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

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5.4-stable review patch.  If anyone has any objections, please let me know.

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

From: John Ogness <john.ogness@xxxxxxxxxxxxx>

[ 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>
---
 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







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