[PATCH 4.4 102/133] xtensa: ISS: dont panic in rs_init

[Greg Kroah-Hartman]

From: Jiri Slaby <jslaby@xxxxxxx>

[ 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@xxxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: linux-xtensa@xxxxxxxxxxxxxxxx
Acked-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Link: https://lore.kernel.org/r/20210723074317.32690-2-jslaby@xxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 92d785fefb6d..5d264ae517f5 100644
--- a/arch/xtensa/platforms/iss/console.c
+++ b/arch/xtensa/platforms/iss/console.c
@@ -186,9 +186,13 @@ static const struct tty_operations serial_ops = {
 
 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);
 
 	printk ("%s %s\n", serial_name, serial_version);
 
@@ -208,8 +212,15 @@ 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