net: skb->dst accessors

Define three accessors to get/set dst attached to a skb

struct dst_entry *skb_dst(const struct sk_buff *skb)

void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)

void skb_dst_drop(struct sk_buff *skb)
This one should replace occurrences of :
dst_release(skb->dst)
skb->dst = NULL;

Delete skb->dst field

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/arp.c

@@ -468,7 +468,7 @@ int arp_find(unsigned char *haddr, struct sk_buff *skb)
 	__be32 paddr;
 	struct neighbour *n;
 
-	if (!skb->dst) {
+	if (!skb_dst(skb)) {
 		printk(KERN_DEBUG "arp_find is called with dst==NULL\n");
 		kfree_skb(skb);
 		return 1;

net/ipv4/icmp.c

@@ -591,13 +591,13 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 				goto relookup_failed;
 
 			/* Ugh! */
-			odst = skb_in->dst;
+			odst = skb_dst(skb_in);
 			err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src,
 					     RT_TOS(tos), rt2->u.dst.dev);
 
 			dst_release(&rt2->u.dst);
 			rt2 = skb_rtable(skb_in);
-			skb_in->dst = odst;
+			skb_dst_set(skb_in, odst);
 		}
 
 		if (err)
@@ -659,7 +659,7 @@ static void icmp_unreach(struct sk_buff *skb)
 	u32 info = 0;
 	struct net *net;
 
-	net = dev_net(skb->dst->dev);
+	net = dev_net(skb_dst(skb)->dev);
 
 	/*
 	 *	Incomplete header ?
@@ -822,7 +822,7 @@ static void icmp_echo(struct sk_buff *skb)
 {
 	struct net *net;
 
-	net = dev_net(skb->dst->dev);
+	net = dev_net(skb_dst(skb)->dev);
 	if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
 		struct icmp_bxm icmp_param;
 
@@ -873,7 +873,7 @@ static void icmp_timestamp(struct sk_buff *skb)
 out:
 	return;
 out_err:
-	ICMP_INC_STATS_BH(dev_net(skb->dst->dev), ICMP_MIB_INERRORS);
+	ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
 	goto out;
 }
 

net/ipv4/igmp.c

@@ -311,7 +311,7 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size)
 		return NULL;
 	}
 
-	skb->dst = &rt->u.dst;
+	skb_dst_set(skb, &rt->u.dst);
 	skb->dev = dev;
 
 	skb_reserve(skb, LL_RESERVED_SPACE(dev));
@@ -659,7 +659,7 @@ static int igmp_send_report(struct in_device *in_dev, struct ip_mc_list *pmc,
 		return -1;
 	}
 
-	skb->dst = &rt->u.dst;
+	skb_dst_set(skb, &rt->u.dst);
 
 	skb_reserve(skb, LL_RESERVED_SPACE(dev));
 

net/ipv4/ip_forward.c

@@ -42,7 +42,7 @@ static int ip_forward_finish(struct sk_buff *skb)
 {
 	struct ip_options * opt	= &(IPCB(skb)->opt);
 
-	IP_INC_STATS_BH(dev_net(skb->dst->dev), IPSTATS_MIB_OUTFORWDATAGRAMS);
+	IP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_OUTFORWDATAGRAMS);
 
 	if (unlikely(opt->optlen))
 		ip_forward_options(skb);
@@ -123,7 +123,7 @@ sr_failed:
 
 too_many_hops:
 	/* Tell the sender its packet died... */
-	IP_INC_STATS_BH(dev_net(skb->dst->dev), IPSTATS_MIB_INHDRERRORS);
+	IP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_INHDRERRORS);
 	icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
 drop:
 	kfree_skb(skb);

net/ipv4/ip_fragment.c

@@ -573,7 +573,7 @@ int ip_defrag(struct sk_buff *skb, u32 user)
 	struct ipq *qp;
 	struct net *net;
 
-	net = skb->dev ? dev_net(skb->dev) : dev_net(skb->dst->dev);
+	net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev);
 	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS);
 
