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41 lines
1.0 KiB
41 lines
1.0 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef __LINUX_OSQ_LOCK_H |
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#define __LINUX_OSQ_LOCK_H |
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/* |
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* An MCS like lock especially tailored for optimistic spinning for sleeping |
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* lock implementations (mutex, rwsem, etc). |
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*/ |
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struct optimistic_spin_node { |
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struct optimistic_spin_node *next, *prev; |
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int locked; /* 1 if lock acquired */ |
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int cpu; /* encoded CPU # + 1 value */ |
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}; |
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struct optimistic_spin_queue { |
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/* |
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* Stores an encoded value of the CPU # of the tail node in the queue. |
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* If the queue is empty, then it's set to OSQ_UNLOCKED_VAL. |
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*/ |
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atomic_t tail; |
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}; |
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#define OSQ_UNLOCKED_VAL (0) |
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/* Init macro and function. */ |
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#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) } |
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static inline void osq_lock_init(struct optimistic_spin_queue *lock) |
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{ |
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atomic_set(&lock->tail, OSQ_UNLOCKED_VAL); |
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} |
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extern bool osq_lock(struct optimistic_spin_queue *lock); |
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extern void osq_unlock(struct optimistic_spin_queue *lock); |
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static inline bool osq_is_locked(struct optimistic_spin_queue *lock) |
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{ |
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return atomic_read(&lock->tail) != OSQ_UNLOCKED_VAL; |
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} |
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#endif
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