From e5f4d3394a52ac351f1a479fe136d92fa5228eff Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri, 10 Sep 2010 17:38:06 +0200
Subject: perf: Fix perf_init_event()

We ought to return -ENOENT when non of the registered PMUs
recognise the requested event.

This fixes a boot crash that occurs if no PMU is available
but the NMI watchdog tries to register an event.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index f395fb4..f29b525 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -5236,12 +5236,15 @@ struct pmu *perf_init_event(struct perf_event *event)
 	list_for_each_entry_rcu(pmu, &pmus, entry) {
 		int ret = pmu->event_init(event);
 		if (!ret)
-			break;
+			goto unlock;
+
 		if (ret != -ENOENT) {
 			pmu = ERR_PTR(ret);
-			break;
+			goto unlock;
 		}
 	}
+	pmu = ERR_PTR(-ENOENT);
+unlock:
 	srcu_read_unlock(&pmus_srcu, idx);
 
 	return pmu;
-- 
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