int rio_register_scan()

in rio.c [1900:1961]

• 35 lines of code
• 9 McCabe index (conditional complexity)

int rio_register_scan(int mport_id, struct rio_scan *scan_ops)
{
	struct rio_mport *port;
	struct rio_scan_node *scan;
	int rc = 0;

	pr_debug("RIO: %s for mport_id=%d\n", __func__, mport_id);

	if ((mport_id != RIO_MPORT_ANY && mport_id >= RIO_MAX_MPORTS) ||
	    !scan_ops)
		return -EINVAL;

	mutex_lock(&rio_mport_list_lock);

	/*
	 * Check if there is another enumerator already registered for
	 * the same mport ID (including RIO_MPORT_ANY). Multiple enumerators
	 * for the same mport ID are not supported.
	 */
	list_for_each_entry(scan, &rio_scans, node) {
		if (scan->mport_id == mport_id) {
			rc = -EBUSY;
			goto err_out;
		}
	}

	/*
	 * Allocate and initialize new scan registration node.
	 */
	scan = kzalloc(sizeof(*scan), GFP_KERNEL);
	if (!scan) {
		rc = -ENOMEM;
		goto err_out;
	}

	scan->mport_id = mport_id;
	scan->ops = scan_ops;

	/*
	 * Traverse the list of registered mports to attach this new scan.
	 *
	 * The new scan with matching mport ID overrides any previously attached
	 * scan assuming that old scan (if any) is the default one (based on the
	 * enumerator registration check above).
	 * If the new scan is the global one, it will be attached only to mports
	 * that do not have their own individual operations already attached.
	 */
	list_for_each_entry(port, &rio_mports, node) {
		if (port->id == mport_id) {
			port->nscan = scan_ops;
			break;
		} else if (mport_id == RIO_MPORT_ANY && !port->nscan)
			port->nscan = scan_ops;
	}

	list_add_tail(&scan->node, &rio_scans);

err_out:
	mutex_unlock(&rio_mport_list_lock);

	return rc;
}