[PATCH 5.4 096/215] printk: Update @console_may_schedule in console_trylock_spinning()

Greg Kroah-Hartman
2024-04-11T10:18:47Z

From: John Ogness <john.ogness@linutronix.de>

[ 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>
---
kernel/printk/printk.c | 6 ++++++
1 file changed, 6 insertions(+)

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;
}

--
2.43.0