Subject: + lib-percpu_counterc-__this_cpu_write-doesnt-need-to-be-protected-by-spinlock.patch added to -mm tree
To: fan.du@xxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 01 Jul 2013 16:07:48 -0700
The patch titled
Subject: lib/percpu_counter.c: __this_cpu_write() doesn't need to be protected by spinlock
has been added to the -mm tree. Its filename is
lib-percpu_counterc-__this_cpu_write-doesnt-need-to-be-protected-by-spinlock.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-percpu_counterc-__this_cpu_write-doesnt-need-to-be-protected-by-spinlock.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-percpu_counterc-__this_cpu_write-doesnt-need-to-be-protected-by-spinlock.patch
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------------------------------------------------------
From: Fan Du <fan.du@xxxxxxxxxxxxx>
Subject: lib/percpu_counter.c: __this_cpu_write() doesn't need to be protected by spinlock
__this_cpu_write doesn't need to be protected by spinlock, AS we are doing
per cpu write with preempt disabled. And another reason to remove
__this_cpu_write outside of spinlock: __percpu_counter_sum is not an
accurate counter.
Signed-off-by: Fan Du <fan.du@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/percpu_counter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN lib/percpu_counter.c~lib-percpu_counterc-__this_cpu_write-doesnt-need-to-be-protected-by-spinlock lib/percpu_counter.c
--- a/lib/percpu_counter.c~lib-percpu_counterc-__this_cpu_write-doesnt-need-to-be-protected-by-spinlock
+++ a/lib/percpu_counter.c
@@ -80,8 +80,8 @@ void __percpu_counter_add(struct percpu_
if (count >= batch || count <= -batch) {
raw_spin_lock(&fbc->lock);
fbc->count += count;
- __this_cpu_write(*fbc->counters, 0);
raw_spin_unlock(&fbc->lock);
+ __this_cpu_write(*fbc->counters, 0);
} else {
__this_cpu_write(*fbc->counters, count);
}
_
Patches currently in -mm which might be from fan.du@xxxxxxxxxxxxx are
linux-next.patch
lib-percpu_counterc-__this_cpu_write-doesnt-need-to-be-protected-by-spinlock.patch
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