locking/spinlocks/mcs: Introduce and use init macro and function for osq locks

Currently, we initialize the osq lock by directly setting the lock's values. It
would be preferable if we use an init macro to do the initialization like we do
with other locks.

This patch introduces and uses a macro and function for initializing the osq lock.

Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fusionio.com>
Link: http://lkml.kernel.org/r/1405358872-3732-4-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 9 insertions, 1 deletions

diff --git a/include/linux/osq_lock.h b/include/linux/osq_lock.h
index b001682bf7cb..90230d5811c5 100644
--- a/include/linux/osq_lock.h
+++ b/include/linux/osq_lock.h
@@ -16,4 +16,12 @@ struct optimistic_spin_queue {
         atomic_t tail;
 };
 
+/* Init macro and function. */
+#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) }
+
+static inline void osq_lock_init(struct optimistic_spin_queue *lock)
+{
+        atomic_set(&lock->tail, OSQ_UNLOCKED_VAL);
+}
+
 #endif
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 9fdcdd03507d..25cd9aa2f3d7 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -69,7 +69,7 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
           __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock),     \
           LIST_HEAD_INIT((name).wait_list),             \
           NULL, /* owner */                             \
-          { ATOMIC_INIT(OSQ_UNLOCKED_VAL) } /* osq */   \
+          OSQ_LOCK_UNLOCKED /* osq */                   \
           __RWSEM_DEP_MAP_INIT(name) }
 #else
 #define __RWSEM_INITIALIZER(name)                       \