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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. #include <synch/spinlock.h>
  30. #include <arch/atomic.h>
  31. #include <arch/barrier.h>
  32. #include <arch.h>
  33. #include <preemption.h>
  34. #include <print.h>
  35. #include <debug.h>
  36. #include <symtab.h>
  37.  
  38. #ifdef CONFIG_SMP
  39.  
  40. /** Initialize spinlock
  41.  *
  42.  * Initialize spinlock.
  43.  *
  44.  * @param sl Pointer to spinlock_t structure.
  45.  */
  46. void spinlock_initialize(spinlock_t *sl, char *name)
  47. {
  48.     sl->val = 0;
  49. #ifdef CONFIG_DEBUG_SPINLOCK
  50.     sl->name = name;
  51. #endif 
  52. }
  53.  
  54. #ifdef CONFIG_DEBUG_SPINLOCK
  55. /** Lock spinlock
  56.  *
  57.  * Lock spinlock.
  58.  * This version has limitted ability to report
  59.  * possible occurence of deadlock.
  60.  *
  61.  * @param sl Pointer to spinlock_t structure.
  62.  */
  63. void spinlock_lock(spinlock_t *sl)
  64. {
  65.     count_t i = 0;
  66.     __address caller = CALLER(sl);
  67.     char *symbol;
  68.     bool deadlock_reported = false;
  69.  
  70.     preemption_disable();
  71.     while (test_and_set(&sl->val)) {
  72.         if (i++ > 300000) {
  73.             printf("cpu%d: looping on spinlock %p:%s, caller=%p",
  74.                    CPU->id, sl, sl->name, caller);
  75.             symbol = get_symtab_entry(caller);
  76.             if (symbol)
  77.                 printf("(%s)", symbol);
  78.             printf("\n");
  79.             i = 0;
  80.             deadlock_reported = true;
  81.         }
  82.     }
  83.  
  84.     if (deadlock_reported)
  85.         printf("cpu%d: not deadlocked\n", CPU->id);
  86.  
  87.     /*
  88.      * Prevent critical section code from bleeding out this way up.
  89.      */
  90.     CS_ENTER_BARRIER();
  91.  
  92. }
  93.  
  94. #else
  95.  
  96. /** Lock spinlock
  97.  *
  98.  * Lock spinlock.
  99.  *
  100.  * @param sl Pointer to spinlock_t structure.
  101.  */
  102. void spinlock_lock(spinlock_t *sl)
  103. {
  104.     preemption_disable();
  105.  
  106.     /*
  107.      * Each architecture has its own efficient/recommended
  108.      * implementation of spinlock.
  109.      */
  110.     spinlock_arch(&sl->val);
  111.  
  112.     /*
  113.      * Prevent critical section code from bleeding out this way up.
  114.      */
  115.     CS_ENTER_BARRIER();
  116. }
  117. #endif
  118.  
  119. /** Lock spinlock conditionally
  120.  *
  121.  * Lock spinlock conditionally.
  122.  * If the spinlock is not available at the moment,
  123.  * signal failure.
  124.  *
  125.  * @param sl Pointer to spinlock_t structure.
  126.  *
  127.  * @return Zero on failure, non-zero otherwise.
  128.  */
  129. int spinlock_trylock(spinlock_t *sl)
  130. {
  131.     int rc;
  132.    
  133.     preemption_disable();
  134.     rc = !test_and_set(&sl->val);
  135.  
  136.     /*
  137.      * Prevent critical section code from bleeding out this way up.
  138.      */
  139.     CS_ENTER_BARRIER();
  140.  
  141.     if (!rc)
  142.         preemption_enable();
  143.    
  144.     return rc;
  145. }
  146.  
  147. /** Unlock spinlock
  148.  *
  149.  * Unlock spinlock.
  150.  *
  151.  * @param sl Pointer to spinlock_t structure.
  152.  */
  153. void spinlock_unlock(spinlock_t *sl)
  154. {
  155.     ASSERT(sl->val != 0);
  156.  
  157.     /*
  158.      * Prevent critical section code from bleeding out this way down.
  159.      */
  160.     CS_LEAVE_BARRIER();
  161.    
  162.     sl->val = 0;
  163.     preemption_enable();
  164. }
  165.  
  166. #endif
  167.