forked from Minki/linux
499d79559f
preempt_schedule_common() is marked notrace, but it does not use _notrace() preempt_count functions and __schedule() is also not marked notrace, which means that its perfectly possible to end up in the tracer from preempt_schedule_common(). Steve says: | Yep, there's some history to this. This was originally the issue that | caused function tracing to go into infinite recursion. But now we have | preempt_schedule_notrace(), which is used by the function tracer, and | that function must not be traced till preemption is disabled. | | Now if function tracing is running and we take an interrupt when | NEED_RESCHED is set, it calls | | preempt_schedule_common() (not traced) | | But then that calls preempt_disable() (traced) | | function tracer calls preempt_disable_notrace() followed by | preempt_enable_notrace() which will see NEED_RESCHED set, and it will | call preempt_schedule_notrace(), which stops the recursion, but | still calls __schedule() here, and that means when we return, we call | the __schedule() from preempt_schedule_common(). | | That said, I prefer this patch. Preemption is disabled before calling | __schedule(), and we get rid of a one round recursion with the | scheduler. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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| .. | ||
| auto_group.c | ||
| auto_group.h | ||
| clock.c | ||
| completion.c | ||
| core.c | ||
| cpuacct.c | ||
| cpuacct.h | ||
| cpudeadline.c | ||
| cpudeadline.h | ||
| cpupri.c | ||
| cpupri.h | ||
| cputime.c | ||
| deadline.c | ||
| debug.c | ||
| fair.c | ||
| features.h | ||
| idle_task.c | ||
| idle.c | ||
| loadavg.c | ||
| Makefile | ||
| rt.c | ||
| sched.h | ||
| stats.c | ||
| stats.h | ||
| stop_task.c | ||
| wait.c | ||