Messages in this thread | | | Subject | Re: [PATCH] perf: fix possible divide-by-zero in perf_swevent_overflow() | From | Peter Zijlstra <> | Date | Thu, 26 Aug 2010 14:12:07 +0200 |
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On Thu, 2010-08-26 at 20:07 +0800, Dongdong Deng wrote: > The event->hw.last_period is possible to zero, thus it will > cause divide_by_zero later in perf_swevent_set_period().
How can it be zero?
> This patch checks event->hw.last_period before invoke > perf_swevent_set_period() and replaces "event->hw" with "hwc". > > Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > Cc: Paul Mackerras <paulus@samba.org> > --- > kernel/perf_event.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/perf_event.c b/kernel/perf_event.c > index 403d180..ccba741 100644 > --- a/kernel/perf_event.c > +++ b/kernel/perf_event.c > @@ -4050,8 +4050,8 @@ static void perf_swevent_overflow(struct perf_event *event, u64 overflow, > struct hw_perf_event *hwc = &event->hw; > int throttle = 0; > > - data->period = event->hw.last_period; > - if (!overflow) > + data->period = hwc->last_period; > + if (!overflow && hwc->last_period) > overflow = perf_swevent_set_period(event); > > if (hwc->interrupts == MAX_INTERRUPTS)
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