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  1. /*
  2.  * Copyright (c) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup sync
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #ifndef KERN_RWLOCK_H_
  36. #define KERN_RWLOCK_H_
  37.  
  38. #include <arch/types.h>
  39. #include <synch/mutex.h>
  40. #include <synch/synch.h>
  41. #include <synch/spinlock.h>
  42.  
  43. typedef enum {
  44.     RWLOCK_NONE,
  45.     RWLOCK_READER,
  46.     RWLOCK_WRITER
  47. } rwlock_type_t;
  48.  
  49. typedef struct {
  50.     SPINLOCK_DECLARE(lock);
  51.     /**
  52.      * Mutex for writers, readers can bypass it if readers_in is positive.
  53.      */
  54.     mutex_t exclusive;
  55.     /** Number of readers in critical section. */
  56.     size_t readers_in;
  57. } rwlock_t;
  58.  
  59. #define rwlock_write_lock(rwl) \
  60.     _rwlock_write_lock_timeout((rwl), SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE)
  61. #define rwlock_read_lock(rwl) \
  62.     _rwlock_read_lock_timeout((rwl), SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE)
  63. #define rwlock_write_trylock(rwl) \
  64.     _rwlock_write_lock_timeout((rwl), SYNCH_NO_TIMEOUT, \
  65.         SYNCH_FLAGS_NON_BLOCKING)
  66. #define rwlock_read_trylock(rwl) \
  67.     _rwlock_read_lock_timeout((rwl), SYNCH_NO_TIMEOUT, \
  68.         SYNCH_FLAGS_NON_BLOCKING)
  69. #define rwlock_write_lock_timeout(rwl, usec) \
  70.     _rwlock_write_lock_timeout((rwl), (usec), SYNCH_FLAGS_NONE)
  71. #define rwlock_read_lock_timeout(rwl, usec) \
  72.     _rwlock_read_lock_timeout((rwl), (usec), SYNCH_FLAGS_NONE)
  73.  
  74. extern void rwlock_initialize(rwlock_t *rwl);
  75. extern void rwlock_read_unlock(rwlock_t *rwl);
  76. extern void rwlock_write_unlock(rwlock_t *rwl);
  77. extern int _rwlock_read_lock_timeout(rwlock_t *rwl, uint32_t usec, int flags);
  78. extern int _rwlock_write_lock_timeout(rwlock_t *rwl, uint32_t usec, int flags);
  79.  
  80. #endif
  81.  
  82. /** @}
  83.  */
  84.