[PATCH 0/5] tracing/core: various fixes

[PATCH 0/5] tracing/core: various fixes

[Frederic Weisbecker]

Hi Ingo, Steven,

I've gathered various tracing fixes that were posted recently.

Note: the commit b11c53e12f94a46b50bccc7a1a953d7ca1d54a31
	(ftrace: Add task_comm support for trace_event)
      looks good to me. This v3 solves the two following unhandled
      dependencies in v1:

ENABLE_EVENT_TRACING -> CONTEXT_SWITCH_TRACER
EVENT_TRACING -> CONTEXT_SWITCH_TRACER

The latter is tricky because CONTEXT_SWITCH_TRACER depends
on CONFIG_FTRACE (the tracers menu) from which EVENT_TRACING
is excluded. A build error can then occur if something selects
CONFIG_TRACING elsewhere.

The fix written by Zhaolei follows the {ENABLE_}EVENT_TRACING
view: we now have CONTEXT_SWITCH_TRACER and ENABLE_CONTEXT_SWITCH_TRACER.

The former is used by EVENT_TRACING to record cmdlines.
The latter selects CONTEXT_SWITCH_TRACER plus CONFIG_TRACING.
To sum up, ENABLE_CONTEXT_SWITCH_TRACER acts only as a "relay".

It looks good to me, tell me and Zhaolei if you have doubts
about it.

Thanks.

The following changes since commit 5537937696c55530447c20aa27daccb8d0d29b33:
  Ming Lei (1):
        ftrace: fix check for return value of register_module_notifier in event_trace_init

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
	tracing/core

Lai Jiangshan (1):
      tracing: add trace_event_read_lock()

Li Zefan (1):
      tracing/events: change the type of __str_loc_item to unsigned short

Pekka Enberg (1):
      kmemtrace: fix kernel parameter documentation

Zhaolei (2):
      ftrace: Add task_comm support for trace_event
      ftrace: clean up of using ftrace_event_enable_disable()

 Documentation/kernel-parameters.txt |   10 --------
 include/trace/ftrace.h              |    2 +-
 kernel/trace/Kconfig                |    9 +++++-
 kernel/trace/trace.c                |    8 ++++++
 kernel/trace/trace_events.c         |   42 +++++++++++++---------------------
 kernel/trace/trace_output.c         |   25 +++++++++++++++-----
 kernel/trace/trace_output.h         |    2 +
 7 files changed, 52 insertions(+), 46 deletions(-)

[PATCH 1/5] tracing: add trace_event_read_lock()

[Frederic Weisbecker]

From: Lai Jiangshan <laijs@cn.fujitsu.com>

I found that there is nothing to protect event_hash in
ftrace_find_event(). Rcu protects the event hashlist
but not the event itself while we use it after its extraction
through ftrace_find_event().

This lack of a proper locking in this spot opens a race
window between any event dereferencing and module removal.

Eg:

--Task A--

print_trace_line(trace) {
  event = find_ftrace_event(trace)

--Task B--

trace_module_remove_events(mod) {
  list_trace_events_module(ev, mod) {
    unregister_ftrace_event(ev->event) {
      hlist_del(ev->event->node)
        list_del(....)
    }
  }
}
|--> module removed, the event has been dropped

--Task A--

  event->print(trace); // Dereferencing freed memory

If the event retrieved belongs to a module and this module
is concurrently removed, we may end up dereferencing a data
from a freed module.

RCU could solve this, but it would add latency to the kernel and
forbid tracers output callbacks to call any sleepable code.
So this fix converts 'trace_event_mutex' to a read/write semaphore,
and adds trace_event_read_lock() to protect ftrace_find_event().

[ Impact: fix possible freed memory dereference in ftrace ]

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A114806.7090302@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/trace/trace.c        |    8 ++++++++
 kernel/trace/trace_output.c |   25 ++++++++++++++++++-------
 kernel/trace/trace_output.h |    2 ++
 3 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dd40d23..02d32ba 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1569,12 +1569,14 @@ static void *s_start(struct seq_file *m, loff_t *pos)
 		p = s_next(m, p, &l);
 	}
 
+	trace_event_read_lock();
 	return p;
 }
 
 static void s_stop(struct seq_file *m, void *p)
 {
 	atomic_dec(&trace_record_cmdline_disabled);
+	trace_event_read_unlock();
 }
 
 static void print_lat_help_header(struct seq_file *m)
@@ -1817,6 +1819,7 @@ static int trace_empty(struct trace_iterator *iter)
 	return 1;
 }
 
