cp/nucleus/mutex.c

   1 /*
   2  * (C) Copyright 2007-2011  Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
   3  *
   4  * This file is released under the GPLv2.  See the COPYING file for more
   5  * details.
   6  */
   7
   8 #include <mutex.h>
   9
  10 /* slow-path mutex locking */
  11 void __mutex_lock_slow(mutex_t *lock)
  12 {
  13         spin_lock(&lock->queue_lock);
  14
  15         if (unlikely(atomic_add_unless(&lock->state, -1, 0))) {
  16                 spin_unlock(&lock->queue_lock);
  17                 return; /* aha! someone released it & it's ours now! */
  18         }
  19
  20         list_add_tail(&current->blocked_list, &lock->queue);
  21
  22         spin_unlock(&lock->queue_lock);
  23
  24         schedule_blocked();
  25 }