diff options
| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2015-02-13 14:36:13 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-13 21:21:35 -0800 |
| commit | dba94c2553da1928303c2a6c6410247c88cafc1d (patch) | |
| tree | f6721644e3f883db6d2edccffad73756941b8c00 /lib | |
| parent | cfac1d080a00544e5cecd2d7c9ebe3d6a5cc18e6 (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>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/bitmap.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c index db88512c3451..74bdf3601245 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -148,18 +148,19 @@ 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; |