Hi Peter, hpa, Arnd, On Wed, 18 Dec 2013, Paul Walmsley wrote: > > 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 ʽhweight_longʼ: > 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@xxxxxxxxxx> > Cc: H. Peter Anvin <hpa@xxxxxxxxx> > Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> > Cc: Arnd Bergmann <arnd@xxxxxxxx> > --- > Intended for v3.14. Ping. Just checking to see if you have any comments on this one, or if you're planning to send it upstream for v3.14. - Paul > > 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..40966203804d 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)) > -- > 1.8.5.1 > - Paul
