{pktgen, xfrm} Add statistics counting when transforming

so /proc/net/xfrm_stat could give user clue about what's
wrong in this process.
Signed-off-by: NFan Du <fan.du@windriver.com>
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>

net/core/pktgen.c

@@ -2479,6 +2479,7 @@ static int pktgen_output_ipsec(struct sk_buff *skb, struct pktgen_dev *pkt_dev)
 {
 	struct xfrm_state *x = pkt_dev->flows[pkt_dev->curfl].x;
 	int err = 0;
+	struct net *net = dev_net(pkt_dev->odev);
 
 	if (!x)
 		return 0;
@@ -2488,12 +2489,15 @@ static int pktgen_output_ipsec(struct sk_buff *skb, struct pktgen_dev *pkt_dev)
 		return 0;
 
 	err = x->outer_mode->output(x, skb);
-	if (err)
+	if (err) {
+		XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
 		goto error;
+	}
 	err = x->type->output(x, skb);
-	if (err)
+	if (err) {
+		XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
 		goto error;
-
+	}
 	spin_lock_bh(&x->lock);
 	x->curlft.bytes += skb->len;
 	x->curlft.packets++;