+/*  Called with trace_event_read_lock() held. */
 static enum print_line_t print_trace_line(struct trace_iterator *iter)
 {
 	enum print_line_t ret;
@@ -3008,6 +3011,7 @@ waitagain:
 	       offsetof(struct trace_iterator, seq));
 	iter->pos = -1;
 
+	trace_event_read_lock();
 	while (find_next_entry_inc(iter) != NULL) {
 		enum print_line_t ret;
 		int len = iter->seq.len;
@@ -3024,6 +3028,7 @@ waitagain:
 		if (iter->seq.len >= cnt)
 			break;
 	}
+	trace_event_read_unlock();
 
 	/* Now copy what we have to the user */
 	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
@@ -3146,6 +3151,8 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		goto out_err;
 	}
 
+	trace_event_read_lock();
+
 	/* Fill as many pages as possible. */
 	for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) {
 		pages[i] = alloc_page(GFP_KERNEL);
@@ -3168,6 +3175,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		trace_seq_init(&iter->seq);
 	}
 
+	trace_event_read_unlock();
 	mutex_unlock(&iter->mutex);
 
 	spd.nr_pages = i;
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 489c0e8..7136420 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -14,7 +14,7 @@
 /* must be a power of 2 */
 #define EVENT_HASHSIZE	128
 
-static DEFINE_MUTEX(trace_event_mutex);
+static DECLARE_RWSEM(trace_event_mutex);
 static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;
 
 static int next_event_type = __TRACE_LAST_TYPE + 1;
@@ -466,6 +466,7 @@ static int task_state_char(unsigned long state)
  * @type: the type of event to look for
  *
  * Returns an event of type @type otherwise NULL
+ * Called with trace_event_read_lock() held.
  */
 struct trace_event *ftrace_find_event(int type)
 {
@@ -475,7 +476,7 @@ struct trace_event *ftrace_find_event(int type)
 
 	key = type & (EVENT_HASHSIZE - 1);
 
-	hlist_for_each_entry_rcu(event, n, &event_hash[key], node) {
+	hlist_for_each_entry(event, n, &event_hash[key], node) {
 		if (event->type == type)
 			return event;
 	}
@@ -513,6 +514,16 @@ static int trace_search_list(struct list_head **list)
 	return last + 1;
 }
 
+void trace_event_read_lock(void)
+{
+	down_read(&trace_event_mutex);
+}
+
+void trace_event_read_unlock(void)
+{
+	up_read(&trace_event_mutex);
+}
+
 /**
  * register_ftrace_event - register output for an event type
  * @event: the event type to register
@@ -533,7 +544,7 @@ int register_ftrace_event(struct trace_event *event)
 	unsigned key;
 	int ret = 0;
 
-	mutex_lock(&trace_event_mutex);
+	down_write(&trace_event_mutex);
 
 	if (WARN_ON(!event))
 		goto out;
@@ -581,11 +592,11 @@ int register_ftrace_event(struct trace_event *event)
 
 	key = event->type & (EVENT_HASHSIZE - 1);
 
-	hlist_add_head_rcu(&event->node, &event_hash[key]);
+	hlist_add_head(&event->node, &event_hash[key]);
 
 	ret = event->type;
  out:
-	mutex_unlock(&trace_event_mutex);
+	up_write(&trace_event_mutex);
 
 	return ret;
 }
@@ -597,10 +608,10 @@ EXPORT_SYMBOL_GPL(register_ftrace_event);
  */
 int unregister_ftrace_event(struct trace_event *event)
 {
-	mutex_lock(&trace_event_mutex);
+	down_write(&trace_event_mutex);
 	hlist_del(&event->node);
 	list_del(&event->list);
-	mutex_unlock(&trace_event_mutex);
+	up_write(&trace_event_mutex);
 
 	return 0;
 }
diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h
index 6e220a8..ac240e7 100644
--- a/kernel/trace/trace_output.h
+++ b/kernel/trace/trace_output.h
@@ -20,6 +20,8 @@ extern int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
 extern int trace_print_context(struct trace_iterator *iter);
 extern int trace_print_lat_context(struct trace_iterator *iter);
 
+extern void trace_event_read_lock(void);
+extern void trace_event_read_unlock(void);
 extern struct trace_event *ftrace_find_event(int type);
 
 extern enum print_line_t trace_nop_print(struct trace_iterator *iter,
-- 
1.6.2.3

[PATCH 2/5] tracing/events: change the type of __str_loc_item to unsigned short

[Frederic Weisbecker]

From: Li Zefan <lizf@cn.fujitsu.com>

When defining a dynamic size string, we add __str_loc_##item to the
trace entry, and it stores the location of the actual string in
entry->_str_data[]

'unsigned short' should be sufficient to store this information, thus
we save 2 bytes per dyn-size string in the ring buffer.

