Messages in this thread Patch in this message | | | Date | Fri, 4 Dec 2015 03:50:10 -0800 | From | tip-bot for Peter Zijlstra <> | Subject | [tip:perf/core] perf: Fix PERF_EVENT_IOC_PERIOD deadlock |
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Commit-ID: 642c2d671ceff40e9453203ea0c66e991e11e249 Gitweb: http://git.kernel.org/tip/642c2d671ceff40e9453203ea0c66e991e11e249 Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Mon, 30 Nov 2015 12:56:15 +0100 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Fri, 4 Dec 2015 10:08:03 +0100
perf: Fix PERF_EVENT_IOC_PERIOD deadlock
Dmitry reported a fairly silly recursive lock deadlock for PERF_EVENT_IOC_PERIOD, fix this by explicitly doing the inactive part of __perf_event_period() instead of calling that function.
Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> Cc: Alexander Potapenko <glider@google.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Fixes: c7999c6f3fed ("perf: Fix PERF_EVENT_IOC_PERIOD migration race") Link: http://lkml.kernel.org/r/20151130115615.GJ17308@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/events/core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 5854fcf..49a5118 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4225,7 +4225,14 @@ retry: goto retry; } - __perf_event_period(&pe); + if (event->attr.freq) { + event->attr.sample_freq = value; + } else { + event->attr.sample_period = value; + event->hw.sample_period = value; + } + + local64_set(&event->hw.period_left, 0); raw_spin_unlock_irq(&ctx->lock); return 0;
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