Messages in this thread | | | Date | Wed, 10 Aug 2016 13:04:38 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2 1/4] perf/core: check return value of perf_event_read IPI |
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* David Carrillo-Cisneros <davidcc@google.com> wrote:
> The call to smp_call_function_single in perf_event_read() may fail and, > when it does, its error value is the one to return. > > Signed-off-by: David Carrillo-Cisneros <davidcc@google.com> > Reviewed-by: Stephane Eranian <eranian@google.com> > --- > kernel/events/core.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 9345028..96523fd 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -3469,9 +3469,9 @@ static int perf_event_read(struct perf_event *event, bool group) > .group = group, > .ret = 0, > }; > - smp_call_function_single(event->oncpu, > - __perf_event_read, &data, 1); > - ret = data.ret; > + ret = smp_call_function_single(event->oncpu, > + __perf_event_read, &data, 1); > + ret = ret ? : data.ret; > } else if (event->state == PERF_EVENT_STATE_INACTIVE) { > struct perf_event_context *ctx = event->ctx; > unsigned long flags;
Please also describe the symptoms of the bug - under what circumstances may the smp-call fail and how does the user notice?
Thanks,
Ingo
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