linux-kernel - [PATCH 1/8] xtensa: ISS: don't panic in rs

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Date:   Fri, 23 Jul 2021 09:43:10 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     gregkh@...uxfoundation.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiri Slaby <jslaby@...e.cz>, Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        linux-xtensa@...ux-xtensa.org
Subject: [PATCH 1/8] xtensa: ISS: don't panic in rs_init

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.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Cc: Chris Zankel <chris@...kel.net>
Cc: Max Filippov <jcmvbkbc@...il.com>
Cc: linux-xtensa@...ux-xtensa.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 21184488c277..0108504dfb45 100644
--- a/arch/xtensa/platforms/iss/console.c
+++ b/arch/xtensa/platforms/iss/console.c
@@ -136,9 +136,13 @@ 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 */
 
@@ -156,8 +160,15 @@ 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;
 }
 
-- 
2.32.0