Commit-ID: f9852b74bec0117b888da39d070c323ea1cb7f4c Gitweb: http://git.kernel.org/tip/f9852b74bec0117b888da39d070c323ea1cb7f4c Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Mon, 18 Apr 2016 01:27:03 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Thu, 16 Jun 2016 10:48:34 +0200 locking/atomic, arch/qrwlock: Employ atomic_fetch_add_acquire() The only reason for the current code is to make GCC emit only the "LOCK XADD" instruction on x86 (and not do a pointless extra ADD on the result), do so nicer. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Waiman Long <waiman.long@xxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: linux-arch@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/locking/qrwlock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c index fec0823..19248dd 100644 --- a/kernel/locking/qrwlock.c +++ b/kernel/locking/qrwlock.c @@ -93,7 +93,7 @@ void queued_read_lock_slowpath(struct qrwlock *lock, u32 cnts) * that accesses can't leak upwards out of our subsequent critical * section in the case that the lock is currently held for write. */ - cnts = atomic_add_return_acquire(_QR_BIAS, &lock->cnts) - _QR_BIAS; + cnts = atomic_fetch_add_acquire(_QR_BIAS, &lock->cnts); rspin_until_writer_unlock(lock, cnts); /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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