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include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible

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Several callers have constant 'start' and an 'nbits' that is a multiple
of 8, so we can turn them into calls to memset.  We don't need the
entirety of 'start' and 'nbits' to be constant, we just need to know
whether they're divisible by 8.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox <[email protected]>
Acked-by: Rasmus Villemoes <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Matthew Wilcox authored and Linus Torvalds committed 2017-07-10 16:32:34 -07:00
1 parent e5af323c9b
commit 2a98dc028f
1 file changed
+6
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include/linux/bitmap.h
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@@ -319,6 +319,9 @@ static __always_inline void bitmap_set(unsigned long *map, unsigned int start,
{
if (__builtin_constant_p(nbits) && nbits == 1)
__set_bit(start, map);
else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) &&
__builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
memset((char *)map + start / 8, 0xff, nbits / 8);
else
__bitmap_set(map, start, nbits);
}
@@ -328,6 +331,9 @@ static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
{
if (__builtin_constant_p(nbits) && nbits == 1)
__clear_bit(start, map);
else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) &&
__builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
memset((char *)map + start / 8, 0, nbits / 8);
else
__bitmap_clear(map, start, nbits);
}