Ejemplo n.º 1
0
static int fifo_open(struct inode *inode, struct file *filp)
{
	int ret;

	ret = -ERESTARTSYS;
	lock_kernel();
	if (down_interruptible(PIPE_SEM(*inode)))
		goto err_nolock_nocleanup;

	if (!inode->i_pipe) {
		ret = -ENOMEM;
		if(!pipe_new(inode))
			goto err_nocleanup;
	}
	filp->f_version = 0;

	switch (filp->f_mode) {
	case 1:
	/*
	 *  O_RDONLY
	 *  POSIX.1 says that O_NONBLOCK means return with the FIFO
	 *  opened, even when there is no process writing the FIFO.
	 */
		filp->f_op = &read_fifo_fops;
		PIPE_RCOUNTER(*inode)++;
		if (PIPE_READERS(*inode)++ == 0)
			wake_up_partner(inode);

		if (!PIPE_WRITERS(*inode)) {
			if ((filp->f_flags & O_NONBLOCK)) {
				/* suppress POLLHUP until we have
				 * seen a writer */
				filp->f_version = PIPE_WCOUNTER(*inode);
			} else 
			{
				wait_for_partner(inode, &PIPE_WCOUNTER(*inode));
				if(signal_pending(current))
					goto err_rd;
			}
		}
		break;
	
	case 2:
	/*
	 *  O_WRONLY
	 *  POSIX.1 says that O_NONBLOCK means return -1 with
	 *  errno=ENXIO when there is no process reading the FIFO.
	 */
		ret = -ENXIO;
		if ((filp->f_flags & O_NONBLOCK) && !PIPE_READERS(*inode))
			goto err;

		filp->f_op = &write_fifo_fops;
		PIPE_WCOUNTER(*inode)++;
		if (!PIPE_WRITERS(*inode)++)
			wake_up_partner(inode);

		if (!PIPE_READERS(*inode)) {
			wait_for_partner(inode, &PIPE_RCOUNTER(*inode));
			if (signal_pending(current))
				goto err_wr;
		}
		break;
	
	case 3:
	/*
	 *  O_RDWR
	 *  POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
	 *  This implementation will NEVER block on a O_RDWR open, since
	 *  the process can at least talk to itself.
	 */
		filp->f_op = &rdwr_fifo_fops;

		PIPE_READERS(*inode)++;
		PIPE_WRITERS(*inode)++;
		PIPE_RCOUNTER(*inode)++;
		PIPE_WCOUNTER(*inode)++;
		if (PIPE_READERS(*inode) == 1 || PIPE_WRITERS(*inode) == 1)
			wake_up_partner(inode);
		break;

	default:
		ret = -EINVAL;
		goto err;
	}

	/* Ok! */
	up(PIPE_SEM(*inode));
	unlock_kernel();
	return 0;

err_rd:
	if (!--PIPE_READERS(*inode))
		wake_up_interruptible(PIPE_WAIT(*inode));
	ret = -ERESTARTSYS;
	goto err;

err_wr:
	if (!--PIPE_WRITERS(*inode))
		wake_up_interruptible(PIPE_WAIT(*inode));
	ret = -ERESTARTSYS;
	goto err;

err:
	if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) {
		struct pipe_inode_info *info = inode->i_pipe;
		inode->i_pipe = NULL;
		free_page((unsigned long)info->base);
		kfree(info);
	}

err_nocleanup:
	up(PIPE_SEM(*inode));

err_nolock_nocleanup:
	unlock_kernel();
	return ret;
}
Ejemplo n.º 2
0
static int fifo_open(struct inode *inode, struct file *filp)
{
	struct pipe_inode_info *pipe;
	int ret;

	mutex_lock(&inode->i_mutex);
	pipe = inode->i_pipe;
	if (!pipe) {
		ret = -ENOMEM;
		pipe = alloc_pipe_info(inode);
		if (!pipe)
			goto err_nocleanup;
		inode->i_pipe = pipe;
	}
	filp->f_version = 0;

	/* We can only do regular read/write on fifos */
	filp->f_mode &= (FMODE_READ | FMODE_WRITE);

	switch (filp->f_mode) {
	case FMODE_READ:
	/*
	 *  O_RDONLY
	 *  POSIX.1 says that O_NONBLOCK means return with the FIFO
	 *  opened, even when there is no process writing the FIFO.
	 */
		filp->f_op = &read_pipefifo_fops;
		pipe->r_counter++;
		if (atomic_inc_return(&pipe->readers) == 1)
			wake_up_partner(inode);

		if (!atomic_read(&pipe->writers)) {
			if ((filp->f_flags & O_NONBLOCK)) {
				/* suppress POLLHUP until we have
				 * seen a writer */
				filp->f_version = pipe->w_counter;
			} else {
				if (wait_for_partner(inode, &pipe->w_counter))
					goto err_rd;
			}
		}
		break;
	
