Commit 90d48290 authored by Valentin Schneider's avatar Valentin Schneider Committed by Yury Norov
Browse files

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: default avatarValentin Schneider <vschneid@redhat.com>
parent 78e5a339

include/linux/find.h

+33 −0
Original line number Diff line number Diff line
@@ -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

lib/find_bit.c

+9 −0
Original line number Diff line number Diff line
@@ -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)