 	/* Start by cleaning up the memory. */

net/ipv4/ip_gre.c

@@ -643,8 +643,7 @@ static int ipgre_rcv(struct sk_buff *skb)
 		stats->rx_packets++;
 		stats->rx_bytes += len;
 		skb->dev = tunnel->dev;
-		dst_release(skb->dst);
-		skb->dst = NULL;
+		skb_dst_drop(skb);
 		nf_reset(skb);
 
 		skb_reset_network_header(skb);
@@ -698,7 +697,7 @@ static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	if ((dst = tiph->daddr) == 0) {
 		/* NBMA tunnel */
 
-		if (skb->dst == NULL) {
+		if (skb_dst(skb) == NULL) {
 			stats->tx_fifo_errors++;
 			goto tx_error;
 		}
@@ -712,7 +711,7 @@ static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 		else if (skb->protocol == htons(ETH_P_IPV6)) {
 			struct in6_addr *addr6;
 			int addr_type;
-			struct neighbour *neigh = skb->dst->neighbour;
+			struct neighbour *neigh = skb_dst(skb)->neighbour;
 
 			if (neigh == NULL)
 				goto tx_error;
@@ -766,10 +765,10 @@ static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (df)
 		mtu = dst_mtu(&rt->u.dst) - dev->hard_header_len - tunnel->hlen;
 	else
-		mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
+		mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
 
-	if (skb->dst)
-		skb->dst->ops->update_pmtu(skb->dst, mtu);
+	if (skb_dst(skb))
+		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 
 	if (skb->protocol == htons(ETH_P_IP)) {
 		df |= (old_iph->frag_off&htons(IP_DF));
@@ -783,14 +782,14 @@ static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 #ifdef CONFIG_IPV6
 	else if (skb->protocol == htons(ETH_P_IPV6)) {
-		struct rt6_info *rt6 = (struct rt6_info *)skb->dst;
+		struct rt6_info *rt6 = (struct rt6_info *)skb_dst(skb);
 
-		if (rt6 && mtu < dst_mtu(skb->dst) && mtu >= IPV6_MIN_MTU) {
+		if (rt6 && mtu < dst_mtu(skb_dst(skb)) && mtu >= IPV6_MIN_MTU) {
 			if ((tunnel->parms.iph.daddr &&
 			     !ipv4_is_multicast(tunnel->parms.iph.daddr)) ||
 			    rt6->rt6i_dst.plen == 128) {
 				rt6->rt6i_flags |= RTF_MODIFIED;
-				skb->dst->metrics[RTAX_MTU-1] = mtu;
+				skb_dst(skb)->metrics[RTAX_MTU-1] = mtu;
 			}
 		}
 
@@ -837,8 +836,8 @@ static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
 			      IPSKB_REROUTED);
-	dst_release(skb->dst);
-	skb->dst = &rt->u.dst;
+	skb_dst_drop(skb);
+	skb_dst_set(skb, &rt->u.dst);
 
 	/*
 	 *	Push down and install the IPIP header.

net/ipv4/ip_input.c

@@ -329,7 +329,7 @@ static int ip_rcv_finish(struct sk_buff *skb)
 	 *	Initialise the virtual path cache for the packet. It describes
 	 *	how the packet travels inside Linux networking.
 	 */
-	if (skb->dst == NULL) {
+	if (skb_dst(skb) == NULL) {
 		int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
 					 skb->dev);
 		if (unlikely(err)) {
@@ -344,9 +344,9 @@ static int ip_rcv_finish(struct sk_buff *skb)
 	}
 
