netdev - Re: [PATCH] lib: objagg: Replace zero-length arrays with flexible-array member

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Date:   Wed, 12 Feb 2020 08:24:54 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Jiri Pirko <jiri@...lanox.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib: objagg: Replace zero-length arrays with
 flexible-array member

Tue, Feb 11, 2020 at 09:53:56PM CET, gustavo@...eddedor.com wrote:
>The current codebase makes use of the zero-length array language
>extension to the C90 standard, but the preferred mechanism to declare
>variable-length types such as these ones is a flexible array member[1][2],
>introduced in C99:
>
>struct foo {
>        int stuff;
>        struct boo array[];
>};
>
>By making use of the mechanism above, we will get a compiler warning
>in case the flexible array does not occur last in the structure, which
>will help us prevent some kind of undefined behavior bugs from being
>inadvertenly introduced[3] to the codebase from now on.
>
>This issue was found with the help of Coccinelle.
>
>[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
>[2] https://github.com/KSPP/linux/issues/21
>[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>
>Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

Acked-by: Jiri Pirko <jiri@...lanox.com>