linux-kernel - [PATCH RT 1/2] locking/rwsem-rt: Remove might_sleep() in __up

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Date:   Fri, 20 Aug 2021 19:46:39 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org,
        linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        John Kacur <jkacur@...hat.com>, Daniel Wagner <wagi@...om.org>,
        Tom Zanussi <zanussi@...nel.org>,
        "Srivatsa S. Bhat" <srivatsa@...il.mit.edu>,
        Chunyu Hu <chuhu@...hat.com>,
        Andrew Halaney <ahalaney@...hat.com>
Subject: [PATCH RT 1/2] locking/rwsem-rt: Remove might_sleep() in __up_read()

5.10.59-rt52-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Andrew Halaney <ahalaney@...hat.com>

There's no chance of sleeping here, the reader is giving up the
lock and possibly waking up the writer who is waiting on it.

Reported-by: Chunyu Hu <chuhu@...hat.com>
Signed-off-by: Andrew Halaney <ahalaney@...hat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/locking/rwsem-rt.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c
index 274172d5bb3a..b61edc4dcb73 100644
--- a/kernel/locking/rwsem-rt.c
+++ b/kernel/locking/rwsem-rt.c
@@ -198,7 +198,6 @@ void __up_read(struct rw_semaphore *sem)
 	if (!atomic_dec_and_test(&sem->readers))
 		return;
 
-	might_sleep();
 	raw_spin_lock_irq(&m->wait_lock);
 	/*
 	 * Wake the writer, i.e. the rtmutex owner. It might release the
-- 
2.30.2