Messages in this thread Patch in this message | | | Date | Mon, 10 Feb 2014 05:30:28 -0800 | From | tip-bot for Paul Walmsley <> | Subject | [tip:core/types] bitops: Fix signedness of compile-time hweight implementations |
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Commit-ID: c32fa99f0b4252633aa464e28d1cb925bd2a79df Gitweb: http://git.kernel.org/tip/c32fa99f0b4252633aa464e28d1cb925bd2a79df Author: Paul Walmsley <pwalmsley@nvidia.com> AuthorDate: Wed, 18 Dec 2013 05:02:14 -0800 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Sun, 9 Feb 2014 13:39:26 +0100
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 <random filename>: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 <pwalmsley@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1312180459580.30198@tamien Signed-off-by: Ingo Molnar <mingo@kernel.org> --- 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 fa2a50b..0a7e066 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))
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