From 5f09fc688936705b2020ca247df39ee27283668a Mon Sep 17 00:00:00 2001
From: Robert Richter <robert.richter@amd.com>
Date: Thu, 5 Apr 2012 18:24:42 +0200
Subject: [PATCH] perf/x86: Fix cmpxchg() usage in amd_put_event_constraints()
Now the return value of cmpxchg() is used to match an event. The
change removes the duplicate event comparison and traverses the list
until an event was removed. This also fixes the following warning:
arch/x86/kernel/cpu/perf_event_amd.c:170: warning: value computed is not used
Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333643084-26776-3-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/cpu/perf_event_amd.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
index 95e7fe1c5f0bf5..589286f2887785 100644
--- a/arch/x86/kernel/cpu/perf_event_amd.c
+++ b/arch/x86/kernel/cpu/perf_event_amd.c
@@ -205,10 +205,8 @@ static void amd_put_event_constraints(struct cpu_hw_events *cpuc,
* when we come here
*/
for (i = 0; i < x86_pmu.num_counters; i++) {
- if (nb->owners[i] == event) {
- cmpxchg(nb->owners+i, event, NULL);
+ if (cmpxchg(nb->owners + i, event, NULL) == event)
break;
- }
}
}
--
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