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  1. /*
  2.  * Copyright (c) 2009 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 libc
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #include <fibril_sync.h>
  36. #include <fibril.h>
  37. #include <async.h>
  38. #include <adt/list.h>
  39. #include <futex.h>
  40. #include <assert.h>
  41.  
  42. void fibril_mutex_initialize(fibril_mutex_t *fm)
  43. {
  44.     fm->counter = 1;
  45.     list_initialize(&fm->waiters);
  46. }
  47.  
  48. void fibril_mutex_lock(fibril_mutex_t *fm)
  49. {
  50.     futex_down(&async_futex);
  51.     if (fm->counter-- <= 0) {
  52.         fibril_t *f = (fibril_t *) fibril_get_id();
  53.         list_append(&f->link, &fm->waiters);
  54.         fibril_switch(FIBRIL_TO_MANAGER);
  55.     } else {
  56.         futex_up(&async_futex);
  57.     }
  58. }
  59.  
  60. bool fibril_mutex_trylock(fibril_mutex_t *fm)
  61. {
  62.     bool locked = false;
  63.    
  64.     futex_down(&async_futex);
  65.     if (fm->counter > 0) {
  66.         fm->counter--;
  67.         locked = true;
  68.     }
  69.     futex_up(&async_futex);
  70.    
  71.     return locked;
  72. }
  73.  
  74. void fibril_mutex_unlock(fibril_mutex_t *fm)
  75. {
  76.     futex_down(&async_futex);
  77.     assert(fm->counter <= 0);
  78.     if (fm->counter++ < 0) {
  79.         link_t *tmp;
  80.         fibril_t *f;
  81.    
  82.         assert(!list_empty(&fm->waiters));
  83.         tmp = fm->waiters.next;
  84.         f = list_get_instance(tmp, fibril_t, link);
  85.         list_remove(&f->link);
  86.         fibril_add_ready((fid_t) f);
  87.     }
  88.     futex_up(&async_futex);
  89. }
  90.  
  91. void fibril_rwlock_initialize(fibril_rwlock_t *frw)
  92. {
  93.     frw->writers = 0;
  94.     frw->readers = 0;
  95.     list_initialize(&frw->waiters);
  96. }
  97.  
  98. void fibril_rwlock_read_lock(fibril_rwlock_t *frw)
  99. {
  100.     futex_down(&async_futex);
  101.     if (frw->writers) {
  102.         fibril_t *f = (fibril_t *) fibril_get_id();
  103.         f->flags &= ~FIBRIL_WRITER;
  104.         list_append(&f->link, &frw->waiters);
  105.         fibril_switch(FIBRIL_TO_MANAGER);
  106.     } else {
  107.         frw->readers++;
  108.         futex_up(&async_futex);
  109.     }
  110. }
  111.  
  112. void fibril_rwlock_write_lock(fibril_rwlock_t *frw)
  113. {
  114.     futex_down(&async_futex);
  115.     if (frw->writers || frw->readers) {
  116.         fibril_t *f = (fibril_t *) fibril_get_id();
  117.         f->flags |= FIBRIL_WRITER;
  118.         list_append(&f->link, &frw->waiters);
  119.         fibril_switch(FIBRIL_TO_MANAGER);
  120.     } else {
  121.         frw->writers++;
  122.         futex_up(&async_futex);
  123.     }
  124. }
  125.  
  126. static void _fibril_rwlock_common_unlock(fibril_rwlock_t *frw)
  127. {
  128.     futex_down(&async_futex);
  129.     assert(frw->readers || (frw->writers == 1));
  130.     if (frw->readers) {
  131.         if (--frw->readers)
  132.             goto out;
  133.     } else {
  134.         frw->writers--;
  135.     }
  136.    
  137.     assert(!frw->readers && !frw->writers);
  138.    
  139.     while (!list_empty(&frw->waiters)) {
  140.         link_t *tmp = frw->waiters.next;
  141.         fibril_t *f = list_get_instance(tmp, fibril_t, link);
  142.        
  143.         if (f->flags & FIBRIL_WRITER) {
  144.             if (frw->readers)
  145.                 break;
  146.             list_remove(&f->link);
  147.             fibril_add_ready((fid_t) f);
  148.             frw->writers++;
  149.             break;
  150.         } else {
  151.             list_remove(&f->link);
  152.             fibril_add_ready((fid_t) f);
  153.             frw->readers++;
  154.         }
  155.     }
  156. out:
  157.     futex_up(&async_futex);
  158. }
  159.  
  160. void fibril_rwlock_read_unlock(fibril_rwlock_t *frw)
  161. {
  162.     _fibril_rwlock_common_unlock(frw);
  163. }
  164.  
  165. void fibril_rwlock_write_unlock(fibril_rwlock_t *frw)
  166. {
  167.     _fibril_rwlock_common_unlock(frw);
  168. }
  169.  
  170. /** @}
  171.  */
  172.