xen/netback: don't leak pages on failure in xen_netbk_tx_check_gop.

Signed-off-by: Matthew Daley <mattjd@gmail.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static int netbk_set_skb_gso(struct xenvif *vif,
			     struct sk_buff *skb,
			     struct xen_netif_extra_info *gso)
{
	if (!gso->u.gso.size) {
		netdev_err(vif->dev, "GSO size must not be zero.\n");
		netbk_fatal_tx_err(vif);
		return -EINVAL;
	}

	/* Currently only TCPv4 S.O. is supported. */
	if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
		netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
		netbk_fatal_tx_err(vif);
		return -EINVAL;
	}

	skb_shinfo(skb)->gso_size = gso->u.gso.size;
	skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;

	/* Header must be checked, and gso_segs computed. */
	skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
	skb_shinfo(skb)->gso_segs = 0;

	return 0;
}

static int netbk_set_skb_gso(struct xenvif *vif,
			     struct sk_buff *skb,
			     struct xen_netif_extra_info *gso)
{
	if (!gso->u.gso.size) {
		netdev_err(vif->dev, "GSO size must not be zero.\n");
		netbk_fatal_tx_err(vif);
		return -EINVAL;
	}

	/* Currently only TCPv4 S.O. is supported. */
	if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
		netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
		netbk_fatal_tx_err(vif);
		return -EINVAL;
	}

	skb_shinfo(skb)->gso_size = gso->u.gso.size;
	skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;

	/* Header must be checked, and gso_segs computed. */
	skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
	skb_shinfo(skb)->gso_segs = 0;

	return 0;
}
