From 7c3fdbb82c67168e2efd0f97a1b37222d5b21b9a Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Wed, 17 Oct 2012 12:01:34 +0100
Subject: [PATCH] --- yaml --- r: 334831 b: refs/heads/master c:
 3581fe0ef37ce12ac7a4f74831168352ae848edc h: refs/heads/master i:   334829:
 376ece5b9554b58571e237b0d1670d5918436dae   334827:
 f300c7fb1d3cec2484710b185edb161674c93040   334823:
 be8927b756e00e86733a8d0804fa9ce04c886d11   334815:
 d9e8f5d43f1755aa1e8820abd1e09b6cb72e7bd6 v: v3

---
 [refs]                             | 2 +-
 trunk/arch/arm/kernel/perf_event.c | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index cc504a6b077a..16aa22143b0f 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2456f44dd7a9aaffc2cd21a13f78198b3d94da08
+refs/heads/master: 3581fe0ef37ce12ac7a4f74831168352ae848edc
diff --git a/trunk/arch/arm/kernel/perf_event.c b/trunk/arch/arm/kernel/perf_event.c
index 93971b1a4f0b..53c0304b734a 100644
--- a/trunk/arch/arm/kernel/perf_event.c
+++ b/trunk/arch/arm/kernel/perf_event.c
@@ -96,6 +96,10 @@ armpmu_event_set_period(struct perf_event *event,
 	s64 period = hwc->sample_period;
 	int ret = 0;
 
+	/* The period may have been changed by PERF_EVENT_IOC_PERIOD */
+	if (unlikely(period != hwc->last_period))
+		left = period - (hwc->last_period - left);
+
 	if (unlikely(left <= -period)) {
 		left = period;
 		local64_set(&hwc->period_left, left);