| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 020/128] perf: Fix PERF_EVENT_IOC_PERIOD deadlock | Date | Sun, 24 Jan 2016 21:59:35 +0000 |
| |
3.16.7-ckt23 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Peter Zijlstra <peterz@infradead.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@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.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> Signed-off-by: Luis Henriques <luis.henriques@canonical.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 259b9fdb6ba4..db2f2cfb58e3 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3692,7 +3692,14 @@ 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;
|