static ssize_t adb_write()

in adb.c [772:839]

• 55 lines of code
• 14 McCabe index (conditional complexity)

static ssize_t adb_write(struct file *file, const char __user *buf,
			 size_t count, loff_t *ppos)
{
	int ret/*, i*/;
	struct adbdev_state *state = file->private_data;
	struct adb_request *req;

	if (count < 2 || count > sizeof(req->data))
		return -EINVAL;
	if (adb_controller == NULL)
		return -ENXIO;

	req = kmalloc(sizeof(struct adb_request),
					     GFP_KERNEL);
	if (req == NULL)
		return -ENOMEM;

	req->nbytes = count;
	req->done = adb_write_done;
	req->arg = (void *) state;
	req->complete = 0;
	
	ret = -EFAULT;
	if (copy_from_user(req->data, buf, count))
		goto out;

	atomic_inc(&state->n_pending);

	/* If a probe is in progress or we are sleeping, wait for it to complete */
	down(&adb_probe_mutex);

	/* Queries are special requests sent to the ADB driver itself */
	if (req->data[0] == ADB_QUERY) {
		if (count > 1)
			ret = do_adb_query(req);
		else
			ret = -EINVAL;
		up(&adb_probe_mutex);
	}
	/* Special case for ADB_BUSRESET request, all others are sent to
	   the controller */
	else if ((req->data[0] == ADB_PACKET) && (count > 1)
		&& (req->data[1] == ADB_BUSRESET)) {
		ret = do_adb_reset_bus();
		up(&adb_probe_mutex);
		atomic_dec(&state->n_pending);
		if (ret == 0)
			ret = count;
		goto out;
	} else {	
		req->reply_expected = ((req->data[1] & 0xc) == 0xc);
		if (adb_controller && adb_controller->send_request)
			ret = adb_controller->send_request(req, 0);
		else
			ret = -ENXIO;
		up(&adb_probe_mutex);
	}

	if (ret != 0) {
		atomic_dec(&state->n_pending);
		goto out;
	}
	return count;

out:
	kfree(req);
	return ret;
}