linux-kernel - [RFC PATCH v5 3/6] printk: Flag register_console() if console is set on command line

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Message-ID: <20231218071020.21805-4-tony@atomide.com>
Date: Mon, 18 Dec 2023 09:09:50 +0200
From: Tony Lindgren <tony@...mide.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Petr Mladek <pmladek@...e.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: "David S . Miller" <davem@...emloft.net>,
	Andy Shevchenko <andriy.shevchenko@...el.com>,
	Dhruva Gole <d-gole@...com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Johan Hovold <johan@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Vignesh Raghavendra <vigneshr@...com>,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: [RFC PATCH v5 3/6] printk: Flag register_console() if console is set on command line

If add_preferred_console() is not called early in setup_console(), we can
end up having register_console() call try_enable_default_console() before a
console device has called add_preferred_console().

Let's set console_set_on_cmdline flag in console_setup() to prevent this
from happening.

Signed-off-by: Tony Lindgren <tony@...mide.com>
---
 kernel/printk/printk.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2459,6 +2459,9 @@ static int __init console_setup(char *str)
 	if (console_opt_save(str, brl_options))
 		return 1;
 
+	/* Flag register_console() to not call try_enable_default_console() */
+	console_set_on_cmdline = 1;
+
 	/* Don't attempt to parse a DEVNAME:0.0 style console */
 	if (strchr(str, ':'))
 		return 1;
@@ -3480,7 +3483,7 @@ void register_console(struct console *newcon)
 	 * Note that a console with tty binding will have CON_CONSDEV
 	 * flag set and will be first in the list.
 	 */
-	if (preferred_console < 0) {
+	if (preferred_console < 0 && !console_set_on_cmdline) {
 		if (hlist_empty(&console_list) || !console_first()->device ||
 		    console_first()->flags & CON_BOOT) {
 			try_enable_default_console(newcon);
-- 
2.43.0