xfrm: remove output_finish indirection from xfrm_state_afinfo

There are only two implementaions, one for ipv4 and one for ipv6.

Both are almost identical, they clear skb->cb[], set the TRANSFORMED flag
in IP(6)CB and then call the common xfrm_output() function.

By placing the IPCB handling into the common function, we avoid the need
for the output_finish indirection as the output functions can simply
use xfrm_output().

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/net/ipv4/xfrm4_output.c b/net/ipv4/xfrm4_output.c
index 21c8fa0..502eb18 100644
--- a/net/ipv4/xfrm4_output.c
+++ b/net/ipv4/xfrm4_output.c
@@ -14,22 +14,9 @@
 #include <net/xfrm.h>
 #include <net/icmp.h>
 
-int xfrm4_output_finish(struct sock *sk, struct sk_buff *skb)
-{
-	memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
-
-#ifdef CONFIG_NETFILTER
-	IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
-#endif
-
-	return xfrm_output(sk, skb);
-}
-
 static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	struct xfrm_state *x = skb_dst(skb)->xfrm;
-	const struct xfrm_state_afinfo *afinfo;
-	int ret = -EAFNOSUPPORT;
 
 #ifdef CONFIG_NETFILTER
 	if (!x) {
@@ -38,15 +25,7 @@ static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 	}
 #endif
 
-	rcu_read_lock();
-	afinfo = xfrm_state_afinfo_get_rcu(x->outer_mode.family);
-	if (likely(afinfo))
-		ret = afinfo->output_finish(sk, skb);
-	else
-		kfree_skb(skb);
-	rcu_read_unlock();
-
-	return ret;
+	return xfrm_output(sk, skb);
 }
 
 int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)