[ Impact: reduce memory occupied by dyn-size strings in ring buffer ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A14EDB6.2050507@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 include/trace/ftrace.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index edb02bc..b5ff2e8 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -25,7 +25,7 @@
 #define __field(type, item)		type	item;
 
 #undef __string
-#define __string(item, src)		int	__str_loc_##item;
+#define __string(item, src)		unsigned short	__str_loc_##item;
 
 #undef TP_STRUCT__entry
 #define TP_STRUCT__entry(args...) args
-- 
1.6.2.3

[PATCH 3/5] kmemtrace: fix kernel parameter documentation

[Frederic Weisbecker]

From: Pekka Enberg <penberg@cs.helsinki.fi>

The kmemtrace.enable kernel parameter no longer works. To enable
kmemtrace at boot-time, you must pass "ftrace=kmemtrace" instead.

[ Impact: remove obsolete kernel parameter documentation ]

Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
LKML-Reference: <alpine.DEB.2.00.0905241112190.10296@rocky>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 Documentation/kernel-parameters.txt |   10 ----------
 1 files changed, 0 insertions(+), 10 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e87bdbf..9243dd8 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -56,7 +56,6 @@ parameter is applicable:
 	ISAPNP	ISA PnP code is enabled.
 	ISDN	Appropriate ISDN support is enabled.
 	JOY	Appropriate joystick support is enabled.
-	KMEMTRACE kmemtrace is enabled.
 	LIBATA  Libata driver is enabled
 	LP	Printer support is enabled.
 	LOOP	Loopback device support is enabled.
@@ -1054,15 +1053,6 @@ and is between 256 and 4096 characters. It is defined in the file
 			use the HighMem zone if it exists, and the Normal
 			zone if it does not.
 
-	kmemtrace.enable=	[KNL,KMEMTRACE] Format: { yes | no }
-				Controls whether kmemtrace is enabled
-				at boot-time.
-
-	kmemtrace.subbufs=n	[KNL,KMEMTRACE] Overrides the number of
-			subbufs kmemtrace's relay channel has. Set this
-			higher than default (KMEMTRACE_N_SUBBUFS in code) if
-			you experience buffer overruns.
-
 	kgdboc=		[HW] kgdb over consoles.
 			Requires a tty driver that supports console polling.
 			(only serial suported for now)
-- 
1.6.2.3

[PATCH 4/5] ftrace: Add task_comm support for trace_event

[Frederic Weisbecker]

From: Zhaolei <zhaolei@cn.fujitsu.com>

If we enable a trace event alone without any tracer running (such as
function tracer, sched switch tracer, etc...) it can't output enough
task command information.

We need to use the tracing_{start/stop}_cmdline_record() helpers
which are designed to keep track of cmdlines for any tasks that
were scheduled during the tracing.

Before this patch:
 # echo 1 > debugfs/tracing/events/sched/sched_switch/enable
 # cat debugfs/tracing/trace
 # tracer: nop
 #
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
            <...>-2289  [000] 526276.724790: sched_switch: task bash:2289 [120] ==> sshd:2287 [120]
            <...>-2287  [000] 526276.725231: sched_switch: task sshd:2287 [120] ==> bash:2289 [120]
            <...>-2289  [000] 526276.725452: sched_switch: task bash:2289 [120] ==> sshd:2287 [120]
            <...>-2287  [000] 526276.727181: sched_switch: task sshd:2287 [120] ==> swapper:0 [140]
           <idle>-0     [000] 526277.032734: sched_switch: task swapper:0 [140] ==> events/0:5 [115]
            <...>-5     [000] 526277.032782: sched_switch: task events/0:5 [115] ==> swapper:0 [140]
 ...

