From 39953dfd40077c7480b1d5deb4d617e086b1c865 Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Date: Tue, 12 Aug 2014 10:47:48 -0700
Subject: [PATCH] rcu: Avoid misordering in __call_rcu_nocb_enqueue()

The NOCB leader wakeup ordering depends on the store to the header
happening before the check for the leader already being awake.  However,
because atomic_long_add() does not return a value, it does not provide
ordering guarantees, the incorrect comment in wake_nocb_leader()
notwithstanding.  This commit therefore adds a smp_mb__after_atomic()
after the final atomic_long_add() to provide the needed ordering
guarantee.

Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
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