include/asm-generic/bitops/generic-non-atomic.h

Source file repositories/reference/linux-study-clean/include/asm-generic/bitops/generic-non-atomic.h

File Facts

System
Linux kernel
Corpus path
include/asm-generic/bitops/generic-non-atomic.h
Extension
.h
Size
5310 bytes
Lines
176
Domain
Repository Root And Misc
Bucket
include
Inferred role
Repository Root And Misc: implementation source
Status
source implementation candidate

Why This File Exists

Top-level or miscellaneous repository surface. Use this as map coverage unless a later manual pass promotes the file into a deeper subsystem dossier.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H
#define __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H

#include <linux/bits.h>
#include <asm/barrier.h>

#ifndef _LINUX_BITOPS_H
#error only <linux/bitops.h> can be included directly
#endif

/*
 * Generic definitions for bit operations, should not be used in regular code
 * directly.
 */

/**
 * generic___set_bit - Set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * Unlike set_bit(), this function is non-atomic and may be reordered.
 * If it's called on the same region of memory simultaneously, the effect
 * may be that only one operation succeeds.
 */
static __always_inline void
generic___set_bit(unsigned long nr, volatile unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

	*p  |= mask;
}

static __always_inline void
generic___clear_bit(unsigned long nr, volatile unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

	*p &= ~mask;
}

/**
 * generic___change_bit - Toggle a bit in memory
 * @nr: the bit to change
 * @addr: the address to start counting from
 *
 * Unlike change_bit(), this function is non-atomic and may be reordered.
 * If it's called on the same region of memory simultaneously, the effect
 * may be that only one operation succeeds.
 */
static __always_inline void
generic___change_bit(unsigned long nr, volatile unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

	*p ^= mask;
}

/**
 * generic___test_and_set_bit - Set a bit and return its old value
 * @nr: Bit to set
 * @addr: Address to count from
 *
 * This operation is non-atomic and can be reordered.
 * If two examples of this operation race, one can appear to succeed
 * but actually fail.  You must protect multiple accesses with a lock.
 */
static __always_inline bool
generic___test_and_set_bit(unsigned long nr, volatile unsigned long *addr)
{
	unsigned long mask = BIT_MASK(nr);
	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
	unsigned long old = *p;

	*p = old | mask;
	return (old & mask) != 0;
}

/**
 * generic___test_and_clear_bit - Clear a bit and return its old value
 * @nr: Bit to clear
 * @addr: Address to count from
 *
 * This operation is non-atomic and can be reordered.
 * If two examples of this operation race, one can appear to succeed
 * but actually fail.  You must protect multiple accesses with a lock.
 */
static __always_inline bool

Annotation

Implementation Notes