linux-kernel - [tip: locking/core] rtmutex: Check explicit for TASK_RTLOCK

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Date:   Fri, 01 Oct 2021 15:05:27 -0000
From:   "tip-bot2 for Sebastian Andrzej Siewior" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: locking/core] rtmutex: Check explicit for TASK_RTLOCK_WAIT.

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     8fe46535e10dbfebad68ad9f2f8260e49f5852c9
Gitweb:        https://git.kernel.org/tip/8fe46535e10dbfebad68ad9f2f8260e49f5852c9
Author:        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate:    Tue, 28 Sep 2021 17:00:05 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 01 Oct 2021 13:57:52 +02:00

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@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20210928150006.597310-2-bigeasy@linutronix.de
---
 kernel/locking/rtmutex.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 6bb116c..cafc259 100644
--- a/kernel/locking/rtmutex.c
+++ b/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);