tty: serial: kgdboc: use console_list_lock to trap exit

kgdboc_earlycon_init() uses the console_lock to ensure that no consoles
are unregistered until the kgdboc_earlycon is setup. The console_list_lock
should be used instead because list synchronization responsibility will
be removed from the console_lock in a later change.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-39-john.ogness@linutronix.de

drivers/tty/serial/kgdboc.c

@@ -558,13 +558,13 @@ static int __init kgdboc_earlycon_init(char *opt)
 	 */
 
 	/*
-	 * Hold the console_lock to guarantee that no consoles are
+	 * Hold the console_list_lock to guarantee that no consoles are
 	 * unregistered until the kgdboc_earlycon setup is complete.
 	 * Trapping the exit() callback relies on exit() not being
 	 * called until the trap is setup. This also allows safe
 	 * traversal of the console list and race-free reading of @flags.
 	 */
-	console_lock();
+	console_list_lock();
 	for_each_console(con) {
 		if (con->write && con->read &&
 		    (con->flags & (CON_BOOT | CON_ENABLED)) &&
@@ -606,7 +606,7 @@ static int __init kgdboc_earlycon_init(char *opt)
 	}
 
 unlock:
-	console_unlock();
+	console_list_unlock();
 
 	/* Non-zero means malformed option so we always return zero */
 	return 0;