diff options
author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-04-16 15:30:54 -0300 |
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committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-04-16 15:30:54 -0300 |
commit | bdcfd44fb5b5fb8fd660e7f93f1095c507481024 (patch) | |
tree | e423b07154d422b711ddfadedb87c43317d3c4f6 /arch/x86/kernel/cpu/perf_event.c | |
parent | 4a327fcef90ba27150a3e8741441b68c605ae248 (diff) |
Linux-libre 4.5.1-gnupck-4.5.1-gnu
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event.c')
-rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 1b443db2d..6532f5b40 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -596,6 +596,19 @@ void x86_pmu_disable_all(void) } } +/* + * There may be PMI landing after enabled=0. The PMI hitting could be before or + * after disable_all. + * + * If PMI hits before disable_all, the PMU will be disabled in the NMI handler. + * It will not be re-enabled in the NMI handler again, because enabled=0. After + * handling the NMI, disable_all will be called, which will not change the + * state either. If PMI hits after disable_all, the PMU is already disabled + * before entering NMI handler. The NMI handler will not change the state + * either. + * + * So either situation is harmless. + */ static void x86_pmu_disable(struct pmu *pmu) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); |