
@@ -1339,7 +1327,7 @@ static void blk_tracer_reset(struct trace_array *tr)
 
 static const struct {
 	const char *act[2];
-	int	   (*print)(struct trace_seq *s, const struct trace_entry *ent);
+	void	   (*print)(struct trace_seq *s, const struct trace_entry *ent);
 } what2act[] = {
 	[__BLK_TA_QUEUE]	= {{  "Q", "queue" },	   blk_log_generic },
 	[__BLK_TA_BACKMERGE]	= {{  "M", "backmerge" },  blk_log_generic },
@@ -1364,7 +1352,6 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
 	struct trace_seq *s = &iter->seq;
 	const struct blk_io_trace *t;
 	u16 what;
-	int ret;
 	bool long_act;
 	blk_log_action_t *log_action;
 
@@ -1374,21 +1361,18 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
 	log_action = classic ? &blk_log_action_classic : &blk_log_action;
 
 	if (t->action == BLK_TN_MESSAGE) {
-		ret = log_action(iter, long_act ? "message" : "m");
-		if (ret)
-			ret = blk_log_msg(s, iter->ent);
-		goto out;
+		log_action(iter, long_act ? "message" : "m");
+		blk_log_msg(s, iter->ent);
 	}
 
 	if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
-		ret = trace_seq_printf(s, "Unknown action %x\n", what);
+		trace_seq_printf(s, "Unknown action %x\n", what);
 	else {
-		ret = log_action(iter, what2act[what].act[long_act]);
-		if (ret)
-			ret = what2act[what].print(s, iter->ent);
+		log_action(iter, what2act[what].act[long_act]);
+		what2act[what].print(s, iter->ent);
 	}
-out:
-	return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
+
+	return trace_handle_return(s);
 }
 
 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
@@ -1397,7 +1381,7 @@ static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
 	return print_one_line(iter, false);
 }
 
-static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
+static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
 {
 	struct trace_seq *s = &iter->seq;
 	struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
@@ -1407,18 +1391,18 @@ static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
 		.time     = iter->ts,
 	};
 
-	if (!trace_seq_putmem(s, &old, offset))
-		return 0;
-	return trace_seq_putmem(s, &t->sector,
-				sizeof(old) - offset + t->pdu_len);
+	trace_seq_putmem(s, &old, offset);
+	trace_seq_putmem(s, &t->sector,
+			 sizeof(old) - offset + t->pdu_len);
 }
 
 static enum print_line_t
 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
 			     struct trace_event *event)
 {
-	return blk_trace_synthesize_old_trace(iter) ?
-			TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
+	blk_trace_synthesize_old_trace(iter);
+
+	return trace_handle_return(&iter->seq);
 }
 
 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 04/26 v5] ring-buffer: Remove check of trace_seq_{puts,printf}() return values
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (2 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 03/26 v5] blktrace/tracing: Use trace_seq_has_overflowed() helper function Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-15  4:58 ` [PATCH 05/26 v5] tracing: Have branch tracer use trace_handle_return() helper function Steven Rostedt
                   ` (23 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0004-ring-buffer-Remove-check-of-trace_seq_-puts-printf-r.patch --]
[-- Type: text/plain, Size: 4068 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Remove checking the return value of all trace_seq_puts(). It was wrong
anyway as only the last return value mattered. But as the trace_seq_puts()
is going to be a void function in the future, we should not be checking
the return value of it anyway.

Just return !trace_seq_has_overflowed() instead.

Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/ring_buffer.c | 75 ++++++++++++++++++++++------------------------
 1 file changed, 36 insertions(+), 39 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 2d75c94ae87d..a28bdd17c853 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -34,21 +34,19 @@ static void update_pages_handler(struct work_struct *work);
  */
 int ring_buffer_print_entry_header(struct trace_seq *s)
 {
-	int ret;
-
-	ret = trace_seq_puts(s, "# compressed entry header\n");
-	ret = trace_seq_puts(s, "\ttype_len    :    5 bits\n");
-	ret = trace_seq_puts(s, "\ttime_delta  :   27 bits\n");
-	ret = trace_seq_puts(s, "\tarray       :   32 bits\n");
-	ret = trace_seq_putc(s, '\n');
-	ret = trace_seq_printf(s, "\tpadding     : type == %d\n",
-			       RINGBUF_TYPE_PADDING);
-	ret = trace_seq_printf(s, "\ttime_extend : type == %d\n",
-			       RINGBUF_TYPE_TIME_EXTEND);
-	ret = trace_seq_printf(s, "\tdata max type_len  == %d\n",
-			       RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
+	trace_seq_puts(s, "# compressed entry header\n");
+	trace_seq_puts(s, "\ttype_len    :    5 bits\n");
+	trace_seq_puts(s, "\ttime_delta  :   27 bits\n");
+	trace_seq_puts(s, "\tarray       :   32 bits\n");
+	trace_seq_putc(s, '\n');
+	trace_seq_printf(s, "\tpadding     : type == %d\n",
+			 RINGBUF_TYPE_PADDING);
+	trace_seq_printf(s, "\ttime_extend : type == %d\n",
+			 RINGBUF_TYPE_TIME_EXTEND);
+	trace_seq_printf(s, "\tdata max type_len  == %d\n",
+			 RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
 
-	return ret;
+	return !trace_seq_has_overflowed(s);
 }
 
 /*
@@ -419,32 +417,31 @@ static inline int test_time_stamp(u64 delta)
 int ring_buffer_print_page_header(struct trace_seq *s)
 {
 	struct buffer_data_page field;
-	int ret;
-
-	ret = trace_seq_printf(s, "\tfield: u64 timestamp;\t"
-			       "offset:0;\tsize:%u;\tsigned:%u;\n",
-			       (unsigned int)sizeof(field.time_stamp),
-			       (unsigned int)is_signed_type(u64));
-
-	ret = trace_seq_printf(s, "\tfield: local_t commit;\t"
-			       "offset:%u;\tsize:%u;\tsigned:%u;\n",
-			       (unsigned int)offsetof(typeof(field), commit),
-			       (unsigned int)sizeof(field.commit),
-			       (unsigned int)is_signed_type(long));
-
-	ret = trace_seq_printf(s, "\tfield: int overwrite;\t"
-			       "offset:%u;\tsize:%u;\tsigned:%u;\n",
-			       (unsigned int)offsetof(typeof(field), commit),
-			       1,
-			       (unsigned int)is_signed_type(long));
-
-	ret = trace_seq_printf(s, "\tfield: char data;\t"
-			       "offset:%u;\tsize:%u;\tsigned:%u;\n",
-			       (unsigned int)offsetof(typeof(field), data),
-			       (unsigned int)BUF_PAGE_SIZE,
-			       (unsigned int)is_signed_type(char));
 
-	return ret;
+	trace_seq_printf(s, "\tfield: u64 timestamp;\t"
+			 "offset:0;\tsize:%u;\tsigned:%u;\n",
+			 (unsigned int)sizeof(field.time_stamp),
+			 (unsigned int)is_signed_type(u64));
+
+	trace_seq_printf(s, "\tfield: local_t commit;\t"
+			 "offset:%u;\tsize:%u;\tsigned:%u;\n",
+			 (unsigned int)offsetof(typeof(field), commit),
+			 (unsigned int)sizeof(field.commit),
+			 (unsigned int)is_signed_type(long));
+
+	trace_seq_printf(s, "\tfield: int overwrite;\t"
+			 "offset:%u;\tsize:%u;\tsigned:%u;\n",
+			 (unsigned int)offsetof(typeof(field), commit),
+			 1,
+			 (unsigned int)is_signed_type(long));
+
+	trace_seq_printf(s, "\tfield: char data;\t"
+			 "offset:%u;\tsize:%u;\tsigned:%u;\n",
+			 (unsigned int)offsetof(typeof(field), data),
+			 (unsigned int)BUF_PAGE_SIZE,
+			 (unsigned int)is_signed_type(char));
+
+	return !trace_seq_has_overflowed(s);
 }
 
 struct rb_irq_work {
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 05/26 v5] tracing: Have branch tracer use trace_handle_return() helper function
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (3 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 04/26 v5] ring-buffer: Remove check of trace_seq_{puts,printf}() return values Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-15  4:58 ` [PATCH 06/26 v5] tracing: Have function_graph use trace_seq_has_overflowed() Steven Rostedt
                   ` (22 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0005-tracing-Have-branch-tracer-use-trace_handle_return-h.patch --]
[-- Type: text/plain, Size: 1328 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The branch tracer should not be checking the trace_seq_printf() return value
as that will soon be void. There's a new trace_handle_return() helper function
that will return TRACE_TYPE_PARTIAL_LINE if the trace_seq overflowed
and TRACE_TYPE_HANDLED otherwise.

Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_branch.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index a3916f68a1c7..7d6e2afde669 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -151,14 +151,13 @@ static enum print_line_t trace_branch_print(struct trace_iterator *iter,
 
 	trace_assign_type(field, iter->ent);
 
-	if (trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n",
-			     field->correct ? "  ok  " : " MISS ",
-			     field->func,
-			     field->file,
-			     field->line))
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return TRACE_TYPE_HANDLED;
+	trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n",
+			 field->correct ? "  ok  " : " MISS ",
+			 field->func,
+			 field->file,
+			 field->line);
+
+	return trace_handle_return(&iter->seq);
 }
 
 static void branch_print_header(struct seq_file *s)
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 06/26 v5] tracing: Have function_graph use trace_seq_has_overflowed()
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (4 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 05/26 v5] tracing: Have branch tracer use trace_handle_return() helper function Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-15  4:58 ` [PATCH 07/26 v5] kprobes/tracing: Use trace_seq_has_overflowed() for overflow checks Steven Rostedt
                   ` (21 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0006-tracing-Have-function_graph-use-trace_seq_has_overfl.patch --]
[-- Type: text/plain, Size: 19665 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Instead of doing individual checks all over the place that makes the code
very messy. Just check trace_seq_has_overflowed() at the end or in
strategic places.

This makes the code much cleaner and also helps with getting closer
to removing the return values of trace_seq_printf() and friends.

Link: http://lkml.kernel.org/r/20141114011410.987913836@goodmis.org

Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.h                 |   2 +-
 kernel/trace/trace_functions_graph.c | 382 +++++++++++------------------------
 2 files changed, 118 insertions(+), 266 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 19418221b302..c3a37e55ec8b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -726,7 +726,7 @@ extern unsigned long trace_flags;
 extern enum print_line_t
 print_graph_function_flags(struct trace_iterator *iter, u32 flags);
 extern void print_graph_headers_flags(struct seq_file *s, u32 flags);
-extern enum print_line_t
+extern void
 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);
 extern void graph_trace_open(struct trace_iterator *iter);
 extern void graph_trace_close(struct trace_iterator *iter);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 55bdf9d7f714..100288d10e1f 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -107,7 +107,7 @@ enum {
 	FLAGS_FILL_END   = 3 << TRACE_GRAPH_PRINT_FILL_SHIFT,
 };
 
-static enum print_line_t
+static void
 print_graph_duration(unsigned long long duration, struct trace_seq *s,
 		     u32 flags);
 
@@ -483,33 +483,24 @@ static int graph_trace_update_thresh(struct trace_array *tr)
 
 static int max_bytes_for_cpu;
 
-static enum print_line_t
-print_graph_cpu(struct trace_seq *s, int cpu)
+static void print_graph_cpu(struct trace_seq *s, int cpu)
 {
-	int ret;
-
 	/*
 	 * Start with a space character - to make it stand out
 	 * to the right a bit when trace output is pasted into
 	 * email:
 	 */
-	ret = trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return TRACE_TYPE_HANDLED;
+	trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
 }
 
 #define TRACE_GRAPH_PROCINFO_LENGTH	14
 
-static enum print_line_t
-print_graph_proc(struct trace_seq *s, pid_t pid)
+static void print_graph_proc(struct trace_seq *s, pid_t pid)
 {
 	char comm[TASK_COMM_LEN];
 	/* sign + log10(MAX_INT) + '\0' */
 	char pid_str[11];
 	int spaces = 0;
-	int ret;
 	int len;
 	int i;
 
@@ -524,56 +515,43 @@ print_graph_proc(struct trace_seq *s, pid_t pid)
 		spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
 
 	/* First spaces to align center */
-	for (i = 0; i < spaces / 2; i++) {
-		ret = trace_seq_putc(s, ' ');
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	for (i = 0; i < spaces / 2; i++)
+		trace_seq_putc(s, ' ');
 
-	ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_printf(s, "%s-%s", comm, pid_str);
 
 	/* Last spaces to align center */
-	for (i = 0; i < spaces - (spaces / 2); i++) {
-		ret = trace_seq_putc(s, ' ');
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
-	return TRACE_TYPE_HANDLED;
+	for (i = 0; i < spaces - (spaces / 2); i++)
+		trace_seq_putc(s, ' ');
 }
 
 
-static enum print_line_t
-print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
+static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
 {
-	if (!trace_seq_putc(s, ' '))
-		return 0;
-
-	return trace_print_lat_fmt(s, entry);
+	trace_seq_putc(s, ' ');
+	trace_print_lat_fmt(s, entry);
 }
 
 /* If the pid changed since the last trace, output this event */
-static enum print_line_t
+static void
 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
 {
 	pid_t prev_pid;
 	pid_t *last_pid;
-	int ret;
 
 	if (!data)
-		return TRACE_TYPE_HANDLED;
+		return;
 
 	last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
 
 	if (*last_pid == pid)
-		return TRACE_TYPE_HANDLED;
+		return;
 
 	prev_pid = *last_pid;
 	*last_pid = pid;
 
 	if (prev_pid == -1)
-		return TRACE_TYPE_HANDLED;
+		return;
 /*
  * Context-switch trace line:
 
@@ -582,33 +560,12 @@ verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
  ------------------------------------------
 
  */
-	ret = trace_seq_puts(s,
-		" ------------------------------------------\n");
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	ret = print_graph_cpu(s, cpu);
-	if (ret == TRACE_TYPE_PARTIAL_LINE)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	ret = print_graph_proc(s, prev_pid);
-	if (ret == TRACE_TYPE_PARTIAL_LINE)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	ret = trace_seq_puts(s, " => ");
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	ret = print_graph_proc(s, pid);
-	if (ret == TRACE_TYPE_PARTIAL_LINE)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	ret = trace_seq_puts(s,
-		"\n ------------------------------------------\n\n");
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return TRACE_TYPE_HANDLED;
+	trace_seq_puts(s, " ------------------------------------------\n");
+	print_graph_cpu(s, cpu);
+	print_graph_proc(s, prev_pid);
+	trace_seq_puts(s, " => ");
+	print_graph_proc(s, pid);
+	trace_seq_puts(s, "\n ------------------------------------------\n\n");
 }
 
 static struct ftrace_graph_ret_entry *
@@ -682,103 +639,74 @@ get_return_for_leaf(struct trace_iterator *iter,
 	return next;
 }
 
-static int print_graph_abs_time(u64 t, struct trace_seq *s)
+static void print_graph_abs_time(u64 t, struct trace_seq *s)
 {
 	unsigned long usecs_rem;
 
 	usecs_rem = do_div(t, NSEC_PER_SEC);
 	usecs_rem /= 1000;
 
-	return trace_seq_printf(s, "%5lu.%06lu |  ",
-			(unsigned long)t, usecs_rem);
+	trace_seq_printf(s, "%5lu.%06lu |  ",
+			 (unsigned long)t, usecs_rem);
 }
 
-static enum print_line_t
+static void
 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 		enum trace_type type, int cpu, pid_t pid, u32 flags)
 {
-	int ret;
 	struct trace_seq *s = &iter->seq;
 	struct trace_entry *ent = iter->ent;
 
 	if (addr < (unsigned long)__irqentry_text_start ||
 		addr >= (unsigned long)__irqentry_text_end)
-		return TRACE_TYPE_UNHANDLED;
+		return;
 
 	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
 		/* Absolute time */
-		if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
-			ret = print_graph_abs_time(iter->ts, s);
-			if (!ret)
-				return TRACE_TYPE_PARTIAL_LINE;
-		}
+		if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
+			print_graph_abs_time(iter->ts, s);
 
 		/* Cpu */
-		if (flags & TRACE_GRAPH_PRINT_CPU) {
-			ret = print_graph_cpu(s, cpu);
-			if (ret == TRACE_TYPE_PARTIAL_LINE)
-				return TRACE_TYPE_PARTIAL_LINE;
-		}
+		if (flags & TRACE_GRAPH_PRINT_CPU)
+			print_graph_cpu(s, cpu);
 
 		/* Proc */
 		if (flags & TRACE_GRAPH_PRINT_PROC) {
-			ret = print_graph_proc(s, pid);
-			if (ret == TRACE_TYPE_PARTIAL_LINE)
-				return TRACE_TYPE_PARTIAL_LINE;
-			ret = trace_seq_puts(s, " | ");
-			if (!ret)
-				return TRACE_TYPE_PARTIAL_LINE;
+			print_graph_proc(s, pid);
+			trace_seq_puts(s, " | ");
 		}
 
 		/* Latency format */
-		if (trace_flags & TRACE_ITER_LATENCY_FMT) {
-			ret = print_graph_lat_fmt(s, ent);
-			if (ret == TRACE_TYPE_PARTIAL_LINE)
-				return TRACE_TYPE_PARTIAL_LINE;
-		}
-
+		if (trace_flags & TRACE_ITER_LATENCY_FMT)
+			print_graph_lat_fmt(s, ent);
 	}
 
 	/* No overhead */
-	ret = print_graph_duration(0, s, flags | FLAGS_FILL_START);
-	if (ret != TRACE_TYPE_HANDLED)
-		return ret;
+	print_graph_duration(0, s, flags | FLAGS_FILL_START);
 
 	if (type == TRACE_GRAPH_ENT)
-		ret = trace_seq_puts(s, "==========>");
+		trace_seq_puts(s, "==========>");
 	else
-		ret = trace_seq_puts(s, "<==========");
-
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	ret = print_graph_duration(0, s, flags | FLAGS_FILL_END);
-	if (ret != TRACE_TYPE_HANDLED)
-		return ret;
+		trace_seq_puts(s, "<==========");
 
-	ret = trace_seq_putc(s, '\n');
-
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-	return TRACE_TYPE_HANDLED;
+	print_graph_duration(0, s, flags | FLAGS_FILL_END);
+	trace_seq_putc(s, '\n');
 }
 
-enum print_line_t
+void
 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
 {
 	unsigned long nsecs_rem = do_div(duration, 1000);
 	/* log10(ULONG_MAX) + '\0' */
 	char usecs_str[21];
 	char nsecs_str[5];
-	int ret, len;
+	int len;
 	int i;
 
 	sprintf(usecs_str, "%lu", (unsigned long) duration);
 
 	/* Print msecs */
-	ret = trace_seq_printf(s, "%s", usecs_str);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_printf(s, "%s", usecs_str);
 
 	len = strlen(usecs_str);
 
@@ -787,79 +715,63 @@ trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
 		size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len);
 
 		snprintf(nsecs_str, slen, "%03lu", nsecs_rem);
-		ret = trace_seq_printf(s, ".%s", nsecs_str);
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
+		trace_seq_printf(s, ".%s", nsecs_str);
 		len += strlen(nsecs_str);
 	}
 
-	ret = trace_seq_puts(s, " us ");
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_puts(s, " us ");
 
 	/* Print remaining spaces to fit the row's width */
-	for (i = len; i < 7; i++) {
-		ret = trace_seq_putc(s, ' ');
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
-	return TRACE_TYPE_HANDLED;
+	for (i = len; i < 7; i++)
+		trace_seq_putc(s, ' ');
 }
 
-static enum print_line_t
+static void
 print_graph_duration(unsigned long long duration, struct trace_seq *s,
 		     u32 flags)
 {
-	int ret = -1;
+	bool duration_printed = false;
 
 	if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
 	    !(trace_flags & TRACE_ITER_CONTEXT_INFO))
-			return TRACE_TYPE_HANDLED;
+		return;
 
 	/* No real adata, just filling the column with spaces */
 	switch (flags & TRACE_GRAPH_PRINT_FILL_MASK) {
 	case FLAGS_FILL_FULL:
-		ret = trace_seq_puts(s, "              |  ");
-		return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
+		trace_seq_puts(s, "              |  ");
+		return;
 	case FLAGS_FILL_START:
-		ret = trace_seq_puts(s, "  ");
-		return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
+		trace_seq_puts(s, "  ");
+		return;
 	case FLAGS_FILL_END:
-		ret = trace_seq_puts(s, " |");
-		return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
+		trace_seq_puts(s, " |");
+		return;
 	}
 
 	/* Signal a overhead of time execution to the output */
 	if (flags & TRACE_GRAPH_PRINT_OVERHEAD) {
 		/* Duration exceeded 100 usecs */
-		if (duration > 100000ULL)
-			ret = trace_seq_puts(s, "! ");
+		if (duration > 100000ULL) {
+			trace_seq_puts(s, "! ");
+			duration_printed = true;
+
 		/* Duration exceeded 10 usecs */
-		else if (duration > 10000ULL)
-			ret = trace_seq_puts(s, "+ ");
+		} else if (duration > 10000ULL) {
+			trace_seq_puts(s, "+ ");
+			duration_printed = true;
+		}
 	}
 
 	/*
-	 * The -1 means we either did not exceed the duration tresholds
-	 * or we dont want to print out the overhead. Either way we need
-	 * to fill out the space.
+	 * If we did not exceed the duration tresholds or we dont want
+	 * to print out the overhead. Either way we need to fill out the space.
 	 */
-	if (ret == -1)
-		ret = trace_seq_puts(s, "  ");
-
-	/* Catching here any failure happenned above */
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	ret = trace_print_graph_duration(duration, s);
-	if (ret != TRACE_TYPE_HANDLED)
-		return ret;
+	if (!duration_printed)
+		trace_seq_puts(s, "  ");
 
-	ret = trace_seq_puts(s, "|  ");
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return TRACE_TYPE_HANDLED;
+	trace_print_graph_duration(duration, s);
+	trace_seq_puts(s, "|  ");
 }
 
 /* Case of a leaf function on its call entry */
@@ -873,7 +785,6 @@ print_graph_entry_leaf(struct trace_iterator *iter,
 	struct ftrace_graph_ret *graph_ret;
 	struct ftrace_graph_ent *call;
 	unsigned long long duration;
-	int ret;
 	int i;
 
 	graph_ret = &ret_entry->ret;
@@ -899,22 +810,15 @@ print_graph_entry_leaf(struct trace_iterator *iter,
 	}
 
 	/* Overhead and duration */
-	ret = print_graph_duration(duration, s, flags);
-	if (ret == TRACE_TYPE_PARTIAL_LINE)
-		return TRACE_TYPE_PARTIAL_LINE;
+	print_graph_duration(duration, s, flags);
 
 	/* Function */
-	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
-		ret = trace_seq_putc(s, ' ');
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
+		trace_seq_putc(s, ' ');
 
-	ret = trace_seq_printf(s, "%ps();\n", (void *)call->func);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_printf(s, "%ps();\n", (void *)call->func);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t
@@ -924,7 +828,6 @@ print_graph_entry_nested(struct trace_iterator *iter,
 {
 	struct ftrace_graph_ent *call = &entry->graph_ent;
 	struct fgraph_data *data = iter->private;
-	int ret;
 	int i;
 
 	if (data) {
@@ -940,19 +843,15 @@ print_graph_entry_nested(struct trace_iterator *iter,
 	}
 
 	/* No time */
-	ret = print_graph_duration(0, s, flags | FLAGS_FILL_FULL);
-	if (ret != TRACE_TYPE_HANDLED)
-		return ret;
+	print_graph_duration(0, s, flags | FLAGS_FILL_FULL);
 
 	/* Function */
-	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
-		ret = trace_seq_putc(s, ' ');
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
+		trace_seq_putc(s, ' ');
+
+	trace_seq_printf(s, "%ps() {\n", (void *)call->func);
 
-	ret = trace_seq_printf(s, "%ps() {\n", (void *)call->func);
-	if (!ret)
+	if (trace_seq_has_overflowed(s))
 		return TRACE_TYPE_PARTIAL_LINE;
 
 	/*
@@ -962,62 +861,43 @@ print_graph_entry_nested(struct trace_iterator *iter,
 	return TRACE_TYPE_NO_CONSUME;
 }
 
-static enum print_line_t
+static void
 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
 		     int type, unsigned long addr, u32 flags)
 {
 	struct fgraph_data *data = iter->private;
 	struct trace_entry *ent = iter->ent;
 	int cpu = iter->cpu;
-	int ret;
 
 	/* Pid */
-	if (verif_pid(s, ent->pid, cpu, data) == TRACE_TYPE_PARTIAL_LINE)
-		return TRACE_TYPE_PARTIAL_LINE;
+	verif_pid(s, ent->pid, cpu, data);
 
-	if (type) {
+	if (type)
 		/* Interrupt */
-		ret = print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
-		if (ret == TRACE_TYPE_PARTIAL_LINE)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+		print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
 
 	if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
-		return 0;
+		return;
 
 	/* Absolute time */
-	if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
-		ret = print_graph_abs_time(iter->ts, s);
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
+		print_graph_abs_time(iter->ts, s);
 
 	/* Cpu */
-	if (flags & TRACE_GRAPH_PRINT_CPU) {
-		ret = print_graph_cpu(s, cpu);
-		if (ret == TRACE_TYPE_PARTIAL_LINE)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	if (flags & TRACE_GRAPH_PRINT_CPU)
+		print_graph_cpu(s, cpu);
 
 	/* Proc */
 	if (flags & TRACE_GRAPH_PRINT_PROC) {
-		ret = print_graph_proc(s, ent->pid);
-		if (ret == TRACE_TYPE_PARTIAL_LINE)
-			return TRACE_TYPE_PARTIAL_LINE;
-
-		ret = trace_seq_puts(s, " | ");
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
+		print_graph_proc(s, ent->pid);
+		trace_seq_puts(s, " | ");
 	}
 
 	/* Latency format */
-	if (trace_flags & TRACE_ITER_LATENCY_FMT) {
-		ret = print_graph_lat_fmt(s, ent);
-		if (ret == TRACE_TYPE_PARTIAL_LINE)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	if (trace_flags & TRACE_ITER_LATENCY_FMT)
+		print_graph_lat_fmt(s, ent);
 
-	return 0;
+	return;
 }
 
 /*
@@ -1135,8 +1015,7 @@ print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
 	if (check_irq_entry(iter, flags, call->func, call->depth))
 		return TRACE_TYPE_HANDLED;
 
-	if (print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags))
-		return TRACE_TYPE_PARTIAL_LINE;
+	print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags);
 
 	leaf_ret = get_return_for_leaf(iter, field);
 	if (leaf_ret)
@@ -1169,7 +1048,6 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 	pid_t pid = ent->pid;
 	int cpu = iter->cpu;
 	int func_match = 1;
-	int ret;
 	int i;
 
 	if (check_irq_return(iter, flags, trace->depth))
@@ -1195,20 +1073,14 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 		}
 	}
 
-	if (print_graph_prologue(iter, s, 0, 0, flags))
-		return TRACE_TYPE_PARTIAL_LINE;
+	print_graph_prologue(iter, s, 0, 0, flags);
 
 	/* Overhead and duration */
-	ret = print_graph_duration(duration, s, flags);
-	if (ret == TRACE_TYPE_PARTIAL_LINE)
-		return TRACE_TYPE_PARTIAL_LINE;
+	print_graph_duration(duration, s, flags);
 
 	/* Closing brace */
-	for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
-		ret = trace_seq_putc(s, ' ');
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++)
+		trace_seq_putc(s, ' ');
 
 	/*
 	 * If the return function does not have a matching entry,
@@ -1217,30 +1089,20 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 	 * belongs to, write out the function name. Always do
 	 * that if the funcgraph-tail option is enabled.
 	 */
-	if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL)) {
-		ret = trace_seq_puts(s, "}\n");
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	} else {
-		ret = trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
+		trace_seq_puts(s, "}\n");
+	else
+		trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
 
 	/* Overrun */
-	if (flags & TRACE_GRAPH_PRINT_OVERRUN) {
-		ret = trace_seq_printf(s, " (Overruns: %lu)\n",
-					trace->overrun);
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	if (flags & TRACE_GRAPH_PRINT_OVERRUN)
+		trace_seq_printf(s, " (Overruns: %lu)\n",
+				 trace->overrun);
 
-	ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
-			      cpu, pid, flags);
-	if (ret == TRACE_TYPE_PARTIAL_LINE)
-		return TRACE_TYPE_PARTIAL_LINE;
+	print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
+			cpu, pid, flags);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t
@@ -1257,26 +1119,18 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 	if (data)
 		depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;
 
-	if (print_graph_prologue(iter, s, 0, 0, flags))
-		return TRACE_TYPE_PARTIAL_LINE;
+	print_graph_prologue(iter, s, 0, 0, flags);
 
 	/* No time */
-	ret = print_graph_duration(0, s, flags | FLAGS_FILL_FULL);
-	if (ret != TRACE_TYPE_HANDLED)
-		return ret;
+	print_graph_duration(0, s, flags | FLAGS_FILL_FULL);
 
 	/* Indentation */
 	if (depth > 0)
-		for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) {
-			ret = trace_seq_putc(s, ' ');
-			if (!ret)
-				return TRACE_TYPE_PARTIAL_LINE;
-		}
+		for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++)
+			trace_seq_putc(s, ' ');
 
 	/* The comment */
-	ret = trace_seq_puts(s, "/* ");
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_puts(s, "/* ");
 
 	switch (iter->ent->type) {
 	case TRACE_BPRINT:
@@ -1305,11 +1159,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 		s->len--;
 	}
 
-	ret = trace_seq_puts(s, " */\n");
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_puts(s, " */\n");
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 07/26 v5] kprobes/tracing: Use trace_seq_has_overflowed() for overflow checks
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (5 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 06/26 v5] tracing: Have function_graph use trace_seq_has_overflowed() Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-18 14:02   ` Petr Mladek
  2014-11-15  4:58 ` [PATCH 08/26 v5] tracing: Do not check return values of trace_seq_p*() for mmio tracer Steven Rostedt
                   ` (20 subsequent siblings)
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel
  Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek,
	Srikar Dronamraju, Masami Hiramatsu

[-- Attachment #1: 0007-kprobes-tracing-Use-trace_seq_has_overflowed-for-ove.patch --]
[-- Type: text/plain, Size: 2977 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Instead of checking the return value of trace_seq_printf() and friends
for overflowing of the buffer, use the trace_seq_has_overflowed() helper
function.

