linux-kernel - [GIT pull] locking fix for 4.16

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Date:   Sun, 11 Mar 2018 08:56:27 -0700 (PDT)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>
Subject: [GIT pull] locking fix for 4.16

Linus,

please pull the latest locking-urgent-for-linus git tree from:

  git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking-urgent-for-linus

rt_mutex_futex_unlock() grew a new irq-off call site, but the function
assumes that its always called from irq enabled context. Use the
(un)lock_irqsafe to handle te new call site correctly.

Thanks,

	tglx

------------------>
Boqun Feng (1):
      rtmutex: Make rt_mutex_futex_unlock() safe for irq-off callsites


 kernel/locking/rtmutex.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 65cc0cb984e6..940633c63254 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1616,11 +1616,12 @@ bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
 void __sched rt_mutex_futex_unlock(struct rt_mutex *lock)
 {
 	DEFINE_WAKE_Q(wake_q);
+	unsigned long flags;
 	bool postunlock;
 
-	raw_spin_lock_irq(&lock->wait_lock);
+	raw_spin_lock_irqsave(&lock->wait_lock, flags);
 	postunlock = __rt_mutex_futex_unlock(lock, &wake_q);
-	raw_spin_unlock_irq(&lock->wait_lock);
+	raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
 
 	if (postunlock)
 		rt_mutex_postunlock(&wake_q);