[PATCH 0/3] [GIT PULL] tracing: cleanups

[PATCH 0/3] [GIT PULL] tracing: cleanups

[Steven Rostedt]

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Ingo,

Please pull the latest tip/perf/core tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
tip/perf/core

Head SHA1: 68179686ac67cb08f08b1ef28b860d5ed899f242


Jiri Olsa (1):
      tracing: Use seq_*_private interface for some seq files

Minho Ban (1):
      tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off

Steven Rostedt (1):
      tracing: Remove ftrace_disable/enable_cpu()

----
 include/linux/ftrace.h |    8 ++++--
 kernel/trace/ftrace.c  |   44 +++++++---------------------
 kernel/trace/trace.c   |   74 +++++-------------------------------------------
 3 files changed, 24 insertions(+), 102 deletions(-)

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[PATCH 1/3] tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off

[Steven Rostedt]

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From: Minho Ban <mhban@samsung.com>

This fixes spending time for evaluating parameters in trace_preempt_on/off when
the tracer config is off.

The patch mainly inspired by Steven Rostedt, thanks Steven.

Link: http://lkml.kernel.org/r/4FA73510.7070705@samsung.com

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Turner <pjt@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Minho Ban <mhban@samsung.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ftrace.h |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 0b55903..d32cc5e 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -491,8 +491,12 @@ static inline void __ftrace_enabled_restore(int enabled)
   extern void trace_preempt_on(unsigned long a0, unsigned long a1);
   extern void trace_preempt_off(unsigned long a0, unsigned long a1);
 #else
-  static inline void trace_preempt_on(unsigned long a0, unsigned long a1) { }
-  static inline void trace_preempt_off(unsigned long a0, unsigned long a1) { }
+/*
+ * Use defines instead of static inlines because some arches will make code out
+ * of the CALLER_ADDR, when we really want these to be a real nop.
+ */
+# define trace_preempt_on(a0, a1) do { } while (0)
+# define trace_preempt_off(a0, a1) do { } while (0)
 #endif
 
 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
-- 
1.7.10



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[PATCH 2/3] tracing: Use seq_*_private interface for some seq files

[Steven Rostedt]

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From: Jiri Olsa <jolsa@redhat.com>

It's appropriate to use __seq_open_private interface to open
some of trace seq files, because it covers all steps we are
duplicating in tracing code - zallocating the iterator and
setting it as seq_file's private.

Using this for following files:
  trace
  available_filter_functions
  enabled_functions

Link: http://lkml.kernel.org/r/1335342219-2782-5-git-send-email-jolsa@redhat.com

Signed-off-by: Jiri Olsa <jolsa@redhat.com>

[
 Fixed warnings for:
   kernel/trace/trace.c: In function '__tracing_open':
   kernel/trace/trace.c:2418:11: warning: unused variable 'ret' [-Wunused-variable]
   kernel/trace/trace.c:2417:19: warning: unused variable 'm' [-Wunused-variable]
]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c |   44 +++++++++++---------------------------------
 kernel/trace/trace.c  |   30 +++++-------------------------
 2 files changed, 16 insertions(+), 58 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0fa92f6..cf81f27 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2469,57 +2469,35 @@ static int
 ftrace_avail_open(struct inode *inode, struct file *file)
 {
 	struct ftrace_iterator *iter;
-	int ret;
 
 	if (unlikely(ftrace_disabled))
 		return -ENODEV;
 
-	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
-	if (!iter)
-		return -ENOMEM;
-
-	iter->pg = ftrace_pages_start;
-	iter->ops = &global_ops;
-
-	ret = seq_open(file, &show_ftrace_seq_ops);
-	if (!ret) {
-		struct seq_file *m = file->private_data;
-
-		m->private = iter;
-	} else {
-		kfree(iter);
+	iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
+	if (iter) {
+		iter->pg = ftrace_pages_start;
+		iter->ops = &global_ops;
 	}
 
-	return ret;
+	return iter ? 0 : -ENOMEM;
 }
 
 static int
 ftrace_enabled_open(struct inode *inode, struct file *file)
 {
 	struct ftrace_iterator *iter;
-	int ret;
 
 	if (unlikely(ftrace_disabled))
 		return -ENODEV;
 
-	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
-	if (!iter)
-		return -ENOMEM;
-
-	iter->pg = ftrace_pages_start;
-	iter->flags = FTRACE_ITER_ENABLED;
-	iter->ops = &global_ops;
-
-	ret = seq_open(file, &show_ftrace_seq_ops);
-	if (!ret) {
-		struct seq_file *m = file->private_data;
-
-		m->private = iter;
-	} else {
-		kfree(iter);
+	iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
+	if (iter) {
+		iter->pg = ftrace_pages_start;
+		iter->flags = FTRACE_ITER_ENABLED;
+		iter->ops = &global_ops;
 	}
 
