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Message-Id: <1512157876-24665-8-git-send-email-paulmck@linux.vnet.ibm.com>
Date:   Fri,  1 Dec 2017 11:51:03 -0800
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...hat.com>
Subject: [PATCH tip/core/rcu 08/21] 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@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
---
 include/linux/seqlock.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index f189a8a3bbb8..bcf4cf26b8c8 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;
 }
 
-- 
2.5.2

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