LXR linux/arch/sparc/include/asm/rwsem.h

   1/*
   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
  20struct rwsem_waiter;
  21
  22struct rw_semaphore {
  23        signed int count;
  24        spinlock_t              wait_lock;
  25        struct list_head        wait_list;
  26#ifdef CONFIG_DEBUG_LOCK_ALLOC
  27        struct lockdep_map      dep_map;
  28#endif
  29};
  30
  31#ifdef CONFIG_DEBUG_LOCK_ALLOC
  32# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
  33#else
  34# define __RWSEM_DEP_MAP_INIT(lockname)
  35#endif
  36
  37#define __RWSEM_INITIALIZER(name) \
  38{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) \
  39  __RWSEM_DEP_MAP_INIT(name) }
  40
  41#define DECLARE_RWSEM(name) \
  42        struct rw_semaphore name = __RWSEM_INITIALIZER(name)
  43
  44extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
  45                         struct lock_class_key *key);
  46
  47#define init_rwsem(sem)                                         \
  48do {                                                            \
  49        static struct lock_class_key __key;                     \
  50                                                                \
  51        __init_rwsem((sem), #sem, &__key);                      \
  52} while (0)
  53
  54extern void __down_read(struct rw_semaphore *sem);
  55extern int __down_read_trylock(struct rw_semaphore *sem);
  56extern void __down_write(struct rw_semaphore *sem);
  57extern int __down_write_trylock(struct rw_semaphore *sem);
  58extern void __up_read(struct rw_semaphore *sem);
  59extern void __up_write(struct rw_semaphore *sem);
  60extern void __downgrade_write(struct rw_semaphore *sem);
  61
  62static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
  63{
  64        __down_write(sem);
  65}
  66
  67static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
  68{
  69        return atomic_add_return(delta, (atomic_t *)(&sem->count));
  70}
  71
  72static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
  73{
  74        atomic_add(delta, (atomic_t *)(&sem->count));
  75}
  76
  77static inline int rwsem_is_locked(struct rw_semaphore *sem)
  78{
  79        return (sem->count != 0);
  80}
  81
  82#endif /* __KERNEL__ */
  83
  84#endif /* _SPARC64_RWSEM_H */
  85