After this patch:
 # tracer: nop
 #
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
             bash-2269  [000] 527347.989229: sched_switch: task bash:2269 [120] ==> sshd:2267 [120]
             sshd-2267  [000] 527347.990960: sched_switch: task sshd:2267 [120] ==> bash:2269 [120]
             bash-2269  [000] 527347.991143: sched_switch: task bash:2269 [120] ==> sshd:2267 [120]
             sshd-2267  [000] 527347.992959: sched_switch: task sshd:2267 [120] ==> swapper:0 [140]
           <idle>-0     [000] 527348.531989: sched_switch: task swapper:0 [140] ==> events/0:5 [115]
         events/0-5     [000] 527348.532115: sched_switch: task events/0:5 [115] ==> swapper:0 [140]
 ...

Changelog:
v1->v2: Update Kconfig to select CONTEXT_SWITCH_TRACER in
        ENABLE_EVENT_TRACING
v2->v3: v2 can solve problem that was caused by config EVENT_TRACING
        alone, but when CONFIG_FTRACE is off and CONFIG_TRACING is
        selected by other config, compile fail happened again.
        This version solves it.

[ Impact: fix incomplete output of event tracing ]

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A14FDFE.2080402@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/trace/Kconfig        |    9 +++++++--
 kernel/trace/trace_events.c |    6 ++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index f61be30..a508b9d 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -49,6 +49,11 @@ config FTRACE_NMI_ENTER
        default y
 
 config EVENT_TRACING
+	select CONTEXT_SWITCH_TRACER
+	bool
+
+config CONTEXT_SWITCH_TRACER
+	select MARKERS
 	bool
 
 config TRACING
@@ -176,10 +181,10 @@ config SCHED_TRACER
 	  This tracer tracks the latency of the highest priority task
 	  to be scheduled in, starting from the point it has woken up.
 
-config CONTEXT_SWITCH_TRACER
+config ENABLE_CONTEXT_SWITCH_TRACER
 	bool "Trace process context switches"
 	select TRACING
-	select MARKERS
+	select CONTEXT_SWITCH_TRACER
 	help
 	  This tracer gets called from the context switch and records
 	  all switching of tasks.
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 9e91c4a..9b246eb 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -85,6 +85,7 @@ static void ftrace_clear_events(void)
 
 		if (call->enabled) {
 			call->enabled = 0;
+			tracing_stop_cmdline_record();
 			call->unregfunc();
 		}
 	}
@@ -99,12 +100,14 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
 	case 0:
 		if (call->enabled) {
 			call->enabled = 0;
+			tracing_stop_cmdline_record();
 			call->unregfunc();
 		}
 		break;
 	case 1:
 		if (!call->enabled) {
 			call->enabled = 1;
+			tracing_start_cmdline_record();
 			call->regfunc();
 		}
 		break;
@@ -1058,6 +1061,7 @@ static void trace_module_remove_events(struct module *mod)
 			found = true;
 			if (call->enabled) {
 				call->enabled = 0;
+				tracing_stop_cmdline_record();
 				call->unregfunc();
 			}
 			if (call->event)
@@ -1262,11 +1266,13 @@ static __init void event_trace_self_tests(void)
 		}
 
 		call->enabled = 1;
+		tracing_start_cmdline_record();
 		call->regfunc();
 
 		event_test_stuff();
 
 		call->unregfunc();
+		tracing_stop_cmdline_record();
 		call->enabled = 0;
 
 		pr_cont("OK\n");
-- 
1.6.2.3

[PATCH 5/5] ftrace: clean up of using ftrace_event_enable_disable()

[Frederic Weisbecker]

From: Zhaolei <zhaolei@cn.fujitsu.com>

Always use ftrace_event_enable_disable() to enable/disable an event
so that we can factorize out the event toggling code.

