Commit | Line | Data |
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90631822 JL |
1 | #ifndef __LINUX_OSQ_LOCK_H |
2 | #define __LINUX_OSQ_LOCK_H | |
3 | ||
4 | /* | |
5 | * An MCS like lock especially tailored for optimistic spinning for sleeping | |
6 | * lock implementations (mutex, rwsem, etc). | |
7 | */ | |
8 | ||
9 | #define OSQ_UNLOCKED_VAL (0) | |
10 | ||
11 | struct optimistic_spin_queue { | |
12 | /* | |
13 | * Stores an encoded value of the CPU # of the tail node in the queue. | |
14 | * If the queue is empty, then it's set to OSQ_UNLOCKED_VAL. | |
15 | */ | |
16 | atomic_t tail; | |
17 | }; | |
18 | ||
4d9d951e JL |
19 | /* Init macro and function. */ |
20 | #define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) } | |
21 | ||
22 | static inline void osq_lock_init(struct optimistic_spin_queue *lock) | |
23 | { | |
24 | atomic_set(&lock->tail, OSQ_UNLOCKED_VAL); | |
25 | } | |
26 | ||
90631822 | 27 | #endif |