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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_GENERIC_BITOPS_LOCK_H_
#define _ASM_GENERIC_BITOPS_LOCK_H_
#include <linux/atomic.h>
#include <linux/compiler.h>
#include <asm/barrier.h>
/**
* test_and_set_bit_lock - Set a bit and return its old value, for lock
* @nr: Bit to set
* @addr: Address to count from
*
* This operation is atomic and provides acquire barrier semantics if
* the returned value is 0.
* It can be used to implement bit locks.
*/
static inline int test_and_set_bit_lock(unsigned int nr,
volatile unsigned long *p)
{
long old;
unsigned long mask = BIT_MASK(nr);
p += BIT_WORD(nr);
if (READ_ONCE(*p) & mask)
return 1;
old = atomic_long_fetch_or_acquire(mask, (atomic_long_t *)p);
return !!(old & mask);
}
/**
* clear_bit_unlock - Clear a bit in memory, for unlock
* @nr: the bit to set
* @addr: the address to start counting from
*
* This operation is atomic and provides release barrier semantics.
*/
static inline void clear_bit_unlock(unsigned int nr, volatile unsigned long *p)
{
p += BIT_WORD(nr);
atomic_long_fetch_andnot_release(BIT_MASK(nr), (atomic_long_t *)p);
}
/**
* __clear_bit_unlock - Clear a bit in memory, for unlock
* @nr: the bit to set
* @addr: the address to start counting from
*
* A weaker form of clear_bit_unlock() as used by __bit_lock_unlock(). If all
* the bits in the word are protected by this lock some archs can use weaker
* ops to safely unlock.
*
* See for example x86's implementation.
*/
static inline void __clear_bit_unlock(unsigned int nr,
volatile unsigned long *p)
{
unsigned long old;
p += BIT_WORD(nr);
old = READ_ONCE(*p);
old &= ~BIT_MASK(nr);
atomic_long_set_release((atomic_long_t *)p, old);
}
/**
* clear_bit_unlock_is_negative_byte - Clear a bit in memory and test if bottom
* byte is negative, for unlock.
* @nr: the bit to clear
* @addr: the address to start counting from
*
* This is a bit of a one-trick-pony for the filemap code, which clears
* PG_locked and tests PG_waiters,
*/
#ifndef clear_bit_unlock_is_negative_byte
static inline bool clear_bit_unlock_is_negative_byte(unsigned int nr,
volatile unsigned long *p)
{
long old;
unsigned long mask = BIT_MASK(nr);
p += BIT_WORD(nr);
old = atomic_long_fetch_andnot_release(mask, (atomic_long_t *)p);
return !!(old & BIT(7));
}
#define clear_bit_unlock_is_negative_byte clear_bit_unlock_is_negative_byte
#endif
#endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
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