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authorXiao Guangrong <xiaoguangrong@cn.fujitsu.com>2009-12-09 11:30:36 +0800
committerIngo Molnar <mingo@elte.hu>2009-12-09 09:56:27 +0100
commitec89a06fd4e12301f11ab039ee07d2353a18addc (patch)
tree507d33bda6504dd8422b9952156d338b0200fb2b
parentb93f7978ad6b46133e9453b90ccc057dc2429e75 (diff)
downloadlinux-linaro-ec89a06fd4e12301f11ab039ee07d2353a18addc.tar.gz
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> Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul Mackerras <paulus@samba.org> LKML-Reference: <4B1F19DC.90204@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/perf_event.c3
1 files changed, 1 insertions, 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);
}