locking/atomic, arch/rwsem: Employ atomic_long_fetch_add()

Peter Zijlstra · Ingo Molnar · commit 86a3b5f34fc1 · 2016-06-16T10:48:35.000+02:00
Now that we have fetch_add() we can stop using add_return() - val.

Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Jason Low &lt;jason.low2@hpe.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Waiman Long &lt;waiman.long@hpe.com&gt;
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
@@ -153,7 +153,7 @@ __rwsem_mark_wake(struct rw_semaphore *sem,
 	if (wake_type != RWSEM_WAKE_READ_OWNED) {
 		adjustment = RWSEM_ACTIVE_READ_BIAS;
  try_reader_grant:
-		oldcount = atomic_long_add_return(adjustment, &sem->count) - adjustment;
+		oldcount = atomic_long_fetch_add(adjustment, &sem->count);
 
 		if (unlikely(oldcount < RWSEM_WAITING_BIAS)) {
 			/*
