Пример #1
0
int __sched __down_interruptible(struct semaphore * sem)
{
	int retval = 0;
	struct task_struct *tsk = current;
	DECLARE_WAITQUEUE(wait, tsk);

	__set_task_state(tsk, TASK_INTERRUPTIBLE);
	add_wait_queue_exclusive(&sem->wait, &wait);

	while (__sem_update_count(sem, -1) <= 0) {
		if (signal_pending(current)) {
			/*
			 * A signal is pending - give up trying.
			 * Set sem->count to 0 if it is negative,
			 * since we are no longer sleeping.
			 */
			__sem_update_count(sem, 0);
			retval = -EINTR;
			break;
		}
		schedule();
		set_task_state(tsk, TASK_INTERRUPTIBLE);
	}
	remove_wait_queue(&sem->wait, &wait);
	__set_task_state(tsk, TASK_RUNNING);

	wake_up(&sem->wait);
	return retval;
}
Пример #2
0
/*
 * Note that when we come in to __down or __down_interruptible,
 * we have already decremented count, but that decrement was
 * ineffective since the result was < 0, and any negative value
 * of count is equivalent to 0.
 * Thus it is only when we decrement count from some value > 0
 * that we have actually got the semaphore.
 */
void __sched __down(struct semaphore *sem)
{
	struct task_struct *tsk = current;
	DECLARE_WAITQUEUE(wait, tsk);

	__set_task_state(tsk, TASK_UNINTERRUPTIBLE);
	add_wait_queue_exclusive(&sem->wait, &wait);

	/*
	 * Try to get the semaphore.  If the count is > 0, then we've
	 * got the semaphore; we decrement count and exit the loop.
	 * If the count is 0 or negative, we set it to -1, indicating
	 * that we are asleep, and then sleep.
	 */
	while (__sem_update_count(sem, -1) <= 0) {
		schedule();
		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
	}
	remove_wait_queue(&sem->wait, &wait);
	__set_task_state(tsk, TASK_RUNNING);

	/*
	 * If there are any more sleepers, wake one of them up so
	 * that it can either get the semaphore, or set count to -1
	 * indicating that there are still processes sleeping.
	 */
	wake_up(&sem->wait);
}
Пример #3
0
int __sched
__down_failed_interruptible(struct semaphore *sem)
{
	struct task_struct *tsk = current;
	DECLARE_WAITQUEUE(wait, tsk);
	long ret = 0;

#ifdef CONFIG_DEBUG_SEMAPHORE
	printk("%s(%d): down failed(%p)\n",
	       tsk->comm, tsk->pid, sem);
#endif

	tsk->state = TASK_INTERRUPTIBLE;
	wmb();
	add_wait_queue_exclusive(&sem->wait, &wait);

	while (__sem_update_count(sem, -1) <= 0) {
		if (signal_pending(current)) {
			/*
			 * A signal is pending - give up trying.
			 * Set sem->count to 0 if it is negative,
			 * since we are no longer sleeping.
			 */
			__sem_update_count(sem, 0);
			ret = -EINTR;
			break;
		}
		schedule();
		set_task_state(tsk, TASK_INTERRUPTIBLE);
	}

	remove_wait_queue(&sem->wait, &wait);
	tsk->state = TASK_RUNNING;
	wake_up(&sem->wait);

#ifdef CONFIG_DEBUG_SEMAPHORE
	printk("%s(%d): down %s(%p)\n",
	       current->comm, current->pid,
	       (ret < 0 ? "interrupted" : "acquired"), sem);
#endif
	return ret;
}
Пример #4
0
void __up(struct semaphore *sem)
{
	/*
	 * Note that we incremented count in up() before we came here,
	 * but that was ineffective since the result was <= 0, and
	 * any negative value of count is equivalent to 0.
	 * This ends up setting count to 1, unless count is now > 0
	 * (i.e. because some other cpu has called up() in the meantime),
	 * in which case we just increment count.
	 */
	__sem_update_count(sem, 1);
	wake_up(&sem->wait);
}
Пример #5
0
int __down_interruptible(struct semaphore * sem)
{
	int retval = 0;
	struct task_struct *tsk = current;
	DECLARE_WAITQUEUE(wait, tsk);

	tsk->state = TASK_INTERRUPTIBLE;
	add_wait_queue_exclusive(&sem->wait, &wait);

	while (__sem_update_count(sem, -1) <= 0) {
		if (signal_pending(current)) {
			__sem_update_count(sem, 0);
			retval = -EINTR;
			break;
		}
		schedule();
		tsk->state = TASK_INTERRUPTIBLE;
	}
	tsk->state = TASK_RUNNING;
	remove_wait_queue(&sem->wait, &wait);
	wake_up(&sem->wait);
	return retval;
}
Пример #6
0
void __down(struct semaphore * sem)
{
	struct task_struct *tsk = current;
	DECLARE_WAITQUEUE(wait, tsk);

	tsk->state = TASK_UNINTERRUPTIBLE;
	add_wait_queue_exclusive(&sem->wait, &wait);

	while (__sem_update_count(sem, -1) <= 0) {
		schedule();
		tsk->state = TASK_UNINTERRUPTIBLE;
	}
	remove_wait_queue(&sem->wait, &wait);
	tsk->state = TASK_RUNNING;

	wake_up(&sem->wait);
}
Пример #7
0
void __sched
__down_failed(struct semaphore *sem)
{
	struct task_struct *tsk = current;
	DECLARE_WAITQUEUE(wait, tsk);

#ifdef CONFIG_DEBUG_SEMAPHORE
	printk("%s(%d): down failed(%p)\n",
	       tsk->comm, tsk->pid, sem);
#endif

	tsk->state = TASK_UNINTERRUPTIBLE;
	wmb();
	add_wait_queue_exclusive(&sem->wait, &wait);

	/*
	 * Try to get the semaphore.  If the count is > 0, then we've
	 * got the semaphore; we decrement count and exit the loop.
	 * If the count is 0 or negative, we set it to -1, indicating
	 * that we are asleep, and then sleep.
	 */
	while (__sem_update_count(sem, -1) <= 0) {
		schedule();
		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
	}
	remove_wait_queue(&sem->wait, &wait);
	tsk->state = TASK_RUNNING;

	/*
	 * If there are any more sleepers, wake one of them up so
	 * that it can either get the semaphore, or set count to -1
	 * indicating that there are still processes sleeping.
	 */
	wake_up(&sem->wait);

#ifdef CONFIG_DEBUG_SEMAPHORE
	printk("%s(%d): down acquired(%p)\n",
	       tsk->comm, tsk->pid, sem);
#endif
}
Пример #8
0
static void __up(struct semaphore *sem)
{
	__sem_update_count(sem, 1);
	wake_up(&sem->wait);
}