From 963988262c3c8f4234f64a0dde59446a295e07bb Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed, 24 Nov 2010 18:55:29 +0100
Subject: [PATCH] perf: Ignore non-sampling overflows

Some arch implementations call perf_event_overflow() by 'accident',
ignore this.

Reported-by: Francis Moreau <francis.moro@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/perf_event.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 98c5549c8e29..af1e63f249f3 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4240,6 +4240,13 @@ static int __perf_event_overflow(struct perf_event *event, int nmi,
 	struct hw_perf_event *hwc = &event->hw;
 	int ret = 0;
 
+	/*
+	 * Non-sampling counters might still use the PMI to fold short
+	 * hardware counters, ignore those.
+	 */
+	if (unlikely(!is_sampling_event(event)))
+		return 0;
+
 	if (!throttle) {
 		hwc->interrupts++;
 	} else {