linux-kernel - Re: [PATCH] crypto: ccree - avoid out-of-range warnings from clang

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Message-ID: <20211008122336.GB31060@gondor.apana.org.au>
Date:   Fri, 8 Oct 2021 20:23:36 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Gilad Ben-Yossef <gilad@...yossef.com>,
        "David S. Miller" <davem@...emloft.net>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        YueHaibing <yuehaibing@...wei.com>, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] crypto: ccree - avoid out-of-range warnings from clang

On Mon, Sep 27, 2021 at 02:18:03PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> clang points out inconsistencies in the FIELD_PREP() invocation in
> this driver that result from the 'mask' being a 32-bit value:
> 
> drivers/crypto/ccree/cc_driver.c:117:18: error: result of comparison of constant 18446744073709551615 with expression of type 'u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>         cache_params |= FIELD_PREP(mask, val);
>                         ^~~~~~~~~~~~~~~~~~~~~
> include/linux/bitfield.h:94:3: note: expanded from macro 'FIELD_PREP'
>                 __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: ");    \
>                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/linux/bitfield.h:52:28: note: expanded from macro '__BF_FIELD_CHECK'
>                 BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull,         \
>                 ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> This does not happen in other places that just pass a constant here.
> 
> Work around the warnings by widening the type of the temporary variable.
> 
> Fixes: 05c2a705917b ("crypto: ccree - rework cache parameters handling")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/crypto/ccree/cc_driver.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt