Messages in this thread Patch in this message | | | From | Justin Stitt <> | Subject | [PATCH v3] include/uapi/linux/swab.h: move explicit cast outside ternary | Date | Wed, 8 Jun 2022 15:35:39 -0700 |
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From: Justin Stitt <jstitt007@gmail.com>
A cast inside __builtin_constant_p doesn't do anything since it should evaluate as constant at compile time irrespective of this cast. Instead, I moved this cast outside the ternary to ensure the return type is as expected.
Additionally, if __HAVE_BUILTIN_BSWAP16__ was not defined then __swab16 is actually returning an `int` not a `u16` due to integer promotion.
As Al Viro notes: You *can't* get smaller-than-int out of ? :, same as you can't get it out of addition, etc.
This also fixes some clang -Wformat warnings involving default argument promotion.
Link: https://github.com/ClangBuiltLinux/linux/issues/378 Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Suggested-by: Nathan Chancellor <nathan@kernel.org> Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Justin Stitt <jstitt007@gmail.com> --- diff from v2 -> v3: * re-insert respective (u16, u32, u64) cast to __builtin_bswap as per Nick's suggestion * added note from Al Viro
include/uapi/linux/swab.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/uapi/linux/swab.h b/include/uapi/linux/swab.h index 7272f85d6d6a..0723a9cce747 100644 --- 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(x) ? \ ___constant_swab16(x) : \ __fswab16(x)) #endif @@ -115,7 +115,7 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val) #define __swab32(x) (__u32)__builtin_bswap32((__u32)(x)) #else #define __swab32(x) \ - (__builtin_constant_p((__u32)(x)) ? \ + (__u32)(__builtin_constant_p(x) ? \ ___constant_swab32(x) : \ __fswab32(x)) #endif @@ -128,7 +128,7 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val) #define __swab64(x) (__u64)__builtin_bswap64((__u64)(x)) #else #define __swab64(x) \ - (__builtin_constant_p((__u64)(x)) ? \ + (__u64)(__builtin_constant_p(x) ? \ ___constant_swab64(x) : \ __fswab64(x)) #endif -- 2.36.1.476.g0c4daa206d-goog
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