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authorPeter Zijlstra <peterz@infradead.org>2016-04-18 01:27:03 +0200
committerIngo Molnar <mingo@kernel.org>2016-06-16 10:48:34 +0200
commitf9852b74bec0117b888da39d070c323ea1cb7f4c (patch)
tree7a0414aeaa3fd15a67754f8f87ce511fff8dc0d6 /kernel/locking
parent4ec45856b698c37e73d973fb4b1a094dfb9d5732 (diff)
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@infradead.org> Acked-by: Waiman Long <waiman.long@hpe.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking')
-rw-r--r--kernel/locking/qrwlock.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c
index fec082338668..19248ddf37ce 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);
/*