Commit e415ed3a authored by Vasily Averin's avatar Vasily Averin Committed by David S. Miller
Browse files

ipv6: use skb_expand_head in ip6_finish_output2 



Unlike skb_realloc_headroom, new helper skb_expand_head does not allocate
a new skb if possible.

Additionally this patch replaces commonly used dereferencing with variables.

Signed-off-by: default avatarVasily Averin <vvs@virtuozzo.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f1260ff1

net/ipv6/ip6_output.c

+16 −35
Original line number Diff line number Diff line
@@ -60,46 +60,29 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * 
{

	struct dst_entry *dst = skb_dst(skb);

	struct net_device *dev = dst->dev;

	struct inet6_dev *idev = ip6_dst_idev(dst);

	unsigned int hh_len = LL_RESERVED_SPACE(dev);

	int delta = hh_len - skb_headroom(skb);

	const struct in6_addr *nexthop;

	const struct in6_addr *daddr, *nexthop;

	struct ipv6hdr *hdr;

	struct neighbour *neigh;

	int ret;



	/* Be paranoid, rather than too clever. */

	if (unlikely(delta > 0) && dev->header_ops) {

		/* pskb_expand_head() might crash, if skb is shared */

		if (skb_shared(skb)) {

			struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);



			if (likely(nskb)) {

				if (skb->sk)

					skb_set_owner_w(nskb, skb->sk);

				consume_skb(skb);

			} else {

				kfree_skb(skb);

			}

			skb = nskb;

		}

		if (skb &&

		    pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {

			kfree_skb(skb);

			skb = NULL;

		}

	if (unlikely(hh_len > skb_headroom(skb)) && dev->header_ops) {

		skb = skb_expand_head(skb, hh_len);

		if (!skb) {

			IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);

			IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);

			return -ENOMEM;

		}

	}



	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {

		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));



	hdr = ipv6_hdr(skb);

	daddr = &hdr->daddr;

	if (ipv6_addr_is_multicast(daddr)) {

		if (!(dev->flags & IFF_LOOPBACK) && sk_mc_loop(sk) &&

		    ((mroute6_is_socket(net, skb) &&

		     !(IP6CB(skb)->flags & IP6SKB_FORWARDED)) ||

		     ipv6_chk_mcast_addr(dev, &ipv6_hdr(skb)->daddr,

					 &ipv6_hdr(skb)->saddr))) {

		     ipv6_chk_mcast_addr(dev, daddr, &hdr->saddr))) {

			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);



			/* Do not check for IFF_ALLMULTI; multicast routing
@@ -110,7 +93,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * 
					net, sk, newskb, NULL, newskb->dev,

					dev_loopback_xmit);



			if (ipv6_hdr(skb)->hop_limit == 0) {

			if (hdr->hop_limit == 0) {

				IP6_INC_STATS(net, idev,

					      IPSTATS_MIB_OUTDISCARDS);

				kfree_skb(skb);
@@ -119,9 +102,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * 
		}



		IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUTMCAST, skb->len);



		if (IPV6_ADDR_MC_SCOPE(&ipv6_hdr(skb)->daddr) <=

		    IPV6_ADDR_SCOPE_NODELOCAL &&

		if (IPV6_ADDR_MC_SCOPE(daddr) <= IPV6_ADDR_SCOPE_NODELOCAL &&

		    !(dev->flags & IFF_LOOPBACK)) {

			kfree_skb(skb);

			return 0;
@@ -136,10 +117,10 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * 
	}



	rcu_read_lock_bh();

	nexthop = rt6_nexthop((struct rt6_info *)dst, &ipv6_hdr(skb)->daddr);

	neigh = __ipv6_neigh_lookup_noref(dst->dev, nexthop);

	nexthop = rt6_nexthop((struct rt6_info *)dst, daddr);

	neigh = __ipv6_neigh_lookup_noref(dev, nexthop);

	if (unlikely(!neigh))

		neigh = __neigh_create(&nd_tbl, nexthop, dst->dev, false);

		neigh = __neigh_create(&nd_tbl, nexthop, dev, false);

	if (!IS_ERR(neigh)) {

		sock_confirm_neigh(skb, neigh);

		ret = neigh_output(neigh, skb, false);
@@ -148,7 +129,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * 
	}

	rcu_read_unlock_bh();



	IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);

	IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTNOROUTES);

	kfree_skb(skb);

	return -EINVAL;

}