diff options
| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2015-02-13 14:36:13 -0800 |
|---|---|---|
| committer | Mister Oyster <oysterized@gmail.com> | 2017-04-11 10:59:36 +0200 |
| commit | fcfcf9fea498504630b0585a3c18add8c1c0fdc9 (patch) | |
| tree | 62cf7121ddede6dfcc04184b5c6c48ca153224b1 | |
| parent | d83e0f90a3a7087d5c8db28e990d807b31781c74 (diff) | |
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>
| -rw-r--r-- | include/linux/bitmap.h | 12 | ||||
| -rw-r--r-- | lib/bitmap.c | 11 |
2 files changed, 12 insertions, 11 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index aac44fd79..1ef674829 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -97,8 +97,8 @@ 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, @@ -307,13 +307,13 @@ 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, diff --git a/lib/bitmap.c b/lib/bitmap.c index 62cac563c..d67b88a6a 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -146,18 +146,19 @@ EXPORT_SYMBOL(__bitmap_shift_right); * @dst : destination bitmap * @src : source bitmap * @shift : shift by this many bits - * @bits : bitmap size, in bits + * @nbits : bitmap size, in bits * * Shifting left (multiplying) means moving bits in the LS -> MS * direction. Zeros are fed into the vacated LS bit positions * and those MS bits shifted off the top are lost. */ -void __bitmap_shift_left(unsigned long *dst, - const unsigned long *src, int shift, int bits) +void __bitmap_shift_left(unsigned long *dst, const unsigned long *src, + unsigned int shift, unsigned int nbits) { - int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG; - int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; + int k; + unsigned int lim = BITS_TO_LONGS(nbits), left = nbits % BITS_PER_LONG; + unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG; for (k = lim - off - 1; k >= 0; --k) { unsigned long upper, lower; |