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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/include/asm-generic/bitops/non-atomic.h
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#ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_

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#define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_

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#include <asm/types.h>

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/**

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 * __set_bit - Set a bit in memory

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 * @nr: the bit to set

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 * @addr: the address to start counting from

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 *

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 * Unlike set_bit(), this function is non-atomic and may be reordered.

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 * If it's called on the same region of memory simultaneously, the effect

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 * may be that only one operation succeeds.

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 */

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static inline void __set_bit(int nr, volatile unsigned long *addr)

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{

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	unsigned long mask = BIT_MASK(nr);

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	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

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	*p  |= mask;

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}

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static inline void __clear_bit(int nr, volatile unsigned long *addr)

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{

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	unsigned long mask = BIT_MASK(nr);

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	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

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	*p &= ~mask;

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}

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/**

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 * __change_bit - Toggle a bit in memory

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 * @nr: the bit to change

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 * @addr: the address to start counting from

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 *

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 * Unlike change_bit(), this function is non-atomic and may be reordered.

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 * If it's called on the same region of memory simultaneously, the effect

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 * may be that only one operation succeeds.

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 */

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static inline void __change_bit(int nr, volatile unsigned long *addr)

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{

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	unsigned long mask = BIT_MASK(nr);

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	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

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	*p ^= mask;

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}

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/**

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 * __test_and_set_bit - Set a bit and return its old value

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 * @nr: Bit to set

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 * @addr: Address to count from

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 *

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 * This operation is non-atomic and can be reordered.

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 * If two examples of this operation race, one can appear to succeed

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 * but actually fail.  You must protect multiple accesses with a lock.

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 */

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static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)

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{

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	unsigned long mask = BIT_MASK(nr);

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	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

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	unsigned long old = *p;

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	*p = old | mask;

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	return (old & mask) != 0;

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}

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/**

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 * __test_and_clear_bit - Clear a bit and return its old value

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 * @nr: Bit to clear

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 * @addr: Address to count from

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 *

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 * This operation is non-atomic and can be reordered.

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 * If two examples of this operation race, one can appear to succeed

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 * but actually fail.  You must protect multiple accesses with a lock.

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 */

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static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)

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{

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	unsigned long mask = BIT_MASK(nr);

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	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

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	unsigned long old = *p;

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	*p = old & ~mask;

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	return (old & mask) != 0;

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}

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/* WARNING: non atomic and it can be reordered! */

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static inline int __test_and_change_bit(int nr,

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					    volatile unsigned long *addr)

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{

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	unsigned long mask = BIT_MASK(nr);

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	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);

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	unsigned long old = *p;

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	*p = old ^ mask;

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	return (old & mask) != 0;

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}

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/**

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 * test_bit - Determine whether a bit is set

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 * @nr: bit number to test

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 * @addr: Address to start counting from

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 */

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static inline int test_bit(int nr, const volatile unsigned long *addr)

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{

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	return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));

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}

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#endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */

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