[PATCH -v4 7/8] locking/mutex: Simplify some ww_mutex code in __mutex_lock_common()

[Peter Zijlstra]

From: Waiman Long <Waiman.Long@xxxxxxx>

This patch removes some of the redundant ww_mutex code in
__mutex_lock_common().

Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Cc: Jason Low <jason.low2@xxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Ding Tianhong <dingtianhong@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Will Deacon <Will.Deacon@xxxxxxx>
Signed-off-by: Waiman Long <Waiman.Long@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 kernel/locking/mutex.c |   13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -580,10 +580,11 @@ __mutex_lock_common(struct mutex *lock,
 	struct mutex_waiter waiter;
 	unsigned long flags;
 	bool first = false;
+	struct ww_mutex *ww;
 	int ret;
 
 	if (use_ww_ctx) {
-		struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
+		ww = container_of(lock, struct ww_mutex, base);
 		if (unlikely(ww_ctx == READ_ONCE(ww->ctx)))
 			return -EALREADY;
 	}
@@ -595,12 +596,8 @@ __mutex_lock_common(struct mutex *lock,
 	    mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx)) {
 		/* got the lock, yay! */
 		lock_acquired(&lock->dep_map, ip);
-		if (use_ww_ctx) {
-			struct ww_mutex *ww;
-			ww = container_of(lock, struct ww_mutex, base);
-
+		if (use_ww_ctx)
 			ww_mutex_set_context_fastpath(ww, ww_ctx);
-		}
 		preempt_enable();
 		return 0;
 	}
@@ -680,10 +677,8 @@ __mutex_lock_common(struct mutex *lock,
 	/* got the lock - cleanup and rejoice! */
 	lock_acquired(&lock->dep_map, ip);
 
-	if (use_ww_ctx) {
-		struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
+	if (use_ww_ctx)
 		ww_mutex_set_context_slowpath(ww, ww_ctx);
-	}
 
 	spin_unlock_mutex(&lock->wait_lock, flags);
 	preempt_enable();