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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_SPINLOCK_H_
  36. #define KERN_SPINLOCK_H_
  37.  
  38. #include <arch/types.h>
  39. #include <preemption.h>
  40. #include <atomic.h>
  41. #include <debug.h>
  42.  
  43. #ifdef CONFIG_SMP
  44. typedef struct {
  45. #ifdef CONFIG_DEBUG_SPINLOCK
  46.     char *name;
  47. #endif
  48.     atomic_t val;
  49. } spinlock_t;
  50.  
  51. /*
  52.  * SPINLOCK_DECLARE is to be used for dynamically allocated spinlocks,
  53.  * where the lock gets initialized in run time.
  54.  */
  55. #define SPINLOCK_DECLARE(slname)    spinlock_t slname
  56.  
  57. /*
  58.  * SPINLOCK_INITIALIZE is to be used for statically allocated spinlocks.
  59.  * It declares and initializes the lock.
  60.  */
  61. #ifdef CONFIG_DEBUG_SPINLOCK
  62. #define SPINLOCK_INITIALIZE(slname)     \
  63.     spinlock_t slname = {       \
  64.         .name = #slname,    \
  65.         .val = { 0 }        \
  66.     }
  67. #else
  68. #define SPINLOCK_INITIALIZE(slname)     \
  69.     spinlock_t slname = {       \
  70.         .val = { 0 }        \
  71.     }
  72. #endif
  73.  
  74. extern void spinlock_initialize(spinlock_t *sl, char *name);
  75. extern int spinlock_trylock(spinlock_t *sl);
  76. extern void spinlock_lock_debug(spinlock_t *sl);
  77.  
  78. #ifdef CONFIG_DEBUG_SPINLOCK
  79. #  define spinlock_lock(x) spinlock_lock_debug(x)
  80. #else
  81. #  define spinlock_lock(x) atomic_lock_arch(&(x)->val)
  82. #endif
  83.  
  84. /** Unlock spinlock
  85.  *
  86.  * Unlock spinlock.
  87.  *
  88.  * @param sl Pointer to spinlock_t structure.
  89.  */
  90. static inline void spinlock_unlock(spinlock_t *sl)
  91. {
  92.     ASSERT(atomic_get(&sl->val) != 0);
  93.  
  94.     /*
  95.      * Prevent critical section code from bleeding out this way down.
  96.      */
  97.     CS_LEAVE_BARRIER();
  98.    
  99.     atomic_set(&sl->val, 0);
  100.     preemption_enable();
  101. }
  102.  
  103. #else
  104.  
  105. typedef void spinlock_t;
  106.  
  107. /* On UP systems, spinlocks are effectively left out. */
  108. #define SPINLOCK_DECLARE(name)
  109. #define SPINLOCK_INITIALIZE(name)
  110.  
  111. #define spinlock_initialize(x, name)
  112. #define spinlock_lock(x)        preemption_disable()
  113. #define spinlock_trylock(x)         (preemption_disable(), 1)
  114. #define spinlock_unlock(x)      preemption_enable()
  115.  
  116. #endif
  117.  
  118. #endif
  119.  
  120. /** @}
  121.  */
  122.