kernel/generic/include/synch/rwlock.h

   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 <typedefs.h>
  40 #include <synch/mutex.h>
  41 #include <synch/synch.h>
  42 #include <synch/spinlock.h>
  43
  44 enum rwlock_type {
  45         RWLOCK_NONE,
  46         RWLOCK_READER,
  47         RWLOCK_WRITER
  48 };
  49
  50 struct rwlock {
  51         SPINLOCK_DECLARE(lock);
  52         mutex_t exclusive;      /**< Mutex for writers, readers can bypass it if readers_in is positive. */
  53         count_t readers_in;     /**< Number of readers in critical section. */
  54 };
  55
  56 #define rwlock_write_lock(rwl) \
  57         _rwlock_write_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_FLAGS_NONE)
  58 #define rwlock_read_lock(rwl) \
  59         _rwlock_read_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_FLAGS_NONE)
  60 #define rwlock_write_trylock(rwl) \
  61         _rwlock_write_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_FLAGS_NON_BLOCKING)
  62 #define rwlock_read_trylock(rwl) \
  63         _rwlock_read_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_FLAGS_NON_BLOCKING)
  64 #define rwlock_write_lock_timeout(rwl,usec) \
  65         _rwlock_write_lock_timeout((rwl),(usec),SYNCH_FLAGS_NONE)
  66 #define rwlock_read_lock_timeout(rwl,usec) \
  67         _rwlock_read_lock_timeout((rwl),(usec),SYNCH_FLAGS_NONE)
  68
  69 extern void rwlock_initialize(rwlock_t *rwl);
  70 extern void rwlock_read_unlock(rwlock_t *rwl);
  71 extern void rwlock_write_unlock(rwlock_t *rwl);
  72 extern int _rwlock_read_lock_timeout(rwlock_t *rwl, uint32_t usec, int flags);
  73 extern int _rwlock_write_lock_timeout(rwlock_t *rwl, uint32_t usec, int flags);
  74
  75 #endif
  76
  77 /** @}
  78  */