int vringh_getdesc_user()

in vringh.c [687:733]

• 40 lines of code
• 4 McCabe index (conditional complexity)

int vringh_getdesc_user(struct vringh *vrh,
			struct vringh_iov *riov,
			struct vringh_iov *wiov,
			bool (*getrange)(struct vringh *vrh,
					 u64 addr, struct vringh_range *r),
			u16 *head)
{
	int err;

	*head = vrh->vring.num;
	err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx);
	if (err < 0)
		return err;

	/* Empty... */
	if (err == vrh->vring.num)
		return 0;

	/* We need the layouts to be the identical for this to work */
	BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov));
	BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) !=
		     offsetof(struct vringh_iov, iov));
	BUILD_BUG_ON(offsetof(struct vringh_kiov, i) !=
		     offsetof(struct vringh_iov, i));
	BUILD_BUG_ON(offsetof(struct vringh_kiov, used) !=
		     offsetof(struct vringh_iov, used));
	BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) !=
		     offsetof(struct vringh_iov, max_num));
	BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
	BUILD_BUG_ON(offsetof(struct iovec, iov_base) !=
		     offsetof(struct kvec, iov_base));
	BUILD_BUG_ON(offsetof(struct iovec, iov_len) !=
		     offsetof(struct kvec, iov_len));
	BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base)
		     != sizeof(((struct kvec *)NULL)->iov_base));
	BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len)
		     != sizeof(((struct kvec *)NULL)->iov_len));

	*head = err;
	err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
			   (struct vringh_kiov *)wiov,
			   range_check, getrange, GFP_KERNEL, copydesc_user);
	if (err)
		return err;

	return 1;
}