This is a note to let you know that I've just added the patch titled
printk: Update @console_may_schedule in console_trylock_spinning()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
printk-update-console_may_schedule-in-console_tryloc.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f4b6613ffe074449a9c57ec7efe7716097dcb2b0
Author: John Ogness <john.ogness@xxxxxxxxxxxxx>
Date: Mon Feb 26 13:07:24 2024 +0106
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@xxxxxxxxxxx>
Closes: https://lore.kernel.org/lkml/20240222090538.23017-1-quic_mojha@xxxxxxxxxxx
Fixes: dbdda842fe96 ("printk: Add console owner and waiter logic to load balance console writes")
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reviewed-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Link: https://lore.kernel.org/r/875xybmo2z.fsf@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index bb2198b40756d..ae1a97dd0c3cb 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1787,6 +1787,12 @@ 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;
}