-	return ret;
+	return iter ? 0 : -ENOMEM;
 }
 
 static void ftrace_filter_reset(struct ftrace_hash *hash)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f11a285..4fb10ef 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2413,15 +2413,13 @@ static struct trace_iterator *
 __tracing_open(struct inode *inode, struct file *file)
 {
 	long cpu_file = (long) inode->i_private;
-	void *fail_ret = ERR_PTR(-ENOMEM);
 	struct trace_iterator *iter;
-	struct seq_file *m;
-	int cpu, ret;
+	int cpu;
 
 	if (tracing_disabled)
 		return ERR_PTR(-ENODEV);
 
-	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+	iter = __seq_open_private(file, &tracer_seq_ops, sizeof(*iter));
 	if (!iter)
 		return ERR_PTR(-ENOMEM);
 
@@ -2478,32 +2476,15 @@ __tracing_open(struct inode *inode, struct file *file)
 		tracing_iter_reset(iter, cpu);
 	}
 
-	ret = seq_open(file, &tracer_seq_ops);
-	if (ret < 0) {
-		fail_ret = ERR_PTR(ret);
-		goto fail_buffer;
-	}
-
-	m = file->private_data;
-	m->private = iter;
-
 	mutex_unlock(&trace_types_lock);
 
 	return iter;
 
- fail_buffer:
-	for_each_tracing_cpu(cpu) {
-		if (iter->buffer_iter[cpu])
-			ring_buffer_read_finish(iter->buffer_iter[cpu]);
-	}
-	free_cpumask_var(iter->started);
-	tracing_start();
  fail:
 	mutex_unlock(&trace_types_lock);
 	kfree(iter->trace);
-	kfree(iter);
-
-	return fail_ret;
+	seq_release_private(inode, file);
+	return ERR_PTR(-ENOMEM);
 }
 
 int tracing_open_generic(struct inode *inode, struct file *filp)
@@ -2539,11 +2520,10 @@ static int tracing_release(struct inode *inode, struct file *file)
 	tracing_start();
 	mutex_unlock(&trace_types_lock);
 
-	seq_release(inode, file);
 	mutex_destroy(&iter->mutex);
 	free_cpumask_var(iter->started);
 	kfree(iter->trace);
-	kfree(iter);
+	seq_release_private(inode, file);
 	return 0;
 }
 
-- 
1.7.10



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[PATCH 3/3] tracing: Remove ftrace_disable/enable_cpu()

[Steven Rostedt]

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From: Steven Rostedt <srostedt@redhat.com>

The ftrace_disable_cpu() and ftrace_enable_cpu() functions were
needed back before the ring buffer was lockless. Now that the
ring buffer is lockless (and has been for some time), these functions
serve no purpose, and unnecessarily slow down operations of the tracer.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c |   44 ++------------------------------------------
 1 file changed, 2 insertions(+), 42 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4fb10ef..48ef496 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -87,18 +87,6 @@ static int tracing_disabled = 1;
 
 DEFINE_PER_CPU(int, ftrace_cpu_disabled);
 
-static inline void ftrace_disable_cpu(void)
-{
-	preempt_disable();
-	__this_cpu_inc(ftrace_cpu_disabled);
-}
-
-static inline void ftrace_enable_cpu(void)
-{
-	__this_cpu_dec(ftrace_cpu_disabled);
-	preempt_enable();
-}
-
 cpumask_var_t __read_mostly	tracing_buffer_mask;
 
 /*
@@ -748,8 +736,6 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
 	arch_spin_lock(&ftrace_max_lock);
 
-	ftrace_disable_cpu();
-
 	ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
 
 	if (ret == -EBUSY) {
@@ -763,8 +749,6 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 			"Failed to swap buffers due to commit in progress\n");
 	}
 
-	ftrace_enable_cpu();
-
 	WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
 
 	__update_max_tr(tr, tsk, cpu);
@@ -916,13 +900,6 @@ out:
 	mutex_unlock(&trace_types_lock);
 }
 
-static void __tracing_reset(struct ring_buffer *buffer, int cpu)
-{
-	ftrace_disable_cpu();
-	ring_buffer_reset_cpu(buffer, cpu);
-	ftrace_enable_cpu();
-}
-
 void tracing_reset(struct trace_array *tr, int cpu)
 {
 	struct ring_buffer *buffer = tr->buffer;
@@ -931,7 +908,7 @@ void tracing_reset(struct trace_array *tr, int cpu)
 
