diff options
Diffstat (limited to 'include/linux/rwsem-spinlock.h')
| -rw-r--r-- | include/linux/rwsem-spinlock.h | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h new file mode 100644 index 00000000000..b52a2af25f1 --- /dev/null +++ b/include/linux/rwsem-spinlock.h @@ -0,0 +1,65 @@ +/* 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 + +#include <linux/spinlock.h> +#include <linux/list.h> + +#ifdef __KERNEL__ + +#include <linux/types.h> + +struct rwsem_waiter; + +/* + * 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; +#if RWSEM_DEBUG + int debug; +#endif +}; + +/* + * initialisation + */ +#if RWSEM_DEBUG +#define __RWSEM_DEBUG_INIT , 0 +#else +#define __RWSEM_DEBUG_INIT /* */ +#endif + +#define __RWSEM_INITIALIZER(name) \ +{ 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT } + +#define DECLARE_RWSEM(name) \ + struct rw_semaphore name = __RWSEM_INITIALIZER(name) + +extern void FASTCALL(init_rwsem(struct rw_semaphore *sem)); +extern void FASTCALL(__down_read(struct rw_semaphore *sem)); +extern int FASTCALL(__down_read_trylock(struct rw_semaphore *sem)); +extern void FASTCALL(__down_write(struct rw_semaphore *sem)); +extern int FASTCALL(__down_write_trylock(struct rw_semaphore *sem)); +extern void FASTCALL(__up_read(struct rw_semaphore *sem)); +extern void FASTCALL(__up_write(struct rw_semaphore *sem)); +extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem)); + +#endif /* __KERNEL__ */ +#endif /* _LINUX_RWSEM_SPINLOCK_H */ |