locking/ww_mutex: Gather mutex_waiter initialization

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211304.281927514@linutronix.de

kernel/locking/mutex-debug.c

@@ -30,6 +30,7 @@ void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
 	memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
 	waiter->magic = waiter;
 	INIT_LIST_HEAD(&waiter->list);
+	waiter->ww_ctx = MUTEX_POISON_WW_CTX;
 }
 
 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)

kernel/locking/mutex.c

@@ -982,17 +982,15 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
 	}
 
 	debug_mutex_lock_common(lock, &waiter);
+	waiter.task = current;
+	if (ww_ctx)
+		waiter.ww_ctx = ww_ctx;
 
 	lock_contended(&lock->dep_map, ip);
 
 	if (!use_ww_ctx) {
 		/* add waiting tasks to the end of the waitqueue (FIFO): */
 		__mutex_add_waiter(lock, &waiter, &lock->wait_list);
-
-
-#ifdef CONFIG_DEBUG_MUTEXES
-		waiter.ww_ctx = MUTEX_POISON_WW_CTX;
-#endif
 	} else {
 		/*
 		 * Add in stamp order, waking up waiters that must kill
@@ -1001,12 +999,8 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas
 		ret = __ww_mutex_add_waiter(&waiter, lock, ww_ctx);
 		if (ret)
 			goto err_early_kill;
-
-		waiter.ww_ctx = ww_ctx;
 	}
 
-	waiter.task = current;
-
 	set_current_state(state);
 	for (;;) {
 		bool first;