Commit a4f4bb6d authored Feb 24, 2016 by Peter Zijlstra Committed by Ingo Molnar Feb 25, 2016

perf: Allow perf_release() with !event->ctx



In the err_file: fput(event_file) case, the event will not yet have
been attached to a context. However perf_release() does assume it has
been. Cure this.

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/20160224174947.793996260@infradead.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 13005627

kernel/events/core.c

+13 −3

Original line number	Diff line number	Diff line
		@@ -3754,9 +3754,19 @@ static void put_event(struct perf_event *event)
		*/
		int perf_event_release_kernel(struct perf_event *event)
		{
		struct perf_event_context *ctx;
		struct perf_event_context *ctx = event->ctx;
		struct perf_event child, tmp;

		/*
		* If we got here through err_file: fput(event_file); we will not have
		* attached to a context yet.
		*/
		if (!ctx) {
		WARN_ON_ONCE(event->attach_state &
		(PERF_ATTACH_CONTEXT\|PERF_ATTACH_GROUP));
		goto no_ctx;
		}

		if (!is_kernel_event(event))
		perf_remove_from_owner(event);

		@@ -3832,8 +3842,8 @@ again:
		}
		mutex_unlock(&event->child_mutex);

		/* Must be the last reference */
		put_event(event);
		no_ctx:
		put_event(event); /* Must be the 'last' reference */
		return 0;
		}
		EXPORT_SYMBOL_GPL(perf_event_release_kernel);

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