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Subject[PATCH 3/3] perf_event: cleanup for cpu_clock_perf_event_update()
Using atomic64_xchg() instead of atomic64_read() and atomic64_set().

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
kernel/perf_event.c | 3 +--
1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 592b293..8f46012 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4079,8 +4079,7 @@ static void cpu_clock_perf_event_update(struct perf_event *event)
u64 now;

now = cpu_clock(cpu);
- prev = atomic64_read(&event->hw.prev_count);
- atomic64_set(&event->hw.prev_count, now);
+ prev = atomic64_xchg(&event->hw.prev_count, now);
atomic64_add(now - prev, &event->count);
}

--
1.6.1.2



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