This cleans up the code quite a bit and also takes us a step closer to
changing the return values of trace_seq_printf() and friends to void.

Link: http://lkml.kernel.org/r/20141114011411.181812785@goodmis.org

Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_kprobe.c | 42 ++++++++++++++++--------------------------
 1 file changed, 16 insertions(+), 26 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ef7e7f16ed1a..5edb518be345 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1024,27 +1024,22 @@ print_kprobe_event(struct trace_iterator *iter, int flags,
 	field = (struct kprobe_trace_entry_head *)iter->ent;
 	tp = container_of(event, struct trace_probe, call.event);
 
-	if (!trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call)))
-		goto partial;
+	trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call));
 
 	if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
-		goto partial;
+		goto out;
 
-	if (!trace_seq_putc(s, ')'))
-		goto partial;
+	trace_seq_putc(s, ')');
 
 	data = (u8 *)&field[1];
 	for (i = 0; i < tp->nr_args; i++)
 		if (!tp->args[i].type->print(s, tp->args[i].name,
 					     data + tp->args[i].offset, field))
-			goto partial;
-
-	if (!trace_seq_putc(s, '\n'))
-		goto partial;
+			goto out;
 
-	return TRACE_TYPE_HANDLED;
-partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_putc(s, '\n');
+ out:
+	return trace_handle_return(s);
 }
 
 static enum print_line_t
@@ -1060,33 +1055,28 @@ print_kretprobe_event(struct trace_iterator *iter, int flags,
 	field = (struct kretprobe_trace_entry_head *)iter->ent;
 	tp = container_of(event, struct trace_probe, call.event);
 
-	if (!trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call)))
-		goto partial;
+	trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call));
 
 	if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
-		goto partial;
+		goto out;
 
-	if (!trace_seq_puts(s, " <- "))
-		goto partial;
+	trace_seq_puts(s, " <- ");
 
 	if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
-		goto partial;
+		goto out;
 
-	if (!trace_seq_putc(s, ')'))
-		goto partial;
+	trace_seq_putc(s, ')');
 
 	data = (u8 *)&field[1];
 	for (i = 0; i < tp->nr_args; i++)
 		if (!tp->args[i].type->print(s, tp->args[i].name,
 					     data + tp->args[i].offset, field))
-			goto partial;
+			goto out;
 
-	if (!trace_seq_putc(s, '\n'))
-		goto partial;
+	trace_seq_putc(s, '\n');
 
-	return TRACE_TYPE_HANDLED;
-partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+ out:
+	return trace_handle_return(s);
 }
 
 
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 08/26 v5] tracing: Do not check return values of trace_seq_p*() for mmio tracer
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (6 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 07/26 v5] kprobes/tracing: Use trace_seq_has_overflowed() for overflow checks Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-18 14:06   ` Petr Mladek
  2014-11-15  4:58 ` [PATCH 09/26 v5] tracing/probes: Do not use return value of trace_seq_printf() Steven Rostedt
                   ` (19 subsequent siblings)
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0008-tracing-Do-not-check-return-values-of-trace_seq_p-fo.patch --]
[-- Type: text/plain, Size: 5565 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The return values for trace_seq_printf() and friends are going to be
removed and they will become void functions. The mmio tracer checked
their return and even did so incorrectly.

Some of the funtions which returned the values were never checked
themselves. Removing all the checks simplifies the code.

Use trace_seq_has_overflowed() and trace_handle_return() where
necessary instead.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_mmiotrace.c | 52 +++++++++++++++++-------------------------
 1 file changed, 21 insertions(+), 31 deletions(-)

diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index 0abd9b863474..7a9ba62e9fef 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -59,17 +59,15 @@ static void mmio_trace_start(struct trace_array *tr)
 	mmio_reset_data(tr);
 }
 
-static int mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
+static void mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
 {
-	int ret = 0;
 	int i;
 	resource_size_t start, end;
 	const struct pci_driver *drv = pci_dev_driver(dev);
 
-	/* XXX: incomplete checks for trace_seq_printf() return value */
-	ret += trace_seq_printf(s, "PCIDEV %02x%02x %04x%04x %x",
-				dev->bus->number, dev->devfn,
-				dev->vendor, dev->device, dev->irq);
+	trace_seq_printf(s, "PCIDEV %02x%02x %04x%04x %x",
+			 dev->bus->number, dev->devfn,
+			 dev->vendor, dev->device, dev->irq);
 	/*
 	 * XXX: is pci_resource_to_user() appropriate, since we are
 	 * supposed to interpret the __ioremap() phys_addr argument based on
@@ -77,21 +75,20 @@ static int mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
 	 */
 	for (i = 0; i < 7; i++) {
 		pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
-		ret += trace_seq_printf(s, " %llx",
+		trace_seq_printf(s, " %llx",
 			(unsigned long long)(start |
 			(dev->resource[i].flags & PCI_REGION_FLAG_MASK)));
 	}
 	for (i = 0; i < 7; i++) {
 		pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
-		ret += trace_seq_printf(s, " %llx",
+		trace_seq_printf(s, " %llx",
 			dev->resource[i].start < dev->resource[i].end ?
 			(unsigned long long)(end - start) + 1 : 0);
 	}
 	if (drv)
-		ret += trace_seq_printf(s, " %s\n", drv->name);
+		trace_seq_printf(s, " %s\n", drv->name);
 	else
-		ret += trace_seq_puts(s, " \n");
-	return ret;
+		trace_seq_puts(s, " \n");
 }
 
 static void destroy_header_iter(struct header_iter *hiter)
@@ -179,28 +176,27 @@ static enum print_line_t mmio_print_rw(struct trace_iterator *iter)
 	unsigned long long t	= ns2usecs(iter->ts);
 	unsigned long usec_rem	= do_div(t, USEC_PER_SEC);
 	unsigned secs		= (unsigned long)t;
-	int ret = 1;
 
 	trace_assign_type(field, entry);
 	rw = &field->rw;
 
 	switch (rw->opcode) {
 	case MMIO_READ:
-		ret = trace_seq_printf(s,
+		trace_seq_printf(s,
 			"R %d %u.%06lu %d 0x%llx 0x%lx 0x%lx %d\n",
 			rw->width, secs, usec_rem, rw->map_id,
 			(unsigned long long)rw->phys,
 			rw->value, rw->pc, 0);
 		break;
 	case MMIO_WRITE:
-		ret = trace_seq_printf(s,
+		trace_seq_printf(s,
 			"W %d %u.%06lu %d 0x%llx 0x%lx 0x%lx %d\n",
 			rw->width, secs, usec_rem, rw->map_id,
 			(unsigned long long)rw->phys,
 			rw->value, rw->pc, 0);
 		break;
 	case MMIO_UNKNOWN_OP:
-		ret = trace_seq_printf(s,
+		trace_seq_printf(s,
 			"UNKNOWN %u.%06lu %d 0x%llx %02lx,%02lx,"
 			"%02lx 0x%lx %d\n",
 			secs, usec_rem, rw->map_id,
@@ -209,12 +205,11 @@ static enum print_line_t mmio_print_rw(struct trace_iterator *iter)
 			(rw->value >> 0) & 0xff, rw->pc, 0);
 		break;
 	default:
-		ret = trace_seq_puts(s, "rw what?\n");
+		trace_seq_puts(s, "rw what?\n");
 		break;
 	}
-	if (ret)
-		return TRACE_TYPE_HANDLED;
-	return TRACE_TYPE_PARTIAL_LINE;
+
+	return trace_handle_return(s);
 }
 
 static enum print_line_t mmio_print_map(struct trace_iterator *iter)
@@ -226,31 +221,29 @@ static enum print_line_t mmio_print_map(struct trace_iterator *iter)
 	unsigned long long t	= ns2usecs(iter->ts);
 	unsigned long usec_rem	= do_div(t, USEC_PER_SEC);
 	unsigned secs		= (unsigned long)t;
-	int ret;
 
 	trace_assign_type(field, entry);
 	m = &field->map;
 
 	switch (m->opcode) {
 	case MMIO_PROBE:
-		ret = trace_seq_printf(s,
+		trace_seq_printf(s,
 			"MAP %u.%06lu %d 0x%llx 0x%lx 0x%lx 0x%lx %d\n",
 			secs, usec_rem, m->map_id,
 			(unsigned long long)m->phys, m->virt, m->len,
 			0UL, 0);
 		break;
 	case MMIO_UNPROBE:
-		ret = trace_seq_printf(s,
+		trace_seq_printf(s,
 			"UNMAP %u.%06lu %d 0x%lx %d\n",
 			secs, usec_rem, m->map_id, 0UL, 0);
 		break;
 	default:
-		ret = trace_seq_puts(s, "map what?\n");
+		trace_seq_puts(s, "map what?\n");
 		break;
 	}
-	if (ret)
-		return TRACE_TYPE_HANDLED;
-	return TRACE_TYPE_PARTIAL_LINE;
+
+	return trace_handle_return(s);
 }
 
 static enum print_line_t mmio_print_mark(struct trace_iterator *iter)
@@ -262,14 +255,11 @@ static enum print_line_t mmio_print_mark(struct trace_iterator *iter)
 	unsigned long long t	= ns2usecs(iter->ts);
 	unsigned long usec_rem	= do_div(t, USEC_PER_SEC);
 	unsigned secs		= (unsigned long)t;
-	int ret;
 
 	/* The trailing newline must be in the message. */
-	ret = trace_seq_printf(s, "MARK %u.%06lu %s", secs, usec_rem, msg);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_printf(s, "MARK %u.%06lu %s", secs, usec_rem, msg);
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t mmio_print_line(struct trace_iterator *iter)
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 09/26 v5] tracing/probes: Do not use return value of trace_seq_printf()
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (7 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 08/26 v5] tracing: Do not check return values of trace_seq_p*() for mmio tracer Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-18 14:09   ` Petr Mladek
  2014-11-15  4:58 ` [PATCH 10/26 v5] tracing/uprobes: Do not use return values " Steven Rostedt
                   ` (18 subsequent siblings)
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel
  Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek,
	Namhyung Kim, Masami Hiramatsu

[-- Attachment #1: 0009-tracing-probes-Do-not-use-return-value-of-trace_seq_.patch --]
[-- Type: text/plain, Size: 1742 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The functions trace_seq_printf() and friends will soon not have a return
value and will only be a void function. Use trace_seq_has_overflowed()
instead to know if the trace_seq operations succeeded or not.

Link: http://lkml.kernel.org/r/20141114011411.530216306@goodmis.org

Cc: Namhyung Kim <namhyung@kernel.org>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_probe.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index d4b9fc22cd27..b983b2fd2ca1 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -40,7 +40,8 @@ const char *reserved_field_names[] = {
 int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, const char *name,	\
 				void *data, void *ent)			\
 {									\
-	return trace_seq_printf(s, " %s=" fmt, name, *(type *)data);	\
+	trace_seq_printf(s, " %s=" fmt, name, *(type *)data);		\
+	return !trace_seq_has_overflowed(s);				\
 }									\
 const char PRINT_TYPE_FMT_NAME(type)[] = fmt;				\
 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(type));
@@ -61,10 +62,11 @@ int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, const char *name,
 	int len = *(u32 *)data >> 16;
 
 	if (!len)
-		return trace_seq_printf(s, " %s=(fault)", name);
+		trace_seq_printf(s, " %s=(fault)", name);
 	else
-		return trace_seq_printf(s, " %s=\"%s\"", name,
-					(const char *)get_loc_data(data, ent));
+		trace_seq_printf(s, " %s=\"%s\"", name,
+				 (const char *)get_loc_data(data, ent));
+	return !trace_seq_has_overflowed(s);
 }
 NOKPROBE_SYMBOL(PRINT_TYPE_FUNC_NAME(string));
 
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 10/26 v5] tracing/uprobes: Do not use return values of trace_seq_printf()
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (8 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 09/26 v5] tracing/probes: Do not use return value of trace_seq_printf() Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-17  5:28   ` Masami Hiramatsu
                     ` (2 more replies)
  2014-11-15  4:58 ` [PATCH 11/26 v5] tracing: Do not use return values of trace_seq_printf() in syscall tracing Steven Rostedt
                   ` (17 subsequent siblings)
  27 siblings, 3 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel
  Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek,
	Masami Hiramatsu, Namhyung Kim, Srikar Dronamraju

[-- Attachment #1: 0010-tracing-uprobes-Do-not-use-return-values-of-trace_se.patch --]
[-- Type: text/plain, Size: 2094 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The functions trace_seq_printf() and friends will soon no longer have
return values. Using trace_seq_has_overflowed() and trace_handle_return()
should be used instead.

Link: http://lkml.kernel.org/r/20141114011411.693008134@goodmis.org

Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_uprobe.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index e35327c787f7..fd76f8e108ef 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -852,16 +852,14 @@ print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *e
 	tu = container_of(event, struct trace_uprobe, tp.call.event);
 
 	if (is_ret_probe(tu)) {
-		if (!trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
-					ftrace_event_name(&tu->tp.call),
-					entry->vaddr[1], entry->vaddr[0]))
-			goto partial;
+		trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
+				 ftrace_event_name(&tu->tp.call),
+				 entry->vaddr[1], entry->vaddr[0]);
 		data = DATAOF_TRACE_ENTRY(entry, true);
 	} else {
-		if (!trace_seq_printf(s, "%s: (0x%lx)",
-					ftrace_event_name(&tu->tp.call),
-					entry->vaddr[0]))
-			goto partial;
+		trace_seq_printf(s, "%s: (0x%lx)",
+				 ftrace_event_name(&tu->tp.call),
+				 entry->vaddr[0]);
 		data = DATAOF_TRACE_ENTRY(entry, false);
 	}
 
@@ -869,14 +867,13 @@ print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *e
 		struct probe_arg *parg = &tu->tp.args[i];
 
 		if (!parg->type->print(s, parg->name, data + parg->offset, entry))
-			goto partial;
+			goto out;
 	}
 
-	if (trace_seq_putc(s, '\n'))
-		return TRACE_TYPE_HANDLED;
+	trace_seq_putc(s, '\n');
 
-partial:
-	return TRACE_TYPE_PARTIAL_LINE;
+ out:
+	return trace_handle_return(s);
 }
 
 typedef bool (*filter_func_t)(struct uprobe_consumer *self,
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 11/26 v5] tracing: Do not use return values of trace_seq_printf() in syscall tracing
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (9 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 10/26 v5] tracing/uprobes: Do not use return values " Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-15  4:58 ` [PATCH 12/26 v5] tracing: Remove return values of most trace_seq_*() functions Steven Rostedt
                   ` (16 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0011-tracing-Do-not-use-return-values-of-trace_seq_printf.patch --]
[-- Type: text/plain, Size: 3073 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The functions trace_seq_printf() and friends will not be returning values
soon and will be void functions. To know if they succeeded or not, the
functions trace_seq_has_overflowed() and trace_handle_return() should be
used instead.

Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_syscalls.c | 43 +++++++++++++++----------------------------
 1 file changed, 15 insertions(+), 28 deletions(-)

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 4dc8b79c5f75..2193e8038681 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -114,7 +114,7 @@ print_syscall_enter(struct trace_iterator *iter, int flags,
 	struct trace_entry *ent = iter->ent;
 	struct syscall_trace_enter *trace;
 	struct syscall_metadata *entry;
-	int i, ret, syscall;
+	int i, syscall;
 
 	trace = (typeof(trace))ent;
 	syscall = trace->nr;
@@ -128,35 +128,24 @@ print_syscall_enter(struct trace_iterator *iter, int flags,
 		goto end;
 	}
 
-	ret = trace_seq_printf(s, "%s(", entry->name);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_printf(s, "%s(", entry->name);
 
 	for (i = 0; i < entry->nb_args; i++) {
 		/* parameter types */
-		if (trace_flags & TRACE_ITER_VERBOSE) {
-			ret = trace_seq_printf(s, "%s ", entry->types[i]);
-			if (!ret)
-				return TRACE_TYPE_PARTIAL_LINE;
-		}
+		if (trace_flags & TRACE_ITER_VERBOSE)
+			trace_seq_printf(s, "%s ", entry->types[i]);
+
 		/* parameter values */
-		ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],
-				       trace->args[i],
-				       i == entry->nb_args - 1 ? "" : ", ");
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
+		trace_seq_printf(s, "%s: %lx%s", entry->args[i],
+				 trace->args[i],
+				 i == entry->nb_args - 1 ? "" : ", ");
 	}
 
-	ret = trace_seq_putc(s, ')');
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
+	trace_seq_putc(s, ')');
 end:
-	ret =  trace_seq_putc(s, '\n');
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	trace_seq_putc(s, '\n');
 
-	return TRACE_TYPE_HANDLED;
+	return trace_handle_return(s);
 }
 
 static enum print_line_t
@@ -168,7 +157,6 @@ print_syscall_exit(struct trace_iterator *iter, int flags,
 	struct syscall_trace_exit *trace;
 	int syscall;
 	struct syscall_metadata *entry;
-	int ret;
 
 	trace = (typeof(trace))ent;
 	syscall = trace->nr;
@@ -176,7 +164,7 @@ print_syscall_exit(struct trace_iterator *iter, int flags,
 
 	if (!entry) {
 		trace_seq_putc(s, '\n');
-		return TRACE_TYPE_HANDLED;
+		goto out;
 	}
 
 	if (entry->exit_event->event.type != ent->type) {
@@ -184,12 +172,11 @@ print_syscall_exit(struct trace_iterator *iter, int flags,
 		return TRACE_TYPE_UNHANDLED;
 	}
 
-	ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
+	trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
 				trace->ret);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
 
-	return TRACE_TYPE_HANDLED;
+ out:
+	return trace_handle_return(s);
 }
 
 extern char *__bad_type_size(void);
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 12/26 v5] tracing: Remove return values of most trace_seq_*() functions
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (10 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 11/26 v5] tracing: Do not use return values of trace_seq_printf() in syscall tracing Steven Rostedt
@ 2014-11-15  4:58 ` Steven Rostedt
  2014-11-18 14:18   ` Petr Mladek
  2014-11-15  4:59 ` [PATCH 13/26 v5] tracing: Fix return value of ftrace_raw_output_prep() Steven Rostedt
                   ` (15 subsequent siblings)
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:58 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0012-tracing-Remove-return-values-of-most-trace_seq_-func.patch --]
[-- Type: text/plain, Size: 10589 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The trace_seq_printf() and friends are used to store strings into a buffer
that can be passed around from function to function. If the trace_seq buffer
fills up, it will not print any more. The return values were somewhat
inconsistant and using trace_seq_has_overflowed() was a better way to know
if the write to the trace_seq buffer succeeded or not.

Now that all users have removed reading the return value of the printf()
type functions, they can safely return void and keep future users of them
from reading the inconsistent values as well.

Link: http://lkml.kernel.org/r/20141114011411.992510720@goodmis.org

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/trace_seq.h | 37 +++++++++------------
 kernel/trace/trace_seq.c  | 84 +++++++++++++----------------------------------
 2 files changed, 38 insertions(+), 83 deletions(-)

diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 07eda413dfcf..db8a73224f1a 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -57,40 +57,37 @@ static inline bool trace_seq_has_overflowed(struct trace_seq *s)
  */
 #ifdef CONFIG_TRACING
 extern __printf(2, 3)
-int trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
+void trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
 extern __printf(2, 0)
-int trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
-extern int
+void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
+extern void
 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
 extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
 extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
 			     int cnt);
-extern int trace_seq_puts(struct trace_seq *s, const char *str);
-extern int trace_seq_putc(struct trace_seq *s, unsigned char c);
-extern int trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
-extern int trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
+extern void trace_seq_puts(struct trace_seq *s, const char *str);
+extern void trace_seq_putc(struct trace_seq *s, unsigned char c);
+extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
+extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
 				unsigned int len);
 extern int trace_seq_path(struct trace_seq *s, const struct path *path);
 
-extern int trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
+extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 			     int nmaskbits);
 
 #else /* CONFIG_TRACING */
-static inline int trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
+static inline void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 {
-	return 0;
 }
-static inline int
+static inline void
 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 {
-	return 0;
 }
 
-static inline int
+static inline void
 trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 		  int nmaskbits)
 {
-	return 0;
 }
 
 static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
@@ -102,23 +99,19 @@ static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
 {
 	return 0;
 }
-static inline int trace_seq_puts(struct trace_seq *s, const char *str)
+static inline void trace_seq_puts(struct trace_seq *s, const char *str)
 {
-	return 0;
 }
-static inline int trace_seq_putc(struct trace_seq *s, unsigned char c)
+static inline void trace_seq_putc(struct trace_seq *s, unsigned char c)
 {
-	return 0;
 }
-static inline int
+static inline void
 trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
 {
-	return 0;
 }
-static inline int trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
+static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
 				       unsigned int len)
 {
-	return 0;
 }
 static inline int trace_seq_path(struct trace_seq *s, const struct path *path)
 {
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index b100994a17fe..fabfa0f190a3 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -69,20 +69,15 @@ int trace_print_seq(struct seq_file *m, struct trace_seq *s)
  * trace_seq_printf() is used to store strings into a special
  * buffer (@s). Then the output may be either used by
  * the sequencer or pulled into another buffer.
- *
- * Returns 1 if we successfully written all the contents to
- *   the buffer.
-  * Returns 0 if we the length to write is bigger than the
- *   reserved buffer space. In this case, nothing gets written.
  */
-int trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
+void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 {
 	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
 	va_list ap;
 	int ret;
 
 	if (s->full || !len)
-		return 0;
+		return;
 
 	va_start(ap, fmt);
 	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
@@ -91,12 +86,10 @@ int trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 	/* If we can't write it all, don't bother writing anything */
 	if (ret >= len) {
 		s->full = 1;
-		return 0;
+		return;
 	}
 
 	s->len += ret;
-
-	return 1;
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
 
@@ -107,25 +100,18 @@ EXPORT_SYMBOL_GPL(trace_seq_printf);
  * @nmaskbits:	The number of bits that are valid in @maskp
  *
  * Writes a ASCII representation of a bitmask string into @s.
- *
- * Returns 1 if we successfully written all the contents to
- *   the buffer.
- * Returns 0 if we the length to write is bigger than the
- *   reserved buffer space. In this case, nothing gets written.
  */
-int trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
+void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 		      int nmaskbits)
 {
 	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
 	int ret;
 
 	if (s->full || !len)
-		return 0;
+		return;
 
 	ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
 	s->len += ret;
-
-	return 1;
 }
 EXPORT_SYMBOL_GPL(trace_seq_bitmask);
 
@@ -139,28 +125,24 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask);
  * trace_seq_printf is used to store strings into a special
  * buffer (@s). Then the output may be either used by
  * the sequencer or pulled into another buffer.
- *
- * Returns how much it wrote to the buffer.
  */
-int trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
+void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
 {
 	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
 	int ret;
 
 	if (s->full || !len)
-		return 0;
+		return;
 
 	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
 
 	/* If we can't write it all, don't bother writing anything */
 	if (ret >= len) {
 		s->full = 1;
-		return 0;
+		return;
 	}
 
 	s->len += ret;
-
-	return len;
 }
 EXPORT_SYMBOL_GPL(trace_seq_vprintf);
 
@@ -178,28 +160,24 @@ EXPORT_SYMBOL_GPL(trace_seq_vprintf);
  *
  * This function will take the format and the binary array and finish
  * the conversion into the ASCII string within the buffer.
- *
- * Returns how much it wrote to the buffer.
  */
-int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
+void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 {
 	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
 	int ret;
 
 	if (s->full || !len)
-		return 0;
+		return;
 
 	ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
 
 	/* If we can't write it all, don't bother writing anything */
 	if (ret >= len) {
 		s->full = 1;
-		return 0;
+		return;
 	}
 
 	s->len += ret;
-
-	return len;
 }
 EXPORT_SYMBOL_GPL(trace_seq_bprintf);
 
@@ -212,25 +190,21 @@ EXPORT_SYMBOL_GPL(trace_seq_bprintf);
  * copy to user routines. This function records a simple string
  * into a special buffer (@s) for later retrieval by a sequencer
  * or other mechanism.
- *
- * Returns how much it wrote to the buffer.
  */
-int trace_seq_puts(struct trace_seq *s, const char *str)
+void trace_seq_puts(struct trace_seq *s, const char *str)
 {
 	unsigned int len = strlen(str);
 
 	if (s->full)
-		return 0;
+		return;
 
 	if (len > TRACE_SEQ_BUF_LEFT(s)) {
 		s->full = 1;
-		return 0;
+		return;
 	}
 
 	memcpy(s->buffer + s->len, str, len);
 	s->len += len;
-
-	return len;
 }
 EXPORT_SYMBOL_GPL(trace_seq_puts);
 
@@ -243,22 +217,18 @@ EXPORT_SYMBOL_GPL(trace_seq_puts);
  * copy to user routines. This function records a simple charater
  * into a special buffer (@s) for later retrieval by a sequencer
  * or other mechanism.
- *
- * Returns how much it wrote to the buffer.
  */
-int trace_seq_putc(struct trace_seq *s, unsigned char c)
+void trace_seq_putc(struct trace_seq *s, unsigned char c)
 {
 	if (s->full)
-		return 0;
+		return;
 
 	if (TRACE_SEQ_BUF_LEFT(s) < 1) {
 		s->full = 1;
-		return 0;
+		return;
 	}
 
 	s->buffer[s->len++] = c;
-
-	return 1;
 }
 EXPORT_SYMBOL_GPL(trace_seq_putc);
 
@@ -271,23 +241,19 @@ EXPORT_SYMBOL_GPL(trace_seq_putc);
  * There may be cases where raw memory needs to be written into the
  * buffer and a strcpy() would not work. Using this function allows
  * for such cases.
- *
- * Returns how much it wrote to the buffer.
  */
-int trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
+void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
 {
 	if (s->full)
-		return 0;
+		return;
 
 	if (len > TRACE_SEQ_BUF_LEFT(s)) {
 		s->full = 1;
-		return 0;
+		return;
 	}
 
 	memcpy(s->buffer + s->len, mem, len);
 	s->len += len;
-
-	return len;
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem);
 
@@ -303,20 +269,17 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem);
  * This is similar to trace_seq_putmem() except instead of just copying the
  * raw memory into the buffer it writes its ASCII representation of it
  * in hex characters.
- *
- * Returns how much it wrote to the buffer.
  */
-int trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
+void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
 			 unsigned int len)
 {
 	unsigned char hex[HEX_CHARS];
 	const unsigned char *data = mem;
 	unsigned int start_len;
 	int i, j;
-	int cnt = 0;
 
 	if (s->full)
-		return 0;
+		return;
 
 	while (len) {
 		start_len = min(len, HEX_CHARS - 1);
@@ -335,9 +298,8 @@ int trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
 		len -= j / 2;
 		hex[j++] = ' ';
 
-		cnt += trace_seq_putmem(s, hex, j);
+		trace_seq_putmem(s, hex, j);
 	}
-	return cnt;
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
 
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 13/26 v5] tracing: Fix return value of ftrace_raw_output_prep()
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (11 preceding siblings ...)
  2014-11-15  4:58 ` [PATCH 12/26 v5] tracing: Remove return values of most trace_seq_*() functions Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-18 14:24   ` Petr Mladek
  2014-11-15  4:59 ` [PATCH 14/26 v5] tracing: Create seq_buf layer in trace_seq Steven Rostedt
                   ` (14 subsequent siblings)
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0013-tracing-Fix-return-value-of-ftrace_raw_output_prep.patch --]
[-- Type: text/plain, Size: 1670 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

If the trace_seq of ftrace_raw_output_prep() is full this function
returns TRACE_TYPE_PARTIAL_LINE, otherwise it returns zero.

The problem is that TRACE_TYPE_PARTIAL_LINE happens to be zero!

The thing is, the caller of ftrace_raw_output_prep() expects a
success to be zero. Change that to expect it to be
TRACE_TYPE_HANDLED.

Link: http://lkml.kernel.org/r/20141114112522.GA2988@dhcp128.suse.cz

Reminded-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/trace/ftrace.h      | 2 +-
 kernel/trace/trace_output.c | 5 +----
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index f13471b5d27a..139b5067345b 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -277,7 +277,7 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags,	\
 	field = (typeof(field))iter->ent;				\
 									\
 	ret = ftrace_raw_output_prep(iter, trace_event);		\
-	if (ret)							\
+	if (ret != TRACE_TYPE_HANDLED)					\
 		return ret;						\
 									\
 	trace_seq_printf(s, print);					\
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 163c11b6b8ff..723818bc83b4 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -196,10 +196,7 @@ int ftrace_raw_output_prep(struct trace_iterator *iter,
 	trace_seq_init(p);
 	trace_seq_printf(s, "%s: ", ftrace_event_name(event));
 
-	if (trace_seq_has_overflowed(s))
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return 0;
+	return trace_handle_return(s);
 }
 EXPORT_SYMBOL(ftrace_raw_output_prep);
 
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 14/26 v5] tracing: Create seq_buf layer in trace_seq
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (12 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 13/26 v5] tracing: Fix return value of ftrace_raw_output_prep() Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-19 14:51   ` Petr Mladek
  2014-11-15  4:59 ` [PATCH 15/26 v5] tracing: Convert seq_buf_path() to be like seq_path() Steven Rostedt
                   ` (13 subsequent siblings)
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0014-tracing-Create-seq_buf-layer-in-trace_seq.patch --]
[-- Type: text/plain, Size: 26603 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Create a seq_buf layer that trace_seq sits on. The seq_buf will not
be limited to page size. This will allow other usages of seq_buf
instead of a hard set PAGE_SIZE one that trace_seq has.

