From: Andrew Morton <akpm@linux-foundation.org>
To: Justin Stitt <jstitt007@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Tom Rix <trix@redhat.com>,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH] include/uapi/linux/swab.h: add __u16 cast to __swab16 conditional
Date: Tue, 7 Jun 2022 15:27:44 -0700 [thread overview]
Message-ID: <20220607152744.d7c801d092529309500ac9a6@linux-foundation.org> (raw)
In-Reply-To: <20220607222006.22719-1-jstitt007@gmail.com>
On Tue, 7 Jun 2022 15:20:06 -0700 Justin Stitt <jstitt007@gmail.com> wrote:
> if __HAVE_BUILTIN_BSWAP16__ is defined then __swab16 utilizes a __u16 cast.
> This same cast should be used if __HAVE_BUILTIN_BSWAP16__ is not defined as
> well. This should fix loads (at least a few) clang -Wformat warnings
> specifically with `ntohs()`
>
> ...
>
> --- a/include/uapi/linux/swab.h
> +++ b/include/uapi/linux/swab.h
> @@ -102,7 +102,7 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val)
> #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
> #else
> #define __swab16(x) \
> - (__builtin_constant_p((__u16)(x)) ? \
> + (__u16)(__builtin_constant_p((__u16)(x)) ? \
> ___constant_swab16(x) : \
> __fswab16(x))
> #endif
More explanation, please? Both ___constant_swab16() and __fswab16()
return __u16, so why does this patch have any effect?
next prev parent reply other threads:[~2022-06-07 22:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-07 22:20 [PATCH] include/uapi/linux/swab.h: add __u16 cast to __swab16 conditional Justin Stitt
2022-06-07 22:27 ` Andrew Morton [this message]
2022-06-07 22:42 ` Nick Desaulniers
2022-06-07 23:21 ` Andrew Morton
2022-06-07 23:43 ` Nick Desaulniers
2022-06-08 4:54 ` Al Viro
2022-06-08 19:35 ` Nick Desaulniers
2022-06-10 7:19 ` David Laight
2022-06-07 23:20 ` Nick Desaulniers
2022-06-08 0:14 ` [PATCH v2] include/uapi/linux/swab.h: move explicit cast outside ternary Justin Stitt
2022-06-08 20:09 ` Andrew Morton
2022-06-08 21:16 ` Nick Desaulniers
2022-06-08 21:19 ` Nick Desaulniers
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