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lib: bitmap: remove redundant code from __bitmap_shift_left 

The first of these conditionals is completely redundant: If k == lim-1, we
must have off==0, so the second conditional will also trigger and then it
wouldn't matter if upper had some high bits set.  But the second
conditional is in fact also redundant, since it only serves to clear out
some high-order "don't care" bits of dst, about which no guarantee is
made.

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>
This commit is contained in:
Rasmus Villemoes 2015-02-13 14:36:19 -08:00 committed by Linus Torvalds
parent 6d874eca65
commit 7f59065793
1 changed files with 2 additions and 7 deletions
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9
lib/bitmap.c
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@ -159,7 +159,7 @@ void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
unsigned int shift, unsigned int nbits)
{
int k;
unsigned int lim = BITS_TO_LONGS(nbits), left = nbits % BITS_PER_LONG;
unsigned int lim = BITS_TO_LONGS(nbits);
unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
for (k = lim - off - 1; k >= 0; --k) {
unsigned long upper, lower;
@ -172,13 +172,8 @@ void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
lower = src[k - 1] >> (BITS_PER_LONG - rem);
else
lower = 0;
upper = src[k];
if (left && k == lim - 1)
upper &= (1UL << left) - 1;
upper <<= rem;
upper = src[k] << rem;
dst[k + off] = lower | upper;
if (left && k + off == lim - 1)
dst[k + off] &= (1UL << left) - 1;
}
if (off)
memset(dst, 0, off*sizeof(unsigned long));