linux-kernel - [PATCH 1/2] s390/sclp: deactivate sclp after all its users

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Message-Id: <20241014-s390-kunit-v1-1-941defa765a6@linutronix.de>
Date: Mon, 14 Oct 2024 07:50:06 +0200
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>, 
 Alexander Gordeev <agordeev@...ux.ibm.com>, 
 Christian Borntraeger <borntraeger@...ux.ibm.com>, 
 Sven Schnelle <svens@...ux.ibm.com>, 
 "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>, 
 stable@...r.kernel.org
Subject: [PATCH 1/2] s390/sclp: deactivate sclp after all its users

On reboot the SCLP interface is deactivated through a reboot notifier.
This happens before other components using SCLP have the chance to run
their own reboot notifiers.
Two of those components are the SCLP console and tty drivers which try
to flush the last outstanding messages.
At that point the SCLP interface is already unusable and the messages
are discarded.

Execute sclp_deactivate() as late as possible to avoid this issue.

Fixes: 4ae46db99cd8 ("s390/consoles: improve panic notifiers reliability")
Cc: stable@...r.kernel.org
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
 drivers/s390/char/sclp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/char/sclp.c b/drivers/s390/char/sclp.c
index f3621adbd5debc59d2b71fc1be2790e0cbd31f76..fbffd451031fdb526d9b802da50df7f3eba5c48e 100644
--- a/drivers/s390/char/sclp.c
+++ b/drivers/s390/char/sclp.c
@@ -1195,7 +1195,8 @@ sclp_reboot_event(struct notifier_block *this, unsigned long event, void *ptr)
 }

 static struct notifier_block sclp_reboot_notifier = {
-	.notifier_call = sclp_reboot_event
+	.notifier_call = sclp_reboot_event,
+	.priority      = INT_MIN,
 };

 static ssize_t con_pages_show(struct device_driver *dev, char *buf)

-- 
2.47.0