static int xillybus_open()

in xillybus/xillybus_core.c [1427:1562]

• 99 lines of code
• 34 McCabe index (conditional complexity)

static int xillybus_open(struct inode *inode, struct file *filp)
{
	int rc;
	unsigned long flags;
	struct xilly_endpoint *endpoint;
	struct xilly_channel *channel;
	int index;

	rc = xillybus_find_inode(inode, (void **)&endpoint, &index);
	if (rc)
		return rc;

	if (endpoint->fatal_error)
		return -EIO;

	channel = endpoint->channels[1 + index];
	filp->private_data = channel;

	/*
	 * It gets complicated because:
	 * 1. We don't want to take a mutex we don't have to
	 * 2. We don't want to open one direction if the other will fail.
	 */

	if ((filp->f_mode & FMODE_READ) && (!channel->num_wr_buffers))
		return -ENODEV;

	if ((filp->f_mode & FMODE_WRITE) && (!channel->num_rd_buffers))
		return -ENODEV;

	if ((filp->f_mode & FMODE_READ) && (filp->f_flags & O_NONBLOCK) &&
	    (channel->wr_synchronous || !channel->wr_allow_partial ||
	     !channel->wr_supports_nonempty)) {
		dev_err(endpoint->dev,
			"open() failed: O_NONBLOCK not allowed for read on this device\n");
		return -ENODEV;
	}

	if ((filp->f_mode & FMODE_WRITE) && (filp->f_flags & O_NONBLOCK) &&
	    (channel->rd_synchronous || !channel->rd_allow_partial)) {
		dev_err(endpoint->dev,
			"open() failed: O_NONBLOCK not allowed for write on this device\n");
		return -ENODEV;
	}

	/*
	 * Note: open() may block on getting mutexes despite O_NONBLOCK.
	 * This shouldn't occur normally, since multiple open of the same
	 * file descriptor is almost always prohibited anyhow
	 * (*_exclusive_open is normally set in real-life systems).
	 */

	if (filp->f_mode & FMODE_READ) {
		rc = mutex_lock_interruptible(&channel->wr_mutex);
		if (rc)
			return rc;
	}

	if (filp->f_mode & FMODE_WRITE) {
		rc = mutex_lock_interruptible(&channel->rd_mutex);
		if (rc)
			goto unlock_wr;
	}

	if ((filp->f_mode & FMODE_READ) &&
	    (channel->wr_ref_count != 0) &&
	    (channel->wr_exclusive_open)) {
		rc = -EBUSY;
		goto unlock;
	}

	if ((filp->f_mode & FMODE_WRITE) &&
	    (channel->rd_ref_count != 0) &&
	    (channel->rd_exclusive_open)) {
		rc = -EBUSY;
		goto unlock;
	}

	if (filp->f_mode & FMODE_READ) {
		if (channel->wr_ref_count == 0) { /* First open of file */
			/* Move the host to first buffer */
			spin_lock_irqsave(&channel->wr_spinlock, flags);
			channel->wr_host_buf_idx = 0;
			channel->wr_host_buf_pos = 0;
			channel->wr_fpga_buf_idx = -1;
			channel->wr_empty = 1;
			channel->wr_ready = 0;
			channel->wr_sleepy = 1;
			channel->wr_eof = -1;
			channel->wr_hangup = 0;

			spin_unlock_irqrestore(&channel->wr_spinlock, flags);

			iowrite32(1 | (channel->chan_num << 1) |
				  (4 << 24) |  /* Opcode 4, open channel */
				  ((channel->wr_synchronous & 1) << 23),
				  channel->endpoint->registers +
				  fpga_buf_ctrl_reg);
		}

		channel->wr_ref_count++;
	}

	if (filp->f_mode & FMODE_WRITE) {
		if (channel->rd_ref_count == 0) { /* First open of file */
			/* Move the host to first buffer */
			spin_lock_irqsave(&channel->rd_spinlock, flags);
			channel->rd_host_buf_idx = 0;
			channel->rd_host_buf_pos = 0;
			channel->rd_leftovers[3] = 0; /* No leftovers. */
			channel->rd_fpga_buf_idx = channel->num_rd_buffers - 1;
			channel->rd_full = 0;

			spin_unlock_irqrestore(&channel->rd_spinlock, flags);

			iowrite32((channel->chan_num << 1) |
				  (4 << 24),   /* Opcode 4, open channel */
				  channel->endpoint->registers +
				  fpga_buf_ctrl_reg);
		}

		channel->rd_ref_count++;
	}

unlock:
	if (filp->f_mode & FMODE_WRITE)
		mutex_unlock(&channel->rd_mutex);
unlock_wr:
	if (filp->f_mode & FMODE_READ)
		mutex_unlock(&channel->wr_mutex);

	if (!rc && (!channel->seekable))
		return nonseekable_open(inode, filp);

	return rc;
}