static int xillyusb_open()

in xillybus/xillyusb.c [1230:1417]

• 127 lines of code
• 37 McCabe index (conditional complexity)

static int xillyusb_open(struct inode *inode, struct file *filp)
{
	struct xillyusb_dev *xdev;
	struct xillyusb_channel *chan;
	struct xillyfifo *in_fifo = NULL;
	struct xillyusb_endpoint *out_ep = NULL;
	int rc;
	int index;

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

	chan = &xdev->channels[index];
	filp->private_data = chan;

	mutex_lock(&chan->lock);

	rc = -ENODEV;

	if (xdev->error)
		goto unmutex_fail;

	if (((filp->f_mode & FMODE_READ) && !chan->readable) ||
	    ((filp->f_mode & FMODE_WRITE) && !chan->writable))
		goto unmutex_fail;

	if ((filp->f_flags & O_NONBLOCK) && (filp->f_mode & FMODE_READ) &&
	    chan->in_synchronous) {
		dev_err(xdev->dev,
			"open() failed: O_NONBLOCK not allowed for read on this device\n");
		goto unmutex_fail;
	}

	if ((filp->f_flags & O_NONBLOCK) && (filp->f_mode & FMODE_WRITE) &&
	    chan->out_synchronous) {
		dev_err(xdev->dev,
			"open() failed: O_NONBLOCK not allowed for write on this device\n");
		goto unmutex_fail;
	}

	rc = -EBUSY;

	if (((filp->f_mode & FMODE_READ) && chan->open_for_read) ||
	    ((filp->f_mode & FMODE_WRITE) && chan->open_for_write))
		goto unmutex_fail;

	kref_get(&xdev->kref);

	if (filp->f_mode & FMODE_READ)
		chan->open_for_read = 1;

	if (filp->f_mode & FMODE_WRITE)
		chan->open_for_write = 1;

	mutex_unlock(&chan->lock);

	if (filp->f_mode & FMODE_WRITE) {
		out_ep = endpoint_alloc(xdev,
					(chan->chan_idx + 2) | USB_DIR_OUT,
					bulk_out_work, BUF_SIZE_ORDER, BUFNUM);

		if (!out_ep) {
			rc = -ENOMEM;
			goto unopen;
		}

		rc = fifo_init(&out_ep->fifo, chan->out_log2_fifo_size);

		if (rc)
			goto late_unopen;

		out_ep->fill_mask = -(1 << chan->out_log2_element_size);
		chan->out_bytes = 0;
		chan->flushed = 0;

		/*
		 * Sending a flush request to a previously closed stream
		 * effectively opens it, and also waits until the command is
		 * confirmed by the FPGA. The latter is necessary because the
		 * data is sent through a separate BULK OUT endpoint, and the
		 * xHCI controller is free to reorder transmissions.
		 *
		 * This can't go wrong unless there's a serious hardware error
		 * (or the computer is stuck for 500 ms?)
		 */
		rc = flush_downstream(chan, XILLY_RESPONSE_TIMEOUT, false);

		if (rc == -ETIMEDOUT) {
			rc = -EIO;
			report_io_error(xdev, rc);
		}

		if (rc)
			goto late_unopen;
	}

	if (filp->f_mode & FMODE_READ) {
		in_fifo = kzalloc(sizeof(*in_fifo), GFP_KERNEL);

		if (!in_fifo) {
			rc = -ENOMEM;
			goto late_unopen;
		}

		rc = fifo_init(in_fifo, chan->in_log2_fifo_size);

		if (rc) {
			kfree(in_fifo);
			goto late_unopen;
		}
	}

	mutex_lock(&chan->lock);
	if (in_fifo) {
		chan->in_fifo = in_fifo;
		chan->read_data_ok = 1;
	}
	if (out_ep)
		chan->out_ep = out_ep;
	mutex_unlock(&chan->lock);

	if (in_fifo) {
		u32 in_checkpoint = 0;

		if (!chan->in_synchronous)
			in_checkpoint = in_fifo->size >>
				chan->in_log2_element_size;

		chan->in_consumed_bytes = 0;
		chan->poll_used = 0;
		chan->in_current_checkpoint = in_checkpoint;
		rc = xillyusb_send_opcode(xdev, (chan->chan_idx << 1) | 1,
					  OPCODE_SET_CHECKPOINT,
					  in_checkpoint);

		if (rc) /* Failure guarantees that opcode wasn't sent */
			goto unfifo;

		/*
		 * In non-blocking mode, request the FPGA to send any data it
		 * has right away. Otherwise, the first read() will always
		 * return -EAGAIN, which is OK strictly speaking, but ugly.
		 * Checking and unrolling if this fails isn't worth the
		 * effort -- the error is propagated to the first read()
		 * anyhow.
		 */
		if (filp->f_flags & O_NONBLOCK)
			request_read_anything(chan, OPCODE_SET_PUSH);
	}

	return 0;

unfifo:
	chan->read_data_ok = 0;
	safely_assign_in_fifo(chan, NULL);
	fifo_mem_release(in_fifo);
	kfree(in_fifo);

	if (out_ep) {
		mutex_lock(&chan->lock);
		chan->out_ep = NULL;
		mutex_unlock(&chan->lock);
	}

late_unopen:
	if (out_ep)
		endpoint_dealloc(out_ep);

unopen:
	mutex_lock(&chan->lock);

	if (filp->f_mode & FMODE_READ)
		chan->open_for_read = 0;

	if (filp->f_mode & FMODE_WRITE)
		chan->open_for_write = 0;

	mutex_unlock(&chan->lock);

	kref_put(&xdev->kref, cleanup_dev);

	return rc;

unmutex_fail:
	mutex_unlock(&chan->lock);
	return rc;
}