Link: http://lkml.kernel.org/r/20141104160221.864997179@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/seq_buf.h              |  81 +++++++++
 include/linux/trace_seq.h            |  12 +-
 kernel/trace/Makefile                |   1 +
 kernel/trace/seq_buf.c               | 341 +++++++++++++++++++++++++++++++++++
 kernel/trace/trace.c                 |  39 ++--
 kernel/trace/trace_events.c          |   6 +-
 kernel/trace/trace_functions_graph.c |   6 +-
 kernel/trace/trace_seq.c             | 177 +++++++++---------
 8 files changed, 538 insertions(+), 125 deletions(-)
 create mode 100644 include/linux/seq_buf.h
 create mode 100644 kernel/trace/seq_buf.c

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
new file mode 100644
index 000000000000..4f7a96a9d71a
--- /dev/null
+++ b/include/linux/seq_buf.h
@@ -0,0 +1,81 @@
+#ifndef _LINUX_SEQ_BUF_H
+#define _LINUX_SEQ_BUF_H
+
+#include <linux/fs.h>
+
+/*
+ * Trace sequences are used to allow a function to call several other functions
+ * to create a string of data to use.
+ */
+
+/**
+ * seq_buf - seq buffer structure
+ * @buffer:	pointer to the buffer
+ * @size:	size of the buffer
+ * @len:	the amount of data inside the buffer
+ * @readpos:	The next position to read in the buffer.
+ */
+struct seq_buf {
+	unsigned char		*buffer;
+	unsigned int		size;
+	unsigned int		len;
+	unsigned int		readpos;
+};
+
+static inline void
+seq_buf_init(struct seq_buf *s, unsigned char *buf, unsigned int size)
+{
+	s->buffer = buf;
+	s->size = size;
+	s->len = 0;
+	s->readpos = 0;
+}
+
+/*
+ * seq_buf have a buffer that might overflow. When this happens
+ * the len and size are set to be equal.
+ */
+static inline bool
+seq_buf_has_overflowed(struct seq_buf *s)
+{
+	return s->len == s->size;
+}
+
+static inline void
+seq_buf_set_overflow(struct seq_buf *s)
+{
+	s->len = s->size;
+}
+
+/*
+ * How much buffer is left on the seq_buf?
+ */
+static inline unsigned int
+seq_buf_buffer_left(struct seq_buf *s)
+{
+	if (seq_buf_has_overflowed(s))
+		return 0;
+
+	return (s->size - 1) - s->len;
+}
+
+extern __printf(2, 3)
+int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
+extern __printf(2, 0)
+int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
+extern int
+seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
+extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
+extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
+			   int cnt);
+extern int seq_buf_puts(struct seq_buf *s, const char *str);
+extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
+extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
+extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
+			      unsigned int len);
+extern int seq_buf_path(struct seq_buf *s, const struct path *path);
+
+extern int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
+			   int nmaskbits);
+
+#endif /* _LINUX_SEQ_BUF_H */
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index db8a73224f1a..85d37106be3d 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -1,7 +1,7 @@
 #ifndef _LINUX_TRACE_SEQ_H
 #define _LINUX_TRACE_SEQ_H
 
-#include <linux/fs.h>
+#include <linux/seq_buf.h>
 
 #include <asm/page.h>
 
@@ -12,16 +12,14 @@
 
 struct trace_seq {
 	unsigned char		buffer[PAGE_SIZE];
-	unsigned int		len;
-	unsigned int		readpos;
+	struct seq_buf		seq;
 	int			full;
 };
 
 static inline void
 trace_seq_init(struct trace_seq *s)
 {
-	s->len = 0;
-	s->readpos = 0;
+	seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
 	s->full = 0;
 }
 
@@ -37,7 +35,7 @@ trace_seq_init(struct trace_seq *s)
 static inline unsigned char *
 trace_seq_buffer_ptr(struct trace_seq *s)
 {
-	return s->buffer + s->len;
+	return s->buffer + s->seq.len;
 }
 
 /**
@@ -49,7 +47,7 @@ trace_seq_buffer_ptr(struct trace_seq *s)
  */
 static inline bool trace_seq_has_overflowed(struct trace_seq *s)
 {
-	return s->full || s->len > PAGE_SIZE - 1;
+	return s->full || seq_buf_has_overflowed(&s->seq);
 }
 
 /*
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 67d6369ddf83..edc98c72a634 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
 obj-$(CONFIG_TRACING) += trace.o
 obj-$(CONFIG_TRACING) += trace_output.o
 obj-$(CONFIG_TRACING) += trace_seq.o
+obj-$(CONFIG_TRACING) += seq_buf.o
 obj-$(CONFIG_TRACING) += trace_stat.o
 obj-$(CONFIG_TRACING) += trace_printk.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
new file mode 100644
index 000000000000..e9a7861595d2
--- /dev/null
+++ b/kernel/trace/seq_buf.c
@@ -0,0 +1,341 @@
+/*
+ * seq_buf.c
+ *
+ * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * The seq_buf is a handy tool that allows you to pass a descriptor around
+ * to a buffer that other functions can write to. It is similar to the
+ * seq_file functionality but has some differences.
+ *
+ * To use it, the seq_buf must be initialized with seq_buf_init().
+ * This will set up the counters within the descriptor. You can call
+ * seq_buf_init() more than once to reset the seq_buf to start
+ * from scratch.
+ */
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/seq_buf.h>
+
+/* How much buffer is written? */
+#define SEQ_BUF_USED(s) min((s)->len, (s)->size - 1)
+
+/**
+ * seq_buf_print_seq - move the contents of seq_buf into a seq_file
+ * @m: the seq_file descriptor that is the destination
+ * @s: the seq_buf descriptor that is the source.
+ *
+ * Returns zero on success, non zero otherwise
+ */
+int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
+{
+	unsigned int len = SEQ_BUF_USED(s);
+
+	return seq_write(m, s->buffer, len);
+}
+
+/**
+ * seq_buf_vprintf - sequence printing of information.
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ * @args: va_list of arguments from a printf() type function
+ *
+ * Writes a vnprintf() format into the sequencce buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
+{
+	int len;
+
+	WARN_ON(s->size == 0);
+
+	if (s->len < s->size) {
+		len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
+		if (s->len + len < s->size) {
+			s->len += len;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_printf - sequence printing of information
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ *
+ * Writes a printf() format into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	va_start(ap, fmt);
+	ret = seq_buf_vprintf(s, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
+
+/**
+ * seq_buf_bitmask - write a bitmask array in its ASCII representation
+ * @s:		seq_buf descriptor
+ * @maskp:	points to an array of unsigned longs that represent a bitmask
+ * @nmaskbits:	The number of bits that are valid in @maskp
+ *
+ * Writes a ASCII representation of a bitmask string into @s.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
+		    int nmaskbits)
+{
+	unsigned int len = seq_buf_buffer_left(s);
+	int ret;
+
+	WARN_ON(s->size == 0);
+
+	/*
+	 * The last byte of the buffer is used to determine if we
+	 * overflowed or not.
+	 */
+	if (len > 1) {
+		ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
+		if (ret < len) {
+			s->len += ret;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_bprintf - Write the printf string from binary arguments
+ * @s: seq_buf descriptor
+ * @fmt: The format string for the @binary arguments
+ * @binary: The binary arguments for @fmt.
+ *
+ * When recording in a fast path, a printf may be recorded with just
+ * saving the format and the arguments as they were passed to the
+ * function, instead of wasting cycles converting the arguments into
+ * ASCII characters. Instead, the arguments are saved in a 32 bit
+ * word array that is defined by the format string constraints.
+ *
+ * This function will take the format and the binary array and finish
+ * the conversion into the ASCII string within the buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
+{
+	unsigned int len = seq_buf_buffer_left(s);
+	int ret;
+
+	WARN_ON(s->size == 0);
+
+	if (s->len < s->size) {
+		ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+		if (s->len + ret < s->size) {
+			s->len += ret;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_puts - sequence printing of simple string
+ * @s: seq_buf descriptor
+ * @str: simple string to record
+ *
+ * Copy a simple string into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_puts(struct seq_buf *s, const char *str)
+{
+	unsigned int len = strlen(str);
+
+	WARN_ON(s->size == 0);
+
+	if (s->len + len < s->size) {
+		memcpy(s->buffer + s->len, str, len);
+		s->len += len;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_putc - sequence printing of simple character
+ * @s: seq_buf descriptor
+ * @c: simple character to record
+ *
+ * Copy a single character into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putc(struct seq_buf *s, unsigned char c)
+{
+	WARN_ON(s->size == 0);
+
+	if (s->len + 1 < s->size) {
+		s->buffer[s->len++] = c;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_putmem - write raw data into the sequenc buffer
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to copy into the buffer
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * There may be cases where raw memory needs to be written into the
+ * buffer and a strcpy() would not work. Using this function allows
+ * for such cases.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
+{
+	WARN_ON(s->size == 0);
+
+	if (s->len + len < s->size) {
+		memcpy(s->buffer + s->len, mem, len);
+		s->len += len;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+#define MAX_MEMHEX_BYTES	8U
+#define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)
+
+/**
+ * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to write its hex ASCII representation of
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * This is similar to seq_buf_putmem() except instead of just copying the
+ * raw memory into the buffer it writes its ASCII representation of it
+ * in hex characters.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
+		       unsigned int len)
+{
+	unsigned char hex[HEX_CHARS];
+	const unsigned char *data = mem;
+	unsigned int start_len;
+	int i, j;
+
+	WARN_ON(s->size == 0);
+
+	while (len) {
+		start_len = min(len, HEX_CHARS - 1);
+#ifdef __BIG_ENDIAN
+		for (i = 0, j = 0; i < start_len; i++) {
+#else
+		for (i = start_len-1, j = 0; i >= 0; i--) {
+#endif
+			hex[j++] = hex_asc_hi(data[i]);
+			hex[j++] = hex_asc_lo(data[i]);
+		}
+		if (WARN_ON_ONCE(j == 0 || j/2 > len))
+			break;
+
+		/* j increments twice per loop */
+		len -= j / 2;
+		hex[j++] = ' ';
+
+		seq_buf_putmem(s, hex, j);
+		if (seq_buf_has_overflowed(s))
+			return -1;
+	}
+	return 0;
+}
+
+/**
+ * seq_buf_path - copy a path into the sequence buffer
+ * @s: seq_buf descriptor
+ * @path: path to write into the sequence buffer.
+ *
+ * Write a path name into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_path(struct seq_buf *s, const struct path *path)
+{
+	unsigned int len = seq_buf_buffer_left(s);
+	unsigned char *p;
+
+	WARN_ON(s->size == 0);
+
+	p = d_path(path, s->buffer + s->len, len);
+	if (!IS_ERR(p)) {
+		p = mangle_path(s->buffer + s->len, p, "\n");
+		if (p) {
+			s->len = p - s->buffer;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_to_user - copy the squence buffer to user space
+ * @s: seq_buf descriptor
+ * @ubuf: The userspace memory location to copy to
+ * @cnt: The amount to copy
+ *
+ * Copies the sequence buffer into the userspace memory pointed to
+ * by @ubuf. It starts from the last read position (@s->readpos)
+ * and writes up to @cnt characters or till it reaches the end of
+ * the content in the buffer (@s->len), which ever comes first.
+ *
+ * On success, it returns a positive number of the number of bytes
+ * it copied.
+ *
+ * On failure it returns -EBUSY if all of the content in the
+ * sequence has been already read, which includes nothing in the
+ * sequence (@s->len == @s->readpos).
+ *
+ * Returns -EFAULT if the copy to userspace fails.
+ */
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+{
+	int len;
+	int ret;
+
+	if (!cnt)
+		return 0;
+
+	if (s->len <= s->readpos)
+		return -EBUSY;
+
+	len = s->len - s->readpos;
+	if (cnt > len)
+		cnt = len;
+	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+	if (ret == cnt)
+		return -EFAULT;
+
+	cnt -= ret;
+
+	s->readpos += cnt;
+	return cnt;
+}
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3ce3c4ccfc94..7d7a07e9b9e9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -939,19 +939,20 @@ out:
 	return ret;
 }
 
+/* TODO add a seq_buf_to_buffer() */
 static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 {
 	int len;
 
-	if (s->len <= s->readpos)
+	if (s->seq.len <= s->seq.readpos)
 		return -EBUSY;
 
-	len = s->len - s->readpos;
+	len = s->seq.len - s->seq.readpos;
 	if (cnt > len)
 		cnt = len;
-	memcpy(buf, s->buffer + s->readpos, cnt);
+	memcpy(buf, s->buffer + s->seq.readpos, cnt);
 
-	s->readpos += cnt;
+	s->seq.readpos += cnt;
 	return cnt;
 }
 
@@ -4315,6 +4316,8 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
 		goto out;
 	}
 
+	trace_seq_init(&iter->seq);
+
 	/*
 	 * We make a copy of the current tracer to avoid concurrent
 	 * changes on it while we are reading.
@@ -4511,18 +4514,18 @@ waitagain:
 	trace_access_lock(iter->cpu_file);
 	while (trace_find_next_entry_inc(iter) != NULL) {
 		enum print_line_t ret;
-		int len = iter->seq.len;
+		int len = iter->seq.seq.len;
 
 		ret = print_trace_line(iter);
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
 			/* don't print partial lines */
-			iter->seq.len = len;
+			iter->seq.seq.len = len;
 			break;
 		}
 		if (ret != TRACE_TYPE_NO_CONSUME)
 			trace_consume(iter);
 
-		if (iter->seq.len >= cnt)
+		if (iter->seq.seq.len >= cnt)
 			break;
 
 		/*
@@ -4538,7 +4541,7 @@ waitagain:
 
 	/* Now copy what we have to the user */
 	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
-	if (iter->seq.readpos >= iter->seq.len)
+	if (iter->seq.seq.readpos >= iter->seq.seq.len)
 		trace_seq_init(&iter->seq);
 
 	/*
@@ -4576,16 +4579,16 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 
 	/* Seq buffer is page-sized, exactly what we need. */
 	for (;;) {
-		count = iter->seq.len;
+		count = iter->seq.seq.len;
 		ret = print_trace_line(iter);
-		count = iter->seq.len - count;
+		count = iter->seq.seq.len - count;
 		if (rem < count) {
 			rem = 0;
-			iter->seq.len -= count;
+			iter->seq.seq.len -= count;
 			break;
 		}
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
-			iter->seq.len -= count;
+			iter->seq.seq.len -= count;
 			break;
 		}
 
@@ -4666,13 +4669,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		/* Copy the data into the page, so we can start over. */
 		ret = trace_seq_to_buffer(&iter->seq,
 					  page_address(spd.pages[i]),
-					  iter->seq.len);
+					  iter->seq.seq.len);
 		if (ret < 0) {
 			__free_page(spd.pages[i]);
 			break;
 		}
 		spd.partial[i].offset = 0;
-		spd.partial[i].len = iter->seq.len;
+		spd.partial[i].len = iter->seq.seq.len;
 
 		trace_seq_init(&iter->seq);
 	}
@@ -5673,7 +5676,7 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 	cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "read events: %ld\n", cnt);
 
-	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
+	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->seq.len);
 
 	kfree(s);
 
@@ -6636,11 +6639,11 @@ void
 trace_printk_seq(struct trace_seq *s)
 {
 	/* Probably should print a warning here. */
-	if (s->len >= TRACE_MAX_PRINT)
-		s->len = TRACE_MAX_PRINT;
+	if (s->seq.len >= TRACE_MAX_PRINT)
+		s->seq.len = TRACE_MAX_PRINT;
 
 	/* should be zero ended, but we are paranoid. */
-	s->buffer[s->len] = 0;
+	s->buffer[s->seq.len] = 0;
 
 	printk(KERN_TRACE "%s", s->buffer);
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index f9d0cbe014b7..4d0067dd7f88 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1044,7 +1044,7 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 	mutex_unlock(&event_mutex);
 
 	if (file)
-		r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+		r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
 
 	kfree(s);
 
@@ -1210,7 +1210,7 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 	trace_seq_init(s);
 
 	print_subsystem_event_filter(system, s);
-	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
 
 	kfree(s);
 
@@ -1265,7 +1265,7 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 	trace_seq_init(s);
 
 	func(s);
-	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
 
 	kfree(s);
 
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 100288d10e1f..6d1342ae7a44 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1154,9 +1154,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 	}
 
 	/* Strip ending newline */
-	if (s->buffer[s->len - 1] == '\n') {
-		s->buffer[s->len - 1] = '\0';
-		s->len--;
+	if (s->buffer[s->seq.len - 1] == '\n') {
+		s->buffer[s->seq.len - 1] = '\0';
+		s->seq.len--;
 	}
 
 	trace_seq_puts(s, " */\n");
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index fabfa0f190a3..b623b7295864 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -27,10 +27,19 @@
 #include <linux/trace_seq.h>
 
 /* How much buffer is left on the trace_seq? */
-#define TRACE_SEQ_BUF_LEFT(s) ((PAGE_SIZE - 1) - (s)->len)
+#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
 
 /* How much buffer is written? */
-#define TRACE_SEQ_BUF_USED(s) min((s)->len, (unsigned int)(PAGE_SIZE - 1))
+#define TRACE_SEQ_BUF_USED(s) min((s)->seq.len, (unsigned int)(PAGE_SIZE - 1))
+
+/*
+ * trace_seq should work with being initialized with 0s.
+ */
+static inline void __trace_seq_init(struct trace_seq *s)
+{
+	if (unlikely(!s->seq.size))
+		trace_seq_init(s);
+}
 
 /**
  * trace_print_seq - move the contents of trace_seq into a seq_file
@@ -43,10 +52,11 @@
  */
 int trace_print_seq(struct seq_file *m, struct trace_seq *s)
 {
-	unsigned int len = TRACE_SEQ_BUF_USED(s);
 	int ret;
 
-	ret = seq_write(m, s->buffer, len);
+	__trace_seq_init(s);
+
+	ret = seq_buf_print_seq(m, &s->seq);
 
 	/*
 	 * Only reset this buffer if we successfully wrote to the
@@ -72,24 +82,23 @@ int trace_print_seq(struct seq_file *m, struct trace_seq *s)
  */
 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 {
-	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+	unsigned int save_len = s->seq.len;
 	va_list ap;
-	int ret;
 
-	if (s->full || !len)
+	if (s->full)
 		return;
 
+	__trace_seq_init(s);
+
 	va_start(ap, fmt);
-	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
+	seq_buf_vprintf(&s->seq, fmt, ap);
 	va_end(ap);
 
 	/* If we can't write it all, don't bother writing anything */
-	if (ret >= len) {
+	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+		s->seq.len = save_len;
 		s->full = 1;
-		return;
 	}
-
-	s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
 
@@ -104,14 +113,19 @@ EXPORT_SYMBOL_GPL(trace_seq_printf);
 void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 		      int nmaskbits)
 {
-	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
-	int ret;
+	unsigned int save_len = s->seq.len;
 
-	if (s->full || !len)
+	if (s->full)
 		return;
 
-	ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
-	s->len += ret;
+	__trace_seq_init(s);
+
+	seq_buf_bitmask(&s->seq, maskp, nmaskbits);
+
+	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+		s->seq.len = save_len;
+		s->full = 1;
+	}
 }
 EXPORT_SYMBOL_GPL(trace_seq_bitmask);
 
@@ -128,21 +142,20 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask);
  */
 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
 {
-	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
-	int ret;
+	unsigned int save_len = s->seq.len;
 
-	if (s->full || !len)
+	if (s->full)
 		return;
 
-	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
+	__trace_seq_init(s);
+
+	seq_buf_vprintf(&s->seq, fmt, args);
 
 	/* If we can't write it all, don't bother writing anything */
-	if (ret >= len) {
+	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+		s->seq.len = save_len;
 		s->full = 1;
-		return;
 	}
-
-	s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_vprintf);
 
@@ -163,21 +176,22 @@ EXPORT_SYMBOL_GPL(trace_seq_vprintf);
  */
 void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 {
-	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+	unsigned int save_len = s->seq.len;
 	int ret;
 
-	if (s->full || !len)
+	if (s->full)
 		return;
 
-	ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+	__trace_seq_init(s);
+
+	ret = seq_buf_bprintf(&s->seq, fmt, binary);
 
 	/* If we can't write it all, don't bother writing anything */
-	if (ret >= len) {
+	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+		s->seq.len = save_len;
 		s->full = 1;
 		return;
 	}
-
-	s->len += ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_bprintf);
 
@@ -198,13 +212,14 @@ void trace_seq_puts(struct trace_seq *s, const char *str)
 	if (s->full)
 		return;
 
+	__trace_seq_init(s);
+
 	if (len > TRACE_SEQ_BUF_LEFT(s)) {
 		s->full = 1;
 		return;
 	}
 
-	memcpy(s->buffer + s->len, str, len);
-	s->len += len;
+	seq_buf_putmem(&s->seq, str, len);
 }
 EXPORT_SYMBOL_GPL(trace_seq_puts);
 
@@ -223,12 +238,14 @@ void trace_seq_putc(struct trace_seq *s, unsigned char c)
 	if (s->full)
 		return;
 
+	__trace_seq_init(s);
+
 	if (TRACE_SEQ_BUF_LEFT(s) < 1) {
 		s->full = 1;
 		return;
 	}
 
-	s->buffer[s->len++] = c;
+	seq_buf_putc(&s->seq, c);
 }
 EXPORT_SYMBOL_GPL(trace_seq_putc);
 
@@ -247,19 +264,17 @@ void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
 	if (s->full)
 		return;
 
+	__trace_seq_init(s);
+
 	if (len > TRACE_SEQ_BUF_LEFT(s)) {
 		s->full = 1;
 		return;
 	}
 
-	memcpy(s->buffer + s->len, mem, len);
-	s->len += len;
+	seq_buf_putmem(&s->seq, mem, len);
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem);
 
-#define MAX_MEMHEX_BYTES	8U
-#define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)
-
 /**
  * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex
  * @s: trace sequence descriptor
@@ -273,32 +288,26 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem);
 void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
 			 unsigned int len)
 {
-	unsigned char hex[HEX_CHARS];
-	const unsigned char *data = mem;
-	unsigned int start_len;
-	int i, j;
+	unsigned int save_len = s->seq.len;
 
 	if (s->full)
 		return;
 
-	while (len) {
-		start_len = min(len, HEX_CHARS - 1);
-#ifdef __BIG_ENDIAN
-		for (i = 0, j = 0; i < start_len; i++) {
-#else
-		for (i = start_len-1, j = 0; i >= 0; i--) {
-#endif
-			hex[j++] = hex_asc_hi(data[i]);
-			hex[j++] = hex_asc_lo(data[i]);
-		}
-		if (WARN_ON_ONCE(j == 0 || j/2 > len))
-			break;
-
-		/* j increments twice per loop */
-		len -= j / 2;
-		hex[j++] = ' ';
-
-		trace_seq_putmem(s, hex, j);
+	__trace_seq_init(s);
+
+	/* Each byte is represented by two chars */
+	if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) {
+		s->full = 1;
+		return;
+	}
+
+	/* The added spaces can still cause an overflow */
+	seq_buf_putmem_hex(&s->seq, mem, len);
+
+	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+		s->seq.len = save_len;
+		s->full = 1;
+		return;
 	}
 }
 EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
@@ -317,30 +326,28 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
  */
 int trace_seq_path(struct trace_seq *s, const struct path *path)
 {
-	unsigned char *p;
+	unsigned int save_len = s->seq.len;
+	int ret;
 
 	if (s->full)
 		return 0;
 
+	__trace_seq_init(s);
+
 	if (TRACE_SEQ_BUF_LEFT(s) < 1) {
 		s->full = 1;
 		return 0;
 	}
 
-	p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
-	if (!IS_ERR(p)) {
-		p = mangle_path(s->buffer + s->len, p, "\n");
-		if (p) {
-			s->len = p - s->buffer;
-			return 1;
-		}
-	} else {
-		s->buffer[s->len++] = '?';
-		return 1;
+	ret = seq_buf_path(&s->seq, path);
+
+	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+		s->seq.len = save_len;
+		s->full = 1;
+		return 0;
 	}
 
-	s->full = 1;
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(trace_seq_path);
 
@@ -366,25 +373,7 @@ EXPORT_SYMBOL_GPL(trace_seq_path);
  */
 int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
 {
-	int len;
-	int ret;
-
-	if (!cnt)
-		return 0;
-
-	if (s->len <= s->readpos)
-		return -EBUSY;
-
-	len = s->len - s->readpos;
-	if (cnt > len)
-		cnt = len;
-	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
-	if (ret == cnt)
-		return -EFAULT;
-
-	cnt -= ret;
-
-	s->readpos += cnt;
-	return cnt;
+	__trace_seq_init(s);
+	return seq_buf_to_user(&s->seq, ubuf, cnt);
 }
 EXPORT_SYMBOL_GPL(trace_seq_to_user);
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 15/26 v5] tracing: Convert seq_buf_path() to be like seq_path()
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (13 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 14/26 v5] tracing: Create seq_buf layer in trace_seq Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 16/26 v5] tracing: Convert seq_buf fields to be like seq_file fields Steven Rostedt
                   ` (12 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0015-tracing-Convert-seq_buf_path-to-be-like-seq_path.patch --]
[-- Type: text/plain, Size: 3435 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Rewrite seq_buf_path() like it is done in seq_path() and allow
it to accept any escape character instead of just "\n".

Making seq_buf_path() like seq_path() will help prevent problems
when converting seq_file to use the seq_buf logic.

Link: http://lkml.kernel.org/r/20141104160222.048795666@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.338523371@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/seq_buf.h  |  2 +-
 kernel/trace/seq_buf.c   | 28 ++++++++++++++++------------
 kernel/trace/trace_seq.c |  4 ++--
 3 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 4f7a96a9d71a..38770688a627 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -73,7 +73,7 @@ extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
 extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
 extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
 			      unsigned int len);
-extern int seq_buf_path(struct seq_buf *s, const struct path *path);
+extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc);
 
 extern int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
 			   int nmaskbits);
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index e9a7861595d2..7dac34d1235b 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -272,28 +272,32 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
  * seq_buf_path - copy a path into the sequence buffer
  * @s: seq_buf descriptor
  * @path: path to write into the sequence buffer.
+ * @esc: set of characters to escape in the output
  *
  * Write a path name into the sequence buffer.
  *
- * Returns zero on success, -1 on overflow
+ * Returns the number of written bytes on success, -1 on overflow
  */
-int seq_buf_path(struct seq_buf *s, const struct path *path)
+int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
 {
-	unsigned int len = seq_buf_buffer_left(s);
-	unsigned char *p;
+	char *buf = s->buffer + s->len;
+	size_t size = seq_buf_buffer_left(s);
+	int res = -1;
 
 	WARN_ON(s->size == 0);
 
-	p = d_path(path, s->buffer + s->len, len);
-	if (!IS_ERR(p)) {
-		p = mangle_path(s->buffer + s->len, p, "\n");
-		if (p) {
-			s->len = p - s->buffer;
-			return 0;
+	if (size) {
+		char *p = d_path(path, buf, size);
+		if (!IS_ERR(p)) {
+			char *end = mangle_path(buf, p, esc);
+			if (end)
+				res = end - buf;
 		}
 	}
-	seq_buf_set_overflow(s);
-	return -1;
+	if (res > 0)
+		s->len += res;
+
+	return res;
 }
 
 /**
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index b623b7295864..087fa514069d 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -339,7 +339,7 @@ int trace_seq_path(struct trace_seq *s, const struct path *path)
 		return 0;
 	}
 
-	ret = seq_buf_path(&s->seq, path);
+	ret = seq_buf_path(&s->seq, path, "\n");
 
 	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
 		s->seq.len = save_len;
@@ -347,7 +347,7 @@ int trace_seq_path(struct trace_seq *s, const struct path *path)
 		return 0;
 	}
 
-	return ret;
+	return 1;
 }
 EXPORT_SYMBOL_GPL(trace_seq_path);
 
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 16/26 v5] tracing: Convert seq_buf fields to be like seq_file fields
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (14 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 15/26 v5] tracing: Convert seq_buf_path() to be like seq_path() Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 17/26 v5] tracing: Add a seq_buf_clear() helper and clear len and readpos in init Steven Rostedt
                   ` (11 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0016-tracing-Convert-seq_buf-fields-to-be-like-seq_file-f.patch --]
[-- Type: text/plain, Size: 975 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

In facilitating the conversion of seq_file to use seq_buf,
have the seq_buf fields match the types used by seq_file.

Link: http://lkml.kernel.org/r/20141104160222.195301024@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/seq_buf.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 38770688a627..d14dc9023dde 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -16,10 +16,10 @@
  * @readpos:	The next position to read in the buffer.
  */
 struct seq_buf {
-	unsigned char		*buffer;
-	unsigned int		size;
-	unsigned int		len;
-	unsigned int		readpos;
+	char			*buffer;
+	size_t			size;
+	size_t			len;
+	loff_t			readpos;
 };
 
 static inline void
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 17/26 v5] tracing: Add a seq_buf_clear() helper and clear len and readpos in init
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (15 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 16/26 v5] tracing: Convert seq_buf fields to be like seq_file fields Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 18/26 v5] seq_buf: Create seq_buf_used() to find out how much was written Steven Rostedt
                   ` (10 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0017-tracing-Add-a-seq_buf_clear-helper-and-clear-len-and.patch --]
[-- Type: text/plain, Size: 1114 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Add a helper function seq_buf_clear() that resets the len and readpos
fields of a seq_buf. Currently it is only used in the seq_buf_init()
but will be used later when updating the seq_file code.

Link: http://lkml.kernel.org/r/20141104160222.352309995@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/seq_buf.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index d14dc9023dde..5d91262433e2 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -22,13 +22,18 @@ struct seq_buf {
 	loff_t			readpos;
 };
 
+static inline void seq_buf_clear(struct seq_buf *s)
+{
+	s->len = 0;
+	s->readpos = 0;
+}
+
 static inline void
 seq_buf_init(struct seq_buf *s, unsigned char *buf, unsigned int size)
 {
 	s->buffer = buf;
 	s->size = size;
-	s->len = 0;
-	s->readpos = 0;
+	seq_buf_clear(s);
 }
 
 /*
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 18/26 v5] seq_buf: Create seq_buf_used() to find out how much was written
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (16 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 17/26 v5] tracing: Add a seq_buf_clear() helper and clear len and readpos in init Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-18 15:02   ` Petr Mladek
  2014-11-15  4:59 ` [PATCH 19/26 v5] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
                   ` (9 subsequent siblings)
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0018-seq_buf-Create-seq_buf_used-to-find-out-how-much-was.patch --]
[-- Type: text/plain, Size: 1712 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
private macro to let callers have a method to know how much of the
seq_buf was written to.

Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
Link: http://lkml.kernel.org/r/20141114011413.321654244@goodmis.org

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/seq_buf.h | 6 ++++++
 kernel/trace/seq_buf.c  | 5 +----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 5d91262433e2..93718e570d4c 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -64,6 +64,12 @@ seq_buf_buffer_left(struct seq_buf *s)
 	return (s->size - 1) - s->len;
 }
 
+/* How much buffer was written? */
+static inline unsigned int seq_buf_used(struct seq_buf *s)
+{
+	return min(s->len, s->size);
+}
+
 extern __printf(2, 3)
 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
 extern __printf(2, 0)
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 7dac34d1235b..9ec5305d9da7 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -16,9 +16,6 @@
 #include <linux/seq_file.h>
 #include <linux/seq_buf.h>
 
-/* How much buffer is written? */
-#define SEQ_BUF_USED(s) min((s)->len, (s)->size - 1)
-
 /**
  * seq_buf_print_seq - move the contents of seq_buf into a seq_file
  * @m: the seq_file descriptor that is the destination
@@ -28,7 +25,7 @@
  */
 int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
 {
-	unsigned int len = SEQ_BUF_USED(s);
+	unsigned int len = seq_buf_used(s);
 
 	return seq_write(m, s->buffer, len);
 }
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 19/26 v5] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (17 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 18/26 v5] seq_buf: Create seq_buf_used() to find out how much was written Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-17 17:32   ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function Steven Rostedt
                   ` (8 subsequent siblings)
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0019-tracing-Use-trace_seq_used-and-seq_buf_used-instead-.patch --]
[-- Type: text/plain, Size: 7885 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

As the seq_buf->len will soon be +1 size when there's an overflow, we
must use trace_seq_used() or seq_buf_used() methods to get the real
length. This will prevent buffer overflow issues if just the len
of the seq_buf descriptor is used to copy memory.

Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.home

Reported-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/trace_seq.h            | 20 +++++++++++++++-
 kernel/trace/seq_buf.c               |  2 +-
 kernel/trace/trace.c                 | 44 ++++++++++++++++++++++++------------
 kernel/trace/trace_events.c          |  9 +++++---
 kernel/trace/trace_functions_graph.c |  5 +++-
 kernel/trace/trace_seq.c             |  2 +-
 6 files changed, 60 insertions(+), 22 deletions(-)

diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 85d37106be3d..cfaf5a1d4bad 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -24,6 +24,24 @@ trace_seq_init(struct trace_seq *s)
 }
 
 /**
+ * trace_seq_used - amount of actual data written to buffer
+ * @s: trace sequence descriptor
+ *
+ * Returns the amount of data written to the buffer.
+ *
+ * IMPORTANT!
+ *
+ * Use this instead of @s->seq.len if you need to pass the amount
+ * of data from the buffer to another buffer (userspace, or what not).
+ * The @s->seq.len on overflow is bigger than the buffer size and
+ * using it can cause access to undefined memory.
+ */
+static inline int trace_seq_used(struct trace_seq *s)
+{
+	return seq_buf_used(&s->seq);
+}
+
+/**
  * trace_seq_buffer_ptr - return pointer to next location in buffer
  * @s: trace sequence descriptor
  *
@@ -35,7 +53,7 @@ trace_seq_init(struct trace_seq *s)
 static inline unsigned char *
 trace_seq_buffer_ptr(struct trace_seq *s)
 {
-	return s->buffer + s->seq.len;
+	return s->buffer + seq_buf_used(&s->seq);
 }
 
 /**
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 9ec5305d9da7..ce17f65268ed 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -328,7 +328,7 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
 	if (s->len <= s->readpos)
 		return -EBUSY;
 
-	len = s->len - s->readpos;
+	len = seq_buf_used(s) - s->readpos;
 	if (cnt > len)
 		cnt = len;
 	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7d7a07e9b9e9..9f1ffc707f3b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -944,10 +944,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 {
 	int len;
 
-	if (s->seq.len <= s->seq.readpos)
+	if (trace_seq_used(s) <= s->seq.readpos)
 		return -EBUSY;
 
-	len = s->seq.len - s->seq.readpos;
+	len = trace_seq_used(s) - s->seq.readpos;
 	if (cnt > len)
 		cnt = len;
 	memcpy(buf, s->buffer + s->seq.readpos, cnt);
@@ -4514,18 +4514,18 @@ waitagain:
 	trace_access_lock(iter->cpu_file);
 	while (trace_find_next_entry_inc(iter) != NULL) {
 		enum print_line_t ret;
-		int len = iter->seq.seq.len;
+		int save_len = iter->seq.seq.len;
 
 		ret = print_trace_line(iter);
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
 			/* don't print partial lines */
-			iter->seq.seq.len = len;
+			iter->seq.seq.len = save_len;
 			break;
 		}
 		if (ret != TRACE_TYPE_NO_CONSUME)
 			trace_consume(iter);
 
-		if (iter->seq.seq.len >= cnt)
+		if (trace_seq_used(&iter->seq) >= cnt)
 			break;
 
 		/*
@@ -4541,7 +4541,7 @@ waitagain:
 
 	/* Now copy what we have to the user */
 	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
-	if (iter->seq.seq.readpos >= iter->seq.seq.len)
+	if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
 		trace_seq_init(&iter->seq);
 
 	/*
@@ -4575,20 +4575,33 @@ static size_t
 tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 {
 	size_t count;
+	int save_len;
 	int ret;
 
 	/* Seq buffer is page-sized, exactly what we need. */
 	for (;;) {
-		count = iter->seq.seq.len;
+		save_len = iter->seq.seq.len;
 		ret = print_trace_line(iter);
-		count = iter->seq.seq.len - count;
-		if (rem < count) {
-			rem = 0;
-			iter->seq.seq.len -= count;
+
+		if (trace_seq_has_overflowed(&iter->seq)) {
+			iter->seq.seq.len = save_len;
 			break;
 		}
+
+		/*
+		 * This should not be hit, because it should only
+		 * be set if the iter->seq overflowed. But check it
+		 * anyway to be safe.
+		 */
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
-			iter->seq.seq.len -= count;
+			iter->seq.seq.len = save_len;
+			break;
+		}
+
+		count = trace_seq_used(&iter->seq) - save_len;
+		if (rem < count) {
+			rem = 0;
+			iter->seq.seq.len = save_len;;
 			break;
 		}
 
@@ -4669,13 +4682,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		/* Copy the data into the page, so we can start over. */
 		ret = trace_seq_to_buffer(&iter->seq,
 					  page_address(spd.pages[i]),
-					  iter->seq.seq.len);
+					  trace_seq_used(&iter->seq));
 		if (ret < 0) {
 			__free_page(spd.pages[i]);
 			break;
 		}
 		spd.partial[i].offset = 0;
-		spd.partial[i].len = iter->seq.seq.len;
+		spd.partial[i].len = trace_seq_used(&iter->seq);
 
 		trace_seq_init(&iter->seq);
 	}
@@ -5676,7 +5689,8 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 	cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "read events: %ld\n", cnt);
 
-	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->seq.len);
+	count = simple_read_from_buffer(ubuf, count, ppos,
+					s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 4d0067dd7f88..935cbea78532 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1044,7 +1044,8 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 	mutex_unlock(&event_mutex);
 
 	if (file)
-		r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+		r = simple_read_from_buffer(ubuf, cnt, ppos,
+					    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
@@ -1210,7 +1211,8 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 	trace_seq_init(s);
 
 	print_subsystem_event_filter(system, s);
-	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+	r = simple_read_from_buffer(ubuf, cnt, ppos,
+				    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
@@ -1265,7 +1267,8 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 	trace_seq_init(s);
 
 	func(s);
-	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+	r = simple_read_from_buffer(ubuf, cnt, ppos,
+				    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 6d1342ae7a44..ec35468349a7 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1153,6 +1153,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 			return ret;
 	}
 
+	if (trace_seq_has_overflowed(s))
+		goto out;
+
 	/* Strip ending newline */
 	if (s->buffer[s->seq.len - 1] == '\n') {
 		s->buffer[s->seq.len - 1] = '\0';
@@ -1160,7 +1163,7 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 	}
 
 	trace_seq_puts(s, " */\n");
-
+ out:
 	return trace_handle_return(s);
 }
 
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index 087fa514069d..0c7aab4dd94f 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -30,7 +30,7 @@
 #define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
 
 /* How much buffer is written? */
-#define TRACE_SEQ_BUF_USED(s) min((s)->seq.len, (unsigned int)(PAGE_SIZE - 1))
+#define TRACE_SEQ_BUF_USED(s) seq_buf_used(&(s)->seq)
 
 /*
  * trace_seq should work with being initialized with 0s.
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (18 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 19/26 v5] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-17 17:36   ` Steven Rostedt
  2014-11-18 16:40   ` Petr Mladek
  2014-11-15  4:59 ` [PATCH 21/26 v5] tracing: Have seq_buf use full buffer Steven Rostedt
                   ` (7 subsequent siblings)
  27 siblings, 2 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0020-seq_buf-Add-seq_buf_can_fit-helper-function.patch --]
[-- Type: text/plain, Size: 2134 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Add a seq_buf_can_fit() helper function that removes the possible mistakes
of comparing the seq_buf length plus added data compared to the size of
the buffer.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/seq_buf.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index ce17f65268ed..89d1bd5c27fe 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -16,6 +16,11 @@
 #include <linux/seq_file.h>
 #include <linux/seq_buf.h>
 
+static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
+{
+	return s->len + len < s->size;
+}
+
 /**
  * seq_buf_print_seq - move the contents of seq_buf into a seq_file
  * @m: the seq_file descriptor that is the destination
@@ -48,7 +53,7 @@ int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
 
 	if (s->len < s->size) {
 		len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
-		if (s->len + len < s->size) {
+		if (seq_buf_can_fit(s, len)) {
 			s->len += len;
 			return 0;
 		}
@@ -137,7 +142,7 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
 
 	if (s->len < s->size) {
 		ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
-		if (s->len + ret < s->size) {
+		if (seq_buf_can_fit(s, ret)) {
 			s->len += ret;
 			return 0;
 		}
@@ -161,7 +166,7 @@ int seq_buf_puts(struct seq_buf *s, const char *str)
 
 	WARN_ON(s->size == 0);
 
-	if (s->len + len < s->size) {
+	if (seq_buf_can_fit(s, len)) {
 		memcpy(s->buffer + s->len, str, len);
 		s->len += len;
 		return 0;
@@ -183,7 +188,7 @@ int seq_buf_putc(struct seq_buf *s, unsigned char c)
 {
 	WARN_ON(s->size == 0);
 
-	if (s->len + 1 < s->size) {
+	if (seq_buf_can_fit(s, 1)) {
 		s->buffer[s->len++] = c;
 		return 0;
 	}
@@ -207,7 +212,7 @@ int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
 {
 	WARN_ON(s->size == 0);
 
-	if (s->len + len < s->size) {
+	if (seq_buf_can_fit(s, len)) {
 		memcpy(s->buffer + s->len, mem, len);
 		s->len += len;
 		return 0;
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 21/26 v5] tracing: Have seq_buf use full buffer
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (19 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 22/26 v5] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions Steven Rostedt
                   ` (6 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0021-tracing-Have-seq_buf-use-full-buffer.patch --]
[-- Type: text/plain, Size: 2514 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Currently seq_buf is full when all but one byte of the buffer is
filled. Change it so that the seq_buf is full when all of the
buffer is filled.

Some of the functions would fill the buffer completely and report
everything was fine. This was inconsistent with the max of size - 1.
Changing this to be max of size makes all functions consistent.

Link: http://lkml.kernel.org/r/20141104160222.502133196@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.811957882@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/seq_buf.h | 6 +++---
 kernel/trace/seq_buf.c  | 9 ++++++---
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 93718e570d4c..0800a24b4348 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -43,13 +43,13 @@ seq_buf_init(struct seq_buf *s, unsigned char *buf, unsigned int size)
 static inline bool
 seq_buf_has_overflowed(struct seq_buf *s)
 {
-	return s->len == s->size;
+	return s->len > s->size;
 }
 
 static inline void
 seq_buf_set_overflow(struct seq_buf *s)
 {
-	s->len = s->size;
+	s->len = s->size + 1;
 }
 
 /*
@@ -61,7 +61,7 @@ seq_buf_buffer_left(struct seq_buf *s)
 	if (seq_buf_has_overflowed(s))
 		return 0;
 
-	return (s->size - 1) - s->len;
+	return s->size - s->len;
 }
 
 /* How much buffer was written? */
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 89d1bd5c27fe..27e48348ae67 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -18,7 +18,7 @@
 
 static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
 {
-	return s->len + len < s->size;
+	return s->len + len <= s->size;
 }
 
 /**
@@ -102,8 +102,11 @@ int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
 	WARN_ON(s->size == 0);
 
 	/*
-	 * The last byte of the buffer is used to determine if we
-	 * overflowed or not.
+	 * Note, because bitmap_scnprintf() only returns the number of bytes
+	 * written and not the number that would be written, we use the last
+	 * byte of the buffer to let us know if we overflowed. There's a small
+	 * chance that the bitmap could have fit exactly inside the buffer, but
+	 * it's not that critical if that does happen.
 	 */
 	if (len > 1) {
 		ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 22/26 v5] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (20 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 21/26 v5] tracing: Have seq_buf use full buffer Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 23/26 v5] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF Steven Rostedt
                   ` (5 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0022-tracing-Add-seq_buf_get_buf-and-seq_buf_commit-helpe.patch --]
[-- Type: text/plain, Size: 2922 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Add two helper functions; seq_buf_get_buf() and seq_buf_commit() that
are used by seq_buf_path(). This makes the code similar to the
seq_file: seq_path() function, and will help to be able to consolidate
the functions between seq_file and trace_seq.

Link: http://lkml.kernel.org/r/20141104160222.644881406@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.977571447@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/seq_buf.h | 41 +++++++++++++++++++++++++++++++++++++++++
 kernel/trace/seq_buf.c  |  7 +++----
 2 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 0800a24b4348..12c64282aa98 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -70,6 +70,47 @@ static inline unsigned int seq_buf_used(struct seq_buf *s)
 	return min(s->len, s->size);
 }
 
+/**
+ * seq_buf_get_buf - get buffer to write arbitrary data to
+ * @s: the seq_buf handle
+ * @bufp: the beginning of the buffer is stored here
+ *
+ * Return the number of bytes available in the buffer, or zero if
+ * there's no space.
+ */
+static inline size_t seq_buf_get_buf(struct seq_buf *s, char **bufp)
+{
+	WARN_ON(s->len > s->size + 1);
+
+	if (s->len < s->size) {
+		*bufp = s->buffer + s->len;
+		return s->size - s->len;
+	}
+
+	*bufp = NULL;
+	return 0;
+}
+
+/**
+ * seq_buf_commit - commit data to the buffer
+ * @s: the seq_buf handle
+ * @num: the number of bytes to commit
+ *
+ * Commit @num bytes of data written to a buffer previously acquired
+ * by seq_buf_get.  To signal an error condition, or that the data
+ * didn't fit in the available space, pass a negative @num value.
+ */
+static inline void seq_buf_commit(struct seq_buf *s, int num)
+{
+	if (num < 0) {
+		seq_buf_set_overflow(s);
+	} else {
+		/* num must be negative on overflow */
+		BUG_ON(s->len + num > s->size);
+		s->len += num;
+	}
+}
+
 extern __printf(2, 3)
 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
 extern __printf(2, 0)
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 27e48348ae67..3319dfbbb75b 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -285,8 +285,8 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
  */
 int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
 {
-	char *buf = s->buffer + s->len;
-	size_t size = seq_buf_buffer_left(s);
+	char *buf;
+	size_t size = seq_buf_get_buf(s, &buf);
 	int res = -1;
 
 	WARN_ON(s->size == 0);
@@ -299,8 +299,7 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
 				res = end - buf;
 		}
 	}
-	if (res > 0)
-		s->len += res;
+	seq_buf_commit(s, res);
 
 	return res;
 }
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 23/26 v5] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (21 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 22/26 v5] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 24/26 v5] seq_buf: Move the seq_buf code to lib/ Steven Rostedt
                   ` (4 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0023-seq-buf-Make-seq_buf_bprintf-conditional-on-CONFIG_B.patch --]
[-- Type: text/plain, Size: 2612 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The function bstr_printf() from lib/vsprnintf.c is only available if
CONFIG_BINARY_PRINTF is defined. This is due to the only user currently
being the tracing infrastructure, which needs to select this config
when tracing is configured. Until there is another user of the binary
printf formats, this will continue to be the case.

Since seq_buf.c is now lives in lib/ and is compiled even without
tracing, it must encompass its use of bstr_printf() which is used
by seq_buf_printf(). This too is only used by the tracing infrastructure
and is still encapsulated by the CONFIG_BINARY_PRINTF.

Link: http://lkml.kernel.org/r/20141104160222.969013383@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/seq_buf.h | 7 +++++--
 kernel/trace/seq_buf.c  | 2 ++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 12c64282aa98..9aafe0e24c68 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -115,8 +115,6 @@ extern __printf(2, 3)
 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
 extern __printf(2, 0)
 int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
-extern int
-seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
 extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
 extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
 			   int cnt);
@@ -130,4 +128,9 @@ extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *
 extern int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
 			   int nmaskbits);
 
+#ifdef CONFIG_BINARY_PRINTF
+extern int
+seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
+#endif
+
 #endif /* _LINUX_SEQ_BUF_H */
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 3319dfbbb75b..a2288ca567a3 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -119,6 +119,7 @@ int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
 	return -1;
 }
 
+#ifdef CONFIG_BINARY_PRINTF
 /**
  * seq_buf_bprintf - Write the printf string from binary arguments
  * @s: seq_buf descriptor
@@ -153,6 +154,7 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
 	seq_buf_set_overflow(s);
 	return -1;
 }
+#endif /* CONFIG_BINARY_PRINTF */
 
 /**
  * seq_buf_puts - sequence printing of simple string
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 24/26 v5] seq_buf: Move the seq_buf code to lib/
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (22 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 23/26 v5] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 25/26 v5] printk: Add per_cpu printk func to allow printk to be diverted Steven Rostedt
                   ` (3 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

[-- Attachment #1: 0024-seq_buf-Move-the-seq_buf-code-to-lib.patch --]
[-- Type: text/plain, Size: 21225 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The seq_buf functions are rather useful outside of tracing. Instead
of having it be dependent on CONFIG_TRACING, move the code into lib/
and allow other users to have access to it even when tracing is not
configured.

The seq_buf utility is similar to the seq_file utility, but instead of
writing sending data back up to userland, it writes it into a buffer
defined at seq_buf_init(). This allows us to send a descriptor around
that writes printf() formatted strings into it that can be retrieved
later.

It is currently used by the tracing facility for such things like trace
events to convert its binary saved data in the ring buffer into an
ASCII human readable context to be displayed in /sys/kernel/debug/trace.

It can also be used for doing NMI prints safely from NMI context into
the seq_buf and retrieved later and dumped to printk() safely. Doing
printk() from an NMI context is dangerous because an NMI can preempt
a current printk() and deadlock on it.

Link: http://lkml.kernel.org/p/20140619213952.058255809@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/Makefile  |   1 -
 kernel/trace/seq_buf.c | 351 -------------------------------------------------
 lib/Makefile           |   2 +-
 lib/seq_buf.c          | 351 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 352 insertions(+), 353 deletions(-)
 delete mode 100644 kernel/trace/seq_buf.c
 create mode 100644 lib/seq_buf.c

diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index edc98c72a634..67d6369ddf83 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -29,7 +29,6 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
 obj-$(CONFIG_TRACING) += trace.o
 obj-$(CONFIG_TRACING) += trace_output.o
 obj-$(CONFIG_TRACING) += trace_seq.o
-obj-$(CONFIG_TRACING) += seq_buf.o
 obj-$(CONFIG_TRACING) += trace_stat.o
 obj-$(CONFIG_TRACING) += trace_printk.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
deleted file mode 100644
index a2288ca567a3..000000000000
--- a/kernel/trace/seq_buf.c
+++ /dev/null
@@ -1,351 +0,0 @@
-/*
- * seq_buf.c
- *
- * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
- *
- * The seq_buf is a handy tool that allows you to pass a descriptor around
- * to a buffer that other functions can write to. It is similar to the
- * seq_file functionality but has some differences.
- *
- * To use it, the seq_buf must be initialized with seq_buf_init().
- * This will set up the counters within the descriptor. You can call
- * seq_buf_init() more than once to reset the seq_buf to start
- * from scratch.
- */
-#include <linux/uaccess.h>
-#include <linux/seq_file.h>
-#include <linux/seq_buf.h>
-
-static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
-{
-	return s->len + len <= s->size;
-}
-
-/**
- * seq_buf_print_seq - move the contents of seq_buf into a seq_file
- * @m: the seq_file descriptor that is the destination
- * @s: the seq_buf descriptor that is the source.
- *
- * Returns zero on success, non zero otherwise
- */
-int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
-{
-	unsigned int len = seq_buf_used(s);
-
-	return seq_write(m, s->buffer, len);
-}
-
-/**
- * seq_buf_vprintf - sequence printing of information.
- * @s: seq_buf descriptor
- * @fmt: printf format string
- * @args: va_list of arguments from a printf() type function
- *
- * Writes a vnprintf() format into the sequencce buffer.
- *
- * Returns zero on success, -1 on overflow.
- */
-int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
-{
-	int len;
-
-	WARN_ON(s->size == 0);
-
-	if (s->len < s->size) {
-		len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
-		if (seq_buf_can_fit(s, len)) {
-			s->len += len;
-			return 0;
-		}
-	}
-	seq_buf_set_overflow(s);
-	return -1;
-}
-
-/**
- * seq_buf_printf - sequence printing of information
- * @s: seq_buf descriptor
- * @fmt: printf format string
- *
- * Writes a printf() format into the sequence buffer.
- *
- * Returns zero on success, -1 on overflow.
- */
-int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
-{
-	va_list ap;
-	int ret;
-
-	va_start(ap, fmt);
-	ret = seq_buf_vprintf(s, fmt, ap);
-	va_end(ap);
-
-	return ret;
-}
-
-/**
- * seq_buf_bitmask - write a bitmask array in its ASCII representation
- * @s:		seq_buf descriptor
- * @maskp:	points to an array of unsigned longs that represent a bitmask
- * @nmaskbits:	The number of bits that are valid in @maskp
- *
- * Writes a ASCII representation of a bitmask string into @s.
- *
- * Returns zero on success, -1 on overflow.
- */
-int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
-		    int nmaskbits)
-{
-	unsigned int len = seq_buf_buffer_left(s);
-	int ret;
-
-	WARN_ON(s->size == 0);
-
-	/*
-	 * Note, because bitmap_scnprintf() only returns the number of bytes
-	 * written and not the number that would be written, we use the last
-	 * byte of the buffer to let us know if we overflowed. There's a small
-	 * chance that the bitmap could have fit exactly inside the buffer, but
-	 * it's not that critical if that does happen.
-	 */
-	if (len > 1) {
-		ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
-		if (ret < len) {
-			s->len += ret;
-			return 0;
-		}
-	}
-	seq_buf_set_overflow(s);
-	return -1;
-}
-
-#ifdef CONFIG_BINARY_PRINTF
-/**
- * seq_buf_bprintf - Write the printf string from binary arguments
- * @s: seq_buf descriptor
- * @fmt: The format string for the @binary arguments
- * @binary: The binary arguments for @fmt.
- *
- * When recording in a fast path, a printf may be recorded with just
- * saving the format and the arguments as they were passed to the
- * function, instead of wasting cycles converting the arguments into
- * ASCII characters. Instead, the arguments are saved in a 32 bit
- * word array that is defined by the format string constraints.
- *
- * This function will take the format and the binary array and finish
- * the conversion into the ASCII string within the buffer.
- *
- * Returns zero on success, -1 on overflow.
- */
-int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
-{
-	unsigned int len = seq_buf_buffer_left(s);
-	int ret;
-
-	WARN_ON(s->size == 0);
-
-	if (s->len < s->size) {
-		ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
-		if (seq_buf_can_fit(s, ret)) {
-			s->len += ret;
-			return 0;
-		}
-	}
-	seq_buf_set_overflow(s);
-	return -1;
-}
-#endif /* CONFIG_BINARY_PRINTF */
-
-/**
- * seq_buf_puts - sequence printing of simple string
- * @s: seq_buf descriptor
- * @str: simple string to record
- *
- * Copy a simple string into the sequence buffer.
- *
- * Returns zero on success, -1 on overflow
- */
-int seq_buf_puts(struct seq_buf *s, const char *str)
-{
-	unsigned int len = strlen(str);
-
-	WARN_ON(s->size == 0);
-
-	if (seq_buf_can_fit(s, len)) {
-		memcpy(s->buffer + s->len, str, len);
-		s->len += len;
-		return 0;
-	}
-	seq_buf_set_overflow(s);
-	return -1;
-}
-
-/**
- * seq_buf_putc - sequence printing of simple character
- * @s: seq_buf descriptor
- * @c: simple character to record
- *
- * Copy a single character into the sequence buffer.
- *
- * Returns zero on success, -1 on overflow
- */
-int seq_buf_putc(struct seq_buf *s, unsigned char c)
-{
-	WARN_ON(s->size == 0);
-
-	if (seq_buf_can_fit(s, 1)) {
-		s->buffer[s->len++] = c;
-		return 0;
-	}
-	seq_buf_set_overflow(s);
-	return -1;
-}
-
-/**
- * seq_buf_putmem - write raw data into the sequenc buffer
- * @s: seq_buf descriptor
- * @mem: The raw memory to copy into the buffer
- * @len: The length of the raw memory to copy (in bytes)
- *
- * There may be cases where raw memory needs to be written into the
- * buffer and a strcpy() would not work. Using this function allows
- * for such cases.
- *
- * Returns zero on success, -1 on overflow
- */
-int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
-{
-	WARN_ON(s->size == 0);
-
-	if (seq_buf_can_fit(s, len)) {
-		memcpy(s->buffer + s->len, mem, len);
-		s->len += len;
-		return 0;
-	}
-	seq_buf_set_overflow(s);
-	return -1;
-}
-
-#define MAX_MEMHEX_BYTES	8U
-#define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)
-
-/**
- * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
- * @s: seq_buf descriptor
- * @mem: The raw memory to write its hex ASCII representation of
- * @len: The length of the raw memory to copy (in bytes)
- *
- * This is similar to seq_buf_putmem() except instead of just copying the
- * raw memory into the buffer it writes its ASCII representation of it
- * in hex characters.
- *
- * Returns zero on success, -1 on overflow
- */
-int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
-		       unsigned int len)
-{
-	unsigned char hex[HEX_CHARS];
-	const unsigned char *data = mem;
-	unsigned int start_len;
-	int i, j;
-
-	WARN_ON(s->size == 0);
-
-	while (len) {
-		start_len = min(len, HEX_CHARS - 1);
-#ifdef __BIG_ENDIAN
-		for (i = 0, j = 0; i < start_len; i++) {
-#else
-		for (i = start_len-1, j = 0; i >= 0; i--) {
-#endif
-			hex[j++] = hex_asc_hi(data[i]);
-			hex[j++] = hex_asc_lo(data[i]);
-		}
-		if (WARN_ON_ONCE(j == 0 || j/2 > len))
-			break;
-
-		/* j increments twice per loop */
-		len -= j / 2;
-		hex[j++] = ' ';
-
-		seq_buf_putmem(s, hex, j);
-		if (seq_buf_has_overflowed(s))
-			return -1;
-	}
-	return 0;
-}
-
-/**
- * seq_buf_path - copy a path into the sequence buffer
- * @s: seq_buf descriptor
- * @path: path to write into the sequence buffer.
- * @esc: set of characters to escape in the output
- *
- * Write a path name into the sequence buffer.
- *
- * Returns the number of written bytes on success, -1 on overflow
- */
-int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
-{
-	char *buf;
-	size_t size = seq_buf_get_buf(s, &buf);
-	int res = -1;
-
-	WARN_ON(s->size == 0);
-
-	if (size) {
-		char *p = d_path(path, buf, size);
-		if (!IS_ERR(p)) {
-			char *end = mangle_path(buf, p, esc);
-			if (end)
-				res = end - buf;
-		}
-	}
-	seq_buf_commit(s, res);
-
-	return res;
-}
-
-/**
- * seq_buf_to_user - copy the squence buffer to user space
- * @s: seq_buf descriptor
- * @ubuf: The userspace memory location to copy to
- * @cnt: The amount to copy
- *
- * Copies the sequence buffer into the userspace memory pointed to
- * by @ubuf. It starts from the last read position (@s->readpos)
- * and writes up to @cnt characters or till it reaches the end of
- * the content in the buffer (@s->len), which ever comes first.
- *
- * On success, it returns a positive number of the number of bytes
- * it copied.
- *
- * On failure it returns -EBUSY if all of the content in the
- * sequence has been already read, which includes nothing in the
- * sequence (@s->len == @s->readpos).
- *
- * Returns -EFAULT if the copy to userspace fails.
- */
-int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
-{
-	int len;
-	int ret;
-
-	if (!cnt)
-		return 0;
-
-	if (s->len <= s->readpos)
-		return -EBUSY;
-
-	len = seq_buf_used(s) - s->readpos;
-	if (cnt > len)
-		cnt = len;
-	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
-	if (ret == cnt)
-		return -EFAULT;
-
-	cnt -= ret;
-
-	s->readpos += cnt;
-	return cnt;
-}
diff --git a/lib/Makefile b/lib/Makefile
index 7512dc978f18..a1aa1e81ed36 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -13,7 +13,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
 	 proportions.o flex_proportions.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
-	 earlycpio.o
+	 earlycpio.o seq_buf.o
 
 obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
 lib-$(CONFIG_MMU) += ioremap.o
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
new file mode 100644
index 000000000000..a2288ca567a3
--- /dev/null
+++ b/lib/seq_buf.c
@@ -0,0 +1,351 @@
+/*
+ * seq_buf.c
+ *
+ * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * The seq_buf is a handy tool that allows you to pass a descriptor around
+ * to a buffer that other functions can write to. It is similar to the
+ * seq_file functionality but has some differences.
+ *
+ * To use it, the seq_buf must be initialized with seq_buf_init().
+ * This will set up the counters within the descriptor. You can call
+ * seq_buf_init() more than once to reset the seq_buf to start
+ * from scratch.
+ */
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/seq_buf.h>
+
+static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
+{
+	return s->len + len <= s->size;
+}
+
+/**
+ * seq_buf_print_seq - move the contents of seq_buf into a seq_file
+ * @m: the seq_file descriptor that is the destination
+ * @s: the seq_buf descriptor that is the source.
+ *
+ * Returns zero on success, non zero otherwise
+ */
+int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
+{
+	unsigned int len = seq_buf_used(s);
+
+	return seq_write(m, s->buffer, len);
+}
+
+/**
+ * seq_buf_vprintf - sequence printing of information.
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ * @args: va_list of arguments from a printf() type function
+ *
+ * Writes a vnprintf() format into the sequencce buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
+{
+	int len;
+
+	WARN_ON(s->size == 0);
+
+	if (s->len < s->size) {
+		len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
+		if (seq_buf_can_fit(s, len)) {
+			s->len += len;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_printf - sequence printing of information
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ *
+ * Writes a printf() format into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	va_start(ap, fmt);
+	ret = seq_buf_vprintf(s, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
+
+/**
+ * seq_buf_bitmask - write a bitmask array in its ASCII representation
+ * @s:		seq_buf descriptor
+ * @maskp:	points to an array of unsigned longs that represent a bitmask
+ * @nmaskbits:	The number of bits that are valid in @maskp
+ *
+ * Writes a ASCII representation of a bitmask string into @s.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
+		    int nmaskbits)
+{
+	unsigned int len = seq_buf_buffer_left(s);
+	int ret;
+
+	WARN_ON(s->size == 0);
+
+	/*
+	 * Note, because bitmap_scnprintf() only returns the number of bytes
+	 * written and not the number that would be written, we use the last
+	 * byte of the buffer to let us know if we overflowed. There's a small
+	 * chance that the bitmap could have fit exactly inside the buffer, but
+	 * it's not that critical if that does happen.
+	 */
+	if (len > 1) {
+		ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
+		if (ret < len) {
+			s->len += ret;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+#ifdef CONFIG_BINARY_PRINTF
+/**
+ * seq_buf_bprintf - Write the printf string from binary arguments
+ * @s: seq_buf descriptor
+ * @fmt: The format string for the @binary arguments
+ * @binary: The binary arguments for @fmt.
+ *
+ * When recording in a fast path, a printf may be recorded with just
+ * saving the format and the arguments as they were passed to the
+ * function, instead of wasting cycles converting the arguments into
+ * ASCII characters. Instead, the arguments are saved in a 32 bit
+ * word array that is defined by the format string constraints.
+ *
+ * This function will take the format and the binary array and finish
+ * the conversion into the ASCII string within the buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
+{
+	unsigned int len = seq_buf_buffer_left(s);
+	int ret;
+
+	WARN_ON(s->size == 0);
+
+	if (s->len < s->size) {
+		ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+		if (seq_buf_can_fit(s, ret)) {
+			s->len += ret;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+#endif /* CONFIG_BINARY_PRINTF */
+
+/**
+ * seq_buf_puts - sequence printing of simple string
+ * @s: seq_buf descriptor
+ * @str: simple string to record
+ *
+ * Copy a simple string into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_puts(struct seq_buf *s, const char *str)
+{
+	unsigned int len = strlen(str);
+
+	WARN_ON(s->size == 0);
+
+	if (seq_buf_can_fit(s, len)) {
+		memcpy(s->buffer + s->len, str, len);
+		s->len += len;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_putc - sequence printing of simple character
+ * @s: seq_buf descriptor
+ * @c: simple character to record
+ *
+ * Copy a single character into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putc(struct seq_buf *s, unsigned char c)
+{
+	WARN_ON(s->size == 0);
+
+	if (seq_buf_can_fit(s, 1)) {
+		s->buffer[s->len++] = c;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_putmem - write raw data into the sequenc buffer
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to copy into the buffer
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * There may be cases where raw memory needs to be written into the
+ * buffer and a strcpy() would not work. Using this function allows
+ * for such cases.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
+{
+	WARN_ON(s->size == 0);
+
+	if (seq_buf_can_fit(s, len)) {
+		memcpy(s->buffer + s->len, mem, len);
+		s->len += len;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+#define MAX_MEMHEX_BYTES	8U
+#define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)
+
+/**
+ * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to write its hex ASCII representation of
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * This is similar to seq_buf_putmem() except instead of just copying the
+ * raw memory into the buffer it writes its ASCII representation of it
+ * in hex characters.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
+		       unsigned int len)
+{
+	unsigned char hex[HEX_CHARS];
+	const unsigned char *data = mem;
+	unsigned int start_len;
+	int i, j;
+
+	WARN_ON(s->size == 0);
+
+	while (len) {
+		start_len = min(len, HEX_CHARS - 1);
+#ifdef __BIG_ENDIAN
+		for (i = 0, j = 0; i < start_len; i++) {
+#else
+		for (i = start_len-1, j = 0; i >= 0; i--) {
+#endif
+			hex[j++] = hex_asc_hi(data[i]);
+			hex[j++] = hex_asc_lo(data[i]);
+		}
+		if (WARN_ON_ONCE(j == 0 || j/2 > len))
+			break;
+
+		/* j increments twice per loop */
+		len -= j / 2;
+		hex[j++] = ' ';
+
+		seq_buf_putmem(s, hex, j);
+		if (seq_buf_has_overflowed(s))
+			return -1;
+	}
+	return 0;
+}
+
+/**
+ * seq_buf_path - copy a path into the sequence buffer
+ * @s: seq_buf descriptor
+ * @path: path to write into the sequence buffer.
+ * @esc: set of characters to escape in the output
+ *
+ * Write a path name into the sequence buffer.
+ *
+ * Returns the number of written bytes on success, -1 on overflow
+ */
+int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
+{
+	char *buf;
+	size_t size = seq_buf_get_buf(s, &buf);
+	int res = -1;
+
+	WARN_ON(s->size == 0);
+
+	if (size) {
+		char *p = d_path(path, buf, size);
+		if (!IS_ERR(p)) {
+			char *end = mangle_path(buf, p, esc);
+			if (end)
+				res = end - buf;
+		}
+	}
+	seq_buf_commit(s, res);
+
+	return res;
+}
+
+/**
+ * seq_buf_to_user - copy the squence buffer to user space
+ * @s: seq_buf descriptor
+ * @ubuf: The userspace memory location to copy to
+ * @cnt: The amount to copy
+ *
+ * Copies the sequence buffer into the userspace memory pointed to
+ * by @ubuf. It starts from the last read position (@s->readpos)
+ * and writes up to @cnt characters or till it reaches the end of
+ * the content in the buffer (@s->len), which ever comes first.
+ *
+ * On success, it returns a positive number of the number of bytes
+ * it copied.
+ *
+ * On failure it returns -EBUSY if all of the content in the
+ * sequence has been already read, which includes nothing in the
+ * sequence (@s->len == @s->readpos).
+ *
+ * Returns -EFAULT if the copy to userspace fails.
+ */
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+{
+	int len;
+	int ret;
+
+	if (!cnt)
+		return 0;
+
+	if (s->len <= s->readpos)
+		return -EBUSY;
+
+	len = seq_buf_used(s) - s->readpos;
+	if (cnt > len)
+		cnt = len;
+	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+	if (ret == cnt)
+		return -EFAULT;
+
+	cnt -= ret;
+
+	s->readpos += cnt;
+	return cnt;
+}
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 25/26 v5] printk: Add per_cpu printk func to allow printk to be diverted
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (23 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 24/26 v5] seq_buf: Move the seq_buf code to lib/ Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-15  4:59 ` [PATCH 26/26 v5] x86/nmi: Perform a safe NMI stack trace on all CPUs Steven Rostedt
                   ` (2 subsequent siblings)
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel
  Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek, Paul E. McKenney

[-- Attachment #1: 0025-printk-Add-per_cpu-printk-func-to-allow-printk-to-be.patch --]
[-- Type: text/plain, Size: 3548 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Being able to divert printk to call another function besides the normal
logging is useful for such things like NMI handling. If some functions
are to be called from NMI that does printk() it is possible to lock up
the box if the nmi handler triggers when another printk is happening.

One example of this use is to perform a stack trace on all CPUs via NMI.
But if the NMI is to do the printk() it can cause the system to lock up.
By allowing the printk to be diverted to another function that can safely
record the printk output and then print it when it in a safe context
then NMIs will be safe to call these functions like show_regs().

Link: http://lkml.kernel.org/p/20140619213952.209176403@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/percpu.h |  3 +++
 include/linux/printk.h |  2 ++
 kernel/printk/printk.c | 38 +++++++++++++++++++++++++++++---------
 3 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index a3aa63e47637..ba2e85a0ff5b 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -134,4 +134,7 @@ extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
 	(typeof(type) __percpu *)__alloc_percpu(sizeof(type),		\
 						__alignof__(type))
 
+/* To avoid include hell, as printk can not declare this, we declare it here */
+DECLARE_PER_CPU(printk_func_t, printk_func);
+
 #endif /* __LINUX_PERCPU_H */
diff --git a/include/linux/printk.h b/include/linux/printk.h
index d78125f73ac4..3bbd979d32fb 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -162,6 +162,8 @@ extern int kptr_restrict;
 
 extern void wake_up_klogd(void);
 
+typedef int(*printk_func_t)(const char *fmt, va_list args);
+
 void log_buf_kexec_setup(void);
 void __init setup_log_buf(int early);
 void dump_stack_set_arch_desc(const char *fmt, ...);
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index ced2b84b1cb7..f7b723f98cb9 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1807,6 +1807,30 @@ asmlinkage int printk_emit(int facility, int level,
 }
 EXPORT_SYMBOL(printk_emit);
 
+int vprintk_default(const char *fmt, va_list args)
+{
+	int r;
+
+#ifdef CONFIG_KGDB_KDB
+	if (unlikely(kdb_trap_printk)) {
+		r = vkdb_printf(fmt, args);
+		return r;
+	}
+#endif
+	r = vprintk_emit(0, -1, NULL, 0, fmt, args);
+
+	return r;
+}
+EXPORT_SYMBOL_GPL(vprintk_default);
+
+/*
+ * This allows printk to be diverted to another function per cpu.
+ * This is useful for calling printk functions from within NMI
+ * without worrying about race conditions that can lock up the
+ * box.
+ */
+DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default;
+
 /**
  * printk - print a kernel message
  * @fmt: format string
@@ -1830,19 +1854,15 @@ EXPORT_SYMBOL(printk_emit);
  */
 asmlinkage __visible int printk(const char *fmt, ...)
 {
+	printk_func_t vprintk_func;
 	va_list args;
 	int r;
 
-#ifdef CONFIG_KGDB_KDB
-	if (unlikely(kdb_trap_printk)) {
-		va_start(args, fmt);
-		r = vkdb_printf(fmt, args);
-		va_end(args);
-		return r;
-	}
-#endif
 	va_start(args, fmt);
-	r = vprintk_emit(0, -1, NULL, 0, fmt, args);
+	preempt_disable();
+	vprintk_func = this_cpu_read(printk_func);
+	r = vprintk_func(fmt, args);
+	preempt_enable();
 	va_end(args);
 
 	return r;
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 26/26 v5] x86/nmi: Perform a safe NMI stack trace on all CPUs
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (24 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 25/26 v5] printk: Add per_cpu printk func to allow printk to be diverted Steven Rostedt
@ 2014-11-15  4:59 ` Steven Rostedt
  2014-11-18 17:02   ` Petr Mladek
  2014-11-15  5:08 ` [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
  2014-11-18  3:21 ` Steven Rostedt
  27 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  4:59 UTC (permalink / raw)
  To: linux-kernel
  Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek, Paul E. McKenney

[-- Attachment #1: 0026-x86-nmi-Perform-a-safe-NMI-stack-trace-on-all-CPUs.patch --]
[-- Type: text/plain, Size: 5340 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

When trigger_all_cpu_backtrace() is called on x86, it will trigger an
NMI on each CPU and call show_regs(). But this can lead to a hard lock
up if the NMI comes in on another printk().

In order to avoid this, when the NMI triggers, it switches the printk
routine for that CPU to call a NMI safe printk function that records the
printk in a per_cpu seq_buf descriptor. After all NMIs have finished
recording its data, the seq_bufs are printed in a safe context.

Link: http://lkml.kernel.org/p/20140619213952.360076309@goodmis.org

Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/kernel/apic/hw_nmi.c | 91 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 86 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 6a1e71bde323..c95c3e9ce196 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -18,6 +18,7 @@
 #include <linux/nmi.h>
 #include <linux/module.h>
 #include <linux/delay.h>
+#include <linux/seq_buf.h>
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 u64 hw_nmi_get_sample_period(int watchdog_thresh)
@@ -29,14 +30,35 @@ u64 hw_nmi_get_sample_period(int watchdog_thresh)
 #ifdef arch_trigger_all_cpu_backtrace
 /* For reliability, we're prepared to waste bits here. */
 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
+static cpumask_var_t printtrace_mask;
+
+#define NMI_BUF_SIZE		4096
+
+struct nmi_seq_buf {
+	unsigned char		buffer[NMI_BUF_SIZE];
+	struct seq_buf		seq;
+};
+
+/* Safe printing in NMI context */
+static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
 
 /* "in progress" flag of arch_trigger_all_cpu_backtrace */
 static unsigned long backtrace_flag;
 
+static void print_seq_line(struct nmi_seq_buf *s, int start, int end)
+{
+	const char *buf = s->buffer + start;
+
+	printk("%.*s", (end - start) + 1, buf);
+}
+
 void arch_trigger_all_cpu_backtrace(bool include_self)
 {
+	struct nmi_seq_buf *s;
+	int len;
+	int cpu;
 	int i;
-	int cpu = get_cpu();
+	int this_cpu = get_cpu();
 
 	if (test_and_set_bit(0, &backtrace_flag)) {
 		/*
@@ -49,7 +71,17 @@ void arch_trigger_all_cpu_backtrace(bool include_self)
 
 	cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
 	if (!include_self)
-		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
+		cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
+
+	cpumask_copy(printtrace_mask, to_cpumask(backtrace_mask));
+	/*
+	 * Set up per_cpu seq_buf buffers that the NMIs running on the other
+	 * CPUs will write to.
+	 */
+	for_each_cpu(cpu, to_cpumask(backtrace_mask)) {
+		s = &per_cpu(nmi_print_seq, cpu);
+		seq_buf_init(&s->seq, s->buffer, NMI_BUF_SIZE);
+	}
 
 	if (!cpumask_empty(to_cpumask(backtrace_mask))) {
 		pr_info("sending NMI to %s CPUs:\n",
@@ -65,11 +97,58 @@ void arch_trigger_all_cpu_backtrace(bool include_self)
 		touch_softlockup_watchdog();
 	}
 
+	/*
+	 * Now that all the NMIs have triggered, we can dump out their
+	 * back traces safely to the console.
+	 */
+	for_each_cpu(cpu, printtrace_mask) {
+		int last_i = 0;
+
+		s = &per_cpu(nmi_print_seq, cpu);
+		len = seq_buf_used(&s->seq);
+		if (!len)
+			continue;
+
+		/* Print line by line. */
+		for (i = 0; i < len; i++) {
+			if (s->buffer[i] == '\n') {
+				print_seq_line(s, last_i, i);
+				last_i = i + 1;
+			}
+		}
+		/* Check if there was a partial line. */
+		if (last_i < len) {
+			print_seq_line(s, last_i, len - 1);
+			pr_cont("\n");
+		}
+	}
+
 	clear_bit(0, &backtrace_flag);
 	smp_mb__after_atomic();
 	put_cpu();
 }
 
+/*
+ * It is not safe to call printk() directly from NMI handlers.
+ * It may be fine if the NMI detected a lock up and we have no choice
+ * but to do so, but doing a NMI on all other CPUs to get a back trace
+ * can be done with a sysrq-l. We don't want that to lock up, which
+ * can happen if the NMI interrupts a printk in progress.
+ *
+ * Instead, we redirect the vprintk() to this nmi_vprintk() that writes
+ * the content into a per cpu seq_buf buffer. Then when the NMIs are
+ * all done, we can safely dump the contents of the seq_buf to a printk()
+ * from a non NMI context.
+ */
+static int nmi_vprintk(const char *fmt, va_list args)
+{
+	struct nmi_seq_buf *s = this_cpu_ptr(&nmi_print_seq);
+	unsigned int len = seq_buf_used(&s->seq);
+
+	seq_buf_vprintf(&s->seq, fmt, args);
+	return seq_buf_used(&s->seq) - len;
+}
+
 static int
 arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
 {
@@ -78,12 +157,14 @@ arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
 	cpu = smp_processor_id();
 
 	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
-		static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
+		printk_func_t printk_func_save = this_cpu_read(printk_func);
 
-		arch_spin_lock(&lock);
+		/* Replace printk to write into the NMI seq */
+		this_cpu_write(printk_func, nmi_vprintk);
 		printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
 		show_regs(regs);
-		arch_spin_unlock(&lock);
+		this_cpu_write(printk_func, printk_func_save);
+
 		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
 		return NMI_HANDLED;
 	}
-- 
2.1.1



^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (25 preceding siblings ...)
  2014-11-15  4:59 ` [PATCH 26/26 v5] x86/nmi: Perform a safe NMI stack trace on all CPUs Steven Rostedt
@ 2014-11-15  5:08 ` Steven Rostedt
  2014-11-18  3:21 ` Steven Rostedt
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-15  5:08 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Fri, 14 Nov 2014 23:58:47 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> Version 5!
> 
> Full diff between v4 and v5 will be replied to this email.
> 

Here it is:

-- Steve

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index da211dfbcebe..9aafe0e24c68 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -67,7 +67,7 @@ seq_buf_buffer_left(struct seq_buf *s)
 /* How much buffer was written? */
 static inline unsigned int seq_buf_used(struct seq_buf *s)
 {
-	return min((s)->len, (s)->size);
+	return min(s->len, s->size);
 }
 
 /**
@@ -105,7 +105,8 @@ static inline void seq_buf_commit(struct seq_buf *s, int num)
 	if (num < 0) {
 		seq_buf_set_overflow(s);
 	} else {
-		BUG_ON(s->len + num > s->size + 1);
+		/* num must be negative on overflow */
+		BUG_ON(s->len + num > s->size);
 		s->len += num;
 	}
 }
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 85d37106be3d..cfaf5a1d4bad 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -24,6 +24,24 @@ trace_seq_init(struct trace_seq *s)
 }
 
 /**
+ * trace_seq_used - amount of actual data written to buffer
+ * @s: trace sequence descriptor
+ *
+ * Returns the amount of data written to the buffer.
+ *
+ * IMPORTANT!
+ *
+ * Use this instead of @s->seq.len if you need to pass the amount
+ * of data from the buffer to another buffer (userspace, or what not).
+ * The @s->seq.len on overflow is bigger than the buffer size and
+ * using it can cause access to undefined memory.
+ */
+static inline int trace_seq_used(struct trace_seq *s)
+{
+	return seq_buf_used(&s->seq);
+}
+
+/**
  * trace_seq_buffer_ptr - return pointer to next location in buffer
  * @s: trace sequence descriptor
  *
@@ -35,7 +53,7 @@ trace_seq_init(struct trace_seq *s)
 static inline unsigned char *
 trace_seq_buffer_ptr(struct trace_seq *s)
 {
-	return s->buffer + s->seq.len;
+	return s->buffer + seq_buf_used(&s->seq);
 }
 
 /**
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index f13471b5d27a..139b5067345b 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -277,7 +277,7 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags,	\
 	field = (typeof(field))iter->ent;				\
 									\
 	ret = ftrace_raw_output_prep(iter, trace_event);		\
-	if (ret)							\
+	if (ret != TRACE_TYPE_HANDLED)					\
 		return ret;						\
 									\
 	trace_seq_printf(s, print);					\
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7d7a07e9b9e9..9f1ffc707f3b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -944,10 +944,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 {
 	int len;
 
-	if (s->seq.len <= s->seq.readpos)
+	if (trace_seq_used(s) <= s->seq.readpos)
 		return -EBUSY;
 
-	len = s->seq.len - s->seq.readpos;
+	len = trace_seq_used(s) - s->seq.readpos;
 	if (cnt > len)
 		cnt = len;
 	memcpy(buf, s->buffer + s->seq.readpos, cnt);
@@ -4514,18 +4514,18 @@ waitagain:
 	trace_access_lock(iter->cpu_file);
 	while (trace_find_next_entry_inc(iter) != NULL) {
 		enum print_line_t ret;
-		int len = iter->seq.seq.len;
+		int save_len = iter->seq.seq.len;
 
 		ret = print_trace_line(iter);
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
 			/* don't print partial lines */
-			iter->seq.seq.len = len;
+			iter->seq.seq.len = save_len;
 			break;
 		}
 		if (ret != TRACE_TYPE_NO_CONSUME)
 			trace_consume(iter);
 
-		if (iter->seq.seq.len >= cnt)
+		if (trace_seq_used(&iter->seq) >= cnt)
 			break;
 
 		/*
@@ -4541,7 +4541,7 @@ waitagain:
 
 	/* Now copy what we have to the user */
 	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
-	if (iter->seq.seq.readpos >= iter->seq.seq.len)
+	if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
 		trace_seq_init(&iter->seq);
 
 	/*
@@ -4575,20 +4575,33 @@ static size_t
 tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 {
 	size_t count;
+	int save_len;
 	int ret;
 
 	/* Seq buffer is page-sized, exactly what we need. */
 	for (;;) {
-		count = iter->seq.seq.len;
+		save_len = iter->seq.seq.len;
 		ret = print_trace_line(iter);
-		count = iter->seq.seq.len - count;
-		if (rem < count) {
-			rem = 0;
-			iter->seq.seq.len -= count;
+
+		if (trace_seq_has_overflowed(&iter->seq)) {
+			iter->seq.seq.len = save_len;
 			break;
 		}
+
+		/*
+		 * This should not be hit, because it should only
+		 * be set if the iter->seq overflowed. But check it
+		 * anyway to be safe.
+		 */
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
-			iter->seq.seq.len -= count;
+			iter->seq.seq.len = save_len;
+			break;
+		}
+
+		count = trace_seq_used(&iter->seq) - save_len;
+		if (rem < count) {
+			rem = 0;
+			iter->seq.seq.len = save_len;;
 			break;
 		}
 
@@ -4669,13 +4682,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		/* Copy the data into the page, so we can start over. */
 		ret = trace_seq_to_buffer(&iter->seq,
 					  page_address(spd.pages[i]),
-					  iter->seq.seq.len);
+					  trace_seq_used(&iter->seq));
 		if (ret < 0) {
 			__free_page(spd.pages[i]);
 			break;
 		}
 		spd.partial[i].offset = 0;
-		spd.partial[i].len = iter->seq.seq.len;
+		spd.partial[i].len = trace_seq_used(&iter->seq);
 
 		trace_seq_init(&iter->seq);
 	}
@@ -5676,7 +5689,8 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 	cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "read events: %ld\n", cnt);
 
-	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->seq.len);
+	count = simple_read_from_buffer(ubuf, count, ppos,
+					s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 4d0067dd7f88..935cbea78532 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1044,7 +1044,8 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 	mutex_unlock(&event_mutex);
 
 	if (file)
-		r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+		r = simple_read_from_buffer(ubuf, cnt, ppos,
+					    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
@@ -1210,7 +1211,8 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 	trace_seq_init(s);
 
 	print_subsystem_event_filter(system, s);
-	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+	r = simple_read_from_buffer(ubuf, cnt, ppos,
+				    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
@@ -1265,7 +1267,8 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 	trace_seq_init(s);
 
 	func(s);
-	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+	r = simple_read_from_buffer(ubuf, cnt, ppos,
+				    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index ac2300ca0b70..ec35468349a7 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -677,12 +677,8 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 		}
 
 		/* Latency format */
-		if (trace_flags & TRACE_ITER_LATENCY_FMT) {
-			ret = print_graph_lat_fmt(s, ent);
-			if (ret == TRACE_TYPE_PARTIAL_LINE)
-				return TRACE_TYPE_PARTIAL_LINE;
-		}
-
+		if (trace_flags & TRACE_ITER_LATENCY_FMT)
+			print_graph_lat_fmt(s, ent);
 	}
 
 	/* No overhead */
@@ -1157,6 +1153,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 			return ret;
 	}
 
+	if (trace_seq_has_overflowed(s))
+		goto out;
+
 	/* Strip ending newline */
 	if (s->buffer[s->seq.len - 1] == '\n') {
 		s->buffer[s->seq.len - 1] = '\0';
@@ -1164,7 +1163,7 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 	}
 
 	trace_seq_puts(s, " */\n");
-
+ out:
 	return trace_handle_return(s);
 }
 
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 163c11b6b8ff..723818bc83b4 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -196,10 +196,7 @@ int ftrace_raw_output_prep(struct trace_iterator *iter,
 	trace_seq_init(p);
 	trace_seq_printf(s, "%s: ", ftrace_event_name(event));
 
-	if (trace_seq_has_overflowed(s))
-		return TRACE_TYPE_PARTIAL_LINE;
-
-	return 0;
+	return trace_handle_return(s);
 }
 EXPORT_SYMBOL(ftrace_raw_output_prep);
 
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index 475412e31de5..0c7aab4dd94f 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -30,7 +30,7 @@
 #define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
 
 /* How much buffer is written? */
-#define TRACE_SEQ_BUF_USED(s) min((s)->seq.len, (unsigned int)(PAGE_SIZE - 1))
+#define TRACE_SEQ_BUF_USED(s) seq_buf_used(&(s)->seq)
 
 /*
  * trace_seq should work with being initialized with 0s.
@@ -98,7 +98,6 @@ void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
 		s->seq.len = save_len;
 		s->full = 1;
-		return;
 	}
 }
 EXPORT_SYMBOL_GPL(trace_seq_printf);
@@ -144,20 +143,18 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask);
 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
 {
 	unsigned int save_len = s->seq.len;
-	int ret;
 
 	if (s->full)
 		return;
 
 	__trace_seq_init(s);
 
-	ret = seq_buf_vprintf(&s->seq, fmt, args);
+	seq_buf_vprintf(&s->seq, fmt, args);
 
 	/* If we can't write it all, don't bother writing anything */
 	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
 		s->seq.len = save_len;
 		s->full = 1;
-		return;
 	}
 }
 EXPORT_SYMBOL_GPL(trace_seq_vprintf);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index fcc2b5ebcc5a..fd76f8e108ef 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -866,11 +866,13 @@ print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *e
 	for (i = 0; i < tu->tp.nr_args; i++) {
 		struct probe_arg *parg = &tu->tp.args[i];
 
-		parg->type->print(s, parg->name, data + parg->offset, entry);
+		if (!parg->type->print(s, parg->name, data + parg->offset, entry))
+			goto out;
 	}
 
 	trace_seq_putc(s, '\n');
 
+ out:
 	return trace_handle_return(s);
 }
 
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index 84b6377df827..a2288ca567a3 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -16,6 +16,11 @@
 #include <linux/seq_file.h>
 #include <linux/seq_buf.h>
 
+static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
+{
+	return s->len + len <= s->size;
+}
+
 /**
  * seq_buf_print_seq - move the contents of seq_buf into a seq_file
  * @m: the seq_file descriptor that is the destination
@@ -48,7 +53,7 @@ int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
 
 	if (s->len < s->size) {
 		len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
-		if (s->len + len <= s->size) {
+		if (seq_buf_can_fit(s, len)) {
 			s->len += len;
 			return 0;
 		}
@@ -141,7 +146,7 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
 
 	if (s->len < s->size) {
 		ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
-		if (s->len + ret <= s->size) {
+		if (seq_buf_can_fit(s, ret)) {
 			s->len += ret;
 			return 0;
 		}
@@ -166,7 +171,7 @@ int seq_buf_puts(struct seq_buf *s, const char *str)
 
 	WARN_ON(s->size == 0);
 
-	if (s->len + len <= s->size) {
+	if (seq_buf_can_fit(s, len)) {
 		memcpy(s->buffer + s->len, str, len);
 		s->len += len;
 		return 0;
@@ -188,7 +193,7 @@ int seq_buf_putc(struct seq_buf *s, unsigned char c)
 {
 	WARN_ON(s->size == 0);
 
-	if (s->len + 1 <= s->size) {
+	if (seq_buf_can_fit(s, 1)) {
 		s->buffer[s->len++] = c;
 		return 0;
 	}
@@ -212,7 +217,7 @@ int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
 {
 	WARN_ON(s->size == 0);
 
-	if (s->len + len <= s->size) {
+	if (seq_buf_can_fit(s, len)) {
 		memcpy(s->buffer + s->len, mem, len);
 		s->len += len;
 		return 0;
@@ -332,7 +337,7 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
 	if (s->len <= s->readpos)
 		return -EBUSY;
 
-	len = s->len - s->readpos;
+	len = seq_buf_used(s) - s->readpos;
 	if (cnt > len)
 		cnt = len;
 	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 10/26 v5] tracing/uprobes: Do not use return values of trace_seq_printf()
  2014-11-15  4:58 ` [PATCH 10/26 v5] tracing/uprobes: Do not use return values " Steven Rostedt
@ 2014-11-17  5:28   ` Masami Hiramatsu
  2014-11-17  5:58   ` Srikar Dronamraju
  2014-11-18 14:13   ` Petr Mladek
  2 siblings, 0 replies; 70+ messages in thread
From: Masami Hiramatsu @ 2014-11-17  5:28 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina,
	Petr Mladek, Namhyung Kim, Srikar Dronamraju

(2014/11/15 13:58), Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> The functions trace_seq_printf() and friends will soon no longer have
> return values. Using trace_seq_has_overflowed() and trace_handle_return()
> should be used instead.
> 
> Link: http://lkml.kernel.org/r/20141114011411.693008134@goodmis.org
> 

This looks good to me :)

Reviewed-by: Masami Hiramatsu <masami.hiramatu.pt@hitachi.com>

> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  kernel/trace/trace_uprobe.c | 23 ++++++++++-------------
>  1 file changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index e35327c787f7..fd76f8e108ef 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -852,16 +852,14 @@ print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *e
>  	tu = container_of(event, struct trace_uprobe, tp.call.event);
>  
>  	if (is_ret_probe(tu)) {
> -		if (!trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
> -					ftrace_event_name(&tu->tp.call),
> -					entry->vaddr[1], entry->vaddr[0]))
> -			goto partial;
> +		trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
> +				 ftrace_event_name(&tu->tp.call),
> +				 entry->vaddr[1], entry->vaddr[0]);
>  		data = DATAOF_TRACE_ENTRY(entry, true);
>  	} else {
> -		if (!trace_seq_printf(s, "%s: (0x%lx)",
> -					ftrace_event_name(&tu->tp.call),
> -					entry->vaddr[0]))
> -			goto partial;
> +		trace_seq_printf(s, "%s: (0x%lx)",
> +				 ftrace_event_name(&tu->tp.call),
> +				 entry->vaddr[0]);
>  		data = DATAOF_TRACE_ENTRY(entry, false);
>  	}
>  
> @@ -869,14 +867,13 @@ print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *e
>  		struct probe_arg *parg = &tu->tp.args[i];
>  
>  		if (!parg->type->print(s, parg->name, data + parg->offset, entry))
> -			goto partial;
> +			goto out;
>  	}
>  
> -	if (trace_seq_putc(s, '\n'))
> -		return TRACE_TYPE_HANDLED;
> +	trace_seq_putc(s, '\n');
>  
> -partial:
> -	return TRACE_TYPE_PARTIAL_LINE;
> + out:
> +	return trace_handle_return(s);
>  }
>  
>  typedef bool (*filter_func_t)(struct uprobe_consumer *self,



-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com



^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 10/26 v5] tracing/uprobes: Do not use return values of trace_seq_printf()
  2014-11-15  4:58 ` [PATCH 10/26 v5] tracing/uprobes: Do not use return values " Steven Rostedt
  2014-11-17  5:28   ` Masami Hiramatsu
@ 2014-11-17  5:58   ` Srikar Dronamraju
  2014-11-18 14:13   ` Petr Mladek
  2 siblings, 0 replies; 70+ messages in thread
From: Srikar Dronamraju @ 2014-11-17  5:58 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina,
	Petr Mladek, Masami Hiramatsu, Namhyung Kim

* Steven Rostedt <rostedt@goodmis.org> [2014-11-14 23:58:57]:

> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> The functions trace_seq_printf() and friends will soon no longer have
> return values. Using trace_seq_has_overflowed() and trace_handle_return()
> should be used instead.
> 
> Link: http://lkml.kernel.org/r/20141114011411.693008134@goodmis.org
> 
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Looks good to me.

Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
-- 
Thanks and Regards
Srikar Dronamraju


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 19/26 v5] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-15  4:59 ` [PATCH 19/26 v5] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
@ 2014-11-17 17:32   ` Steven Rostedt
  2014-11-17 19:11     ` [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page() Steven Rostedt
  2014-11-17 19:12     ` [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
  0 siblings, 2 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-17 17:32 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Fri, 14 Nov 2014 23:59:06 -0500
  
>  	/*
> @@ -4575,20 +4575,33 @@ static size_t
>  tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
>  {
>  	size_t count;
> +	int save_len;
>  	int ret;
>  
>  	/* Seq buffer is page-sized, exactly what we need. */
>  	for (;;) {
> -		count = iter->seq.seq.len;
> +		save_len = iter->seq.seq.len;
>  		ret = print_trace_line(iter);
> -		count = iter->seq.seq.len - count;
> -		if (rem < count) {
> -			rem = 0;
> -			iter->seq.seq.len -= count;
> +
> +		if (trace_seq_has_overflowed(&iter->seq)) {
> +			iter->seq.seq.len = save_len;
>  			break;
>  		}
> +
> +		/*
> +		 * This should not be hit, because it should only
> +		 * be set if the iter->seq overflowed. But check it
> +		 * anyway to be safe.
> +		 */
>  		if (ret == TRACE_TYPE_PARTIAL_LINE) {
> -			iter->seq.seq.len -= count;
> +			iter->seq.seq.len = save_len;
> +			break;
> +		}
> +
> +		count = trace_seq_used(&iter->seq) - save_len;
> +		if (rem < count) {
> +			rem = 0;
> +			iter->seq.seq.len = save_len;;
>  			break;
>  		}
>  

I don't like the fact that I did a code structure change with this
patch. This patch should be just a simple conversion of len to
seq_buf_used(). I'm going to strip this change out and put it before
this patch.

-- Steve


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-15  4:59 ` [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function Steven Rostedt
@ 2014-11-17 17:36   ` Steven Rostedt
  2014-11-18  0:07     ` Joe Perches
  2014-11-18 16:40   ` Petr Mladek
  1 sibling, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-17 17:36 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Fri, 14 Nov 2014 23:59:07 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> Add a seq_buf_can_fit() helper function that removes the possible mistakes
> of comparing the seq_buf length plus added data compared to the size of
> the buffer.
> 
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  kernel/trace/seq_buf.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
> index ce17f65268ed..89d1bd5c27fe 100644
> --- a/kernel/trace/seq_buf.c
> +++ b/kernel/trace/seq_buf.c
> @@ -16,6 +16,11 @@
>  #include <linux/seq_file.h>
>  #include <linux/seq_buf.h>
>  

I'm adding a comment here:

/**
 * seq_buf_can_fit - can the new data fit in the current buffer?
 * @s: the seq_buf descriptor
 * @len: The length to see if it can fit in the current buffer
 *
 * Returns true if there's enough unused space in the seq_buf buffer
 * to fit the amount of new data according to @len.
 */


-- Steve

> +static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
> +{
> +	return s->len + len < s->size;
> +}
> +

^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page()
  2014-11-17 17:32   ` Steven Rostedt
@ 2014-11-17 19:11     ` Steven Rostedt
  2014-11-18 16:15       ` Petr Mladek
  2014-11-17 19:12     ` [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
  1 sibling, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-17 19:11 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

> 
> I don't like the fact that I did a code structure change with this
> patch. This patch should be just a simple conversion of len to
> seq_buf_used(). I'm going to strip this change out and put it before
> this patch.


The function tracing_fill_pipe_page() logic is a little confusing with the
use of count saving the seq.len and reusing it.

Instead of subtracting a number that is calculated from the saved
value of the seq.len from seq.len, just save the seq.len at the start
and if we need to reset it, just assign it again.

When the seq_buf overflow is len == size + 1, the current logic will
break. Changing it to use a saved length for resetting back to the
original value is more robust and will work when we change the way
seq_buf sets the overflow.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7d7a07e9b9e9..2dbc18e5f929 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4575,23 +4575,37 @@ static size_t
 tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 {
 	size_t count;
+	int save_len;
 	int ret;
 
 	/* Seq buffer is page-sized, exactly what we need. */
 	for (;;) {
-		count = iter->seq.seq.len;
+		save_len = iter->seq.seq.len;
 		ret = print_trace_line(iter);
-		count = iter->seq.seq.len - count;
-		if (rem < count) {
-			rem = 0;
-			iter->seq.seq.len -= count;
+
+		if (trace_seq_has_overflowed(&iter->seq)) {
+			iter->seq.seq.len = save_len;
 			break;
 		}
+
+		/*
+		 * This should not be hit, because it should only
+		 * be set if the iter->seq overflowed. But check it
+		 * anyway to be safe.
+		 */
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
-			iter->seq.seq.len -= count;
+			iter->seq.seq.len = save_len;
 			break;
 		}
 
+		count = iter->seq.seq.len - save_len;
+		if (rem < count) {
+			rem = 0;
+			iter->seq.seq.len = save_len;
+			break;
+		}
+
+
 		if (ret != TRACE_TYPE_NO_CONSUME)
 			trace_consume(iter);
 		rem -= count;
-- 
1.8.1.4


^ permalink raw reply	[flat|nested] 70+ messages in thread

* [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-17 17:32   ` Steven Rostedt
  2014-11-17 19:11     ` [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page() Steven Rostedt
@ 2014-11-17 19:12     ` Steven Rostedt
  2014-11-18 16:33       ` Petr Mladek
  1 sibling, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-17 19:12 UTC (permalink / raw)
  To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek


> I don't like the fact that I did a code structure change with this
> patch. This patch should be just a simple conversion of len to
> seq_buf_used(). I'm going to strip this change out and put it before
> this patch.


As the seq_buf->len will soon be +1 size when there's an overflow, we
must use trace_seq_used() or seq_buf_used() methods to get the real
length. This will prevent buffer overflow issues if just the len
of the seq_buf descriptor is used to copy memory.

Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.home

Reported-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/trace_seq.h            | 20 +++++++++++++++++++-
 kernel/trace/seq_buf.c               |  2 +-
 kernel/trace/trace.c                 | 22 +++++++++++-----------
 kernel/trace/trace_events.c          |  9 ++++++---
 kernel/trace/trace_functions_graph.c |  5 ++++-
 kernel/trace/trace_seq.c             |  2 +-
 6 files changed, 42 insertions(+), 18 deletions(-)

diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 85d37106be3d..cfaf5a1d4bad 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -24,6 +24,24 @@ trace_seq_init(struct trace_seq *s)
 }
 
 /**
+ * trace_seq_used - amount of actual data written to buffer
+ * @s: trace sequence descriptor
+ *
+ * Returns the amount of data written to the buffer.
+ *
+ * IMPORTANT!
+ *
+ * Use this instead of @s->seq.len if you need to pass the amount
+ * of data from the buffer to another buffer (userspace, or what not).
+ * The @s->seq.len on overflow is bigger than the buffer size and
+ * using it can cause access to undefined memory.
+ */
+static inline int trace_seq_used(struct trace_seq *s)
+{
+	return seq_buf_used(&s->seq);
+}
+
+/**
  * trace_seq_buffer_ptr - return pointer to next location in buffer
  * @s: trace sequence descriptor
  *
@@ -35,7 +53,7 @@ trace_seq_init(struct trace_seq *s)
 static inline unsigned char *
 trace_seq_buffer_ptr(struct trace_seq *s)
 {
-	return s->buffer + s->seq.len;
+	return s->buffer + seq_buf_used(&s->seq);
 }
 
 /**
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 9ec5305d9da7..ce17f65268ed 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -328,7 +328,7 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
 	if (s->len <= s->readpos)
 		return -EBUSY;
 
-	len = s->len - s->readpos;
+	len = seq_buf_used(s) - s->readpos;
 	if (cnt > len)
 		cnt = len;
 	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2dbc18e5f929..9023446b2c2b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -944,10 +944,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 {
 	int len;
 
-	if (s->seq.len <= s->seq.readpos)
+	if (trace_seq_used(s) <= s->seq.readpos)
 		return -EBUSY;
 
-	len = s->seq.len - s->seq.readpos;
+	len = trace_seq_used(s) - s->seq.readpos;
 	if (cnt > len)
 		cnt = len;
 	memcpy(buf, s->buffer + s->seq.readpos, cnt);
@@ -4514,18 +4514,18 @@ waitagain:
 	trace_access_lock(iter->cpu_file);
 	while (trace_find_next_entry_inc(iter) != NULL) {
 		enum print_line_t ret;
-		int len = iter->seq.seq.len;
+		int save_len = iter->seq.seq.len;
 
 		ret = print_trace_line(iter);
 		if (ret == TRACE_TYPE_PARTIAL_LINE) {
 			/* don't print partial lines */
-			iter->seq.seq.len = len;
+			iter->seq.seq.len = save_len;
 			break;
 		}
 		if (ret != TRACE_TYPE_NO_CONSUME)
 			trace_consume(iter);
 
-		if (iter->seq.seq.len >= cnt)
+		if (trace_seq_used(&iter->seq) >= cnt)
 			break;
 
 		/*
@@ -4541,7 +4541,7 @@ waitagain:
 
 	/* Now copy what we have to the user */
 	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
-	if (iter->seq.seq.readpos >= iter->seq.seq.len)
+	if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
 		trace_seq_init(&iter->seq);
 
 	/*
@@ -4598,14 +4598,13 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 			break;
 		}
 
-		count = iter->seq.seq.len - save_len;
+		count = trace_seq_used(&iter->seq) - save_len;
 		if (rem < count) {
 			rem = 0;
 			iter->seq.seq.len = save_len;
 			break;
 		}
 
-
 		if (ret != TRACE_TYPE_NO_CONSUME)
 			trace_consume(iter);
 		rem -= count;
@@ -4683,13 +4682,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		/* Copy the data into the page, so we can start over. */
 		ret = trace_seq_to_buffer(&iter->seq,
 					  page_address(spd.pages[i]),
-					  iter->seq.seq.len);
+					  trace_seq_used(&iter->seq));
 		if (ret < 0) {
 			__free_page(spd.pages[i]);
 			break;
 		}
 		spd.partial[i].offset = 0;
-		spd.partial[i].len = iter->seq.seq.len;
+		spd.partial[i].len = trace_seq_used(&iter->seq);
 
 		trace_seq_init(&iter->seq);
 	}
@@ -5690,7 +5689,8 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 	cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
 	trace_seq_printf(s, "read events: %ld\n", cnt);
 
-	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->seq.len);
+	count = simple_read_from_buffer(ubuf, count, ppos,
+					s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 4d0067dd7f88..935cbea78532 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1044,7 +1044,8 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 	mutex_unlock(&event_mutex);
 
 	if (file)
-		r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+		r = simple_read_from_buffer(ubuf, cnt, ppos,
+					    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
@@ -1210,7 +1211,8 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
 	trace_seq_init(s);
 
 	print_subsystem_event_filter(system, s);
-	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+	r = simple_read_from_buffer(ubuf, cnt, ppos,
+				    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
@@ -1265,7 +1267,8 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 	trace_seq_init(s);
 
 	func(s);
-	r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+	r = simple_read_from_buffer(ubuf, cnt, ppos,
+				    s->buffer, trace_seq_used(s));
 
 	kfree(s);
 
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 6d1342ae7a44..ec35468349a7 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1153,6 +1153,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 			return ret;
 	}
 
+	if (trace_seq_has_overflowed(s))
+		goto out;
+
 	/* Strip ending newline */
 	if (s->buffer[s->seq.len - 1] == '\n') {
 		s->buffer[s->seq.len - 1] = '\0';
@@ -1160,7 +1163,7 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 	}
 
 	trace_seq_puts(s, " */\n");
-
+ out:
 	return trace_handle_return(s);
 }
 
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index 087fa514069d..0c7aab4dd94f 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -30,7 +30,7 @@
 #define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
 
 /* How much buffer is written? */
-#define TRACE_SEQ_BUF_USED(s) min((s)->seq.len, (unsigned int)(PAGE_SIZE - 1))
+#define TRACE_SEQ_BUF_USED(s) seq_buf_used(&(s)->seq)
 
 /*
  * trace_seq should work with being initialized with 0s.
-- 
1.8.1.4


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-17 17:36   ` Steven Rostedt
@ 2014-11-18  0:07     ` Joe Perches
  2014-11-18  0:27       ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Joe Perches @ 2014-11-18  0:07 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 2014-11-17 at 12:36 -0500, Steven Rostedt wrote:
> On Fri, 14 Nov 2014 23:59:07 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> > 
> > Add a seq_buf_can_fit() helper function that removes the possible mistakes
> > of comparing the seq_buf length plus added data compared to the size of
> > the buffer.
[]
> > +static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
> > +{
> > +	return s->len + len < s->size;
> > +}
> > +

Why is this useful?


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  0:07     ` Joe Perches
@ 2014-11-18  0:27       ` Steven Rostedt
  2014-11-18  0:35         ` Joe Perches
  0 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-18  0:27 UTC (permalink / raw)
  To: Joe Perches
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 17 Nov 2014 16:07:33 -0800
Joe Perches <joe@perches.com> wrote:

> On Mon, 2014-11-17 at 12:36 -0500, Steven Rostedt wrote:
> > On Fri, 14 Nov 2014 23:59:07 -0500
> > Steven Rostedt <rostedt@goodmis.org> wrote:
> > 
> > > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> > > 
> > > Add a seq_buf_can_fit() helper function that removes the possible mistakes
> > > of comparing the seq_buf length plus added data compared to the size of
> > > the buffer.
> []
> > > +static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
> > > +{
> > > +	return s->len + len < s->size;
> > > +}
> > > +
> 
> Why is this useful?

Places the logic in one place and makes the next patch much shorter.

As the change log states, makes mistakes much less likely to happen
(note, I made one doing the next change and this makes me more
confident not to do another one)

-- Steve

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  0:27       ` Steven Rostedt
@ 2014-11-18  0:35         ` Joe Perches
  2014-11-18  0:56           ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Joe Perches @ 2014-11-18  0:35 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 2014-11-17 at 19:27 -0500, Steven Rostedt wrote:
> On Mon, 17 Nov 2014 16:07:33 -0800
> Joe Perches <joe@perches.com> wrote:
> 
> > On Mon, 2014-11-17 at 12:36 -0500, Steven Rostedt wrote:
> > > On Fri, 14 Nov 2014 23:59:07 -0500
> > > Steven Rostedt <rostedt@goodmis.org> wrote:
> > > 
> > > > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> > > > 
> > > > Add a seq_buf_can_fit() helper function that removes the possible mistakes
> > > > of comparing the seq_buf length plus added data compared to the size of
> > > > the buffer.
> > []
> > > > +static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
> > > > +{
> > > > +	return s->len + len < s->size;
> > > > +}
> > > > +
> > 
> > Why is this useful?
> 
> Places the logic in one place and makes the next patch much shorter.

What "logic" does it place in one place and
how does it matter?

I don't see it making mistakes more or less
likely, I just see it being used to avoid
setting the overflow state which seems like
more of an error than anything else.

Why avoid setting overflow at all?



^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  0:35         ` Joe Perches
@ 2014-11-18  0:56           ` Steven Rostedt
  2014-11-18  1:07             ` Joe Perches
  0 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-18  0:56 UTC (permalink / raw)
  To: Joe Perches
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 17 Nov 2014 16:35:32 -0800
Joe Perches <joe@perches.com> wrote:

 
> What "logic" does it place in one place and
> how does it matter?

Look at the next patch.

> 
> I don't see it making mistakes more or less
> likely, I just see it being used to avoid
> setting the overflow state which seems like
> more of an error than anything else.
> 
> Why avoid setting overflow at all?
> 

It has nothing to do with overflow. Where did you get that from?

It has to do with updating the seq->len value or not.

-- Steve


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  0:56           ` Steven Rostedt
@ 2014-11-18  1:07             ` Joe Perches
  2014-11-18  1:24               ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Joe Perches @ 2014-11-18  1:07 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 2014-11-17 at 19:56 -0500, Steven Rostedt wrote:
> On Mon, 17 Nov 2014 16:35:32 -0800
> Joe Perches <joe@perches.com> wrote:
> 
>  
> > What "logic" does it place in one place and
> > how does it matter?
> 
> Look at the next patch.

I don't have it and you are not cc'ing me.
I think you are getting carried away with the helpers.

> > I don't see it making mistakes more or less
> > likely, I just see it being used to avoid
> > setting the overflow state which seems like
> > more of an error than anything else.
> > 
> > Why avoid setting overflow at all?
[]
> It has nothing to do with overflow. Where did you get that from?

writing to seq_buf really only cares about overflow.

seq_buf -> write to buffer -> overflowed?
expand buffer, redo everything else when finished,
dump buffer


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  1:07             ` Joe Perches
@ 2014-11-18  1:24               ` Steven Rostedt
  2014-11-18  1:48                 ` Joe Perches
  0 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-18  1:24 UTC (permalink / raw)
  To: Joe Perches
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 17 Nov 2014 17:07:58 -0800
Joe Perches <joe@perches.com> wrote:


> > Look at the next patch.
> 
> I don't have it and you are not cc'ing me.

It's on LKML.

> I think you are getting carried away with the helpers.

That's nice.

> 
> > > I don't see it making mistakes more or less
> > > likely, I just see it being used to avoid
> > > setting the overflow state which seems like
> > > more of an error than anything else.
> > > 
> > > Why avoid setting overflow at all?
> []
> > It has nothing to do with overflow. Where did you get that from?
> 
> writing to seq_buf really only cares about overflow.
> 
> seq_buf -> write to buffer -> overflowed?
> expand buffer, redo everything else when finished,
> dump buffer

Um, that may be the case for seq_file, but it is not the case for
trace_seq. seq_buf is influenced by seq_file because I have a patch to
make seq_file use it, but it's also the guts of trace_seq that has some
different requirements. And it's also not the case with the users of
seq_buf in the last patch.

-- Steve

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  1:24               ` Steven Rostedt
@ 2014-11-18  1:48                 ` Joe Perches
  2014-11-18  2:37                   ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Joe Perches @ 2014-11-18  1:48 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 2014-11-17 at 20:24 -0500, Steven Rostedt wrote:
> On Mon, 17 Nov 2014 17:07:58 -0800
> Joe Perches <joe@perches.com> wrote:
> > > Look at the next patch.
> > I don't have it and you are not cc'ing me.
> It's on LKML.

And?  There's no convenient way to retrieve it.

> > I think you are getting carried away with the helpers.
> That's nice.

And possibly true.

> > > > I don't see it making mistakes more or less
> > > > likely, I just see it being used to avoid
> > > > setting the overflow state which seems like
> > > > more of an error than anything else.
> > > > 
> > > > Why avoid setting overflow at all?
> > []
> > > It has nothing to do with overflow. Where did you get that from?
> > 
> > writing to seq_buf really only cares about overflow.
> > 
> > seq_buf -> write to buffer -> overflowed?
> > expand buffer, redo everything else when finished,
> > dump buffer
> 
> Um, that may be the case for seq_file, but it is not the case for
> trace_seq. seq_buf is influenced by seq_file because I have a patch to
> make seq_file use it, but it's also the guts of trace_seq that has some
> different requirements. And it's also not the case with the users of
> seq_buf in the last patch.

I think your patch subject description needs expanding.
It says seq_buf, nothing about trace.

Perhaps making trace use seq internals is not the right
thing to do.

I also think you should break up this perhaps overlarge
patch set into multiple independent sets that can be applied
in separate chucks rather than all at once.



^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  1:48                 ` Joe Perches
@ 2014-11-18  2:37                   ` Steven Rostedt
  2014-11-18  2:50                     ` Joe Perches
  0 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-18  2:37 UTC (permalink / raw)
  To: Joe Perches
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 17 Nov 2014 17:48:37 -0800
Joe Perches <joe@perches.com> wrote:

> On Mon, 2014-11-17 at 20:24 -0500, Steven Rostedt wrote:
> > On Mon, 17 Nov 2014 17:07:58 -0800
> > Joe Perches <joe@perches.com> wrote:
> > > > Look at the next patch.
> > > I don't have it and you are not cc'ing me.
> > It's on LKML.
> 
> And?  There's no convenient way to retrieve it.

You're not subscribed?


> > Um, that may be the case for seq_file, but it is not the case for
> > trace_seq. seq_buf is influenced by seq_file because I have a patch to
> > make seq_file use it, but it's also the guts of trace_seq that has some
> > different requirements. And it's also not the case with the users of
> > seq_buf in the last patch.
> 
> I think your patch subject description needs expanding.
> It says seq_buf, nothing about trace.

It doesn't need to. This helps out the code. seq_buf has nothing to do
with seq_file (yet).

> 
> Perhaps making trace use seq internals is not the right
> thing to do.

But this code comes from the trace_seq internals. It's a way to combine
the code between seq_file and trace_seq. It is influenced by seq_file,
but the code is trace_seq. Actually, this patch set has nothing to do
with seq_file and finishes up solving a problem with printks dump
stacks from NMIs.

Look at the path of the seq_buf.c code.

> 
> I also think you should break up this perhaps overlarge
> patch set into multiple independent sets that can be applied
> in separate chucks rather than all at once.
> 

Why? I'm the one that is maintaining it. It's going to go through my
tree and it has almost all the acks I need.

I will say the first 13 patches have already been acked and reviewed,
and are going to be going into my for-next queue soon. I'll be posting
a smaller set with the patches that changed.

Well, all but the last 3 patches. Those are the ones that I'm going to
work with Linus and Andrew on before I pull them into my tree.

-- Steve


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  2:37                   ` Steven Rostedt
@ 2014-11-18  2:50                     ` Joe Perches
  2014-11-18  3:00                       ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Joe Perches @ 2014-11-18  2:50 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 2014-11-17 at 21:37 -0500, Steven Rostedt wrote:
> On Mon, 17 Nov 2014 17:48:37 -0800
> Joe Perches <joe@perches.com> wrote:
> > On Mon, 2014-11-17 at 20:24 -0500, Steven Rostedt wrote:
> > > On Mon, 17 Nov 2014 17:07:58 -0800
> > > Joe Perches <joe@perches.com> wrote:
> > > > > Look at the next patch.
> > > > I don't have it and you are not cc'ing me.
> > > It's on LKML.
> > 
> > And?  There's no convenient way to retrieve it.
> 
> You're not subscribed?

I am subscribed and I delete stuff, don't you?

> > > Um, that may be the case for seq_file, but it is not the case for
> > > trace_seq. seq_buf is influenced by seq_file because I have a patch to
> > > make seq_file use it, but it's also the guts of trace_seq that has some
> > > different requirements. And it's also not the case with the users of
> > > seq_buf in the last patch.
> > 
> > I think your patch subject description needs expanding.
> > It says seq_buf, nothing about trace.
> 
> It doesn't need to. This helps out the code. seq_buf has nothing to do
> with seq_file (yet).

No, I don't think it does help seq_buf.  It only helps trace.

btw:

I think you should cc Al Viro on the entire patch set.



^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-18  2:50                     ` Joe Perches
@ 2014-11-18  3:00                       ` Steven Rostedt
  0 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-18  3:00 UTC (permalink / raw)
  To: Joe Perches
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek

On Mon, 17 Nov 2014 18:50:52 -0800
Joe Perches <joe@perches.com> wrote:

> On Mon, 2014-11-17 at 21:37 -0500, Steven Rostedt wrote:
> > On Mon, 17 Nov 2014 17:48:37 -0800
> > Joe Perches <joe@perches.com> wrote:
> > > On Mon, 2014-11-17 at 20:24 -0500, Steven Rostedt wrote:
> > > > On Mon, 17 Nov 2014 17:07:58 -0800
> > > > Joe Perches <joe@perches.com> wrote:
> > > > > > Look at the next patch.
> > > > > I don't have it and you are not cc'ing me.
> > > > It's on LKML.
> > > 
> > > And?  There's no convenient way to retrieve it.
> > 
> > You're not subscribed?
> 
> I am subscribed and I delete stuff, don't you?

Nope, I keep all LKML messages. I have archives since 2005.

> 
> > > > Um, that may be the case for seq_file, but it is not the case for
> > > > trace_seq. seq_buf is influenced by seq_file because I have a patch to
> > > > make seq_file use it, but it's also the guts of trace_seq that has some
> > > > different requirements. And it's also not the case with the users of
> > > > seq_buf in the last patch.
> > > 
> > > I think your patch subject description needs expanding.
> > > It says seq_buf, nothing about trace.
> > 
> > It doesn't need to. This helps out the code. seq_buf has nothing to do
> > with seq_file (yet).
> 
> No, I don't think it does help seq_buf.  It only helps trace.

What are you talking about? seq_buf did not exist until this patch set.

> 
> btw:
> 
> I think you should cc Al Viro on the entire patch set.
> 

Why? Currently this is only tracing code. There's nothing in here that
has anything to do with VFS.

When I post patches to convert seq_file to use seq_buf, then I'll Cc Al.

