linux-kernel - Re: [PATCH] crypto: af_alg - Fix incorrect boolean values in af_alg

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Message-ID: <CAHk-=wieFY6__aPLEz_2mv-GG6-Utw9NQOLDzi4TF93xFAnCoQ@mail.gmail.com>
Date: Wed, 24 Sep 2025 12:40:29 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Eric Biggers <ebiggers@...nel.org>
Cc: linux-crypto@...r.kernel.org, Herbert Xu <herbert@...dor.apana.org.au>, 
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] crypto: af_alg - Fix incorrect boolean values in af_alg_ctx

On Wed, 24 Sept 2025 at 12:27, Eric Biggers <ebiggers@...nel.org> wrote:
>
> -       u32             more:1,
> -                       merge:1,
> -                       enc:1,
> -                       write:1,
> -                       init:1;
> +       bool more;
> +       bool merge;
> +       bool enc;
> +       bool write;
> +       bool init;

This actually packs horribly, since a 'bool' will take up a byte for
each, so now those five bits take up 8 bytes of storage (because the
five bytes will then cause the next field to have to be aligned too).

You could just keep the bitfield format, but change the 'u32' to
'bool' and get the best of both worlds, ie just do something like

-       u32             more:1,
+       bool             more:1,

and now you get the bit packing _and_ the automatic bool behavior.

           Linus