diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2016-02-24 18:45:46 +0100 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2016-04-20 08:46:49 +0200 |
| commit | 3ea8a50be86da7690db5fd03ae3a3911773164ec (patch) | |
| tree | ab5e43dbfaab30a0cc72d59b002dde1082fe1c80 /kernel | |
| parent | b44d9f302fab3f40535be53f0b7ec5cfa8386643 (diff) | |
perf: Cure event->pending_disable race
commit 28a967c3a2f99fa3b5f762f25cb2a319d933571b upstream.
Because event_sched_out() checks event->pending_disable _before_
actually disabling the event, it can happen that the event fires after
it checks but before it gets disabled.
This would leave event->pending_disable set and the queued irq_work
will try and process it.
However, if the event trigger was during schedule(), the event might
have been de-scheduled by the time the irq_work runs, and
perf_event_disable_local() will fail.
Fix this by checking event->pending_disable _after_ we call
event->pmu->del(). This depends on the latter being a compiler
barrier, such that the compiler does not lift the load and re-creates
the problem.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.040469884@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index b9c4a60f5137..0b3c09a3f7b6 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1389,14 +1389,14 @@ event_sched_out(struct perf_event *event, if (event->state != PERF_EVENT_STATE_ACTIVE) return; + event->tstamp_stopped = tstamp; + event->pmu->del(event, 0); + event->oncpu = -1; event->state = PERF_EVENT_STATE_INACTIVE; if (event->pending_disable) { event->pending_disable = 0; event->state = PERF_EVENT_STATE_OFF; } - event->tstamp_stopped = tstamp; - event->pmu->del(event, 0); - event->oncpu = -1; if (!is_software_event(event)) cpuctx->active_oncpu--; |