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From: Herbert Xu <herbert@gondor.apana.org.au>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: ebiggers@kernel.org, Jason@zx2c4.com, ardb@kernel.org,
	kees@kernel.org, linux-crypto@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH libcrypto 1/2] array_size: introduce min_array_size() function decoration
Date: Sat, 22 Nov 2025 10:37:31 +0800	[thread overview]
Message-ID: <aSEh684nt05JOYor@gondor.apana.org.au> (raw)
In-Reply-To: <CAHk-=wgkKPgsmcC0SFni7hhQM_b3qNjoyzw_JL2ZVs2eWXEZWQ@mail.gmail.com>

Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
> I wouldn't call that "asked for".
> 
> It was more a musing on how random that "static" syntax is and it's
> likely incomprehensible to a lot of people - but also pointing out
> that we already do have users of it, and saying that maybe it won't be
> incomprehensible once we have a lot of users.
> 
> So I'm definitely not pushing for it.
> 
> But I do suspect it makes people understand what the code does more...

Actually there is one reason for using a macro instead of static
directly, sparse still seems to choke on a non-static value for
static:

int foo(int n, int a[static n])
{
        return a[0]++;
}

This compiles correctly with gcc and clang, but sparse chokes on it:

a.c:1:29: error: undefined identifier 'n'
a.c:1:29: error: bad constant expression type

I was trying to use it in crypto/ecc.c where the arrays are
defined as ECC_MAX_DIGITS, but only the first ndigits are valid.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

      reply	other threads:[~2025-11-22  2:37 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-18 17:02 Jason A. Donenfeld
2025-11-18 17:02 ` [PATCH libcrypto 2/2] crypto: chacha20poly1305: statically check fixed array lengths Jason A. Donenfeld
2025-11-19 10:36   ` kernel test robot
2025-11-19 12:45   ` kernel test robot
2025-11-19 16:22     ` Linus Torvalds
2025-11-19 16:46       ` Jason A. Donenfeld
2025-11-19 16:57         ` Linus Torvalds
2025-11-19 18:45         ` Nathan Chancellor
2025-11-18 23:24 ` [PATCH libcrypto 1/2] array_size: introduce min_array_size() function decoration Eric Biggers
2025-11-18 23:31   ` Jason A. Donenfeld
2025-11-19 19:04     ` Jason A. Donenfeld
2025-11-19 19:10       ` Ard Biesheuvel
2025-11-19 23:02       ` david laight
2025-11-18 23:32   ` Linus Torvalds
2025-11-22  2:37     ` Herbert Xu [this message]

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