linux-kernel - [PATCH AUTOSEL 5.13 068/219] xtensa: ISS: don't panic in rs

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Date:   Thu,  9 Sep 2021 07:44:04 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jiri Slaby <jslaby@...e.cz>, Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        linux-xtensa@...ux-xtensa.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.13 068/219] xtensa: ISS: don't panic in rs_init

From: Jiri Slaby <jslaby@...e.cz>

[ Upstream commit 23411c720052ad860b3e579ee4873511e367130a ]

While alloc_tty_driver failure in rs_init would mean we have much bigger
problem, there is no reason to panic when tty_register_driver fails
there. It can fail for various reasons.

So handle the failure gracefully. Actually handle them both while at it.
This will make at least the console functional as it was enabled earlier
by console_initcall in iss_console_init. Instead of shooting down the
whole system.

We move tty_port_init() after alloc_tty_driver(), so that we don't need
to destroy the port in case the latter function fails.

Cc: Chris Zankel <chris@...kel.net>
Cc: Max Filippov <jcmvbkbc@...il.com>
Cc: linux-xtensa@...ux-xtensa.org
Acked-by: Max Filippov <jcmvbkbc@...il.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Link: https://lore.kernel.org/r/20210723074317.32690-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/xtensa/platforms/iss/console.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/xtensa/platforms/iss/console.c b/arch/xtensa/platforms/iss/console.c
index a3dda25a4e45..eed02cf3d6b0 100644
--- a/arch/xtensa/platforms/iss/console.c
+++ b/arch/xtensa/platforms/iss/console.c
@@ -143,9 +143,13 @@ static const struct tty_operations serial_ops = {
 
 static int __init rs_init(void)
 {
-	tty_port_init(&serial_port);
+	int ret;
 
 	serial_driver = alloc_tty_driver(SERIAL_MAX_NUM_LINES);
+	if (!serial_driver)
+		return -ENOMEM;
+
+	tty_port_init(&serial_port);
 
 	/* Initialize the tty_driver structure */
 
@@ -163,8 +167,15 @@ static int __init rs_init(void)
 	tty_set_operations(serial_driver, &serial_ops);
 	tty_port_link_device(&serial_port, serial_driver, 0);
 
-	if (tty_register_driver(serial_driver))
-		panic("Couldn't register serial driver\n");
+	ret = tty_register_driver(serial_driver);
+	if (ret) {
+		pr_err("Couldn't register serial driver\n");
+		tty_driver_kref_put(serial_driver);
+		tty_port_destroy(&serial_port);
+
+		return ret;
+	}
+
 	return 0;
 }
 
-- 
2.30.2