include/asm-sparc64/rwsem.h

   1 /* $Id: rwsem.h,v 1.5 2001/11/18 00:12:56 davem Exp $
   2  * rwsem.h: R/W semaphores implemented using CAS
   3  *
   4  * Written by David S. Miller (davem@redhat.com), 2001.
   5  * Derived from asm-i386/rwsem.h
   6  */
   7 #ifndef _SPARC64_RWSEM_H
   8 #define _SPARC64_RWSEM_H
   9
  10 #ifndef _LINUX_RWSEM_H
  11 #error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
  12 #endif
  13
  14 #ifdef __KERNEL__
  15
  16 #include <linux/list.h>
  17 #include <linux/spinlock.h>
  18 #include <asm/rwsem-const.h>
  19
  20 struct rwsem_waiter;
  21
  22 struct rw_semaphore {
  23         signed int count;
  24         spinlock_t              wait_lock;
  25         struct list_head        wait_list;
  26 };
  27
  28 #define __RWSEM_INITIALIZER(name) \
  29 { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) }
  30
  31 #define DECLARE_RWSEM(name) \
  32         struct rw_semaphore name = __RWSEM_INITIALIZER(name)
  33
  34 static __inline__ void init_rwsem(struct rw_semaphore *sem)
  35 {
  36         sem->count = RWSEM_UNLOCKED_VALUE;
  37         spin_lock_init(&sem->wait_lock);
  38         INIT_LIST_HEAD(&sem->wait_list);
  39 }
  40
  41 extern void __down_read(struct rw_semaphore *sem);
  42 extern int __down_read_trylock(struct rw_semaphore *sem);
  43 extern void __down_write(struct rw_semaphore *sem);
  44 extern int __down_write_trylock(struct rw_semaphore *sem);
  45 extern void __up_read(struct rw_semaphore *sem);
  46 extern void __up_write(struct rw_semaphore *sem);
  47 extern void __downgrade_write(struct rw_semaphore *sem);
  48
  49 static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
  50 {
  51         return atomic_add_return(delta, (atomic_t *)(&sem->count));
  52 }
  53
  54 static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
  55 {
  56         atomic_add(delta, (atomic_t *)(&sem->count));
  57 }
  58
  59 static inline int rwsem_is_locked(struct rw_semaphore *sem)
  60 {
  61         return (sem->count != 0);
  62 }
  63
  64 #endif /* __KERNEL__ */
  65
  66 #endif /* _SPARC64_RWSEM_H */