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| author |   Ingo Molnar <mingo@elte.hu> | 2008-05-12 21:21:14 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-02-26 18:44:05 +0100 |
| commit | 6409c4da289d6905f7ae2bd0630438368439bda2 (patch) | |
| tree | a89ab72b160acabe7e83200f73ba3a2cb3b2a0be /kernel | |
| parent | tracing, genirq: add irq enter and exit trace events (diff) | |
| download | linux-dev-6409c4da289d6905f7ae2bd0630438368439bda2.tar.xz linux-dev-6409c4da289d6905f7ae2bd0630438368439bda2.zip | |
sched: sched_clock() improvement: use in_nmi()
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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched_clock.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c index a0b0852414cc..db69174b1178 100644 --- a/kernel/sched_clock.c +++ b/kernel/sched_clock.c @@ -29,6 +29,7 @@ #include <linux/spinlock.h> #include <linux/ktime.h> #include <linux/module.h> +#include <linux/hardirq.h> /* * 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); 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)) return 0ull; |