netdev - Re: [PATCH net] lib: packing: fix shift wrapping in bit

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Message-ID: <CAHktU2A2MQ4hW0WYcLDXuCuMsN84OmfrnrhTiOKqvHB_oFaVwg@mail.gmail.com>
Date:   Sat, 10 Dec 2022 00:01:28 +0300
From:   Uladzislau Koshchanka <koshchanka@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Dan Carpenter <error27@...il.com>, netdev@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH net] lib: packing: fix shift wrapping in bit_reverse()

Hi Vladimir,

> The problem I see with bitrev8 is that the byte_rev_table[] can
> seemingly be built as a module (the BITREVERSE Kconfig knob is tristate,
> and btw your patch doesn't make PACKING select BITREVERSE). But PACKING
> is bool. IIRC, I got comments during review that it's not worth making
> packing a module, but I may remember wrong.

Do you really think it's a problem? I personally would just select
BITREVERSE with/without making PACKING tristate. BITREVERSE is already
selected by CRC32 which defaults to y, so just adding a select isn't a
change in the default. Can't think of a practical point in avoiding
linking against 256 bytes here.

In any case, it just doesn't look right to have multiple bit-reverse
implementations only because of Kconfig relations.