linux-kernel - Re: [PATCH v4 5/6] console: Introduce ->exit() callback

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Date:   Fri, 31 Jan 2020 10:31:54 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 5/6] console: Introduce ->exit() callback

On (20/01/30 17:25), Andy Shevchenko wrote:
[..]
> diff --git a/include/linux/console.h b/include/linux/console.h
> index f33016b3a401..54759ad0c36b 100644
> --- a/include/linux/console.h
> +++ b/include/linux/console.h
> @@ -148,6 +148,7 @@ struct console {
>  	struct tty_driver *(*device)(struct console *, int *);
>  	void	(*unblank)(void);
>  	int	(*setup)(struct console *, char *);
> +	void	(*exit)(struct console *);

Should console ->exit() be able to return an error code?

>  	int	(*match)(struct console *, char *name, int idx, char *options);
>  	short	flags;
>  	short	index;
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 932345e6cd71..0117d4d92a8e 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2850,6 +2850,10 @@ int unregister_console(struct console *console)
>  	console->flags &= ~CON_ENABLED;
>  	console_unlock();
>  	console_sysfs_notify();
> +
> +	if (!res && console->exit)
> +		console->exit(console);
> +
>  	return res;
>  }

I would probably push it a bit further (I posted this snippet in another
thread). If console is not on the list then there is nothing for us to do
and sysfs notify is pointless.

---

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 0117d4d92a8e..7116e421210b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2837,7 +2837,13 @@ int unregister_console(struct console *console)
 		}
 	}
 
-	if (!res && (console->flags & CON_EXTENDED))
+	if (res) {
+		console->flags &= ~CON_ENABLED;
+		console_unlock();
+		return res;
+	}
+
+	if (console->flags & CON_EXTENDED)
 		nr_ext_console_drivers--;
 
 	/*
@@ -2851,7 +2857,7 @@ int unregister_console(struct console *console)
 	console_unlock();
 	console_sysfs_notify();
 
-	if (!res && console->exit)
+	if (console->exit)
 		console->exit(console);
 
 	return res;