WARNING:'hweight_long' include/linux/bitops.h compile warning problem.

[NamJae Jeon]

Hello. Arnd

I found compile warning while compiling module when using -Wsign-compare option.

include/linux/bitops.h: In function 'hweight_long':
include/linux/bitops.h:49: warning: signed and unsigned type in
conditional expression

I found the reason of this problem that the default return value of
the below macro is signed.

#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))) )

So, I try to add (unsigned long) in __const_hweight8 like this.

#define __const_hweight8(w)     (unsigned long )        \
     ( (!!((w) & (1ULL << 0))) +       \
       (!!((w) & (1ULL << 1))) +       \
       (!!((w) & (1ULL << 2))) +       \
       (!!((w) & (1ULL << 3))) +       \
       (!!((w) & (1ULL << 4))) +       \
       (!!((w) & (1ULL << 5))) +       \
       (!!((w) & (1ULL << 6))) +       \
       (!!((w) & (1ULL << 7))) )

so, I can't see compile warning after fixing it, Would you plz check this ?

Thanks.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/