From dba94c2553da1928303c2a6c6410247c88cafc1d Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Fri, 13 Feb 2015 14:36:13 -0800 Subject: 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/bitmap.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'lib/bitmap.c') 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; -- cgit v1.2.3