diff options
Diffstat (limited to 'include/linux/rwsem-spinlock.h')
| -rw-r--r-- | include/linux/rwsem-spinlock.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h new file mode 100644 index 00000000..34701241 --- /dev/null +++ b/include/linux/rwsem-spinlock.h @@ -0,0 +1,45 @@ +/* rwsem-spinlock.h: fallback C implementation + * + * Copyright (c) 2001 David Howells (dhowells@redhat.com). + * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de> + * - Derived also from comments by Linus + */ + +#ifndef _LINUX_RWSEM_SPINLOCK_H +#define _LINUX_RWSEM_SPINLOCK_H + +#ifndef _LINUX_RWSEM_H +#error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead" +#endif + +#ifdef __KERNEL__ +/* + * the rw-semaphore definition + * - if activity is 0 then there are no active readers or writers + * - if activity is +ve then that is the number of active readers + * - if activity is -1 then there is one active writer + * - if wait_list is not empty, then there are processes waiting for the semaphore + */ +struct rw_semaphore { + __s32 activity; + spinlock_t wait_lock; + struct list_head wait_list; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif +}; + +#define RWSEM_UNLOCKED_VALUE 0x00000000 + +extern void __down_read(struct rw_semaphore *sem); +extern int __down_read_trylock(struct rw_semaphore *sem); +extern void __down_write(struct rw_semaphore *sem); +extern void __down_write_nested(struct rw_semaphore *sem, int subclass); +extern int __down_write_trylock(struct rw_semaphore *sem); +extern void __up_read(struct rw_semaphore *sem); +extern void __up_write(struct rw_semaphore *sem); +extern void __downgrade_write(struct rw_semaphore *sem); +extern int rwsem_is_locked(struct rw_semaphore *sem); + +#endif /* __KERNEL__ */ +#endif /* _LINUX_RWSEM_SPINLOCK_H */ |