-- Steve


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely
  2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
                   ` (26 preceding siblings ...)
  2014-11-15  5:08 ` [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
@ 2014-11-18  3:21 ` Steven Rostedt
  27 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-18  3:21 UTC (permalink / raw)
  To: linux-kernel
  Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek,
	Masami Hiramatsu, Namhyung Kim

So far the only difference between v5 I have is that I split the update
of tracing_fill_pipe_page() out of "tracing: Use trace_seq_used() and
seq_buf_used() instead of len", and this:

-- Steve

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9f1ffc707f3b..9023446b2c2b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4601,7 +4601,7 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
 		count = trace_seq_used(&iter->seq) - save_len;
 		if (rem < count) {
 			rem = 0;
-			iter->seq.seq.len = save_len;;
+			iter->seq.seq.len = save_len;
 			break;
 		}
 
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 2193e8038681..a72f3d8d813e 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -131,6 +131,10 @@ print_syscall_enter(struct trace_iterator *iter, int flags,
 	trace_seq_printf(s, "%s(", entry->name);
 
 	for (i = 0; i < entry->nb_args; i++) {
+
+		if (trace_seq_has_overflowed(s))
+			goto end;
+
 		/* parameter types */
 		if (trace_flags & TRACE_ITER_VERBOSE)
 			trace_seq_printf(s, "%s ", entry->types[i]);
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index a2288ca567a3..4eedfedb9e31 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -16,6 +16,14 @@
 #include <linux/seq_file.h>
 #include <linux/seq_buf.h>
 
+/**
+ * seq_buf_can_fit - can the new data fit in the current buffer?
+ * @s: the seq_buf descriptor
+ * @len: The length to see if it can fit in the current buffer
+ *
+ * Returns true if there's enough unused space in the seq_buf buffer
+ * to fit the amount of new data according to @len.
+ */
 static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
 {
 	return s->len + len <= s->size;

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 07/26 v5] kprobes/tracing: Use trace_seq_has_overflowed() for overflow checks
  2014-11-15  4:58 ` [PATCH 07/26 v5] kprobes/tracing: Use trace_seq_has_overflowed() for overflow checks Steven Rostedt
@ 2014-11-18 14:02   ` Petr Mladek
  0 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 14:02 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina,
	Srikar Dronamraju, Masami Hiramatsu

On Fri 2014-11-14 23:58:54, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> Instead of checking the return value of trace_seq_printf() and friends
> for overflowing of the buffer, use the trace_seq_has_overflowed() helper
> function.
> 
> This cleans up the code quite a bit and also takes us a step closer to
> changing the return values of trace_seq_printf() and friends to void.
> 
> Link: http://lkml.kernel.org/r/20141114011411.181812785@goodmis.org
> 
> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 08/26 v5] tracing: Do not check return values of trace_seq_p*() for mmio tracer
  2014-11-15  4:58 ` [PATCH 08/26 v5] tracing: Do not check return values of trace_seq_p*() for mmio tracer Steven Rostedt
@ 2014-11-18 14:06   ` Petr Mladek
  0 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 14:06 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Fri 2014-11-14 23:58:55, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> The return values for trace_seq_printf() and friends are going to be
> removed and they will become void functions. The mmio tracer checked
> their return and even did so incorrectly.
> 
> Some of the funtions which returned the values were never checked
> themselves. Removing all the checks simplifies the code.
> 
> Use trace_seq_has_overflowed() and trace_handle_return() where
> necessary instead.
> 
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 09/26 v5] tracing/probes: Do not use return value of trace_seq_printf()
  2014-11-15  4:58 ` [PATCH 09/26 v5] tracing/probes: Do not use return value of trace_seq_printf() Steven Rostedt
@ 2014-11-18 14:09   ` Petr Mladek
  0 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 14:09 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina,
	Namhyung Kim, Masami Hiramatsu

On Fri 2014-11-14 23:58:56, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> The functions trace_seq_printf() and friends will soon not have a return
> value and will only be a void function. Use trace_seq_has_overflowed()
> instead to know if the trace_seq operations succeeded or not.
> 
> Link: http://lkml.kernel.org/r/20141114011411.530216306@goodmis.org
> 
> Cc: Namhyung Kim <namhyung@kernel.org>
> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 10/26 v5] tracing/uprobes: Do not use return values of trace_seq_printf()
  2014-11-15  4:58 ` [PATCH 10/26 v5] tracing/uprobes: Do not use return values " Steven Rostedt
  2014-11-17  5:28   ` Masami Hiramatsu
  2014-11-17  5:58   ` Srikar Dronamraju
@ 2014-11-18 14:13   ` Petr Mladek
  2 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 14:13 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina,
	Masami Hiramatsu, Namhyung Kim, Srikar Dronamraju

On Fri 2014-11-14 23:58:57, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> The functions trace_seq_printf() and friends will soon no longer have
> return values. Using trace_seq_has_overflowed() and trace_handle_return()
> should be used instead.
> 
> Link: http://lkml.kernel.org/r/20141114011411.693008134@goodmis.org
> 
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 12/26 v5] tracing: Remove return values of most trace_seq_*() functions
  2014-11-15  4:58 ` [PATCH 12/26 v5] tracing: Remove return values of most trace_seq_*() functions Steven Rostedt
@ 2014-11-18 14:18   ` Petr Mladek
  0 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 14:18 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Fri 2014-11-14 23:58:59, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> The trace_seq_printf() and friends are used to store strings into a buffer
> that can be passed around from function to function. If the trace_seq buffer
> fills up, it will not print any more. The return values were somewhat
> inconsistant and using trace_seq_has_overflowed() was a better way to know
> if the write to the trace_seq buffer succeeded or not.
> 
> Now that all users have removed reading the return value of the printf()
> type functions, they can safely return void and keep future users of them
> from reading the inconsistent values as well.
> 
> Link: http://lkml.kernel.org/r/20141114011411.992510720@goodmis.org
> 
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 13/26 v5] tracing: Fix return value of ftrace_raw_output_prep()
  2014-11-15  4:59 ` [PATCH 13/26 v5] tracing: Fix return value of ftrace_raw_output_prep() Steven Rostedt
@ 2014-11-18 14:24   ` Petr Mladek
  0 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 14:24 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Fri 2014-11-14 23:59:00, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> If the trace_seq of ftrace_raw_output_prep() is full this function
> returns TRACE_TYPE_PARTIAL_LINE, otherwise it returns zero.
> 
> The problem is that TRACE_TYPE_PARTIAL_LINE happens to be zero!
> 
> The thing is, the caller of ftrace_raw_output_prep() expects a
> success to be zero. Change that to expect it to be
> TRACE_TYPE_HANDLED.
> 
> Link: http://lkml.kernel.org/r/20141114112522.GA2988@dhcp128.suse.cz
> 
> Reminded-by: Petr Mladek <pmladek@suse.cz>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 18/26 v5] seq_buf: Create seq_buf_used() to find out how much was written
  2014-11-15  4:59 ` [PATCH 18/26 v5] seq_buf: Create seq_buf_used() to find out how much was written Steven Rostedt
@ 2014-11-18 15:02   ` Petr Mladek
  2014-11-19 15:49     ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 15:02 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Fri 2014-11-14 23:59:05, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
> private macro to let callers have a method to know how much of the
> seq_buf was written to.
> 
> Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
> Link: http://lkml.kernel.org/r/20141114011413.321654244@goodmis.org
> 
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  include/linux/seq_buf.h | 6 ++++++
>  kernel/trace/seq_buf.c  | 5 +----
>  2 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
> index 5d91262433e2..93718e570d4c 100644
> --- a/include/linux/seq_buf.h
> +++ b/include/linux/seq_buf.h
> @@ -64,6 +64,12 @@ seq_buf_buffer_left(struct seq_buf *s)
>  	return (s->size - 1) - s->len;
>  }
>  
> +/* How much buffer was written? */
> +static inline unsigned int seq_buf_used(struct seq_buf *s)
> +{
> +	return min(s->len, s->size);

To be precise, it should do

	return min(s->len, s->size - 1);

at this stage and switch to the above code in ("[PATCH 21/26 v5] tracing: Have
seq_buf use full buffer"). Well, it does not cause any big harm. Feel
free to add:

Reviewed-by: Petr Mladek <pmladek@suse.cz>

for this patch or for the updated one.

Best Regards,
Petr

> +}
> +
>  extern __printf(2, 3)
>  int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
>  extern __printf(2, 0)
> diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
> index 7dac34d1235b..9ec5305d9da7 100644
> --- a/kernel/trace/seq_buf.c
> +++ b/kernel/trace/seq_buf.c
> @@ -16,9 +16,6 @@
>  #include <linux/seq_file.h>
>  #include <linux/seq_buf.h>
>  
> -/* How much buffer is written? */
> -#define SEQ_BUF_USED(s) min((s)->len, (s)->size - 1)
> -
>  /**
>   * seq_buf_print_seq - move the contents of seq_buf into a seq_file
>   * @m: the seq_file descriptor that is the destination
> @@ -28,7 +25,7 @@
>   */
>  int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
>  {
> -	unsigned int len = SEQ_BUF_USED(s);
> +	unsigned int len = seq_buf_used(s);
>  
>  	return seq_write(m, s->buffer, len);
>  }
> -- 
> 2.1.1
> 
> 

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page()
  2014-11-17 19:11     ` [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page() Steven Rostedt
@ 2014-11-18 16:15       ` Petr Mladek
  2014-11-19 16:17         ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 16:15 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Mon 2014-11-17 14:11:08, Steven Rostedt wrote:
> > 
> > I don't like the fact that I did a code structure change with this
> > patch. This patch should be just a simple conversion of len to
> > seq_buf_used(). I'm going to strip this change out and put it before
> > this patch.
> 
> 
> The function tracing_fill_pipe_page() logic is a little confusing with the
> use of count saving the seq.len and reusing it.
> 
> Instead of subtracting a number that is calculated from the saved
> value of the seq.len from seq.len, just save the seq.len at the start
> and if we need to reset it, just assign it again.
> 
> When the seq_buf overflow is len == size + 1, the current logic will
> break. Changing it to use a saved length for resetting back to the
> original value is more robust and will work when we change the way
> seq_buf sets the overflow.
> 
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  kernel/trace/trace.c | 26 ++++++++++++++++++++------
>  1 file changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 7d7a07e9b9e9..2dbc18e5f929 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -4575,23 +4575,37 @@ static size_t
>  tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
>  {
>  	size_t count;
> +	int save_len;
>  	int ret;
>  
>  	/* Seq buffer is page-sized, exactly what we need. */
>  	for (;;) {
> -		count = iter->seq.seq.len;
> +		save_len = iter->seq.seq.len;
>  		ret = print_trace_line(iter);
> -		count = iter->seq.seq.len - count;
> -		if (rem < count) {
> -			rem = 0;
> -			iter->seq.seq.len -= count;
> +
> +		if (trace_seq_has_overflowed(&iter->seq)) {
> +			iter->seq.seq.len = save_len;
>  			break;
>  		}
> +
> +		/*
> +		 * This should not be hit, because it should only
> +		 * be set if the iter->seq overflowed. But check it
> +		 * anyway to be safe.
> +		 */
>  		if (ret == TRACE_TYPE_PARTIAL_LINE) {
> -			iter->seq.seq.len -= count;
> +			iter->seq.seq.len = save_len;
>  			break;
>  		}

The two ifs has the same body. Small optimization would be to do:

		/*
		 * The two checks should be equivalent but rather be
		 * on the safe side.
		 */
		if (trace_seq_has_overflowed(&iter->seq) ||
		    ret == TRACE_TYPE_PARTIAL_LINE) {
			iter->seq.seq.len = save_len;
			break;
		}

To be honest, the code seems to be a bit twisted. This function
is called from tracing_splice_read_pipe(). It copies the
trace_seq buffer into spd.page and call trace_seq_init()
in a for cycle.

Therefore if the overflow happens, trace_find_next_entry_inc()
is not called in tracing_fill_pipe_page() and we work with the same
iterator instance next time. It means that the overflow happens most
likely again and we fill all remaining spd.pages with no data and
are stacked on the same iterator instance.

BTW: The trace_seq_to_buffer() in tracing_splice_read_pipe()
is suspicious as well. It passes trace_seq_used(&iter->seq)
as the "cnt" parameter. I guess that it should pass the
size of the "spd.page" instead.

Also we should somehow handle the situation when some data are not
copied. Well, it seems the spd.page has the page size, so it is
the same size as the trace_seq buffer.


Well, this patch does not change the behavior. We could solve the
above problem later if it is there. Maybe I got it wrong.

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

> +		count = iter->seq.seq.len - save_len;
> +		if (rem < count) {
> +			rem = 0;
> +			iter->seq.seq.len = save_len;
> +			break;
> +		}
> +
> +
>  		if (ret != TRACE_TYPE_NO_CONSUME)
>  			trace_consume(iter);
>  		rem -= count;
> -- 
> 1.8.1.4
> 

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-17 19:12     ` [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
@ 2014-11-18 16:33       ` Petr Mladek
  2014-11-18 17:37         ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 16:33 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Mon 2014-11-17 14:12:15, Steven Rostedt wrote:
> 
> > I don't like the fact that I did a code structure change with this
> > patch. This patch should be just a simple conversion of len to
> > seq_buf_used(). I'm going to strip this change out and put it before
> > this patch.
> 
> 
> As the seq_buf->len will soon be +1 size when there's an overflow, we
> must use trace_seq_used() or seq_buf_used() methods to get the real
> length. This will prevent buffer overflow issues if just the len
> of the seq_buf descriptor is used to copy memory.
> 
> Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.home
> 
> Reported-by: Petr Mladek <pmladek@suse.cz>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  include/linux/trace_seq.h            | 20 +++++++++++++++++++-
>  kernel/trace/seq_buf.c               |  2 +-
>  kernel/trace/trace.c                 | 22 +++++++++++-----------
>  kernel/trace/trace_events.c          |  9 ++++++---
>  kernel/trace/trace_functions_graph.c |  5 ++++-
>  kernel/trace/trace_seq.c             |  2 +-
>  6 files changed, 42 insertions(+), 18 deletions(-)

[...]


> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -944,10 +944,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
>  {
>  	int len;
>  
> -	if (s->seq.len <= s->seq.readpos)
> +	if (trace_seq_used(s) <= s->seq.readpos)
>  		return -EBUSY;
>  
> -	len = s->seq.len - s->seq.readpos;
> +	len = trace_seq_used(s) - s->seq.readpos;
>  	if (cnt > len)
>  		cnt = len;
>  	memcpy(buf, s->buffer + s->seq.readpos, cnt);


There is one more dangerous usage in trace_printk_seq(). It is on
three lines there.

The rest looks good.

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function
  2014-11-15  4:59 ` [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function Steven Rostedt
  2014-11-17 17:36   ` Steven Rostedt
@ 2014-11-18 16:40   ` Petr Mladek
  1 sibling, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 16:40 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Fri 2014-11-14 23:59:07, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> Add a seq_buf_can_fit() helper function that removes the possible mistakes
> of comparing the seq_buf length plus added data compared to the size of
> the buffer.
> 
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 26/26 v5] x86/nmi: Perform a safe NMI stack trace on all CPUs
  2014-11-15  4:59 ` [PATCH 26/26 v5] x86/nmi: Perform a safe NMI stack trace on all CPUs Steven Rostedt
@ 2014-11-18 17:02   ` Petr Mladek
  0 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-18 17:02 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina, Paul E. McKenney

On Fri 2014-11-14 23:59:13, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> When trigger_all_cpu_backtrace() is called on x86, it will trigger an
> NMI on each CPU and call show_regs(). But this can lead to a hard lock
> up if the NMI comes in on another printk().
> 
> In order to avoid this, when the NMI triggers, it switches the printk
> routine for that CPU to call a NMI safe printk function that records the
> printk in a per_cpu seq_buf descriptor. After all NMIs have finished
> recording its data, the seq_bufs are printed in a safe context.
> 
> Link: http://lkml.kernel.org/p/20140619213952.360076309@goodmis.org
> 
> Tested-by: Jiri Kosina <jkosina@suse.cz>
> Acked-by: Jiri Kosina <jkosina@suse.cz>
> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

I really like that the NMI part is fast and we do not longer
block many CPUs until the others are finished with priting.

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-18 16:33       ` Petr Mladek
@ 2014-11-18 17:37         ` Steven Rostedt
  2014-11-19 11:40           ` Petr Mladek
  0 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-18 17:37 UTC (permalink / raw)
  To: Petr Mladek; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Tue, 18 Nov 2014 17:33:54 +0100
Petr Mladek <pmladek@suse.cz> wrote:

> On Mon 2014-11-17 14:12:15, Steven Rostedt wrote:
> > 
> > > I don't like the fact that I did a code structure change with this
> > > patch. This patch should be just a simple conversion of len to
> > > seq_buf_used(). I'm going to strip this change out and put it before
> > > this patch.
> > 
> > 
> > As the seq_buf->len will soon be +1 size when there's an overflow, we
> > must use trace_seq_used() or seq_buf_used() methods to get the real
> > length. This will prevent buffer overflow issues if just the len
> > of the seq_buf descriptor is used to copy memory.
> > 
> > Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.home
> > 
> > Reported-by: Petr Mladek <pmladek@suse.cz>
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > ---
> >  include/linux/trace_seq.h            | 20 +++++++++++++++++++-
> >  kernel/trace/seq_buf.c               |  2 +-
> >  kernel/trace/trace.c                 | 22 +++++++++++-----------
> >  kernel/trace/trace_events.c          |  9 ++++++---
> >  kernel/trace/trace_functions_graph.c |  5 ++++-
> >  kernel/trace/trace_seq.c             |  2 +-
> >  6 files changed, 42 insertions(+), 18 deletions(-)
> 
> [...]
> 
> 
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -944,10 +944,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
> >  {
> >  	int len;
> >  
> > -	if (s->seq.len <= s->seq.readpos)
> > +	if (trace_seq_used(s) <= s->seq.readpos)
> >  		return -EBUSY;
> >  
> > -	len = s->seq.len - s->seq.readpos;
> > +	len = trace_seq_used(s) - s->seq.readpos;
> >  	if (cnt > len)
> >  		cnt = len;
> >  	memcpy(buf, s->buffer + s->seq.readpos, cnt);
> 
> 
> There is one more dangerous usage in trace_printk_seq(). It is on
> three lines there.

You totally confused me. What usage in trace_printk_seq(), and what
three lines?

In this patch, trace_printk_seq() looks like this:

int trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
        int ret;

        __trace_seq_init(s);

        ret = seq_buf_print_seq(m, &s->seq);

        /*
         * Only reset this buffer if we successfully wrote to the
         * seq_file buffer. This lets the caller try again or
         * do something else with the contents.
         */
        if (!ret)
                trace_seq_init(s);

        return ret;
}



-- Steve


> 
> The rest looks good.
> 
> Best Regards,
> Petr


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-18 17:37         ` Steven Rostedt
@ 2014-11-19 11:40           ` Petr Mladek
  2014-11-19 13:48             ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Petr Mladek @ 2014-11-19 11:40 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Tue 2014-11-18 12:37:32, Steven Rostedt wrote:
> On Tue, 18 Nov 2014 17:33:54 +0100
> Petr Mladek <pmladek@suse.cz> wrote:
> 
> > On Mon 2014-11-17 14:12:15, Steven Rostedt wrote:
> > > 
> > > > I don't like the fact that I did a code structure change with this
> > > > patch. This patch should be just a simple conversion of len to
> > > > seq_buf_used(). I'm going to strip this change out and put it before
> > > > this patch.
> > > 
> > > 
> > > As the seq_buf->len will soon be +1 size when there's an overflow, we
> > > must use trace_seq_used() or seq_buf_used() methods to get the real
> > > length. This will prevent buffer overflow issues if just the len
> > > of the seq_buf descriptor is used to copy memory.
> > > 
> > > Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.home
> > > 
> > > Reported-by: Petr Mladek <pmladek@suse.cz>
> > > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > > ---
> > >  include/linux/trace_seq.h            | 20 +++++++++++++++++++-
> > >  kernel/trace/seq_buf.c               |  2 +-
> > >  kernel/trace/trace.c                 | 22 +++++++++++-----------
> > >  kernel/trace/trace_events.c          |  9 ++++++---
> > >  kernel/trace/trace_functions_graph.c |  5 ++++-
> > >  kernel/trace/trace_seq.c             |  2 +-
> > >  6 files changed, 42 insertions(+), 18 deletions(-)
> > 
> > [...]
> > 
> > 
> > > --- a/kernel/trace/trace.c
> > > +++ b/kernel/trace/trace.c
> > > @@ -944,10 +944,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
> > >  {
> > >  	int len;
> > >  
> > > -	if (s->seq.len <= s->seq.readpos)
> > > +	if (trace_seq_used(s) <= s->seq.readpos)
> > >  		return -EBUSY;
> > >  
> > > -	len = s->seq.len - s->seq.readpos;
> > > +	len = trace_seq_used(s) - s->seq.readpos;
> > >  	if (cnt > len)
> > >  		cnt = len;
> > >  	memcpy(buf, s->buffer + s->seq.readpos, cnt);
> > 
> > 
> > There is one more dangerous usage in trace_printk_seq(). It is on
> > three lines there.
> 
> You totally confused me. What usage in trace_printk_seq(), and what
> three lines?
> 
> In this patch, trace_printk_seq() looks like this:
> 
> int trace_print_seq(struct seq_file *m, struct trace_seq *s)
> {
>         int ret;
> 
>         __trace_seq_init(s);
> 
>         ret = seq_buf_print_seq(m, &s->seq);
> 
>         /*
>          * Only reset this buffer if we successfully wrote to the
>          * seq_file buffer. This lets the caller try again or
>          * do something else with the contents.
>          */
>         if (!ret)
>                 trace_seq_init(s);
> 
>         return ret;
> }

The confusion is caused by the 'k' ("print" vs. "printk") in the
function name. I was talking about the following function from
kernel/trace/trace.c:

void
trace_printk_seq(struct trace_seq *s)
{
	/* Probably should print a warning here. */
	if (s->seq.len >= TRACE_MAX_PRINT)
		s->seq.len = TRACE_MAX_PRINT;

	/* should be zero ended, but we are paranoid. */
	s->buffer[s->seq.len] = 0;

	printk(KERN_TRACE "%s", s->buffer);

	trace_seq_init(s);
}

I found it when checking the applied patches in origin/rfc/seq-buf
branch. I hope that it was the correct place.

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-19 11:40           ` Petr Mladek
@ 2014-11-19 13:48             ` Steven Rostedt
  2014-11-19 14:40               ` Petr Mladek
  0 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-19 13:48 UTC (permalink / raw)
  To: Petr Mladek; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed, 19 Nov 2014 12:40:17 +0100
Petr Mladek <pmladek@suse.cz> wrote:

> > > 
> > > There is one more dangerous usage in trace_printk_seq(). It is on
> > > three lines there.
> > 
> > You totally confused me. What usage in trace_printk_seq(), and what
> > three lines?
> > 
> > In this patch, trace_printk_seq() looks like this:
> > 
> > int trace_print_seq(struct seq_file *m, struct trace_seq *s)
> > {
> >         int ret;
> > 
> >         __trace_seq_init(s);
> > 
> >         ret = seq_buf_print_seq(m, &s->seq);
> > 
> >         /*
> >          * Only reset this buffer if we successfully wrote to the
> >          * seq_file buffer. This lets the caller try again or
> >          * do something else with the contents.
> >          */
> >         if (!ret)
> >                 trace_seq_init(s);
> > 
> >         return ret;
> > }
> 
> The confusion is caused by the 'k' ("print" vs. "printk") in the
> function name. I was talking about the following function from
> kernel/trace/trace.c:

Silly 'k', Trix are for kids!

> 
> void
> trace_printk_seq(struct trace_seq *s)
> {
> 	/* Probably should print a warning here. */
> 	if (s->seq.len >= TRACE_MAX_PRINT)
> 		s->seq.len = TRACE_MAX_PRINT;
> 
> 	/* should be zero ended, but we are paranoid. */
> 	s->buffer[s->seq.len] = 0;
> 
> 	printk(KERN_TRACE "%s", s->buffer);
> 
> 	trace_seq_init(s);
> }
> 
> I found it when checking the applied patches in origin/rfc/seq-buf
> branch. I hope that it was the correct place.

Yes, that's the working branch for this code.

Anyway, I saw this and thought about using trace_seq_used(), but then I
realized that this is trace_seq code which has a hard coded buffer
length of PAGE_SIZE which on all archs is more than 1000
(TRACE_MAX_PRINT).

Regardless of overflow or not (or even if trace_seq is full), that if
statement will prevent this from doing any buffer overflows.

s->seq.len will never be more than s->seq.size after the test against
TRACE_MAX_PRINT. So I see no harm here.

trace_printk_seq() is for dumping the ring buffer to console, which is
usually something done on panic. It's special.

-- Steve

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-19 13:48             ` Steven Rostedt
@ 2014-11-19 14:40               ` Petr Mladek
  2014-11-19 15:01                 ` Steven Rostedt
  2014-11-19 16:00                 ` Steven Rostedt
  0 siblings, 2 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-19 14:40 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed 2014-11-19 08:48:00, Steven Rostedt wrote:
> On Wed, 19 Nov 2014 12:40:17 +0100
> Petr Mladek <pmladek@suse.cz> wrote:
> 
> > > > 
> > > > There is one more dangerous usage in trace_printk_seq(). It is on
> > > > three lines there.
> > > 
> > > You totally confused me. What usage in trace_printk_seq(), and what
> > > three lines?
> > > 
> > The confusion is caused by the 'k' ("print" vs. "printk") in the
> > function name. I was talking about the following function from
> > kernel/trace/trace.c:
> 
> Silly 'k', Trix are for kids!

:-)
 
> > 
> > void
> > trace_printk_seq(struct trace_seq *s)
> > {
> > 	/* Probably should print a warning here. */
> > 	if (s->seq.len >= TRACE_MAX_PRINT)
> > 		s->seq.len = TRACE_MAX_PRINT;
> > 
> > 	/* should be zero ended, but we are paranoid. */
> > 	s->buffer[s->seq.len] = 0;
> > 
> > 	printk(KERN_TRACE "%s", s->buffer);
> > 
> > 	trace_seq_init(s);
> > }
> > 
> > I found it when checking the applied patches in origin/rfc/seq-buf
> > branch. I hope that it was the correct place.
> 
> Yes, that's the working branch for this code.
> 
> Anyway, I saw this and thought about using trace_seq_used(), but then I
> realized that this is trace_seq code which has a hard coded buffer
> length of PAGE_SIZE which on all archs is more than 1000
> (TRACE_MAX_PRINT).
> 
> Regardless of overflow or not (or even if trace_seq is full), that if
> statement will prevent this from doing any buffer overflows.
> 
> s->seq.len will never be more than s->seq.size after the test against
> TRACE_MAX_PRINT. So I see no harm here.

Ah, I see. Well, I would feel more comfortable if it uses
trace_seq_used() or if there is some explanation in a comment.
But you are right, it is safe as it is. Feel free to leave it.

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 14/26 v5] tracing: Create seq_buf layer in trace_seq
  2014-11-15  4:59 ` [PATCH 14/26 v5] tracing: Create seq_buf layer in trace_seq Steven Rostedt
@ 2014-11-19 14:51   ` Petr Mladek
  2014-11-19 15:08     ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Petr Mladek @ 2014-11-19 14:51 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Fri 2014-11-14 23:59:01, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> Create a seq_buf layer that trace_seq sits on. The seq_buf will not
> be limited to page size. This will allow other usages of seq_buf
> instead of a hard set PAGE_SIZE one that trace_seq has.
> 
> Link: http://lkml.kernel.org/r/20141104160221.864997179@goodmis.org
> Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
> 
> Tested-by: Jiri Kosina <jkosina@suse.cz>
> Acked-by: Jiri Kosina <jkosina@suse.cz>
> Reviewed-by: Petr Mladek <pmladek@suse.cz>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  include/linux/seq_buf.h              |  81 +++++++++
>  include/linux/trace_seq.h            |  12 +-
>  kernel/trace/Makefile                |   1 +
>  kernel/trace/seq_buf.c               | 341 +++++++++++++++++++++++++++++++++++
>  kernel/trace/trace.c                 |  39 ++--
>  kernel/trace/trace_events.c          |   6 +-
>  kernel/trace/trace_functions_graph.c |   6 +-
>  kernel/trace/trace_seq.c             | 177 +++++++++---------
>  8 files changed, 538 insertions(+), 125 deletions(-)
>  create mode 100644 include/linux/seq_buf.h
>  create mode 100644 kernel/trace/seq_buf.c

[...]
 
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index 100288d10e1f..6d1342ae7a44 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c

[...]

> @@ -163,21 +176,22 @@ EXPORT_SYMBOL_GPL(trace_seq_vprintf);
>   */
>  void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
>  {
> -	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
> +	unsigned int save_len = s->seq.len;
>  	int ret;

Last but one small thing. The "ret" is assigned but not longer used.

JFYI, I have skipped this patch yesterday because it was long and already
marked as reviewed. I could not help myself and double checked it today.

> -	if (s->full || !len)
> +	if (s->full)
>  		return;
>  
> -	ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
> +	__trace_seq_init(s);
> +
> +	ret = seq_buf_bprintf(&s->seq, fmt, binary);
>  
>  	/* If we can't write it all, don't bother writing anything */
> -	if (ret >= len) {
> +	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
> +		s->seq.len = save_len;
>  		s->full = 1;
>  		return;
>  	}
> -
> -	s->len += ret;
>  }
>  EXPORT_SYMBOL_GPL(trace_seq_bprintf);

The last small thing is the same unused "ret" in trace_seq_path(). But
this one should get fixed in "[PATCH 15/26 v5] tracing: Convert
seq_buf_path() to be like seq_path()".

Both these changes are rather cosmetic. Feel free to leave them for
some later clean up.


Eureka, I have finished review of the patchset and am happy with it \o/
I am looking forward to see it in the main tree.

Thanks a lot for the hard work.

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-19 14:40               ` Petr Mladek
@ 2014-11-19 15:01                 ` Steven Rostedt
  2014-11-19 16:00                 ` Steven Rostedt
  1 sibling, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-19 15:01 UTC (permalink / raw)
  To: Petr Mladek; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed, 19 Nov 2014 15:40:05 +0100
Petr Mladek <pmladek@suse.cz> wrote:

> > s->seq.len will never be more than s->seq.size after the test against
> > TRACE_MAX_PRINT. So I see no harm here.
> 
> Ah, I see. Well, I would feel more comfortable if it uses
> trace_seq_used() or if there is some explanation in a comment.
> But you are right, it is safe as it is. Feel free to leave it.

Yeah, a comment would be nice. I may add it late.

> 
> Reviewed-by: Petr Mladek <pmladek@suse.cz>

Thanks,

-- Steve

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 14/26 v5] tracing: Create seq_buf layer in trace_seq
  2014-11-19 14:51   ` Petr Mladek
@ 2014-11-19 15:08     ` Steven Rostedt
  0 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-19 15:08 UTC (permalink / raw)
  To: Petr Mladek; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed, 19 Nov 2014 15:51:38 +0100
Petr Mladek <pmladek@suse.cz> wrote:

> On Fri 2014-11-14 23:59:01, Steven Rostedt wrote:
> > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> > 
> > Create a seq_buf layer that trace_seq sits on. The seq_buf will not
> > be limited to page size. This will allow other usages of seq_buf
> > instead of a hard set PAGE_SIZE one that trace_seq has.
> > 
> > Link: http://lkml.kernel.org/r/20141104160221.864997179@goodmis.org
> > Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
> > 
> > Tested-by: Jiri Kosina <jkosina@suse.cz>
> > Acked-by: Jiri Kosina <jkosina@suse.cz>
> > Reviewed-by: Petr Mladek <pmladek@suse.cz>
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > ---
> >  include/linux/seq_buf.h              |  81 +++++++++
> >  include/linux/trace_seq.h            |  12 +-
> >  kernel/trace/Makefile                |   1 +
> >  kernel/trace/seq_buf.c               | 341 +++++++++++++++++++++++++++++++++++
> >  kernel/trace/trace.c                 |  39 ++--
> >  kernel/trace/trace_events.c          |   6 +-
> >  kernel/trace/trace_functions_graph.c |   6 +-
> >  kernel/trace/trace_seq.c             | 177 +++++++++---------
> >  8 files changed, 538 insertions(+), 125 deletions(-)
> >  create mode 100644 include/linux/seq_buf.h
> >  create mode 100644 kernel/trace/seq_buf.c
> 
> [...]
>  
> > diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> > index 100288d10e1f..6d1342ae7a44 100644
> > --- a/kernel/trace/trace_functions_graph.c
> > +++ b/kernel/trace/trace_functions_graph.c
> 
> [...]
> 
> > @@ -163,21 +176,22 @@ EXPORT_SYMBOL_GPL(trace_seq_vprintf);
> >   */
> >  void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
> >  {
> > -	unsigned int len = TRACE_SEQ_BUF_LEFT(s);
> > +	unsigned int save_len = s->seq.len;
> >  	int ret;
> 
> Last but one small thing. The "ret" is assigned but not longer used.
> 
> JFYI, I have skipped this patch yesterday because it was long and already
> marked as reviewed. I could not help myself and double checked it today.
> 

OK, I'll fix that up.

