[PATCH v2 0/2] ftrace: Add check of sched_stopped for probe_sched_wakeup

[PATCH v2 0/2] ftrace: Add check of sched_stopped for probe_sched_wakeup

[Zhaolei]

Hello, Steven

Thanks for your comments for v1 patch.
I send v2 patch which includes your suggestion.

B.R
Zhaolei

[PATCH v2 1/2] ftrace: Add check of sched_stopped for probe_sched_wakeup

[Zhaolei]

We need check sched_stopped in probe_sched_wakeup() to stop tracing when an
user stops it.

But current code can also do the right thing(stop tracing after
echo 0 > tracing_enabled) just because tracing_sched_wakeup_trace() can return
on buffer->record_disabled.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
 kernel/trace/trace_sched_switch.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index de35f20..9117cea 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -62,6 +62,9 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
 	pc = preempt_count();
 	tracing_record_cmdline(current);
 
+	if (sched_stopped)
+		return;
+
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
 	data = ctx_trace->data[cpu];
-- 
1.5.5.3

[PATCH v2 2/2] ftrace: Clean up enable logic for sched_switch

[Zhaolei]

Unify sched_switch and sched_wakeup's action to following logic:
Do record_cmdline when start_cmdline_record() called.
Trace event when trace is inited and started.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
 kernel/trace/trace_sched_switch.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 9117cea..9d8cccd 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -29,13 +29,13 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
 	int cpu;
 	int pc;
 
-	if (!sched_ref || sched_stopped)
+	if (unlikely(!sched_ref))
 		return;
 
 	tracing_record_cmdline(prev);
 	tracing_record_cmdline(next);
 
-	if (!tracer_enabled)
+	if (!tracer_enabled || sched_stopped)
 		return;
 
 	pc = preempt_count();
@@ -56,15 +56,15 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
 	unsigned long flags;
 	int cpu, pc;
 
-	if (!likely(tracer_enabled))
+	if (unlikely(!sched_ref))
 		return;
 
-	pc = preempt_count();
 	tracing_record_cmdline(current);
 
-	if (sched_stopped)
+	if (!tracer_enabled || sched_stopped)
 		return;
 
+	pc = preempt_count();
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
 	data = ctx_trace->data[cpu];
-- 
1.5.5.3

Re: [PATCH v2 1/2] ftrace: Add check of sched_stopped for probe_sched_wakeup

[Steven Rostedt]

On Tue, 31 Mar 2009, Zhaolei wrote:

> We need check sched_stopped in probe_sched_wakeup() to stop tracing when an
> user stops it.
> 
> But current code can also do the right thing(stop tracing after
> echo 0 > tracing_enabled) just because tracing_sched_wakeup_trace() can return
> on buffer->record_disabled.
> 
> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>

Thanks, applied.

-- Steve

Re: [PATCH v2 2/2] ftrace: Clean up enable logic for sched_switch

[Steven Rostedt]

On Tue, 31 Mar 2009, Zhaolei wrote:

> Unify sched_switch and sched_wakeup's action to following logic:
> Do record_cmdline when start_cmdline_record() called.
> Trace event when trace is inited and started.
> 
> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>

Thanks, applied.

-- Steve

[tip:tracing/urgent] ftrace: Add check of sched_stopped for probe_sched_wakeup

[Zhaolei]

Commit-ID:  8bcae09b93e7f96f700b6bb372c2b3f2b36636dc
Gitweb:     http://git.kernel.org/tip/8bcae09b93e7f96f700b6bb372c2b3f2b36636dc
Author:     Zhaolei <zhaolei@cn.fujitsu.com>
AuthorDate: Tue, 31 Mar 2009 15:24:51 +0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 7 Apr 2009 14:01:11 +0200

ftrace: Add check of sched_stopped for probe_sched_wakeup

The wakeup tracing in sched_switch does not stop when a user
disables tracing. This is because the probe_sched_wakeup() is missing
the check to prevent the wakeup from being traced.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
LKML-Reference: <49D1C543.3010307@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 kernel/trace/trace_sched_switch.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index de35f20..9117cea 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -62,6 +62,9 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
 	pc = preempt_count();
 	tracing_record_cmdline(current);
 
+	if (sched_stopped)
+		return;
+
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
 	data = ctx_trace->data[cpu];

[tip:tracing/core] ftrace: clean up enable logic for sched_switch

[Zhaolei]

Commit-ID:  dcef788eb9659b61a2110284fcce3ca6e63480d2
Gitweb:     http://git.kernel.org/tip/dcef788eb9659b61a2110284fcce3ca6e63480d2
Author:     Zhaolei <zhaolei@cn.fujitsu.com>
AuthorDate: Tue, 31 Mar 2009 15:26:14 +0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 7 Apr 2009 14:43:09 +0200

ftrace: clean up enable logic for sched_switch

Unify sched_switch and sched_wakeup's action to following logic:
Do record_cmdline when start_cmdline_record() is called.
Start tracing events when the tracer is started.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
LKML-Reference: <49D1C596.5050203@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>


---
 kernel/trace/trace_sched_switch.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 9117cea..9d8cccd 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -29,13 +29,13 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
 	int cpu;
 	int pc;
 
-	if (!sched_ref || sched_stopped)
+	if (unlikely(!sched_ref))
 		return;
 
 	tracing_record_cmdline(prev);
 	tracing_record_cmdline(next);
 
-	if (!tracer_enabled)
+	if (!tracer_enabled || sched_stopped)
 		return;
 
 	pc = preempt_count();
@@ -56,15 +56,15 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
 	unsigned long flags;
 	int cpu, pc;
 
-	if (!likely(tracer_enabled))
+	if (unlikely(!sched_ref))
 		return;
 
-	pc = preempt_count();
 	tracing_record_cmdline(current);
 
-	if (sched_stopped)
+	if (!tracer_enabled || sched_stopped)
 		return;
 
+	pc = preempt_count();
 	local_irq_save(flags);
 	cpu = raw_smp_processor_id();
 	data = ctx_trace->data[cpu];