linux/kernel/events
Peter Zijlstra 28a967c3a2 perf: Cure event->pending_disable race
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>
2016-02-25 08:42:34 +01:00
..
callchain.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
core.c perf: Cure event->pending_disable race 2016-02-25 08:42:34 +01:00
hw_breakpoint.c perf: Collapse and fix event_function_call() users 2016-01-21 18:54:24 +01:00
internal.h perf: Fix AUX buffer refcounting 2015-07-06 14:08:30 +02:00
Makefile ftrace: allow architectures to specify ftrace compile options 2015-01-29 09:19:19 +01:00
ring_buffer.c perf: Synchronously free aux pages in case of allocation failure 2016-01-21 18:54:27 +01:00
uprobes.c memcg: adjust to support new THP refcounting 2016-01-15 17:56:32 -08:00