> > -	if (s->full || !len)
> > +	if (s->full)
> >  		return;
> >  
> > -	ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
> > +	__trace_seq_init(s);
> > +
> > +	ret = seq_buf_bprintf(&s->seq, fmt, binary);
> >  
> >  	/* If we can't write it all, don't bother writing anything */
> > -	if (ret >= len) {
> > +	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
> > +		s->seq.len = save_len;
> >  		s->full = 1;
> >  		return;
> >  	}
> > -
> > -	s->len += ret;
> >  }
> >  EXPORT_SYMBOL_GPL(trace_seq_bprintf);
> 
> The last small thing is the same unused "ret" in trace_seq_path(). But
> this one should get fixed in "[PATCH 15/26 v5] tracing: Convert
> seq_buf_path() to be like seq_path()".

OK, I'll try to remember that :-)

> 
> Both these changes are rather cosmetic. Feel free to leave them for
> some later clean up.
> 
> 
> Eureka, I have finished review of the patchset and am happy with it \o/
> I am looking forward to see it in the main tree.

Well now it comes down to Linus or Andrew giving me the OK. I've pulled
all the trace_seq updates into my ftrace/core branch (which will be
going into my for-next branch shortly). I stopped just before this
patch. I didn't want to create the seq_buf until I knew it was going to
be used by something other than trace_seq.

> 
> Thanks a lot for the hard work.
> 

Yeah, let's hope that it was worth it.

Thanks for the in depth reviews.

-- Steve

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 18/26 v5] seq_buf: Create seq_buf_used() to find out how much was written
  2014-11-18 15:02   ` Petr Mladek
@ 2014-11-19 15:49     ` Steven Rostedt
  2014-11-19 16:30       ` Petr Mladek
  0 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-19 15:49 UTC (permalink / raw)
  To: Petr Mladek; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Tue, 18 Nov 2014 16:02:04 +0100
Petr Mladek <pmladek@suse.cz> wrote:

> On Fri 2014-11-14 23:59:05, Steven Rostedt wrote:
> > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> > 
> > Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
> > private macro to let callers have a method to know how much of the
> > seq_buf was written to.
> > 
> > Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
> > Link: http://lkml.kernel.org/r/20141114011413.321654244@goodmis.org
> > 
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > ---
> >  include/linux/seq_buf.h | 6 ++++++
> >  kernel/trace/seq_buf.c  | 5 +----
> >  2 files changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
> > index 5d91262433e2..93718e570d4c 100644
> > --- a/include/linux/seq_buf.h
> > +++ b/include/linux/seq_buf.h
> > @@ -64,6 +64,12 @@ seq_buf_buffer_left(struct seq_buf *s)
> >  	return (s->size - 1) - s->len;
> >  }
> >  
> > +/* How much buffer was written? */
> > +static inline unsigned int seq_buf_used(struct seq_buf *s)
> > +{
> > +	return min(s->len, s->size);
> 
> To be precise, it should do
> 
> 	return min(s->len, s->size - 1);
> 
> at this stage and switch to the above code in ("[PATCH 21/26 v5] tracing: Have
> seq_buf use full buffer"). Well, it does not cause any big harm. Feel
> free to add:

I actually thought about it, but realized that this only replaces the
original use of s->len, and we are only doing this to avoid buffer
overflows. If you get garbage, then so be it, as the original code
would give garbage too. Remember, some of the functions did have real
content in that last byte, even though it was considered "overflowed".

-- Steve


> 
> Reviewed-by: Petr Mladek <pmladek@suse.cz>
> 
> for this patch or for the updated one.
> 

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-19 14:40               ` Petr Mladek
  2014-11-19 15:01                 ` Steven Rostedt
@ 2014-11-19 16:00                 ` Steven Rostedt
  2014-11-19 16:44                   ` Petr Mladek
  1 sibling, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-19 16:00 UTC (permalink / raw)
  To: Petr Mladek; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed, 19 Nov 2014 15:40:05 +0100
Petr Mladek <pmladek@suse.cz> wrote:

> > Regardless of overflow or not (or even if trace_seq is full), that if
> > statement will prevent this from doing any buffer overflows.
> > 
> > s->seq.len will never be more than s->seq.size after the test against
> > TRACE_MAX_PRINT. So I see no harm here.
> 
> Ah, I see. Well, I would feel more comfortable if it uses
> trace_seq_used() or if there is some explanation in a comment.
> But you are right, it is safe as it is. Feel free to leave it.
> 

OK, I added this just for you:

BTW, using trace_seq_used() would not be good enough because it could
return s->seq.size. Which would overflow the buffer on the

	s->buffer[s->seq.len] = 0;

-- Steve

>From 1922acc9987d23d0b9c1ad28dc3eaafc1cf2d6b7 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Date: Wed, 19 Nov 2014 10:56:41 -0500
Subject: [PATCH] tracing: Add paranoid size check in trace_printk_seq()

To be really paranoid about writing out of bound data in
trace_printk_seq(), add another check of len compared to size.

Link: http://lkml.kernel.org/r/20141119144004.GB2332@dhcp128.suse.cz

Suggested-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9023446b2c2b..26facec4625e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6656,6 +6656,14 @@ trace_printk_seq(struct trace_seq *s)
 	if (s->seq.len >= TRACE_MAX_PRINT)
 		s->seq.len = TRACE_MAX_PRINT;
 
+	/*
+	 * More paranoid code. Although the buffer size is set to
+	 * PAGE_SIZE, and TRACE_MAX_PRINT is 1000, this is just
+	 * an extra layer of protection.
+	 */
+	if (WARN_ON_ONCE(s->seq.len >= s->seq.size))
+		s->seq.len = s->seq.size - 1;
+
 	/* should be zero ended, but we are paranoid. */
 	s->buffer[s->seq.len] = 0;
 
-- 
1.8.1.4


^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page()
  2014-11-18 16:15       ` Petr Mladek
@ 2014-11-19 16:17         ` Steven Rostedt
  2014-11-19 16:51           ` Petr Mladek
  0 siblings, 1 reply; 70+ messages in thread
From: Steven Rostedt @ 2014-11-19 16:17 UTC (permalink / raw)
  To: Petr Mladek; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Tue, 18 Nov 2014 17:15:46 +0100
Petr Mladek <pmladek@suse.cz> wrote:

> On Mon 2014-11-17 14:11:08, Steven Rostedt wrote:
> > > 
> > > I don't like the fact that I did a code structure change with this
> > > patch. This patch should be just a simple conversion of len to
> > > seq_buf_used(). I'm going to strip this change out and put it before
> > > this patch.
> > 
> > 
> > The function tracing_fill_pipe_page() logic is a little confusing with the
> > use of count saving the seq.len and reusing it.
> > 
> > Instead of subtracting a number that is calculated from the saved
> > value of the seq.len from seq.len, just save the seq.len at the start
> > and if we need to reset it, just assign it again.
> > 
> > When the seq_buf overflow is len == size + 1, the current logic will
> > break. Changing it to use a saved length for resetting back to the
> > original value is more robust and will work when we change the way
> > seq_buf sets the overflow.
> > 
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > ---
> >  kernel/trace/trace.c | 26 ++++++++++++++++++++------
> >  1 file changed, 20 insertions(+), 6 deletions(-)
> > 
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index 7d7a07e9b9e9..2dbc18e5f929 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -4575,23 +4575,37 @@ static size_t
> >  tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
> >  {
> >  	size_t count;
> > +	int save_len;
> >  	int ret;
> >  
> >  	/* Seq buffer is page-sized, exactly what we need. */
> >  	for (;;) {
> > -		count = iter->seq.seq.len;
> > +		save_len = iter->seq.seq.len;
> >  		ret = print_trace_line(iter);
> > -		count = iter->seq.seq.len - count;
> > -		if (rem < count) {
> > -			rem = 0;
> > -			iter->seq.seq.len -= count;
> > +
> > +		if (trace_seq_has_overflowed(&iter->seq)) {
> > +			iter->seq.seq.len = save_len;
> >  			break;
> >  		}
> > +
> > +		/*
> > +		 * This should not be hit, because it should only
> > +		 * be set if the iter->seq overflowed. But check it
> > +		 * anyway to be safe.
> > +		 */
> >  		if (ret == TRACE_TYPE_PARTIAL_LINE) {
> > -			iter->seq.seq.len -= count;
> > +			iter->seq.seq.len = save_len;
> >  			break;
> >  		}
> 
> The two ifs has the same body. Small optimization would be to do:
> 
> 		/*
> 		 * The two checks should be equivalent but rather be
> 		 * on the safe side.
> 		 */
> 		if (trace_seq_has_overflowed(&iter->seq) ||
> 		    ret == TRACE_TYPE_PARTIAL_LINE) {
> 			iter->seq.seq.len = save_len;
> 			break;
> 		}

Yeah, I originally had something like that, but I wanted to remove that
second check. I left it separate to make it stand out as something that
might be removed in the future. Just a preference I guess.

> 
> To be honest, the code seems to be a bit twisted. This function
> is called from tracing_splice_read_pipe(). It copies the
> trace_seq buffer into spd.page and call trace_seq_init()
> in a for cycle.

Yeah, that splice code confused me too. I'll start looking at it some
more and see if it can be fixed up.

> 
> Therefore if the overflow happens, trace_find_next_entry_inc()
> is not called in tracing_fill_pipe_page() and we work with the same
> iterator instance next time. It means that the overflow happens most
> likely again and we fill all remaining spd.pages with no data and
> are stacked on the same iterator instance.

Luckily, overflows never happen. But if they do, things might break.

> 
> BTW: The trace_seq_to_buffer() in tracing_splice_read_pipe()
> is suspicious as well. It passes trace_seq_used(&iter->seq)
> as the "cnt" parameter. I guess that it should pass the
> size of the "spd.page" instead.

Wow, I should have looked harder at that code when I accepted it. It
just "worked" and I was happy. Oh well, another thing to fix up.

> 
> Also we should somehow handle the situation when some data are not
> copied. Well, it seems the spd.page has the page size, so it is
> the same size as the trace_seq buffer.
> 
> 
> Well, this patch does not change the behavior. We could solve the
> above problem later if it is there. Maybe I got it wrong.

No, that code doesn't look too good. That's some old stuff that got in
when we were still learning, and if it worked, we added it ;-)

That needs to be cleaned up. I'll put it on my ever growing todo list.
Of course if you want to clean it up, feel free to send some patches on
top of this. That is, if we get the OK from Linus or Andrew.


> 
> Reviewed-by: Petr Mladek <pmladek@suse.cz>
> 

Thanks,

-- Steve

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 18/26 v5] seq_buf: Create seq_buf_used() to find out how much was written
  2014-11-19 15:49     ` Steven Rostedt
@ 2014-11-19 16:30       ` Petr Mladek
  0 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-19 16:30 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed 2014-11-19 10:49:56, Steven Rostedt wrote:
> On Tue, 18 Nov 2014 16:02:04 +0100
> Petr Mladek <pmladek@suse.cz> wrote:
> 
> > On Fri 2014-11-14 23:59:05, Steven Rostedt wrote:
> > > From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> > > 
> > > Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
> > > private macro to let callers have a method to know how much of the
> > > seq_buf was written to.
> > > 
> > > Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
> > > Link: http://lkml.kernel.org/r/20141114011413.321654244@goodmis.org
> > > 
> > > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > > ---
> > >  include/linux/seq_buf.h | 6 ++++++
> > >  kernel/trace/seq_buf.c  | 5 +----
> > >  2 files changed, 7 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
> > > index 5d91262433e2..93718e570d4c 100644
> > > --- a/include/linux/seq_buf.h
> > > +++ b/include/linux/seq_buf.h
> > > @@ -64,6 +64,12 @@ seq_buf_buffer_left(struct seq_buf *s)
> > >  	return (s->size - 1) - s->len;
> > >  }
> > >  
> > > +/* How much buffer was written? */
> > > +static inline unsigned int seq_buf_used(struct seq_buf *s)
> > > +{
> > > +	return min(s->len, s->size);
> > 
> > To be precise, it should do
> > 
> > 	return min(s->len, s->size - 1);
> > 
> > at this stage and switch to the above code in ("[PATCH 21/26 v5] tracing: Have
> > seq_buf use full buffer"). Well, it does not cause any big harm. Feel
> > free to add:
> 
> I actually thought about it, but realized that this only replaces the
> original use of s->len, and we are only doing this to avoid buffer
> overflows. If you get garbage, then so be it, as the original code
> would give garbage too. Remember, some of the functions did have real
> content in that last byte, even though it was considered "overflowed".

I thought that it was based on ftrace_seq code that had

#define TRACE_SEQ_BUF_USED(s) min((s)->len, (unsigned int)(PAGE_SIZE -
 1))

But you are right that the callers used s->len because the macro was
local in trace_seq.c.

Well, I think that it does not matter much. As you said, there might be
a garbage a the end of the buffer. Callers used "len" directly.
Also it will be min(s->len, s->size); after the commit "Have seq_buf
use full buffer".

Let's leave it as is.

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len
  2014-11-19 16:00                 ` Steven Rostedt
@ 2014-11-19 16:44                   ` Petr Mladek
  0 siblings, 0 replies; 70+ messages in thread
From: Petr Mladek @ 2014-11-19 16:44 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed 2014-11-19 11:00:37, Steven Rostedt wrote:
> On Wed, 19 Nov 2014 15:40:05 +0100
> Petr Mladek <pmladek@suse.cz> wrote:
> 
> > > Regardless of overflow or not (or even if trace_seq is full), that if
> > > statement will prevent this from doing any buffer overflows.
> > > 
> > > s->seq.len will never be more than s->seq.size after the test against
> > > TRACE_MAX_PRINT. So I see no harm here.
> > 
> > Ah, I see. Well, I would feel more comfortable if it uses
> > trace_seq_used() or if there is some explanation in a comment.
> > But you are right, it is safe as it is. Feel free to leave it.
> > 
> 
> OK, I added this just for you:
>
> BTW, using trace_seq_used() would not be good enough because it could
> return s->seq.size. Which would overflow the buffer on the
> 
> 	s->buffer[s->seq.len] = 0;

Great catch!

> -- Steve
> 
> From 1922acc9987d23d0b9c1ad28dc3eaafc1cf2d6b7 Mon Sep 17 00:00:00 2001
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> Date: Wed, 19 Nov 2014 10:56:41 -0500
> Subject: [PATCH] tracing: Add paranoid size check in trace_printk_seq()
> 
> To be really paranoid about writing out of bound data in
> trace_printk_seq(), add another check of len compared to size.
> 
> Link: http://lkml.kernel.org/r/20141119144004.GB2332@dhcp128.suse.cz
> 
> Suggested-by: Petr Mladek <pmladek@suse.cz>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Thanks a lot for the addition.

Best Regards,
Petr

> ---
>  kernel/trace/trace.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 9023446b2c2b..26facec4625e 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -6656,6 +6656,14 @@ trace_printk_seq(struct trace_seq *s)
>  	if (s->seq.len >= TRACE_MAX_PRINT)
>  		s->seq.len = TRACE_MAX_PRINT;
>  
> +	/*
> +	 * More paranoid code. Although the buffer size is set to
> +	 * PAGE_SIZE, and TRACE_MAX_PRINT is 1000, this is just
> +	 * an extra layer of protection.
> +	 */
> +	if (WARN_ON_ONCE(s->seq.len >= s->seq.size))
> +		s->seq.len = s->seq.size - 1;
> +
>  	/* should be zero ended, but we are paranoid. */
>  	s->buffer[s->seq.len] = 0;
>  
> -- 
> 1.8.1.4
> 

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page()
  2014-11-19 16:17         ` Steven Rostedt
@ 2014-11-19 16:51           ` Petr Mladek
  2014-11-19 17:12             ` Steven Rostedt
  0 siblings, 1 reply; 70+ messages in thread
From: Petr Mladek @ 2014-11-19 16:51 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed 2014-11-19 11:17:18, Steven Rostedt wrote:
> On Tue, 18 Nov 2014 17:15:46 +0100
> Petr Mladek <pmladek@suse.cz> wrote:
> 
> > On Mon 2014-11-17 14:11:08, Steven Rostedt wrote:
> > > > 
> > > > I don't like the fact that I did a code structure change with this
> > > > patch. This patch should be just a simple conversion of len to
> > > > seq_buf_used(). I'm going to strip this change out and put it before
> > > > this patch.
> > > 
> > > 
> > > The function tracing_fill_pipe_page() logic is a little confusing with the
> > > use of count saving the seq.len and reusing it.
> > > 
> > > Instead of subtracting a number that is calculated from the saved
> > > value of the seq.len from seq.len, just save the seq.len at the start
> > > and if we need to reset it, just assign it again.
> > > 
> > > When the seq_buf overflow is len == size + 1, the current logic will
> > > break. Changing it to use a saved length for resetting back to the
> > > original value is more robust and will work when we change the way
> > > seq_buf sets the overflow.
> > > 
> > > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > > ---
> > >  kernel/trace/trace.c | 26 ++++++++++++++++++++------
> > >  1 file changed, 20 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > > index 7d7a07e9b9e9..2dbc18e5f929 100644
> > > --- a/kernel/trace/trace.c
> > > +++ b/kernel/trace/trace.c
> > > @@ -4575,23 +4575,37 @@ static size_t
> > >  tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
> > >  {
> > >  	size_t count;
> > > +	int save_len;
> > >  	int ret;
> > >  
> > >  	/* Seq buffer is page-sized, exactly what we need. */
> > >  	for (;;) {
> > > -		count = iter->seq.seq.len;
> > > +		save_len = iter->seq.seq.len;
> > >  		ret = print_trace_line(iter);
> > > -		count = iter->seq.seq.len - count;
> > > -		if (rem < count) {
> > > -			rem = 0;
> > > -			iter->seq.seq.len -= count;
> > > +
> > > +		if (trace_seq_has_overflowed(&iter->seq)) {
> > > +			iter->seq.seq.len = save_len;
> > >  			break;
> > >  		}
> > > +
> > > +		/*
> > > +		 * This should not be hit, because it should only
> > > +		 * be set if the iter->seq overflowed. But check it
> > > +		 * anyway to be safe.
> > > +		 */
> > >  		if (ret == TRACE_TYPE_PARTIAL_LINE) {
> > > -			iter->seq.seq.len -= count;
> > > +			iter->seq.seq.len = save_len;
> > >  			break;
> > >  		}
> > 
> > The two ifs has the same body. Small optimization would be to do:
> > 
> > 		/*
> > 		 * The two checks should be equivalent but rather be
> > 		 * on the safe side.
> > 		 */
> > 		if (trace_seq_has_overflowed(&iter->seq) ||
> > 		    ret == TRACE_TYPE_PARTIAL_LINE) {
> > 			iter->seq.seq.len = save_len;
> > 			break;
> > 		}
> 
> Yeah, I originally had something like that, but I wanted to remove that
> second check. I left it separate to make it stand out as something that
> might be removed in the future. Just a preference I guess.

Fair enough.

> > To be honest, the code seems to be a bit twisted. This function
> > is called from tracing_splice_read_pipe(). It copies the
> > trace_seq buffer into spd.page and call trace_seq_init()
> > in a for cycle.
> 
> Yeah, that splice code confused me too. I'll start looking at it some
> more and see if it can be fixed up.
> 
> > 
> > Therefore if the overflow happens, trace_find_next_entry_inc()
> > is not called in tracing_fill_pipe_page() and we work with the same
> > iterator instance next time. It means that the overflow happens most
> > likely again and we fill all remaining spd.pages with no data and
> > are stacked on the same iterator instance.
> 
> Luckily, overflows never happen. But if they do, things might break.

I thought so. :-)

> > 
> > BTW: The trace_seq_to_buffer() in tracing_splice_read_pipe()
> > is suspicious as well. It passes trace_seq_used(&iter->seq)
> > as the "cnt" parameter. I guess that it should pass the
> > size of the "spd.page" instead.
> 
> Wow, I should have looked harder at that code when I accepted it. It
> just "worked" and I was happy. Oh well, another thing to fix up.
> 
> > 
> > Also we should somehow handle the situation when some data are not
> > copied. Well, it seems the spd.page has the page size, so it is
> > the same size as the trace_seq buffer.
> > 
> > 
> > Well, this patch does not change the behavior. We could solve the
> > above problem later if it is there. Maybe I got it wrong.
> 
> No, that code doesn't look too good. That's some old stuff that got in
> when we were still learning, and if it worked, we added it ;-)
> 
> That needs to be cleaned up. I'll put it on my ever growing todo
> list.

I believe. I am a bit scared to put it on my todo list because these
kind of working things tend to just fall down.


> Of course if you want to clean it up, feel free to send some patches on
> top of this. That is, if we get the OK from Linus or Andrew.

OK, I'll put it on my todo list. Let's see who is faster ;-) And I
keep my fingers crossed about the OK from Linus and Andrew.

Best Regards,
Petr

^ permalink raw reply	[flat|nested] 70+ messages in thread

* Re: [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page()
  2014-11-19 16:51           ` Petr Mladek
@ 2014-11-19 17:12             ` Steven Rostedt
  0 siblings, 0 replies; 70+ messages in thread
From: Steven Rostedt @ 2014-11-19 17:12 UTC (permalink / raw)
  To: Petr Mladek; +Cc: linux-kernel, Ingo Molnar, Andrew Morton, Jiri Kosina

On Wed, 19 Nov 2014 17:51:49 +0100
Petr Mladek <pmladek@suse.cz> wrote:

 
> OK, I'll put it on my todo list. Let's see who is faster ;-) And I
> keep my fingers crossed about the OK from Linus and Andrew.

I'll assume they are going to be OK'd. I'll place these patches in a
separate branch and after I finish testing (and get acks from my
ftrace/core branch), I'll push them all up to my for-next branch.

Then when the merge window opens, I'll push the normal ftrace/core
code, and then push this one separate, and let Linus decide if he wants
to pull it or not.

Here's the commits that are in this branch and not in ftrace/core:

+ 1293ffff tracing: Create seq_buf layer in trace_seq
+ b5e206f2 tracing: Convert seq_buf_path() to be like seq_path()
+ 79033e01 tracing: Convert seq_buf fields to be like seq_file fields
+ f1698325 tracing: Add a seq_buf_clear() helper and clear len and readpos in init
+ 2b644c7f seq_buf: Create seq_buf_used() to find out how much was written
+ a5c4b79c tracing: Clean up tracing_fill_pipe_page()
+ 359ba4a9 tracing: Use trace_seq_used() and seq_buf_used() instead of len
+ 3ae8769e tracing: Add paranoid size check in trace_printk_seq()
+ e1fb15f1 seq_buf: Add seq_buf_can_fit() helper function
+ 02f09612 tracing: Have seq_buf use full buffer
+ d9c7f4b1 tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions
+ 678a330a seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF
+ a3608c5d seq_buf: Move the seq_buf code to lib/
+ af8f0ef4 printk: Add per_cpu printk func to allow printk to be diverted
+ a066719f x86/nmi: Perform a safe NMI stack trace on all CPUs


-- Steve

^ permalink raw reply	[flat|nested] 70+ messages in thread

end of thread, other threads:[~2014-11-19 17:12 UTC | newest]

Thread overview: 70+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-11-15  4:58 [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
2014-11-15  4:58 ` [PATCH 01/26 v5] tracing: Fix trace_seq_bitmask() to start at current position Steven Rostedt
2014-11-15  4:58 ` [PATCH 02/26 v5] tracing: Add trace_seq_has_overflowed() and trace_handle_return() Steven Rostedt
2014-11-15  4:58 ` [PATCH 03/26 v5] blktrace/tracing: Use trace_seq_has_overflowed() helper function Steven Rostedt
2014-11-15  4:58 ` [PATCH 04/26 v5] ring-buffer: Remove check of trace_seq_{puts,printf}() return values Steven Rostedt
2014-11-15  4:58 ` [PATCH 05/26 v5] tracing: Have branch tracer use trace_handle_return() helper function Steven Rostedt
2014-11-15  4:58 ` [PATCH 06/26 v5] tracing: Have function_graph use trace_seq_has_overflowed() Steven Rostedt
2014-11-15  4:58 ` [PATCH 07/26 v5] kprobes/tracing: Use trace_seq_has_overflowed() for overflow checks Steven Rostedt
2014-11-18 14:02   ` Petr Mladek
2014-11-15  4:58 ` [PATCH 08/26 v5] tracing: Do not check return values of trace_seq_p*() for mmio tracer Steven Rostedt
2014-11-18 14:06   ` Petr Mladek
2014-11-15  4:58 ` [PATCH 09/26 v5] tracing/probes: Do not use return value of trace_seq_printf() Steven Rostedt
2014-11-18 14:09   ` Petr Mladek
2014-11-15  4:58 ` [PATCH 10/26 v5] tracing/uprobes: Do not use return values " Steven Rostedt
2014-11-17  5:28   ` Masami Hiramatsu
2014-11-17  5:58   ` Srikar Dronamraju
2014-11-18 14:13   ` Petr Mladek
2014-11-15  4:58 ` [PATCH 11/26 v5] tracing: Do not use return values of trace_seq_printf() in syscall tracing Steven Rostedt
2014-11-15  4:58 ` [PATCH 12/26 v5] tracing: Remove return values of most trace_seq_*() functions Steven Rostedt
2014-11-18 14:18   ` Petr Mladek
2014-11-15  4:59 ` [PATCH 13/26 v5] tracing: Fix return value of ftrace_raw_output_prep() Steven Rostedt
2014-11-18 14:24   ` Petr Mladek
2014-11-15  4:59 ` [PATCH 14/26 v5] tracing: Create seq_buf layer in trace_seq Steven Rostedt
2014-11-19 14:51   ` Petr Mladek
2014-11-19 15:08     ` Steven Rostedt
2014-11-15  4:59 ` [PATCH 15/26 v5] tracing: Convert seq_buf_path() to be like seq_path() Steven Rostedt
2014-11-15  4:59 ` [PATCH 16/26 v5] tracing: Convert seq_buf fields to be like seq_file fields Steven Rostedt
2014-11-15  4:59 ` [PATCH 17/26 v5] tracing: Add a seq_buf_clear() helper and clear len and readpos in init Steven Rostedt
2014-11-15  4:59 ` [PATCH 18/26 v5] seq_buf: Create seq_buf_used() to find out how much was written Steven Rostedt
2014-11-18 15:02   ` Petr Mladek
2014-11-19 15:49     ` Steven Rostedt
2014-11-19 16:30       ` Petr Mladek
2014-11-15  4:59 ` [PATCH 19/26 v5] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
2014-11-17 17:32   ` Steven Rostedt
2014-11-17 19:11     ` [PATCH 1/2] tracing: Clean up tracing_fill_pipe_page() Steven Rostedt
2014-11-18 16:15       ` Petr Mladek
2014-11-19 16:17         ` Steven Rostedt
2014-11-19 16:51           ` Petr Mladek
2014-11-19 17:12             ` Steven Rostedt
2014-11-17 19:12     ` [PATCH 2/2] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
2014-11-18 16:33       ` Petr Mladek
2014-11-18 17:37         ` Steven Rostedt
2014-11-19 11:40           ` Petr Mladek
2014-11-19 13:48             ` Steven Rostedt
2014-11-19 14:40               ` Petr Mladek
2014-11-19 15:01                 ` Steven Rostedt
2014-11-19 16:00                 ` Steven Rostedt
2014-11-19 16:44                   ` Petr Mladek
2014-11-15  4:59 ` [PATCH 20/26 v5] seq_buf: Add seq_buf_can_fit() helper function Steven Rostedt
2014-11-17 17:36   ` Steven Rostedt
2014-11-18  0:07     ` Joe Perches
2014-11-18  0:27       ` Steven Rostedt
2014-11-18  0:35         ` Joe Perches
2014-11-18  0:56           ` Steven Rostedt
2014-11-18  1:07             ` Joe Perches
2014-11-18  1:24               ` Steven Rostedt
2014-11-18  1:48                 ` Joe Perches
2014-11-18  2:37                   ` Steven Rostedt
2014-11-18  2:50                     ` Joe Perches
2014-11-18  3:00                       ` Steven Rostedt
2014-11-18 16:40   ` Petr Mladek
2014-11-15  4:59 ` [PATCH 21/26 v5] tracing: Have seq_buf use full buffer Steven Rostedt
2014-11-15  4:59 ` [PATCH 22/26 v5] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions Steven Rostedt
2014-11-15  4:59 ` [PATCH 23/26 v5] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF Steven Rostedt
2014-11-15  4:59 ` [PATCH 24/26 v5] seq_buf: Move the seq_buf code to lib/ Steven Rostedt
2014-11-15  4:59 ` [PATCH 25/26 v5] printk: Add per_cpu printk func to allow printk to be diverted Steven Rostedt
2014-11-15  4:59 ` [PATCH 26/26 v5] x86/nmi: Perform a safe NMI stack trace on all CPUs Steven Rostedt
2014-11-18 17:02   ` Petr Mladek
2014-11-15  5:08 ` [PATCH 00/26 v5] trace-seq/seq-buf/x86/printk: Print all stacks from NMI safely Steven Rostedt
2014-11-18  3:21 ` Steven Rostedt

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