linux-kernel - [PATCH printk v4 22/39] tty: nfcon: use console_is

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Date:   Mon, 14 Nov 2022 17:35:15 +0106
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k@...ts.linux-m68k.org
Subject: [PATCH printk v4 22/39] tty: nfcon: use console_is_registered()

Currently CON_ENABLED is being (mis)used to identify if the console
has been registered. This is not reliable because it can be set even
though registration failed or it can be unset, even though the console
is registered. Use console_is_registered() instead.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 arch/m68k/emu/nfcon.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/m68k/emu/nfcon.c b/arch/m68k/emu/nfcon.c
index 557d60867f98..6fdc13610565 100644
--- a/arch/m68k/emu/nfcon.c
+++ b/arch/m68k/emu/nfcon.c
@@ -49,7 +49,7 @@ static void nfcon_write(struct console *con, const char *str,
 static struct tty_driver *nfcon_device(struct console *con, int *index)
 {
 	*index = 0;
-	return (con->flags & CON_ENABLED) ? nfcon_tty_driver : NULL;
+	return console_is_registered(con) ? nfcon_tty_driver : NULL;
 }
 
 static struct console nf_console = {
@@ -107,6 +107,11 @@ static int __init nf_debug_setup(char *arg)
 
 	stderr_id = nf_get_id("NF_STDERR");
 	if (stderr_id) {
+		/*
+		 * The console will be enabled when debug=nfcon is specified
+		 * as a kernel parameter. Since this is a non-standard way
+		 * of enabling consoles, it must be explicitly enabled.
+		 */
 		nf_console.flags |= CON_ENABLED;
 		register_console(&nf_console);
 	}
@@ -151,7 +156,7 @@ static int __init nfcon_init(void)
 
 	nfcon_tty_driver = driver;
 
-	if (!(nf_console.flags & CON_ENABLED))
+	if (!console_is_registered(&nf_console))
 		register_console(&nf_console);
 
 	return 0;
-- 
2.30.2