From ec89a06fd4e12301f11ab039ee07d2353a18addc Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Wed, 9 Dec 2009 11:30:36 +0800 Subject: [PATCH] perf_event: Cleanup for cpu_clock_perf_event_update() Using atomic64_xchg() instead of atomic64_read() and atomic64_set(). Signed-off-by: Xiao Guangrong Reviewed-by: Frederic Weisbecker Cc: Peter Zijlstra Cc: Paul Mackerras LKML-Reference: <4B1F19DC.90204@cn.fujitsu.com> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 77641ae6b23..94e1b28333a 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); }