Commit b2e74a26 authored Nov 26, 2009 by Stephane Eranian Committed by Ingo Molnar Nov 26, 2009

perf_events: Fix read() bogus counts when in error state



When a pinned group cannot be scheduled it goes into error state.

Normally a group cannot go out of error state without being
explicitly re-enabled or disabled. There was a bug in per-thread
mode, whereby upon termination of the thread, the group would
transition from error to off leading to bogus counts and timing
information returned by read().

Fix it by clearing the error state.

Signed-off-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: perfmon2-devel@lists.sourceforge.net
LKML-Reference: <4b0eb9ce.0508d00a.573b.ffffeab6@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 4d795fb1

kernel/perf_event.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -338,6 +338,15 @@ list_del_event(struct perf_event event, struct perf_event_context ctx)
		event->group_leader->nr_siblings--;

		update_event_times(event);

		/*
		* If event was in error state, then keep it
		* that way, otherwise bogus counts will be
		* returned on read(). The only way to get out
		* of error state is by explicit re-enabling
		* of the event
		*/
		if (event->state > PERF_EVENT_STATE_OFF)
		event->state = PERF_EVENT_STATE_OFF;

		/*

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