Commit 52c9d2ba authored May 10, 2015 by Waiman Long Committed by Ingo Molnar May 11, 2015

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>

parent e95e6f17

kernel/locking/qspinlock_paravirt.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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);