AcoSail/kernel_optimize_test
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Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull perf fix from Thomas Gleixner:
 "A single fix for the intel cqm perf facility to prevent IPIs from
  interrupt context"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/cqm: Return cached counter value from IRQ context
This commit is contained in:
Linus Torvalds 2015-07-26 11:46:32 -07:00
commit 2579d019ad
1 changed files with 8 additions and 0 deletions
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arch/x86/kernel/cpu/perf_event_intel_cqm.c
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@ -951,6 +951,14 @@ static u64 intel_cqm_event_count(struct perf_event *event)
if (!cqm_group_leader(event))
return 0;
/*
* Getting up-to-date values requires an SMP IPI which is not
* possible if we're being called in interrupt context. Return
* the cached values instead.
*/
if (unlikely(in_interrupt()))
goto out;
/*
* Notice that we don't perform the reading of an RMID
* atomically, because we can't hold a spin lock across the