long vhost_vring_ioctl()

in vhost.c [1583:1717]

• 121 lines of code
• 38 McCabe index (conditional complexity)

long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
{
	struct file *eventfp, *filep = NULL;
	bool pollstart = false, pollstop = false;
	struct eventfd_ctx *ctx = NULL;
	u32 __user *idxp = argp;
	struct vhost_virtqueue *vq;
	struct vhost_vring_state s;
	struct vhost_vring_file f;
	u32 idx;
	long r;

	r = get_user(idx, idxp);
	if (r < 0)
		return r;
	if (idx >= d->nvqs)
		return -ENOBUFS;

	idx = array_index_nospec(idx, d->nvqs);
	vq = d->vqs[idx];

	if (ioctl == VHOST_SET_VRING_NUM ||
	    ioctl == VHOST_SET_VRING_ADDR) {
		return vhost_vring_set_num_addr(d, vq, ioctl, argp);
	}

	mutex_lock(&vq->mutex);

	switch (ioctl) {
	case VHOST_SET_VRING_BASE:
		/* Moving base with an active backend?
		 * You don't want to do that. */
		if (vq->private_data) {
			r = -EBUSY;
			break;
		}
		if (copy_from_user(&s, argp, sizeof s)) {
			r = -EFAULT;
			break;
		}
		if (s.num > 0xffff) {
			r = -EINVAL;
			break;
		}
		vq->last_avail_idx = s.num;
		/* Forget the cached index value. */
		vq->avail_idx = vq->last_avail_idx;
		break;
	case VHOST_GET_VRING_BASE:
		s.index = idx;
		s.num = vq->last_avail_idx;
		if (copy_to_user(argp, &s, sizeof s))
			r = -EFAULT;
		break;
	case VHOST_SET_VRING_KICK:
		if (copy_from_user(&f, argp, sizeof f)) {
			r = -EFAULT;
			break;
		}
		eventfp = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_fget(f.fd);
		if (IS_ERR(eventfp)) {
			r = PTR_ERR(eventfp);
			break;
		}
		if (eventfp != vq->kick) {
			pollstop = (filep = vq->kick) != NULL;
			pollstart = (vq->kick = eventfp) != NULL;
		} else
			filep = eventfp;
		break;
	case VHOST_SET_VRING_CALL:
		if (copy_from_user(&f, argp, sizeof f)) {
			r = -EFAULT;
			break;
		}
		ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
		if (IS_ERR(ctx)) {
			r = PTR_ERR(ctx);
			break;
		}

		swap(ctx, vq->call_ctx.ctx);
		break;
	case VHOST_SET_VRING_ERR:
		if (copy_from_user(&f, argp, sizeof f)) {
			r = -EFAULT;
			break;
		}
		ctx = f.fd == VHOST_FILE_UNBIND ? NULL : eventfd_ctx_fdget(f.fd);
		if (IS_ERR(ctx)) {
			r = PTR_ERR(ctx);
			break;
		}
		swap(ctx, vq->error_ctx);
		break;
	case VHOST_SET_VRING_ENDIAN:
		r = vhost_set_vring_endian(vq, argp);
		break;
	case VHOST_GET_VRING_ENDIAN:
		r = vhost_get_vring_endian(vq, idx, argp);
		break;
	case VHOST_SET_VRING_BUSYLOOP_TIMEOUT:
		if (copy_from_user(&s, argp, sizeof(s))) {
			r = -EFAULT;
			break;
		}
		vq->busyloop_timeout = s.num;
		break;
	case VHOST_GET_VRING_BUSYLOOP_TIMEOUT:
		s.index = idx;
		s.num = vq->busyloop_timeout;
		if (copy_to_user(argp, &s, sizeof(s)))
			r = -EFAULT;
		break;
	default:
		r = -ENOIOCTLCMD;
	}

	if (pollstop && vq->handle_kick)
		vhost_poll_stop(&vq->poll);

	if (!IS_ERR_OR_NULL(ctx))
		eventfd_ctx_put(ctx);
	if (filep)
		fput(filep);

	if (pollstart && vq->handle_kick)
		r = vhost_poll_start(&vq->poll, vq->kick);

	mutex_unlock(&vq->mutex);

	if (pollstop && vq->handle_kick)
		vhost_poll_flush(&vq->poll);
	return r;
}