perf/core: Limit matching exclusive events to one PMU

An "exclusive" PMU is the one that can only have one event scheduled in
at any given time. There may be more than one of such PMUs in a system,
though, like Intel PT and BTS. It should be allowed to have one event
for either of those inside the same context (there may be other constraints
that may prevent this, but those would be hardware-specific). However,
the exclusivity code is written so that only one event from any of the
"exclusive" PMUs is allowed in a context.

Fix this by making the exclusive event filter explicitly match two events'
PMUs.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
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: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160920154811.3255-3-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/events/core.c

@@ -3929,7 +3929,7 @@ static void exclusive_event_destroy(struct perf_event *event)
 
 static bool exclusive_event_match(struct perf_event *e1, struct perf_event *e2)
 {
-	if ((e1->pmu->capabilities & PERF_PMU_CAP_EXCLUSIVE) &&
+	if ((e1->pmu == e2->pmu) &&
 	    (e1->cpu == e2->cpu ||
 	     e1->cpu == -1 ||
 	     e2->cpu == -1))