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sched: sched_clock() improvement: use in_nmi()

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make sure we dont execute more complex sched_clock() code in NMI context.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2008-05-12 21:21:14 +02:00
parent af39241b90
commit 6409c4da28
1 changed files with 8 additions and 0 deletions
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8
kernel/sched_clock.c
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@ -29,6 +29,7 @@
#include <linux/spinlock.h> #include <linux/spinlock.h>
#include <linux/ktime.h> #include <linux/ktime.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/hardirq.h>
/* /*
* Scheduler clock - returns current time in nanosec units. * Scheduler clock - returns current time in nanosec units.
@ -151,6 +152,13 @@ u64 sched_clock_cpu(int cpu)
struct sched_clock_data *scd = cpu_sdc(cpu); struct sched_clock_data *scd = cpu_sdc(cpu);
u64 now, clock, this_clock, remote_clock; u64 now, clock, this_clock, remote_clock;
/*
* Normally this is not called in NMI context - but if it is,
* trying to do any locking here is totally lethal.
*/
if (unlikely(in_nmi()))
return scd->clock;
if (unlikely(!sched_clock_running)) if (unlikely(!sched_clock_running))
return 0ull; return 0ull;