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

[PATCH 1/2] 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 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..b6a0938 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 (!likely(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 (!likely(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 2/2] ftrace: Clean up enable logic for sched_switch

[Steven Rostedt]

On Tue, 31 Mar 2009, Zhaolei wrote:
> 
> diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
> index 9117cea..b6a0938 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 (!likely(sched_ref))

That should be:

	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 (!likely(sched_ref))

Same here.

-- Steve

>  		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
> 
> 
>