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preempt: Use preempt_schedule_context() as the official tracing preemption point

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preempt_schedule_context() is a tracing safe preemption point but it's
only used when CONFIG_CONTEXT_TRACKING=y. Other configs have tracing
recursion issues since commit:

  b30f0e3ffe ("sched/preempt: Optimize preemption operations on __schedule() callers")

introduced function based preemp_count_*() ops.

Lets make it available on all configs and give it a more appropriate
name for its new position.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1433432349-1021-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Frederic Weisbecker 2015-06-04 17:39:08 +02:00 • committed by Ingo Molnar
commit 4eaca0a887
8 changed files with 13 additions and 32 deletions
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8
kernel/sched/core.c
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@ -2937,9 +2937,8 @@ asmlinkage __visible void __sched notrace preempt_schedule(void)
NOKPROBE_SYMBOL(preempt_schedule);
EXPORT_SYMBOL(preempt_schedule);
#ifdef CONFIG_CONTEXT_TRACKING
/**
* preempt_schedule_context - preempt_schedule called by tracing
* preempt_schedule_notrace - preempt_schedule called by tracing
*
* The tracing infrastructure uses preempt_enable_notrace to prevent
* recursion and tracing preempt enabling caused by the tracing
@ -2952,7 +2951,7 @@ EXPORT_SYMBOL(preempt_schedule);
* instead of preempt_schedule() to exit user context if needed before
* calling the scheduler.
*/
asmlinkage __visible void __sched notrace preempt_schedule_context(void)
asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
{
enum ctx_state prev_ctx;
@ -2980,8 +2979,7 @@ asmlinkage __visible void __sched notrace preempt_schedule_context(void)
__preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET);
} while (need_resched());
}
EXPORT_SYMBOL_GPL(preempt_schedule_context);
#endif /* CONFIG_CONTEXT_TRACKING */
EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
#endif /* CONFIG_PREEMPT */