[ Impact: factorize and cleanup event tracing code ]

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <4A14FDFE.2080402@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/trace/trace_events.c |   44 +++++++++++++-----------------------------
 1 files changed, 14 insertions(+), 30 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 9b246eb..6c81f9c 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -76,26 +76,9 @@ static void trace_destroy_fields(struct ftrace_event_call *call)
 
 #endif /* CONFIG_MODULES */
 
-static void ftrace_clear_events(void)
-{
-	struct ftrace_event_call *call;
-
-	mutex_lock(&event_mutex);
-	list_for_each_entry(call, &ftrace_events, list) {
-
-		if (call->enabled) {
-			call->enabled = 0;
-			tracing_stop_cmdline_record();
-			call->unregfunc();
-		}
-	}
-	mutex_unlock(&event_mutex);
-}
-
 static void ftrace_event_enable_disable(struct ftrace_event_call *call,
 					int enable)
 {
-
 	switch (enable) {
 	case 0:
 		if (call->enabled) {
@@ -114,6 +97,17 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
 	}
 }
 
+static void ftrace_clear_events(void)
+{
+	struct ftrace_event_call *call;
+
+	mutex_lock(&event_mutex);
+	list_for_each_entry(call, &ftrace_events, list) {
+		ftrace_event_enable_disable(call, 0);
+	}
+	mutex_unlock(&event_mutex);
+}
+
 /*
  * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
  */
@@ -1059,11 +1053,7 @@ static void trace_module_remove_events(struct module *mod)
 	list_for_each_entry_safe(call, p, &ftrace_events, list) {
 		if (call->mod == mod) {
 			found = true;
-			if (call->enabled) {
-				call->enabled = 0;
-				tracing_stop_cmdline_record();
-				call->unregfunc();
-			}
+			ftrace_event_enable_disable(call, 0);
 			if (call->event)
 				unregister_ftrace_event(call->event);
 			debugfs_remove_recursive(call->dir);
@@ -1265,15 +1255,9 @@ static __init void event_trace_self_tests(void)
 			continue;
 		}
 
-		call->enabled = 1;
-		tracing_start_cmdline_record();
-		call->regfunc();
-
+		ftrace_event_enable_disable(call, 1);
 		event_test_stuff();
-
-		call->unregfunc();
-		tracing_stop_cmdline_record();
-		call->enabled = 0;
+		ftrace_event_enable_disable(call, 0);
 
 		pr_cont("OK\n");
 	}
-- 
1.6.2.3

[GIT PULL v2][PATCH 0/10] tracing/core: various fixes

[Frederic Weisbecker]

On Tue, May 26, 2009 at 04:04:45AM +0200, Frederic Weisbecker wrote:
> Hi Ingo, Steven,
> 
> I've gathered various tracing fixes that were posted recently.


I based this topic against tracing/core whereas the latest
tracing changes were on tracing/ftrace.

But tracing/ftrace contains the v1 of:

ftrace: Add task_comm support for trace_event
ftrace: clean up of using ftrace_event_enable_disable()

And my pull request contains the v3 of this pair, fixing
some build issue.

As you suggested, I've cherry picked the missing patches
from tracing/ftrace to my tracing/core based tree.
This new pull request then adds 5 Steven's patches that
were on tracing/ftrace.
I'm not posting them because they have been submitted
in LKML already.

Thanks.

The following changes since commit 5537937696c55530447c20aa27daccb8d0d29b33:
  Ming Lei (1):
        ftrace: fix check for return value of register_module_notifier in event_trace_init

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
	tracing/core-2

Lai Jiangshan (1):
      tracing: add trace_event_read_lock()

Li Zefan (1):
      tracing/events: change the type of __str_loc_item to unsigned short

Pekka Enberg (1):
      kmemtrace: fix kernel parameter documentation

Steven Rostedt (5):
      tracing: add __print_flags for events
      tracing: add previous task state info to sched switch event
      tracing: add flag output for kmem events
      tracing: add __print_symbolic to trace events
      tracing: convert irq events to use __print_symbolic

Zhaolei (2):
      ftrace: Add task_comm support for trace_event
      ftrace: clean up of using ftrace_event_enable_disable()

 Documentation/kernel-parameters.txt |   10 ----
 include/linux/ftrace_event.h        |   16 ++++++-
 include/trace/events/irq.h          |   23 +++++++--
 include/trace/events/kmem.h         |   53 ++++++++++++++++++---
 include/trace/events/sched.h        |    9 +++-
 include/trace/ftrace.h              |   24 +++++++++-
 kernel/trace/Kconfig                |    9 +++-
 kernel/trace/trace.c                |    8 +++
 kernel/trace/trace_events.c         |   42 ++++++----------
 kernel/trace/trace_output.c         |   89 ++++++++++++++++++++++++++++++++---
 kernel/trace/trace_output.h         |    2 +
 11 files changed, 223 insertions(+), 62 deletions(-)

Re: [PATCH 0/5] tracing/core: various fixes

[Steven Rostedt]

I'm just coming back off of a holiday.


