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
  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 #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
  44 extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
  45                          struct lock_class_key *key);
  46
  47 #define init_rwsem(sem)                                         \
  48 do {                                                            \
  49         static struct lock_class_key __key;                     \
  50                                                                 \
  51         __init_rwsem((sem), #sem, &__key);                      \
  52 } while (0)
  53
  54 extern void __down_read(struct rw_semaphore *sem);
  55 extern int __down_read_trylock(struct rw_semaphore *sem);
  56 extern void __down_write(struct rw_semaphore *sem);
  57 extern int __down_write_trylock(struct rw_semaphore *sem);
  58 extern void __up_read(struct rw_semaphore *sem);
  59 extern void __up_write(struct rw_semaphore *sem);
  60 extern void __downgrade_write(struct rw_semaphore *sem);
  61
  62 static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
  63 {
  64         __down_write(sem);
  65 }
  66
  67 static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
  68 {
  69         return atomic_add_return(delta, (atomic_t *)(&sem->count));
  70 }
  71
  72 static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
  73 {
  74         atomic_add(delta, (atomic_t *)(&sem->count));
  75 }
  76
  77 static 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 */