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locking/pvqspinlock: Replace xchg() by the more descriptive set_mb() 

The xchg() function was used in pv_wait_node() to set a certain
value and provide a memory barrier which is what the set_mb()
function is for.  This patch replaces the xchg() call by
set_mb().

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Cc: Douglas Hatch <doug.hatch@hp.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Waiman Long 2015-05-10 21:17:10 -04:00 committed by Ingo Molnar
parent e95e6f176c
commit 52c9d2badd
1 changed files with 1 additions and 1 deletions
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2
kernel/locking/qspinlock_paravirt.h
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@ -175,7 +175,7 @@ static void pv_wait_node(struct mcs_spinlock *node)
*
* Matches the xchg() from pv_kick_node().
*/
(void)xchg(&pn->state, vcpu_halted);
set_mb(pn->state, vcpu_halted);
if (!READ_ONCE(node->locked))
pv_wait(&pn->state, vcpu_halted);