LXR linux-old/include/linux/rwsem.h

   1/* rwsem.h: R/W semaphores, public interface
   2 *
   3 * Written by David Howells (dhowells@redhat.com).
   4 * Derived from asm-i386/semaphore.h
   5 *
   6 * Trylock by Brian Watson (Brian.J.Watson@compaq.com).
   7 */
   8
   9#ifndef _LINUX_RWSEM_H
  10#define _LINUX_RWSEM_H
  11
  12#include <linux/linkage.h>
  13
  14#define RWSEM_DEBUG 0
  15
  16#ifdef __KERNEL__
  17
  18#include <linux/config.h>
  19#include <linux/types.h>
  20#include <linux/kernel.h>
  21#include <asm/system.h>
  22#include <asm/atomic.h>
  23
  24struct rw_semaphore;
  25
  26#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
  27#include <linux/rwsem-spinlock.h> /* use a generic implementation */
  28#else
  29#include <asm/rwsem.h> /* use an arch-specific implementation */
  30#endif
  31
  32#ifndef rwsemtrace
  33#if RWSEM_DEBUG
  34extern void FASTCALL(rwsemtrace(struct rw_semaphore *sem, const char *str));
  35#else
  36#define rwsemtrace(SEM,FMT)
  37#endif
  38#endif
  39
  40/*
  41 * lock for reading
  42 */
  43static inline void down_read(struct rw_semaphore *sem)
  44{
  45        rwsemtrace(sem,"Entering down_read");
  46        __down_read(sem);
  47        rwsemtrace(sem,"Leaving down_read");
  48}
  49
  50/*
  51 * trylock for reading -- returns 1 if successful, 0 if contention
  52 */
  53static inline int down_read_trylock(struct rw_semaphore *sem)
  54{
  55        int ret;
  56        rwsemtrace(sem,"Entering down_read_trylock");
  57        ret = __down_read_trylock(sem);
  58        rwsemtrace(sem,"Leaving down_read_trylock");
  59        return ret;
  60}
  61
  62/*
  63 * lock for writing
  64 */
  65static inline void down_write(struct rw_semaphore *sem)
  66{
  67        rwsemtrace(sem,"Entering down_write");
  68        __down_write(sem);
  69        rwsemtrace(sem,"Leaving down_write");
  70}
  71
  72/*
  73 * trylock for writing -- returns 1 if successful, 0 if contention
  74 */
  75static inline int down_write_trylock(struct rw_semaphore *sem)
  76{
  77        int ret;
  78        rwsemtrace(sem,"Entering down_write_trylock");
  79        ret = __down_write_trylock(sem);
  80        rwsemtrace(sem,"Leaving down_write_trylock");
  81        return ret;
  82}
  83
  84/*
  85 * release a read lock
  86 */
  87static inline void up_read(struct rw_semaphore *sem)
  88{
  89        rwsemtrace(sem,"Entering up_read");
  90        __up_read(sem);
  91        rwsemtrace(sem,"Leaving up_read");
  92}
  93
  94/*
  95 * release a write lock
  96 */
  97static inline void up_write(struct rw_semaphore *sem)
  98{
  99        rwsemtrace(sem,"Entering up_write");
 100        __up_write(sem);
 101        rwsemtrace(sem,"Leaving up_write");
 102}
 103
 104
 105#endif /* __KERNEL__ */
 106#endif /* _LINUX_RWSEM_H */
 107