linux-kernel - Re: [PATCH 22/99] fbdev/fsl-diu-fb: Duplicate video-mode option string

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Date:   Tue, 7 Mar 2023 09:28:50 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Timur Tabi <timur@...nel.org>
Cc:     deller@....de, paulus@...ba.org, benh@...nel.crashing.org,
        linux@...linux.org.uk, pjones@...hat.com, adaplas@...il.com,
        s.hauer@...gutronix.de, shawnguo@...nel.org, mbroemme@...mpq.org,
        thomas@...ischhofer.net, James.Bottomley@...senpartnership.com,
        spock@...too.org, sudipm.mukherjee@...il.com,
        teddy.wang@...iconmotion.com, geert+renesas@...der.be,
        corbet@....net, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 22/99] fbdev/fsl-diu-fb: Duplicate video-mode option
 string

Hi

Am 06.03.23 um 21:04 schrieb Timur Tabi:
> On Mon, Mar 6, 2023 at 10:01 AM Thomas Zimmermann <tzimmermann@...e.de> wrote:
>>
>> Assume that the driver does not own the option string or its substrings
>> and hence duplicate the option string for the video mode. The driver only
>> parses the option string once as part of module initialization, so use
>> a static buffer to store the duplicated mode option. Linux automatically
>> frees the memory upon releasing the module.
> 
> So after module_init is finished, mode_option_buf[] no longer exists?

Does the __init attribute on a function affect the static variables in 
that function?

Best regards
Thomas

> 
>> +                       static char mode_option_buf[256];
>> +                       int ret;
>> +
>> +                       ret = snprintf(mode_option_buf, sizeof(mode_option_buf), "%s", opt);
>> +                       if (WARN(ret < 0, "fsl-diu-fb: ignoring invalid option, ret=%d\n", ret))
>> +                               continue;
>> +                       if (WARN(ret >= sizeof(mode_option_buf), "fsl-diu-fb: option too long\n"))
>> +                               continue;
>> +                       fb_mode = mode_option_buf;
> 
> If so, then I'm not sure that's going to work.  fb_mode is used after
> module_init, in install_fb(), which is called by fsl_diu_probe().

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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