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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. static void _fibril_mutex_unlock_unsafe(fibril_mutex_t *fm)
  75. {
  76.     assert(fm->counter <= 0);
  77.     if (fm->counter++ < 0) {
  78.         link_t *tmp;
  79.         fibril_t *f;
  80.    
  81.         assert(!list_empty(&fm->waiters));
  82.         tmp = fm->waiters.next;
  83.         f = list_get_instance(tmp, fibril_t, link);
  84.         list_remove(&f->link);
  85.         fibril_add_ready((fid_t) f);
  86.     }
  87. }
  88.  
  89. void fibril_mutex_unlock(fibril_mutex_t *fm)
  90. {
  91.     futex_down(&async_futex);
  92.     _fibril_mutex_unlock_unsafe(fm);
  93.     futex_up(&async_futex);
  94. }
  95.  
  96. void fibril_rwlock_initialize(fibril_rwlock_t *frw)
  97. {
  98.     frw->writers = 0;
  99.     frw->readers = 0;
  100.     list_initialize(&frw->waiters);
  101. }
  102.  
  103. void fibril_rwlock_read_lock(fibril_rwlock_t *frw)
  104. {
  105.     futex_down(&async_futex);
  106.     if (frw->writers) {
  107.         fibril_t *f = (fibril_t *) fibril_get_id();
  108.         f->flags &= ~FIBRIL_WRITER;
  109.         list_append(&f->link, &frw->waiters);
  110.         fibril_switch(FIBRIL_TO_MANAGER);
  111.     } else {
  112.         frw->readers++;
  113.         futex_up(&async_futex);
  114.     }
  115. }
  116.  
  117. void fibril_rwlock_write_lock(fibril_rwlock_t *frw)
  118. {
  119.     futex_down(&async_futex);
  120.     if (frw->writers || frw->readers) {
  121.         fibril_t *f = (fibril_t *) fibril_get_id();
  122.         f->flags |= FIBRIL_WRITER;
  123.         list_append(&f->link, &frw->waiters);
  124.         fibril_switch(FIBRIL_TO_MANAGER);
  125.     } else {
  126.         frw->writers++;
  127.         futex_up(&async_futex);
  128.     }
  129. }
  130.  
  131. static void _fibril_rwlock_common_unlock(fibril_rwlock_t *frw)
  132. {
  133.     futex_down(&async_futex);
  134.     assert(frw->readers || (frw->writers == 1));
  135.     if (frw->readers) {
  136.         if (--frw->readers)
  137.             goto out;
  138.     } else {
  139.         frw->writers--;
  140.     }
  141.    
  142.     assert(!frw->readers && !frw->writers);
  143.    
  144.     while (!list_empty(&frw->waiters)) {
  145.         link_t *tmp = frw->waiters.next;
  146.         fibril_t *f = list_get_instance(tmp, fibril_t, link);
  147.        
  148.         if (f->flags & FIBRIL_WRITER) {
  149.             if (frw->readers)
  150.                 break;
  151.             list_remove(&f->link);
  152.             fibril_add_ready((fid_t) f);
  153.             frw->writers++;
  154.             break;
  155.         } else {
  156.             list_remove(&f->link);
  157.             fibril_add_ready((fid_t) f);
  158.             frw->readers++;
  159.         }
  160.     }
  161. out:
  162.     futex_up(&async_futex);
  163. }
  164.  
  165. void fibril_rwlock_read_unlock(fibril_rwlock_t *frw)
  166. {
  167.     _fibril_rwlock_common_unlock(frw);
  168. }
  169.  
  170. void fibril_rwlock_write_unlock(fibril_rwlock_t *frw)
  171. {
  172.     _fibril_rwlock_common_unlock(frw);
  173. }
  174.  
  175. void fibril_condvar_initialize(fibril_condvar_t *fcv)
  176. {
  177.     list_initialize(&fcv->waiters);
  178. }
  179.  
  180. void fibril_condvar_wait(fibril_condvar_t *fcv, fibril_mutex_t *fm)
  181. {
  182.     fibril_t *f = (fibril_t *) fibril_get_id();
  183.  
  184.     futex_down(&async_futex);
  185.     list_append(&f->link, &fcv->waiters);
  186.     _fibril_mutex_unlock_unsafe(fm);
  187.     fibril_switch(FIBRIL_TO_MANAGER);
  188.     fibril_mutex_lock(fm);
  189. }
  190.  
  191. static void _fibril_condvar_wakeup_common(fibril_condvar_t *fcv, bool once)
  192. {
  193.     link_t *tmp;
  194.     fibril_t *f;
  195.  
  196.     futex_down(&async_futex);
  197.     while (!list_empty(&fcv->waiters)) {
  198.         tmp = fcv->waiters.next;
  199.         f = list_get_instance(tmp, fibril_t, link);
  200.         list_remove(&f->link);
  201.         fibril_add_ready((fid_t) f);
  202.         if (once)
  203.             break;
  204.     }
  205.     futex_up(&async_futex);
  206. }
  207.  
  208. void fibril_condvar_signal(fibril_condvar_t *fcv)
  209. {
  210.     _fibril_condvar_wakeup_common(fcv, true);
  211. }
  212.  
  213. void fibril_condvar_broadcast(fibril_condvar_t *fcv)
  214. {
  215.     _fibril_condvar_wakeup_common(fcv, false);
  216. }
  217.  
  218. /** @}
  219.  */
  220.