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lib/find_bit: Introduce find_next_andnot_bit() 

In preparation of introducing for_each_cpu_andnot(), add a variant of
find_next_bit() that negate the bits in @addr2 when ANDing them with the
bits in @addr1.

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
This commit is contained in:
Valentin Schneider 2022-10-03 16:34:17 +01:00 committed by Yury Norov
parent 78e5a33994
commit 90d482908e
2 changed files with 42 additions and 0 deletions
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33
include/linux/find.h
View File

@ -12,6 +12,8 @@ unsigned long _find_next_bit(const unsigned long *addr1, unsigned long nbits,
unsigned long start);
unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,
unsigned long nbits, unsigned long start);
unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
unsigned long nbits, unsigned long start);
unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
unsigned long start);
extern unsigned long _find_first_bit(const unsigned long *addr, unsigned long size);
@ -91,6 +93,37 @@ unsigned long find_next_and_bit(const unsigned long *addr1,
}
#endif
#ifndef find_next_andnot_bit
/**
* find_next_andnot_bit - find the next set bit in *addr1 excluding all the bits
* in *addr2
* @addr1: The first address to base the search on
* @addr2: The second address to base the search on
* @size: The bitmap size in bits
* @offset: The bitnumber to start searching at
*
* Returns the bit number for the next set bit
* If no bits are set, returns @size.
*/
static inline
unsigned long find_next_andnot_bit(const unsigned long *addr1,
const unsigned long *addr2, unsigned long size,
unsigned long offset)
{
if (small_const_nbits(size)) {
unsigned long val;
if (unlikely(offset >= size))
return size;
val = *addr1 & ~*addr2 & GENMASK(size - 1, offset);
return val ? __ffs(val) : size;
}
return _find_next_andnot_bit(addr1, addr2, size, offset);
}
#endif
#ifndef find_next_zero_bit
/**
* find_next_zero_bit - find the next cleared bit in a memory region

9
lib/find_bit.c
View File

@ -164,6 +164,15 @@ unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long
EXPORT_SYMBOL(_find_next_and_bit);
#endif
#ifndef find_next_andnot_bit
unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
unsigned long nbits, unsigned long start)
{
return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start);
}
EXPORT_SYMBOL(_find_next_andnot_bit);
#endif
#ifndef find_next_zero_bit
unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
unsigned long start)