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