	case FMODE_WRITE:
	/*
	 *  O_WRONLY
	 *  POSIX.1 says that O_NONBLOCK means return -1 with
	 *  errno=ENXIO when there is no process reading the FIFO.
	 */
		ret = -ENXIO;
		if ((filp->f_flags & O_NONBLOCK) && !atomic_read(&pipe->readers))
			goto err;

		filp->f_op = &write_pipefifo_fops;
		pipe->w_counter++;
		if (atomic_inc_return(&pipe->writers) == 1)
			wake_up_partner(inode);

		if (!atomic_read(&pipe->readers)) {
			if (wait_for_partner(inode, &pipe->r_counter))
				goto err_wr;
		}
		break;
	
	case FMODE_READ | FMODE_WRITE:
	/*
	 *  O_RDWR
	 *  POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
	 *  This implementation will NEVER block on a O_RDWR open, since
	 *  the process can at least talk to itself.
	 */
		filp->f_op = &rdwr_pipefifo_fops;

		atomic_inc(&pipe->readers);
		atomic_inc(&pipe->writers);
		pipe->r_counter++;
		pipe->w_counter++;
		if (atomic_read(&pipe->readers) == 1 || atomic_read(&pipe->writers) == 1)
			wake_up_partner(inode);
		break;

	default:
		ret = -EINVAL;
		goto err;
	}

	/* Ok! */
	mutex_unlock(&inode->i_mutex);
	return 0;

err_rd:
	if (atomic_dec_and_test(&pipe->readers))
		wake_up_interruptible(&pipe->wait);
	ret = -ERESTARTSYS;
	goto err;

err_wr:
	if (atomic_dec_and_test(&pipe->writers))
		wake_up_interruptible(&pipe->wait);
	ret = -ERESTARTSYS;
	goto err;

err:
	if (!atomic_read(&pipe->readers) && !atomic_read(&pipe->writers))
		free_pipe_info(inode);

err_nocleanup:
	mutex_unlock(&inode->i_mutex);
	return ret;
}
Ejemplo n.º 3
0
static int fifo_open(struct inode *inode, struct file *filp)
{
	struct pipe_inode_info *pipe;
	int ret;

	mutex_lock(&inode->i_mutex);
	pipe = inode->i_pipe;
	if (!pipe) {
		ret = -ENOMEM;
		pipe = alloc_pipe_info(inode);
		if (!pipe)
			goto err_nocleanup;
		inode->i_pipe = pipe;
	}
	filp->f_version = 0;

	/*                                            */
	filp->f_mode &= (FMODE_READ | FMODE_WRITE);

	switch (filp->f_mode) {
	case FMODE_READ:
	/*
             
                                                            
                                                            
  */
		filp->f_op = &read_pipefifo_fops;
		pipe->r_counter++;
		if (pipe->readers++ == 0)
			wake_up_partner(inode);

		if (!pipe->writers) {
			if ((filp->f_flags & O_NONBLOCK)) {
				/*                               
                     */
				filp->f_version = pipe->w_counter;
			} else {
				wait_for_partner(inode, &pipe->w_counter);
				if(signal_pending(current))
					goto err_rd;
			}
		}
		break;
	
	case FMODE_WRITE:
	/*
             
                                                      
                                                           
  */
		ret = -ENXIO;
		if ((filp->f_flags & O_NONBLOCK) && !pipe->readers)
			goto err;

		filp->f_op = &write_pipefifo_fops;
		pipe->w_counter++;
		if (!pipe->writers++)
			wake_up_partner(inode);

		if (!pipe->readers) {
			wait_for_partner(inode, &pipe->r_counter);
			if (signal_pending(current))
				goto err_wr;
		}
		break;
	
	case FMODE_READ | FMODE_WRITE:
	/*
           
                                                                 
                                                                 
                                             
  */
		filp->f_op = &rdwr_pipefifo_fops;

		pipe->readers++;
		pipe->writers++;
		pipe->r_counter++;
		pipe->w_counter++;
		if (pipe->readers == 1 || pipe->writers == 1)
			wake_up_partner(inode);
		break;

	default:
		ret = -EINVAL;
		goto err;
	}

	/*     */
	mutex_unlock(&inode->i_mutex);
	return 0;

err_rd:
	if (!--pipe->readers)
		wake_up_interruptible(&pipe->wait);
	ret = -ERESTARTSYS;
	goto err;

err_wr:
	if (!--pipe->writers)
		wake_up_interruptible(&pipe->wait);
	ret = -ERESTARTSYS;
	goto err;

err:
	if (!pipe->readers && !pipe->writers)
		free_pipe_info(inode);

err_nocleanup:
	mutex_unlock(&inode->i_mutex);
	return ret;
}