rtmutex: Check explicit for TASK_RTLOCK_WAIT.

rt_mutex_wake_q_add() needs to  need to distiguish between sleeping
locks (TASK_RTLOCK_WAIT) and normal locks which use TASK_NORMAL to use
the proper wake mechanism.

Instead of checking for != TASK_NORMAL make it more robust and check
explicit for TASK_RTLOCK_WAIT which is the reason why a different wake
mechanism is used.

No functional change.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210928150006.597310-2-bigeasy@linutronix.de

kernel/locking/rtmutex.c

@@ -449,7 +449,7 @@ static __always_inline void rt_mutex_adjust_prio(struct task_struct *p)
 static __always_inline void rt_mutex_wake_q_add(struct rt_wake_q_head *wqh,
 						struct rt_mutex_waiter *w)
 {
-	if (IS_ENABLED(CONFIG_PREEMPT_RT) && w->wake_state != TASK_NORMAL) {
+	if (IS_ENABLED(CONFIG_PREEMPT_RT) && w->wake_state == TASK_RTLOCK_WAIT) {
 		if (IS_ENABLED(CONFIG_PROVE_LOCKING))
 			WARN_ON_ONCE(wqh->rtlock_task);
 		get_task_struct(w->task);