linux-kernel - Re: [PATCH] lib: objagg: Use struct

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Date:   Wed, 05 Jun 2019 19:03:53 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     gustavo@...eddedor.com
Cc:     jiri@...lanox.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib: objagg: Use struct_size() in kzalloc()

From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Date: Wed, 5 Jun 2019 09:45:16 -0500

> 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 objagg_stats {
> 	...
>         struct objagg_obj_stats_info stats_info[];
> };
> 
> size = sizeof(*objagg_stats) + sizeof(objagg_stats->stats_info[0]) * count;
> 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, stats_info, count), GFP_KERNEL);
> 
> Notice that, in this case, variable alloc_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>

Applied.