Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH] sched: Fix preempt_schedule_common() triggering tracing recursion | Date | Mon, 16 Feb 2015 19:20:07 +0100 |
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Since the function graph tracer needs to disable preemption, it might call preempt_schedule() after reenabling it if something triggered the need for rescheduling in between.
Therefore we can't trace preempt_schedule() itself because we would face a function tracing recursion otherwise as the tracer is always called before PREEMPT_ACTIVE gets set to prevent that recursion. This is why preempt_schedule() is tagged as "notrace".
But the same issue applies to every function called by preempt_schedule() before PREEMPT_ACTIVE is actually set. And preempt_schedule_common() is one such example. Unfortunately we forgot to tag it as notrace as well and as a result we are encountering tracing recursion since it got introduced by a18b5d01819235629289212ad428a5ee2b40f0d9 ("sched: Fix missing preemption opportunity").
Let's fix that by applying the appropriate function tag to preempt_schedule_common().
Reported-by: Huang Ying <ying.huang@intel.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Huang Ying <ying.huang@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 13049aa..683e850 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2899,7 +2899,7 @@ void __sched schedule_preempt_disabled(void) preempt_disable(); } -static void preempt_schedule_common(void) +static void __sched notrace preempt_schedule_common(void) { do { __preempt_count_add(PREEMPT_ACTIVE); -- 2.1.4
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