View of xos/kernel/mutex.c

/* Verrou d'exclusion mutuelle */
/* Copyright (C) 2008  Emmanuel Varoquaux
 
   This file is part of XOS.
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
/* Note : pendant la phase d'initialisation, mutex_lock() et mutex_unlock()
 * peuvent etre executes avant l'initialisation des processus (printk()...).
 * Dans ce contexte ces fonctions sont toujours passantes, il n'y a donc aucun
 * risque d'acces a des donnees non initialisees. */
 
#include <mutex_struct.h>
#include <condition.h>
 
void mutex_init(struct mutex_struct *mutex)
{
  mutex->locked = 0;
  condition_init(&mutex->condition);
}
 
int mutex_lock(struct mutex_struct *mutex)
{
  while (mutex->locked)
    if (!condition_wait_interruptible(&mutex->condition))
      return 0;
  mutex->locked = 1;
  return 1;
}
 
void mutex_unlock(struct mutex_struct *mutex)
{
  mutex->locked = 0;
  condition_signal(&mutex->condition);
}