On Tue, 26 May 2009, Frederic Weisbecker wrote:

> Hi Ingo, Steven,
> 
> I've gathered various tracing fixes that were posted recently.
> 
> Note: the commit b11c53e12f94a46b50bccc7a1a953d7ca1d54a31
> 	(ftrace: Add task_comm support for trace_event)
>       looks good to me. This v3 solves the two following unhandled
>       dependencies in v1:
> 
> ENABLE_EVENT_TRACING -> CONTEXT_SWITCH_TRACER
> EVENT_TRACING -> CONTEXT_SWITCH_TRACER
> 
> The latter is tricky because CONTEXT_SWITCH_TRACER depends
> on CONFIG_FTRACE (the tracers menu) from which EVENT_TRACING
> is excluded. A build error can then occur if something selects
> CONFIG_TRACING elsewhere.
> 
> The fix written by Zhaolei follows the {ENABLE_}EVENT_TRACING
> view: we now have CONTEXT_SWITCH_TRACER and ENABLE_CONTEXT_SWITCH_TRACER.
> 
> The former is used by EVENT_TRACING to record cmdlines.
> The latter selects CONTEXT_SWITCH_TRACER plus CONFIG_TRACING.
> To sum up, ENABLE_CONTEXT_SWITCH_TRACER acts only as a "relay".

The sched_switch tracer is very light weight. Not sure we need to keep
it separate.

Basically, when tracing is enabled, we should simply get the event tracer 
and the sched_switch tracer for free. The configs get a bit tricky with 
dependencies. I'll take a look at it.

-- Steve

> 
> It looks good to me, tell me and Zhaolei if you have doubts
> about it.
> 
> Thanks.
> 
> The following changes since commit 5537937696c55530447c20aa27daccb8d0d29b33:
>   Ming Lei (1):
>         ftrace: fix check for return value of register_module_notifier in event_trace_init
> 
> are available in the git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
> 	tracing/core
> 
> Lai Jiangshan (1):
>       tracing: add trace_event_read_lock()
> 
> Li Zefan (1):
>       tracing/events: change the type of __str_loc_item to unsigned short
> 
> Pekka Enberg (1):
>       kmemtrace: fix kernel parameter documentation
> 
> Zhaolei (2):
>       ftrace: Add task_comm support for trace_event
>       ftrace: clean up of using ftrace_event_enable_disable()
> 
>  Documentation/kernel-parameters.txt |   10 --------
>  include/trace/ftrace.h              |    2 +-
>  kernel/trace/Kconfig                |    9 +++++-
>  kernel/trace/trace.c                |    8 ++++++
>  kernel/trace/trace_events.c         |   42 +++++++++++++---------------------
>  kernel/trace/trace_output.c         |   25 +++++++++++++++-----
>  kernel/trace/trace_output.h         |    2 +
>  7 files changed, 52 insertions(+), 46 deletions(-)
> 

Re: [PATCH 0/5] tracing/core: various fixes

[Frederic Weisbecker]

On Tue, May 26, 2009 at 03:46:24PM -0400, Steven Rostedt wrote:
> 
> I'm just coming back off of a holiday.
> 
> 
> On Tue, 26 May 2009, Frederic Weisbecker wrote:
> 
> > Hi Ingo, Steven,
> > 
> > I've gathered various tracing fixes that were posted recently.
> > 
> > Note: the commit b11c53e12f94a46b50bccc7a1a953d7ca1d54a31
> > 	(ftrace: Add task_comm support for trace_event)
> >       looks good to me. This v3 solves the two following unhandled
> >       dependencies in v1:
> > 
> > ENABLE_EVENT_TRACING -> CONTEXT_SWITCH_TRACER
> > EVENT_TRACING -> CONTEXT_SWITCH_TRACER
> > 
> > The latter is tricky because CONTEXT_SWITCH_TRACER depends
> > on CONFIG_FTRACE (the tracers menu) from which EVENT_TRACING
> > is excluded. A build error can then occur if something selects
> > CONFIG_TRACING elsewhere.
> > 
> > The fix written by Zhaolei follows the {ENABLE_}EVENT_TRACING
> > view: we now have CONTEXT_SWITCH_TRACER and ENABLE_CONTEXT_SWITCH_TRACER.
> > 
> > The former is used by EVENT_TRACING to record cmdlines.
> > The latter selects CONTEXT_SWITCH_TRACER plus CONFIG_TRACING.
> > To sum up, ENABLE_CONTEXT_SWITCH_TRACER acts only as a "relay".
> 
> The sched_switch tracer is very light weight. Not sure we need to keep
> it separate.
> 
> Basically, when tracing is enabled, we should simply get the event tracer 
> and the sched_switch tracer for free. The configs get a bit tricky with 
> dependencies. I'll take a look at it.
> 
> -- Steve


So, should I zap these patches from the pull request?
Or do you think about a delta solution?

