Author: Ingo Molnar <mingo@xxxxxxx> AuthorDate: Mon, 12 May 2008 21:21:14 +0200 Commit: Ingo Molnar <mingo@xxxxxxx> CommitDate: Thu, 26 Feb 2009 18:08:33 +0100 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@xxxxxxxxxxxxx> Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- 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 a0b0852..db69174 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; -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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