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Date: Sun, 20 Sep 2015 03:11:51 -0700 From: Davidlohr Bueso <dave@...olabs.net> To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>, Thomas Gleixner <tglx@...utronix.de> Cc: Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Will Deacon <will.deacon@....com>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Davidlohr Bueso <dave@...olabs.net>, linux-kernel@...r.kernel.org, Davidlohr Bueso <dbueso@...e.de> Subject: [PATCH 5/5] locking/mcs: Relax to atomic/release semantics ... by using acquire semantics where appropriate As such, weakly ordered archs can benefit from more relaxed use of barriers when issuing atomics. Signed-off-by: Davidlohr Bueso <dbueso@...e.de> --- kernel/locking/mcs_spinlock.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h index fd91aaa..5b9102a 100644 --- a/kernel/locking/mcs_spinlock.h +++ b/kernel/locking/mcs_spinlock.h @@ -67,7 +67,7 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) node->locked = 0; node->next = NULL; - prev = xchg(lock, node); + prev = xchg_acquire(lock, node); if (likely(prev == NULL)) { /* * Lock acquired, don't need to set node->locked to 1. Threads @@ -98,7 +98,7 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node) /* * Release the lock by setting it to NULL */ - if (likely(cmpxchg(lock, node, NULL) == node)) + if (likely(cmpxchg_release(lock, node, NULL) == node)) return; /* Wait until the next pointer is set */ while (!(next = READ_ONCE(node->next))) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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