Thanks,
Frederic.

 
> > 
> > It looks good to me, tell me and Zhaolei if you have doubts
> > about it.
> > 
> > Thanks.
> > 
> > The following changes since commit 5537937696c55530447c20aa27daccb8d0d29b33:
> >   Ming Lei (1):
> >         ftrace: fix check for return value of register_module_notifier in event_trace_init
> > 
> > are available in the git repository at:
> > 
> >   git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
> > 	tracing/core
> > 
> > Lai Jiangshan (1):
> >       tracing: add trace_event_read_lock()
> > 
> > Li Zefan (1):
> >       tracing/events: change the type of __str_loc_item to unsigned short
> > 
> > Pekka Enberg (1):
> >       kmemtrace: fix kernel parameter documentation
> > 
> > Zhaolei (2):
> >       ftrace: Add task_comm support for trace_event
> >       ftrace: clean up of using ftrace_event_enable_disable()
> > 
> >  Documentation/kernel-parameters.txt |   10 --------
> >  include/trace/ftrace.h              |    2 +-
> >  kernel/trace/Kconfig                |    9 +++++-
> >  kernel/trace/trace.c                |    8 ++++++
> >  kernel/trace/trace_events.c         |   42 +++++++++++++---------------------
> >  kernel/trace/trace_output.c         |   25 +++++++++++++++-----
> >  kernel/trace/trace_output.h         |    2 +
> >  7 files changed, 52 insertions(+), 46 deletions(-)
> > 

Re: [PATCH 0/5] tracing/core: various fixes

[Steven Rostedt]

On Tue, 26 May 2009, Frederic Weisbecker wrote:
> 
> 
> So, should I zap these patches from the pull request?
> Or do you think about a delta solution?

No, keep the config changes out for now.

-- Steve

Re: [GIT PULL v2][PATCH 0/10] tracing/core: various fixes

[Steven Rostedt]

On Tue, 26 May 2009, Frederic Weisbecker wrote:
> Steven Rostedt (5):
>       tracing: add __print_flags for events
>       tracing: add previous task state info to sched switch event
>       tracing: add flag output for kmem events
>       tracing: add __print_symbolic to trace events
>       tracing: convert irq events to use __print_symbolic
> 
> Zhaolei (2):
>       ftrace: Add task_comm support for trace_event
>       ftrace: clean up of using ftrace_event_enable_disable()

BTW, these are in tip/tracing/ftrace :-/

-- Steve

Re: [GIT PULL v2][PATCH 0/10] tracing/core: various fixes

[Frederic Weisbecker]

On Tue, May 26, 2009 at 05:30:43PM -0400, Steven Rostedt wrote:
> 
> On Tue, 26 May 2009, Frederic Weisbecker wrote:
> > Steven Rostedt (5):
> >       tracing: add __print_flags for events
> >       tracing: add previous task state info to sched switch event
> >       tracing: add flag output for kmem events
> >       tracing: add __print_symbolic to trace events
> >       tracing: convert irq events to use __print_symbolic
> > 
> > Zhaolei (2):
> >       ftrace: Add task_comm support for trace_event
> >       ftrace: clean up of using ftrace_event_enable_disable()
> 
> BTW, these are in tip/tracing/ftrace :-/


Yes. I prepared the first request against tracing/core
and have discovered today what was in tracing/ftrace :)

But Zhaolei's patches are not the same. The v1 is on
tracing/ftrace, it doesn't contain the fix for the build
error. Then Ingo suggested me to cherry-pick the missing
patches in tracing/core from tracing/ftrace. And here came
the second pull request.

So, may be I should send a new request containing the last
fixes but against tracing/ftrace. So that we'll have
the same result without the kconfig tricks that solve the
build error.

Hm?