From: John Ogness <john.ogness@linutronix.de>
Date: Mon, 26 Feb 2024 12:01:24 +0000 (+0106)
Subject: printk: Update @console_may_schedule in console_trylock_spinning()
X-Git-Tag: v6.7.12~126
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=de70fa0ae001084b80e2f8872f0c965e1ee1fce9;p=thirdparty%2Fkernel%2Fstable.git

printk: Update @console_may_schedule in console_trylock_spinning()

[ Upstream commit 8076972468584d4a21dab9aa50e388b3ea9ad8c7 ]

console_trylock_spinning() may takeover the console lock from a
schedulable context. Update @console_may_schedule to make sure it
reflects a trylock acquire.

Reported-by: Mukesh Ojha <quic_mojha@quicinc.com>
Closes: https://lore.kernel.org/lkml/20240222090538.23017-1-quic_mojha@quicinc.com
Fixes: dbdda842fe96 ("printk: Add console owner and waiter logic to load balance console writes")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/875xybmo2z.fsf@jogness.linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index a11e1b6f29c04..7a835b277e98d 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2026,6 +2026,12 @@ static int console_trylock_spinning(void)
 	 */
 	mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_);
 
+	/*
+	 * Update @console_may_schedule for trylock because the previous
+	 * owner may have been schedulable.
+	 */
+	console_may_schedule = 0;
+
 	return 1;
 }