ARM: 7556/1: perf: fix updated event period in response to PERF_EVENT_IOC_PERIOD

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / arm / kernel / perf_event.c

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 93971b1a4f0bb0d38eebd573f8618e994273b079..53c0304b734a4e6ad7b1806b147baa3d2d43986f 100644 (file)
--- a/arch/arm/kernel/perf_event.c
+++ b/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);