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authorYoung Xiao <92siuyang@gmail.com>2019-05-29 10:21:48 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-06-25 11:36:52 +0800
commitd52a68399b71044e44977f007dcf3bedf5119b1d (patch)
treea8c77e227798287376dd6ff1cbf6e51738fdf9a8
parentb1013624a8adb9caa83b4c9f487778c7b51467a0 (diff)
sparc: perf: fix updated event period in response to PERF_EVENT_IOC_PERIOD
[ Upstream commit 56cd0aefa475079e9613085b14a0f05037518fed ] The PERF_EVENT_IOC_PERIOD ioctl command can be used to change the sample period of a running perf_event. Consequently, when calculating the next event period, the new period will only be considered after the previous one has overflowed. This patch changes the calculation of the remaining event ticks so that they are offset if the period has changed. See commit 3581fe0ef37c ("ARM: 7556/1: perf: fix updated event period in response to PERF_EVENT_IOC_PERIOD") for details. Signed-off-by: Young Xiao <92siuyang@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--arch/sparc/kernel/perf_event.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index eceb0215bdee..58ea64a29d5f 100644
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -891,6 +891,10 @@ static int sparc_perf_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);