From c32fa99f0b4252633aa464e28d1cb925bd2a79df Mon Sep 17 00:00:00 2001 From: Paul Walmsley Date: Wed, 18 Dec 2013 05:02:14 -0800 Subject: [PATCH] bitops: Fix signedness of compile-time hweight implementations Enabling '-Wsign-compare' compiler warnings on code that includes include/linux/bitops.h can generate the following warning: In file included from include/linux/kernel.h:10:0, from :48: include/linux/bitops.h: In function 'hweight_long': include/linux/bitops.h:77:26: error: signed and unsigned type in conditional expression [-Werror=sign-compare] (converted to an error with -Werror) This is due to the use of the logical negation operator '!' in the __const_hweight8 macro in include/asm-generic/bitops/const_hweight.h. The use of that operator here results in a signed value. Fix by explicitly casting the __const_hweight8 macro expansion to 'unsigned int'. While here, clean up several checkpatch.pl warnings. Signed-off-by: Paul Walmsley Cc: Arnd Bergmann Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Andrew Morton Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1312180459580.30198@tamien Signed-off-by: Ingo Molnar --- include/asm-generic/bitops/const_hweight.h | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/include/asm-generic/bitops/const_hweight.h b/include/asm-generic/bitops/const_hweight.h index fa2a50b7ee66..0a7e06623470 100644 --- a/include/asm-generic/bitops/const_hweight.h +++ b/include/asm-generic/bitops/const_hweight.h @@ -5,14 +5,15 @@ * Compile time versions of __arch_hweightN() */ #define __const_hweight8(w) \ - ( (!!((w) & (1ULL << 0))) + \ - (!!((w) & (1ULL << 1))) + \ - (!!((w) & (1ULL << 2))) + \ - (!!((w) & (1ULL << 3))) + \ - (!!((w) & (1ULL << 4))) + \ - (!!((w) & (1ULL << 5))) + \ - (!!((w) & (1ULL << 6))) + \ - (!!((w) & (1ULL << 7))) ) + ((unsigned int) \ + ((!!((w) & (1ULL << 0))) + \ + (!!((w) & (1ULL << 1))) + \ + (!!((w) & (1ULL << 2))) + \ + (!!((w) & (1ULL << 3))) + \ + (!!((w) & (1ULL << 4))) + \ + (!!((w) & (1ULL << 5))) + \ + (!!((w) & (1ULL << 6))) + \ + (!!((w) & (1ULL << 7))))) #define __const_hweight16(w) (__const_hweight8(w) + __const_hweight8((w) >> 8 )) #define __const_hweight32(w) (__const_hweight16(w) + __const_hweight16((w) >> 16))