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Date: Fri, 15 Jan 2016 15:59:18 -0800 From: Kamal Mostafa <kamal@...onical.com> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org, kernel-team@...ts.ubuntu.com Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>, Alexander Potapenko <glider@...gle.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Arnaldo Carvalho de Melo <acme@...hat.com>, Eric Dumazet <edumazet@...gle.com>, Jiri Olsa <jolsa@...hat.com>, Kostya Serebryany <kcc@...gle.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Sasha Levin <sasha.levin@...cle.com>, Stephane Eranian <eranian@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, Vince Weaver <vincent.weaver@...ne.edu>, Ingo Molnar <mingo@...nel.org>, Kamal Mostafa <kamal@...onical.com> Subject: [PATCH 4.2.y-ckt 144/305] perf: Fix PERF_EVENT_IOC_PERIOD deadlock 4.2.8-ckt2 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Peter Zijlstra <peterz@...radead.org> commit 642c2d671ceff40e9453203ea0c66e991e11e249 upstream. 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@...gle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org> Cc: Alexander Potapenko <glider@...gle.com> Cc: Arnaldo Carvalho de Melo <acme@...nel.org> Cc: Arnaldo Carvalho de Melo <acme@...hat.com> Cc: Eric Dumazet <edumazet@...gle.com> Cc: Jiri Olsa <jolsa@...hat.com> Cc: Kostya Serebryany <kcc@...gle.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Sasha Levin <sasha.levin@...cle.com> Cc: Stephane Eranian <eranian@...gle.com> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: Vince Weaver <vincent.weaver@...ne.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@...nel.org> Signed-off-by: Kamal Mostafa <kamal@...onical.com> --- 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 c06fa66..d86859f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4034,7 +4034,14 @@ 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; -- 1.9.1
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