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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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