linux-kernel - Re: [PATCH] fbdev: Fix logic error in "offb" name match

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Message-ID: <a4e604bf-eeb9-46ce-bc89-5a7b39acecbc@suse.de>
Date: Thu, 9 Oct 2025 13:43:31 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Finn Thain <fthain@...ux-m68k.org>, Simona Vetter <simona@...ll.ch>,
 Helge Deller <deller@....de>, Javier Martinez Canillas <javierm@...hat.com>
Cc: stable@...r.kernel.org, linux-fbdev@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fbdev: Fix logic error in "offb" name match



Am 09.10.25 um 00:56 schrieb Finn Thain:
> A regression was reported to me recently whereby /dev/fb0 had disappeared
> from a PowerBook G3 Series "Wallstreet". The problem shows up when the
> "video=ofonly" parameter is passed to the kernel, which is what the
> bootloader does when "no video driver" is selected. The cause of the
> problem is the "offb" string comparison, which got mangled when it got
> refactored. Fix it.
>
> Cc: stable@...r.kernel.org
> Fixes: 93604a5ade3a ("fbdev: Handle video= parameter in video/cmdline.c")
> Reported-and-tested-by: Stan Johnson <userm57@...oo.com>
> Signed-off-by: Finn Thain <fthain@...ux-m68k.org>

Acked-by: Thomas Zimmermann <tzimmermann@...e.de>

> ---
>   drivers/video/fbdev/core/fb_cmdline.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/core/fb_cmdline.c b/drivers/video/fbdev/core/fb_cmdline.c
> index 4d1634c492ec..594b60424d1c 100644
> --- a/drivers/video/fbdev/core/fb_cmdline.c
> +++ b/drivers/video/fbdev/core/fb_cmdline.c
> @@ -40,7 +40,7 @@ int fb_get_options(const char *name, char **option)
>   	bool enabled;
>   
>   	if (name)
> -		is_of = strncmp(name, "offb", 4);
> +		is_of = !strncmp(name, "offb", 4);
>   
>   	enabled = __video_get_options(name, &options, is_of);
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)