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ftrace: only trace preempt off with preempt tracer

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When PREEMPT_TRACER and IRQSOFF_TRACER are both configured and irqsoff
tracer is running, the preempt_off sections might also be traced.

Thanks to Andrew Morton for pointing out my mistake of spin_lock disabling
interrupts while he was reviewing ftrace.txt. Seems that my example I used
actually hit this bug.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-07-15 09:53:37 -04:00 committed by Ingo Molnar
parent e59494f441
commit 1e01cb0c6f
1 changed files with 4 additions and 2 deletions
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6
kernel/trace/trace_irqsoff.c
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@ -337,12 +337,14 @@ EXPORT_SYMBOL(trace_hardirqs_off_caller);
#ifdef CONFIG_PREEMPT_TRACER
void trace_preempt_on(unsigned long a0, unsigned long a1)
{
stop_critical_timing(a0, a1);
if (preempt_trace())
stop_critical_timing(a0, a1);
}
void trace_preempt_off(unsigned long a0, unsigned long a1)
{
start_critical_timing(a0, a1);
if (preempt_trace())
start_critical_timing(a0, a1);
}
#endif /* CONFIG_PREEMPT_TRACER */