From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Mon, 9 Oct 2017 18:00:32 +0000 (-0700)
Subject: seqlock: Remove now-redundant smp_read_barrier_depends()
X-Git-Tag: v4.16-rc1~169^2^2^4~14
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=98b22737847cc015a797567e32d0a4826003afbf;p=thirdparty%2Fkernel%2Flinux.git

seqlock: Remove now-redundant smp_read_barrier_depends()

READ_ONCE() now implies smp_read_barrier_depends(), so this patch
removes the now-redundant smp_read_barrier_depends() from
raw_read_seqcount_latch().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
---

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index f189a8a3bbb88..bcf4cf26b8c89 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -278,9 +278,8 @@ static inline void raw_write_seqcount_barrier(seqcount_t *s)
 
 static inline int raw_read_seqcount_latch(seqcount_t *s)
 {
-	int seq = READ_ONCE(s->sequence);
 	/* Pairs with the first smp_wmb() in raw_write_seqcount_latch() */
-	smp_read_barrier_depends();
+	int seq = READ_ONCE(s->sequence); /* ^^^ */
 	return seq;
 }