1 /* SPDX-License-Identifier: GPL-2.0 */ 1
2 #ifndef __LINUX_OSQ_LOCK_H
3 #define __LINUX_OSQ_LOCK_H
4
5 /*
6 * An MCS like lock especially tailored for op
7 * lock implementations (mutex, rwsem, etc).
8 */
9
10 struct optimistic_spin_queue {
11 /*
12 * Stores an encoded value of the CPU
13 * If the queue is empty, then it's se
14 */
15 atomic_t tail;
16 };
17
18 #define OSQ_UNLOCKED_VAL (0)
19
20 /* Init macro and function. */
21 #define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UN
22
23 static inline void osq_lock_init(struct optimi
24 {
25 atomic_set(&lock->tail, OSQ_UNLOCKED_V
26 }
27
28 extern bool osq_lock(struct optimistic_spin_qu
29 extern void osq_unlock(struct optimistic_spin_
30
31 static inline bool osq_is_locked(struct optimi
32 {
33 return atomic_read(&lock->tail) != OSQ
34 }
35
36 #endif
37
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