linux-kernel - Re: [PATCH] video: fbdev/mmp/core: Use struct

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Date:   Mon, 19 Aug 2019 16:10:01 +0200
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] video: fbdev/mmp/core: Use struct_size() in kzalloc()


On 8/7/19 6:13 PM, Gustavo A. R. Silva wrote:
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
> 
> struct mmp_path {
> 	...
>         struct mmp_overlay overlays[0];
> };
> 
> size = sizeof(struct mmp_path) + count * sizeof(struct mmp_overlay);
> instance = kzalloc(size, GFP_KERNEL)
> 
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
> 
> instance = kzalloc(struct_size(instance, overlays, count), GFP_KERNEL)
> 
> Notice that, in this case, variable size is not necessary, hence it
> is removed.
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
Patch queued for v5.4, thanks.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics