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    Subject[tip:perf/urgent] perf, x86: P4 PMU - Don't forget to clear cpuc->active_mask on overflow
    Commit-ID:  1ea5a6afd95a4803900c97ed63a47a883ebe7b3e
    Gitweb: http://git.kernel.org/tip/1ea5a6afd95a4803900c97ed63a47a883ebe7b3e
    Author: Cyrill Gorcunov <gorcunov@gmail.com>
    AuthorDate: Thu, 21 Apr 2011 11:03:21 -0400
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Fri, 22 Apr 2011 10:21:34 +0200

    perf, x86: P4 PMU - Don't forget to clear cpuc->active_mask on overflow

    It's not enough to simply disable event on overflow the
    cpuc->active_mask should be cleared as well otherwise counter
    may stall in "active" even in real being already disabled (which
    potentially may lead to the situation that user may not use this
    counter further).

    Don pointed out that:

    " I also noticed this patch fixed some unknown NMIs
    on a P4 when I stressed the box".

    Tested-by: Lin Ming <ming.m.lin@intel.com>
    Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
    Acked-by: Don Zickus <dzickus@redhat.com>
    Signed-off-by: Don Zickus <dzickus@redhat.com>
    Cc: Cyrill Gorcunov <gorcunov@gmail.com>
    Link: http://lkml.kernel.org/r/1303398203-2918-3-git-send-email-dzickus@redhat.com
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    arch/x86/kernel/cpu/perf_event_p4.c | 2 +-
    1 files changed, 1 insertions(+), 1 deletions(-)

    diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
    index c2520e1..d1f77e2 100644
    --- a/arch/x86/kernel/cpu/perf_event_p4.c
    +++ b/arch/x86/kernel/cpu/perf_event_p4.c
    @@ -947,7 +947,7 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
    if (!x86_perf_event_set_period(event))
    continue;
    if (perf_event_overflow(event, 1, &data, regs))
    - p4_pmu_disable_event(event);
    + x86_pmu_stop(event, 0);
    }

    if (handled) {

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