 #ifdef CONFIG_NET_CLS_ROUTE
-	if (unlikely(skb->dst->tclassid)) {
+	if (unlikely(skb_dst(skb)->tclassid)) {
 		struct ip_rt_acct *st = per_cpu_ptr(ip_rt_acct, smp_processor_id());
-		u32 idx = skb->dst->tclassid;
+		u32 idx = skb_dst(skb)->tclassid;
 		st[idx&0xFF].o_packets++;
 		st[idx&0xFF].o_bytes += skb->len;
 		st[(idx>>16)&0xFF].i_packets++;

net/ipv4/ip_options.c

@@ -143,7 +143,7 @@ int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb)
 						__be32 addr;
 
 						memcpy(&addr, sptr+soffset-1, 4);
-						if (inet_addr_type(dev_net(skb->dst->dev), addr) != RTN_LOCAL) {
+						if (inet_addr_type(dev_net(skb_dst(skb)->dev), addr) != RTN_LOCAL) {
 							dopt->ts_needtime = 1;
 							soffset += 8;
 						}
@@ -624,12 +624,12 @@ int ip_options_rcv_srr(struct sk_buff *skb)
 		memcpy(&nexthop, &optptr[srrptr-1], 4);
 
 		rt = skb_rtable(skb);
-		skb->dst = NULL;
+		skb_dst_set(skb, NULL);
 		err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
 		rt2 = skb_rtable(skb);
 		if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
 			ip_rt_put(rt2);
-			skb->dst = &rt->u.dst;
+			skb_dst_set(skb, &rt->u.dst);
 			return -EINVAL;
 		}
 		ip_rt_put(rt);

net/ipv4/ip_output.c

@@ -95,7 +95,7 @@ int __ip_local_out(struct sk_buff *skb)
 
 	iph->tot_len = htons(skb->len);
 	ip_send_check(iph);
-	return nf_hook(PF_INET, NF_INET_LOCAL_OUT, skb, NULL, skb->dst->dev,
+	return nf_hook(PF_INET, NF_INET_LOCAL_OUT, skb, NULL, skb_dst(skb)->dev,
 		       dst_output);
 }
 
@@ -118,7 +118,7 @@ static int ip_dev_loopback_xmit(struct sk_buff *newskb)
 	__skb_pull(newskb, skb_network_offset(newskb));
 	newskb->pkt_type = PACKET_LOOPBACK;
 	newskb->ip_summed = CHECKSUM_UNNECESSARY;
-	WARN_ON(!newskb->dst);
+	WARN_ON(!skb_dst(newskb));
 	netif_rx(newskb);
 	return 0;
 }
@@ -176,7 +176,7 @@ EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 
 static inline int ip_finish_output2(struct sk_buff *skb)
 {
-	struct dst_entry *dst = skb->dst;
+	struct dst_entry *dst = skb_dst(skb);
 	struct rtable *rt = (struct rtable *)dst;
 	struct net_device *dev = dst->dev;
 	unsigned int hh_len = LL_RESERVED_SPACE(dev);
@@ -217,14 +217,14 @@ static inline int ip_skb_dst_mtu(struct sk_buff *skb)
 	struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
 
 	return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
-	       skb->dst->dev->mtu : dst_mtu(skb->dst);
+	       skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
 }
 
 static int ip_finish_output(struct sk_buff *skb)
 {
 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 	/* Policy lookup after SNAT yielded a new policy */
-	if (skb->dst->xfrm != NULL) {
+	if (skb_dst(skb)->xfrm != NULL) {
 		IPCB(skb)->flags |= IPSKB_REROUTED;
 		return dst_output(skb);
 	}
@@ -296,7 +296,7 @@ int ip_mc_output(struct sk_buff *skb)
 
 int ip_output(struct sk_buff *skb)
 {
-	struct net_device *dev = skb->dst->dev;
+	struct net_device *dev = skb_dst(skb)->dev;
 
 	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 
@@ -355,7 +355,7 @@ int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
 		}
 		sk_setup_caps(sk, &rt->u.dst);
 	}
-	skb->dst = dst_clone(&rt->u.dst);
+	skb_dst_set(skb, dst_clone(&rt->u.dst));
 
 packet_routed:
 	if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
@@ -401,8 +401,8 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 	to->pkt_type = from->pkt_type;
 	to->priority = from->priority;
 	to->protocol = from->protocol;
-	dst_release(to->dst);
-	to->dst = dst_clone(from->dst);
+	skb_dst_drop(to);
+	skb_dst_set(to, dst_clone(skb_dst(from)));
 	to->dev = from->dev;
 	to->mark = from->mark;
 
