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Date: Mon, 15 Sep 2014 12:29:51 +0200 From: Stephane Eranian <eranian@...gle.com> To: Peter Zijlstra <peterz@...radead.org> Cc: Jiri Olsa <jolsa@...hat.com>, LKML <linux-kernel@...r.kernel.org>, "mingo@...e.hu" <mingo@...e.hu>, Arnaldo Carvalho de Melo <acme@...hat.com>, Namhyung Kim <namhyung@...nel.org>, "ak@...ux.intel.com" <ak@...ux.intel.com>, David Ahern <dsahern@...il.com> Subject: Re: [PATCH] perf: Do not check PERF_EVENT_STATE_EXIT on syscall read path On Wed, Sep 10, 2014 at 3:49 PM, Stephane Eranian <eranian@...gle.com> wrote: > > Peter, > > > > On Mon, Sep 8, 2014 at 5:22 PM, Peter Zijlstra <peterz@...radead.org> wrote: > > On Mon, Sep 08, 2014 at 04:31:07PM +0200, Jiri Olsa wrote: > >> Revert PERF_EVENT_STATE_EXIT check on read syscall path. > >> It breaks standard way to read counter, which is to open > >> the counter, wait for the monitored process to die and > >> read the counter. > >> > >> Reported-by: Stephane Eranian <eranian@...gle.com> > >> Acked-by: Stephane Eranian <eranian@...gle.com> > >> Cc: Arnaldo Carvalho de Melo <acme@...hat.com> > >> Cc: Frederic Weisbecker <fweisbec@...il.com> > >> Cc: Ingo Molnar <mingo@...nel.org> > >> Cc: Paul Mackerras <paulus@...ba.org> > >> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl> > >> Cc: Stephane Eranian <eranian@...gle.com> > >> Signed-off-by: Jiri Olsa <jolsa@...nel.org> > > > > Thanks! > Still don't see this fix in tip.git. > Still not there. This is a problem. > > >> --- > >> kernel/events/core.c | 3 +-- > >> 1 file changed, 1 insertion(+), 2 deletions(-) > >> > >> diff --git a/kernel/events/core.c b/kernel/events/core.c > >> index d8cb4d21a346..6d1c9ce1643e 100644 > >> --- a/kernel/events/core.c > >> +++ b/kernel/events/core.c > >> @@ -3600,8 +3600,7 @@ perf_read_hw(struct perf_event *event, char __user *buf, size_t count) > >> * error state (i.e. because it was pinned but it couldn't be > >> * scheduled on to the CPU at some point). > >> */ > >> - if ((event->state == PERF_EVENT_STATE_ERROR) || > >> - (event->state == PERF_EVENT_STATE_EXIT)) > >> + if (event->state == PERF_EVENT_STATE_ERROR) > >> return 0; > >> > >> if (count < event->read_size) > >> -- > >> 1.8.3.1 > >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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