diff options
Diffstat (limited to 'kernel/include/linux/osq_lock.h')
| -rw-r--r-- | kernel/include/linux/osq_lock.h | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/kernel/include/linux/osq_lock.h b/kernel/include/linux/osq_lock.h new file mode 100644 index 000000000..3a6490e81 --- /dev/null +++ b/kernel/include/linux/osq_lock.h @@ -0,0 +1,35 @@ +#ifndef __LINUX_OSQ_LOCK_H +#define __LINUX_OSQ_LOCK_H + +/* + * An MCS like lock especially tailored for optimistic spinning for sleeping + * lock implementations (mutex, rwsem, etc). + */ +struct optimistic_spin_node { + struct optimistic_spin_node *next, *prev; + int locked; /* 1 if lock acquired */ + int cpu; /* encoded CPU # + 1 value */ +}; + +struct optimistic_spin_queue { + /* + * Stores an encoded value of the CPU # of the tail node in the queue. + * If the queue is empty, then it's set to OSQ_UNLOCKED_VAL. + */ + atomic_t tail; +}; + +#define OSQ_UNLOCKED_VAL (0) + +/* Init macro and function. */ +#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) } + +static inline void osq_lock_init(struct optimistic_spin_queue *lock) +{ + atomic_set(&lock->tail, OSQ_UNLOCKED_VAL); +} + +extern bool osq_lock(struct optimistic_spin_queue *lock); +extern void osq_unlock(struct optimistic_spin_queue *lock); + +#endif |