lib: bitmap: change bitmap_shift_left to take unsigned parameters

gcc can generate slightly better code for stuff like "nbits %
BITS_PER_LONG" when it knows nbits is not negative.  Since negative size
bitmaps or shift amounts don't make sense, change these parameters of
bitmap_shift_right to unsigned.

If off >= lim (which requires shift >= nbits), k is initialized with a
large positive value, but since I've let k continue to be signed, the loop
will never run and dst will be zeroed as expected.  Inside the loop, k is
guaranteed to be non-negative, so the fact that it is promoted to unsigned
in the various expressions it appears in is harmless.

Also use "shift" and "nbits" consistently for the parameter names.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index c168a807ab9a..5e7f75a6d7d0 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -98,8 +98,8 @@ extern void __bitmap_complement(unsigned long *dst, const unsigned long *src,
                         unsigned int nbits);
 extern void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
                                 unsigned int shift, unsigned int nbits);
-extern void __bitmap_shift_left(unsigned long *dst,
-                        const unsigned long *src, int shift, int bits);
+extern void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
+                                unsigned int shift, unsigned int nbits);
 extern int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
                         const unsigned long *bitmap2, unsigned int nbits);
 extern void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
@@ -322,13 +322,13 @@ static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *s
                 __bitmap_shift_right(dst, src, shift, nbits);
 }
 
-static inline void bitmap_shift_left(unsigned long *dst,
-                        const unsigned long *src, int n, int nbits)
+static inline void bitmap_shift_left(unsigned long *dst, const unsigned long *src,
+                                unsigned int shift, unsigned int nbits)
 {
         if (small_const_nbits(nbits))
-                *dst = (*src << n) & BITMAP_LAST_WORD_MASK(nbits);
+                *dst = (*src << shift) & BITMAP_LAST_WORD_MASK(nbits);
         else
-                __bitmap_shift_left(dst, src, n, nbits);
+                __bitmap_shift_left(dst, src, shift, nbits);
 }
 
 static inline int bitmap_parse(const char *buf, unsigned int buflen,