Commit-ID: 642c2d671ceff40e9453203ea0c66e991e11e249
Gitweb: http://git.kernel.org/tip/642c2d671ceff40e9453203ea0c66e991e11e249
Author: Peter Zijlstra <pet...@infradead.org>
AuthorDate: Mon, 30 Nov 2015 12:56:15 +0100
Committer: Ingo Molnar <mi...@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 <dvyu...@google.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: <sta...@vger.kernel.org>
Cc: Alexander Potapenko <gli...@google.com>
Cc: Arnaldo Carvalho de Melo <a...@kernel.org>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Eric Dumazet <eduma...@google.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Kostya Serebryany <k...@google.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Sasha Levin <sasha.le...@oracle.com>
Cc: Stephane Eranian <eran...@google.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Vince Weaver <vincent.wea...@maine.edu>
Fixes: c7999c6f3fed ("perf: Fix PERF_EVENT_IOC_PERIOD migration race")
Link:
http://lkml.kernel.org/r/20151130115615.gj17...@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mi...@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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