linux-kernel - Re: [PATCH] tty/vt: Remove printable variable

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Message-ID: <Ywk0cq2k7Nhyygyy@ravnborg.org>
Date:   Fri, 26 Aug 2022 23:00:34 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Daniel Vetter <daniel.vetter@...ll.ch>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Yangxi Xiang <xyangxi5@...il.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Xuezhi Zhang <zhangxuezhi1@...lpad.com>,
        nick black <dankamongmen@...il.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        Jiri Slaby <jirislaby@...nel.org>
Subject: Re: [PATCH] tty/vt: Remove printable variable

Hi Daniel,

On Fri, Aug 26, 2022 at 10:24:19PM +0200, Daniel Vetter wrote:
> Every since the 0.99.7A release when console_register() was introduced
> it's become impossible to call vt_console_print (called
> console_print() back then still) directly. Which means the
> initialization issue this variable protected against is no more.
> 
> Give it a send off with style and let it rest in peace.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Jiri Slaby <jirislaby@...nel.org>
> Cc: "Ilpo Järvinen" <ilpo.jarvinen@...ux.intel.com>
> Cc: nick black <dankamongmen@...il.com>
> Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Cc: Yangxi Xiang <xyangxi5@...il.com>
> Cc: Xuezhi Zhang <zhangxuezhi1@...lpad.com>
> ---
>  drivers/tty/vt/vt.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index ae9c926acd6f..4d29e4a17db7 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> @@ -157,7 +157,6 @@ static void set_palette(struct vc_data *vc);
>  
>  #define vt_get_kmsg_redirect() vt_kmsg_redirect(-1)
>  
> -static int printable;		/* Is console ready for printing? */
>  int default_utf8 = true;
>  module_param(default_utf8, int, S_IRUGO | S_IWUSR);
>  int global_cursor_default = -1;
> @@ -3085,8 +3084,6 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
>  	int kmsg_console;
>  
>  	/* console busy or not yet initialized */
> -	if (!printable)
> -		return;
>  	if (!spin_trylock(&printing_lock))
>  		return;

Speaking on locks - it the printing_lock necessary. Or will the caller
serialize the calls to write()?

	Sam

>  
> @@ -3537,7 +3534,6 @@ static int __init con_init(void)
>  	pr_info("Console: %s %s %dx%d\n",
>  		vc->vc_can_do_color ? "colour" : "mono",
>  		display_desc, vc->vc_cols, vc->vc_rows);
> -	printable = 1;
>  
>  	console_unlock();
>  
> -- 
> 2.37.2