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>

diff --git a/include/asm-generic/bitops/const_hweight.h b/include/asm-generic/bitops/const_hweight.h
index fa2a50b7ee660c774313e20f0027302bfb0b495c..0a7e06623470586b0509ef99410dbc54aa572f9e 100644 (file)
--- 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))