linux-kernel - Re: [PATCH v5 2/3] fbcon: Call WARN_CONSOLE

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Date:   Wed, 11 Jul 2018 16:46:11 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Hans de Goede <hdegoede@...hat.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     linux-fbdev@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/3] fbcon: Call WARN_CONSOLE_UNLOCKED() where
 applicable

Hi

Am 28.06.2018 um 11:03 schrieb Hans de Goede:
> Replace comments about places where the console lock should be held with
> calls to WARN_CONSOLE_UNLOCKED() to assert that it is actually held.

Debugging fbcon sometimes requires to not take the console lock. This
patch breaks the debugging workaround provided by
'fb.lockless_register_fb'. The dmesg is now filled with warnings about
the missing lock.

Best regards
Thomas

> Acked-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
> Changes in v3:
> -New patch in v3 of this patchset
>
> Changes in v4:
> -Keep the comments about which fbcon functions need locks in place
> ---
>  drivers/video/fbdev/core/fbcon.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index c910e74d46ff..cd8d52a967aa 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -828,6 +828,8 @@ static int set_con2fb_map(int unit, int newidx, int user)
>  	struct fb_info *oldinfo = NULL;
>   	int found, err = 0;
>  
> +	WARN_CONSOLE_UNLOCKED();
> +
>  	if (oldidx == newidx)
>  		return 0;
>  
> @@ -3044,6 +3046,8 @@ static int fbcon_fb_unbind(int idx)
>  {
>  	int i, new_idx = -1, ret = 0;
>  
> +	WARN_CONSOLE_UNLOCKED();
> +
>  	if (!fbcon_has_console_bind)
>  		return 0;
>  
> @@ -3094,6 +3098,8 @@ static int fbcon_fb_unregistered(struct fb_info *info)
>  {
>  	int i, idx;
>  
> +	WARN_CONSOLE_UNLOCKED();
> +
>  	idx = info->node;
>  	for (i = first_fb_vc; i <= last_fb_vc; i++) {
>  		if (con2fb_map[i] == idx)
> @@ -3131,6 +3137,9 @@ static int fbcon_fb_unregistered(struct fb_info *info)
>  static void fbcon_remap_all(int idx)
>  {
>  	int i;
> +
> +	WARN_CONSOLE_UNLOCKED();
> +
>  	for (i = first_fb_vc; i <= last_fb_vc; i++)
>  		set_con2fb_map(i, idx, 0);
>  
> @@ -3177,6 +3186,8 @@ static int fbcon_fb_registered(struct fb_info *info)
>  {
>  	int ret = 0, i, idx;
>  
> +	WARN_CONSOLE_UNLOCKED();
> +
>  	idx = info->node;
>  	fbcon_select_primary(info);
>  

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstr. 5, D-90409 Nürnberg
Tel: +49-911-74053-0; Fax: +49-911-7417755;  https://www.suse.com/
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard,
Graham Norton, HRB 21284 (AG Nürnberg)




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