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ring-buffer: no preempt for sched_clock() 

Impact: disable preemption when calling sched_clock()

The ring_buffer_time_stamp still uses sched_clock as its counter.
But it is a bug to call it with preemption enabled. This requirement
should not be pushed to the ring_buffer_time_stamp callers, so
the ring_buffer_time_stamp needs to disable preemption when calling
sched_clock.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-11-12 00:01:27 -05:00 committed by Ingo Molnar
parent c1e7abbc7a
commit 47e74f2ba8
1 changed files with 7 additions and 1 deletions
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8
kernel/trace/ring_buffer.c
View File

@ -51,8 +51,14 @@ void tracing_off(void)
/* FIXME!!! */
u64 ring_buffer_time_stamp(int cpu)
{
u64 time;
preempt_disable_notrace();
/* shift to debug/test normalization and TIME_EXTENTS */
return sched_clock() << DEBUG_SHIFT;
time = sched_clock() << DEBUG_SHIFT;
preempt_enable_notrace();
return time;
}
void ring_buffer_normalize_time_stamp(int cpu, u64 *ts)