diff options
author | Kent Overstreet <kent.overstreet@linux.dev> | 2024-01-16 17:00:02 -0500 |
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committer | Kent Overstreet <kent.overstreet@linux.dev> | 2024-01-16 17:17:23 -0500 |
commit | b5fd066153c40a70a29caa1ea7987723ab687763 (patch) | |
tree | 6d43a8b0a90d549a54c65565ac96c92b3e84b594 /include/linux/osq_lock.h | |
parent | 06ff8b55b70fda44d91b31b5511fafd1680a8934 (diff) |
Move c_src dirs back to toplevel
We just wanted c sourcefiles out of the top level, not c source
directories.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'include/linux/osq_lock.h')
-rw-r--r-- | include/linux/osq_lock.h | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/include/linux/osq_lock.h b/include/linux/osq_lock.h new file mode 100644 index 00000000..bde9f0d2 --- /dev/null +++ b/include/linux/osq_lock.h @@ -0,0 +1,44 @@ +#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); +} + +static inline bool osq_lock(struct optimistic_spin_queue *lock) +{ + return false; +} + +static inline void osq_unlock(struct optimistic_spin_queue *lock) {} + +static inline bool osq_is_locked(struct optimistic_spin_queue *lock) +{ + return atomic_read(&lock->tail) != OSQ_UNLOCKED_VAL; +} + +#endif |