rcu: Avoid misordering in __call_rcu_nocb_enqueue()

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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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Paul E. McKenney 2014-08-12 10:47:48 -07:00

parent 663e131090

commit 39953dfd40

1 changed files with 2 additions and 1 deletions

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kernel/rcu/tree_plugin.h

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