Messages in this thread | | | Subject | Re: [PATCH V3 2/2] perf/x86: Reset the dirty counter to prevent the leak for an RDPMC task | From | "Liang, Kan" <> | Date | Wed, 14 Apr 2021 10:27:28 -0400 |
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On 4/14/2021 9:51 AM, Namhyung Kim wrote: > Hi Kan, > > On Wed, Apr 14, 2021 at 4:04 AM <kan.liang@linux.intel.com> wrote: >> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c >> index dd9f3c2..0d4a1a3 100644 >> --- a/arch/x86/events/core.c >> +++ b/arch/x86/events/core.c >> @@ -1585,6 +1585,8 @@ static void x86_pmu_del(struct perf_event *event, int flags) >> if (cpuc->txn_flags & PERF_PMU_TXN_ADD) >> goto do_del; >> >> + __set_bit(event->hw.idx, cpuc->dirty); >> + >> /* >> * Not a TXN, therefore cleanup properly. >> */ >> @@ -2304,12 +2306,46 @@ static int x86_pmu_event_init(struct perf_event *event) >> return err; >> } >> >> +void x86_pmu_clear_dirty_counters(void) >> +{ >> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); >> + int i; >> + >> + if (bitmap_empty(cpuc->dirty, X86_PMC_IDX_MAX)) >> + return; > > Maybe you can check it after clearing assigned counters. >
It should be very likely that the cpuc->dirty is non-empty. Move it after the clearing can skip the for_each_set_bit() and bitmap_zero(). OK. I will change it in V4.
Thanks, Kan
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