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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 <arch/barrier.h>
  40. #include <preemption.h>
  41. #include <atomic.h>
  42. #include <debug.h>
  43.  
  44. #ifdef CONFIG_SMP
  45. typedef struct {
  46. #ifdef CONFIG_DEBUG_SPINLOCK
  47.     char *name;
  48. #endif
  49.     atomic_t val;
  50. } spinlock_t;
  51.  
  52. /*
  53.  * SPINLOCK_DECLARE is to be used for dynamically allocated spinlocks,
  54.  * where the lock gets initialized in run time.
  55.  */
  56. #define SPINLOCK_DECLARE(slname)    spinlock_t slname
  57. #define SPINLOCK_EXTERN(slname)     extern spinlock_t slname
  58.  
  59. /*
  60.  * SPINLOCK_INITIALIZE is to be used for statically allocated spinlocks.
  61.  * It declares and initializes the lock.
  62.  */
  63. #ifdef CONFIG_DEBUG_SPINLOCK
  64. #define SPINLOCK_INITIALIZE(slname)     \
  65.     spinlock_t slname = {       \
  66.         .name = #slname,    \
  67.         .val = { 0 }        \
  68.     }
  69. #else
  70. #define SPINLOCK_INITIALIZE(slname)     \
  71.     spinlock_t slname = {       \
  72.         .val = { 0 }        \
  73.     }
  74. #endif
  75.  
  76. extern void spinlock_initialize(spinlock_t *sl, char *name);
  77. extern int spinlock_trylock(spinlock_t *sl);
  78. extern void spinlock_lock_debug(spinlock_t *sl);
  79.  
  80. #ifdef CONFIG_DEBUG_SPINLOCK
  81. #  define spinlock_lock(x) spinlock_lock_debug(x)
  82. #else
  83. #  define spinlock_lock(x) atomic_lock_arch(&(x)->val)
  84. #endif
  85.  
  86. /** Unlock spinlock
  87.  *
  88.  * Unlock spinlock.
  89.  *
  90.  * @param sl Pointer to spinlock_t structure.
  91.  */
  92. static inline void spinlock_unlock(spinlock_t *sl)
  93. {
  94.     ASSERT(atomic_get(&sl->val) != 0);
  95.  
  96.     /*
  97.      * Prevent critical section code from bleeding out this way down.
  98.      */
  99.     CS_LEAVE_BARRIER();
  100.    
  101.     atomic_set(&sl->val, 0);
  102.     preemption_enable();
  103. }
  104.  
  105. #ifdef CONFIG_DEBUG_SPINLOCK
  106.  
  107. extern int printf(const char *, ...);
  108.  
  109. #define DEADLOCK_THRESHOLD      100000000
  110. #define DEADLOCK_PROBE_INIT(pname)  size_t pname = 0
  111. #define DEADLOCK_PROBE(pname, value)                    \
  112.     if ((pname)++ > (value)) {                  \
  113.         (pname) = 0;                        \
  114.         printf("Deadlock probe %s: exceeded threshold %u\n",    \
  115.             "cpu%u: function=%s, line=%u\n",            \
  116.             #pname, (value), CPU->id, __func__, __LINE__);  \
  117.     }
  118. #else
  119. #define DEADLOCK_PROBE_INIT(pname)
  120. #define DEADLOCK_PROBE(pname, value)
  121. #endif
  122.  
  123. #else
  124.  
  125. /* On UP systems, spinlocks are effectively left out. */
  126. #define SPINLOCK_DECLARE(name)
  127. #define SPINLOCK_EXTERN(name)
  128. #define SPINLOCK_INITIALIZE(name)
  129.  
  130. #define spinlock_initialize(x, name)
  131. #define spinlock_lock(x)        preemption_disable()
  132. #define spinlock_trylock(x)         (preemption_disable(), 1)
  133. #define spinlock_unlock(x)      preemption_enable()
  134.  
  135. #define DEADLOCK_PROBE_INIT(pname)
  136. #define DEADLOCK_PROBE(pname, value)
  137.  
  138. #endif
  139.  
  140. #endif
  141.  
  142. /** @}
  143.  */
  144.