linux/debian/patches-rt/0146-rtmutex-rwlock-preserv...

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From 562b9e1e592b03a33734b74286a03ffc480a27bc Mon Sep 17 00:00:00 2001
Message-Id: <562b9e1e592b03a33734b74286a03ffc480a27bc.1599166691.git.zanussi@kernel.org>
In-Reply-To: <56457dc415803c8abc5acb513ada877a79596f05.1599166690.git.zanussi@kernel.org>
References: <56457dc415803c8abc5acb513ada877a79596f05.1599166690.git.zanussi@kernel.org>
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 11 Jan 2019 21:16:31 +0100
Subject: [PATCH 146/333] rtmutex/rwlock: preserve state like a sleeping lock
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.142-rt63.tar.xz
The rwlock is spinning while acquiring a lock. Therefore it must become
a sleeping lock on RT and preserve its task state while sleeping and
waiting for the lock to become available.
Reported-by: Joe Korty <Joe.Korty@concurrent-rt.com>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/locking/rwlock-rt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/locking/rwlock-rt.c b/kernel/locking/rwlock-rt.c
index aebb7ce25bc6..8f90afe111ce 100644
--- a/kernel/locking/rwlock-rt.c
+++ b/kernel/locking/rwlock-rt.c
@@ -128,7 +128,7 @@ void __sched __read_rt_lock(struct rt_rw_lock *lock)
* That would put Reader1 behind the writer waiting on
* Reader2 to call read_unlock() which might be unbound.
*/
- rt_mutex_init_waiter(&waiter, false);
+ rt_mutex_init_waiter(&waiter, true);
rt_spin_lock_slowlock_locked(m, &waiter, flags);
/*
* The slowlock() above is guaranteed to return with the rtmutex is
--
2.17.1