/include/linux/rwsem-spinlock.h

https://github.com/airy09/android_kernel_sony_apq8064 · C Header · 45 lines · 26 code · 6 blank · 13 comment · 0 complexity · e94c7af1e012183fef218485e888031c MD5 · raw file 

    

  1. /* rwsem-spinlock.h: fallback C implementation
    2. 

  2.  *
    3. 

  3.  * Copyright (c) 2001   David Howells (dhowells@redhat.com).
    4. 

  4.  * - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de>
    5. 

  5.  * - Derived also from comments by Linus
    6. 

  6.  */
    7. 

  7. 

  8. #ifndef _LINUX_RWSEM_SPINLOCK_H
    9. 

  9. #define _LINUX_RWSEM_SPINLOCK_H
    10. 

  10. 

  11. #ifndef _LINUX_RWSEM_H
    12. 

  12. #error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead"
    13. 

  13. #endif
    14. 

  14. 

  15. #ifdef __KERNEL__
    16. 

  16. /*
    17. 

  17.  * the rw-semaphore definition
    18. 

  18.  * - if activity is 0 then there are no active readers or writers
    19. 

  19.  * - if activity is +ve then that is the number of active readers
    20. 

  20.  * - if activity is -1 then there is one active writer
    21. 

  21.  * - if wait_list is not empty, then there are processes waiting for the semaphore
    22. 

  22.  */
    23. 

  23. struct rw_semaphore {
    24. 

  24. 	__s32			activity;
    25. 

  25. 	raw_spinlock_t		wait_lock;
    26. 

  26. 	struct list_head	wait_list;
    27. 

  27. #ifdef CONFIG_DEBUG_LOCK_ALLOC
    28. 

  28. 	struct lockdep_map dep_map;
    29. 

  29. #endif
    30. 

  30. };
    31. 

  31. 

  32. #define RWSEM_UNLOCKED_VALUE		0x00000000
    33. 

  33. 

  34. extern void __down_read(struct rw_semaphore *sem);
    35. 

  35. extern int __down_read_trylock(struct rw_semaphore *sem);
    36. 

  36. extern void __down_write(struct rw_semaphore *sem);
    37. 

  37. extern void __down_write_nested(struct rw_semaphore *sem, int subclass);
    38. 

  38. extern int __down_write_trylock(struct rw_semaphore *sem);
    39. 

  39. extern void __up_read(struct rw_semaphore *sem);
    40. 

  40. extern void __up_write(struct rw_semaphore *sem);
    41. 

  41. extern void __downgrade_write(struct rw_semaphore *sem);
    42. 

  42. extern int rwsem_is_locked(struct rw_semaphore *sem);
    43. 

  43. 

  44. #endif /* __KERNEL__ */
    45. 

  45. #endif /* _LINUX_RWSEM_SPINLOCK_H */
    46.