perf_events: Fix resource leak in x86 __hw_perf_event_init()

If reserve_pmc_hardware() succeeds but reserve_ds_buffers()
fails, then we need to release_pmc_hardware. It won't be done
by the destroy() callback because we return before setting it
in case of error.
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: <stable@kernel.org>
Cc: peterz@infradead.org
Cc: paulus@samba.org
Cc: davem@davemloft.net
Cc: fweisbec@gmail.com
Cc: robert.richter@amd.com
Cc: perfmon2-devel@lists.sf.net
LKML-Reference: <4ba1568b.15185e0a.182a.7802@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--
 arch/x86/kernel/cpu/perf_event.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

arch/x86/kernel/cpu/perf_event.c

@@ -455,8 +455,11 @@ static int __hw_perf_event_init(struct perf_event *event)
 		if (atomic_read(&active_events) == 0) {
 			if (!reserve_pmc_hardware())
 				err = -EBUSY;
-			else
+			else {
 				err = reserve_ds_buffers();
+				if (err)
+					release_pmc_hardware();
+			}
 		}
 		if (!err)
 			atomic_inc(&active_events);