 	/* Make sure all commits have finished */
 	synchronize_sched();
-	__tracing_reset(buffer, cpu);
+	ring_buffer_reset_cpu(buffer, cpu);
 
 	ring_buffer_record_enable(buffer);
 }
@@ -949,7 +926,7 @@ void tracing_reset_online_cpus(struct trace_array *tr)
 	tr->time_start = ftrace_now(tr->cpu);
 
 	for_each_online_cpu(cpu)
-		__tracing_reset(buffer, cpu);
+		ring_buffer_reset_cpu(buffer, cpu);
 
 	ring_buffer_record_enable(buffer);
 }
@@ -1733,14 +1710,9 @@ EXPORT_SYMBOL_GPL(trace_vprintk);
 
 static void trace_iterator_increment(struct trace_iterator *iter)
 {
-	/* Don't allow ftrace to trace into the ring buffers */
-	ftrace_disable_cpu();
-
 	iter->idx++;
 	if (iter->buffer_iter[iter->cpu])
 		ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
-
-	ftrace_enable_cpu();
 }
 
 static struct trace_entry *
@@ -1750,17 +1722,12 @@ peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts,
 	struct ring_buffer_event *event;
 	struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
 
-	/* Don't allow ftrace to trace into the ring buffers */
-	ftrace_disable_cpu();
-
 	if (buf_iter)
 		event = ring_buffer_iter_peek(buf_iter, ts);
 	else
 		event = ring_buffer_peek(iter->tr->buffer, cpu, ts,
 					 lost_events);
 
-	ftrace_enable_cpu();
-
 	if (event) {
 		iter->ent_size = ring_buffer_event_length(event);
 		return ring_buffer_event_data(event);
@@ -1850,11 +1817,8 @@ void *trace_find_next_entry_inc(struct trace_iterator *iter)
 
 static void trace_consume(struct trace_iterator *iter)
 {
-	/* Don't allow ftrace to trace into the ring buffers */
-	ftrace_disable_cpu();
 	ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts,
 			    &iter->lost_events);
-	ftrace_enable_cpu();
 }
 
 static void *s_next(struct seq_file *m, void *v, loff_t *pos)
@@ -1943,16 +1907,12 @@ static void *s_start(struct seq_file *m, loff_t *pos)
 		iter->cpu = 0;
 		iter->idx = -1;
 
-		ftrace_disable_cpu();
-
 		if (cpu_file == TRACE_PIPE_ALL_CPU) {
 			for_each_tracing_cpu(cpu)
 				tracing_iter_reset(iter, cpu);
 		} else
 			tracing_iter_reset(iter, cpu_file);
 
-		ftrace_enable_cpu();
-
 		iter->leftover = 0;
 		for (p = iter; p && l < *pos; p = s_next(m, p, &l))
 			;
-- 
1.7.10



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Re: [PATCH 0/3] [GIT PULL] tracing: cleanups

[Ingo Molnar]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> Ingo,
> 
> Please pull the latest tip/perf/core tree, which can be found at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> tip/perf/core
> 
> Head SHA1: 68179686ac67cb08f08b1ef28b860d5ed899f242
> 
> 
> Jiri Olsa (1):
>       tracing: Use seq_*_private interface for some seq files
> 
> Minho Ban (1):
>       tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off
> 
> Steven Rostedt (1):
>       tracing: Remove ftrace_disable/enable_cpu()
> 
> ----
>  include/linux/ftrace.h |    8 ++++--
>  kernel/trace/ftrace.c  |   44 +++++++---------------------
>  kernel/trace/trace.c   |   74 +++++-------------------------------------------
>  3 files changed, 24 insertions(+), 102 deletions(-)

Pulled, thanks Steve!

	Ingo

Re: [PATCH 0/3] [GIT PULL] tracing: cleanups

[Ingo Molnar]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> 
> Ingo,
> 
> Please pull the latest tip/perf/core tree, which can be found at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> tip/perf/core
> 
> Head SHA1: 68179686ac67cb08f08b1ef28b860d5ed899f242
> 
> 
> Jiri Olsa (1):
>       tracing: Use seq_*_private interface for some seq files
> 
> Minho Ban (1):
>       tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off
> 
> Steven Rostedt (1):
>       tracing: Remove ftrace_disable/enable_cpu()
> 
> ----
>  include/linux/ftrace.h |    8 ++++--
>  kernel/trace/ftrace.c  |   44 +++++++---------------------
>  kernel/trace/trace.c   |   74 +++++-------------------------------------------
>  3 files changed, 24 insertions(+), 102 deletions(-)

Pulled, thanks Steve!

	Ingo