@@ -1294,7 +1294,7 @@ int ip_push_pending_frames(struct sock *sk)
 	 * on dst refcount
 	 */
 	inet->cork.dst = NULL;
-	skb->dst = &rt->u.dst;
+	skb_dst_set(skb, &rt->u.dst);
 
 	if (iph->protocol == IPPROTO_ICMP)
 		icmp_out_count(net, ((struct icmphdr *)

net/ipv4/ipip.c

@@ -370,8 +370,7 @@ static int ipip_rcv(struct sk_buff *skb)
 		tunnel->dev->stats.rx_packets++;
 		tunnel->dev->stats.rx_bytes += skb->len;
 		skb->dev = tunnel->dev;
-		dst_release(skb->dst);
-		skb->dst = NULL;
+		skb_dst_drop(skb);
 		nf_reset(skb);
 		ipip_ecn_decapsulate(iph, skb);
 		netif_rx(skb);
@@ -447,15 +446,15 @@ static int ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (tiph->frag_off)
 		mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
 	else
-		mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
+		mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
 
 	if (mtu < 68) {
 		stats->collisions++;
 		ip_rt_put(rt);
 		goto tx_error;
 	}
-	if (skb->dst)
-		skb->dst->ops->update_pmtu(skb->dst, mtu);
+	if (skb_dst(skb))
+		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
 
 	df |= (old_iph->frag_off&htons(IP_DF));
 
@@ -502,8 +501,8 @@ static int ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
 			      IPSKB_REROUTED);
-	dst_release(skb->dst);
-	skb->dst = &rt->u.dst;
+	skb_dst_drop(skb);
+	skb_dst_set(skb, &rt->u.dst);
 
 	/*
 	 *	Push down and install the IPIP header.

net/ipv4/ipmr.c

@@ -651,7 +651,7 @@ static int ipmr_cache_report(struct net *net,
 	ip_hdr(skb)->protocol = 0;			/* Flag to the kernel this is a route add */
 	msg = (struct igmpmsg *)skb_network_header(skb);
 	msg->im_vif = vifi;
-	skb->dst = dst_clone(pkt->dst);
+	skb_dst_set(skb, dst_clone(skb_dst(pkt)));
 
 	/*
 	 *	Add our header
@@ -1201,7 +1201,7 @@ static void ip_encap(struct sk_buff *skb, __be32 saddr, __be32 daddr)
 	iph->protocol	=	IPPROTO_IPIP;
 	iph->ihl	=	5;
 	iph->tot_len	=	htons(skb->len);
-	ip_select_ident(iph, skb->dst, NULL);
+	ip_select_ident(iph, skb_dst(skb), NULL);
 	ip_send_check(iph);
 
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
@@ -1212,7 +1212,7 @@ static inline int ipmr_forward_finish(struct sk_buff *skb)
 {
 	struct ip_options * opt	= &(IPCB(skb)->opt);
 
-	IP_INC_STATS_BH(dev_net(skb->dst->dev), IPSTATS_MIB_OUTFORWDATAGRAMS);
+	IP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), IPSTATS_MIB_OUTFORWDATAGRAMS);
 
 	if (unlikely(opt->optlen))
 		ip_forward_options(skb);
@@ -1290,8 +1290,8 @@ static void ipmr_queue_xmit(struct sk_buff *skb, struct mfc_cache *c, int vifi)
 	vif->pkt_out++;
 	vif->bytes_out += skb->len;
 
-	dst_release(skb->dst);
-	skb->dst = &rt->u.dst;
+	skb_dst_drop(skb);
+	skb_dst_set(skb, &rt->u.dst);
 	ip_decrease_ttl(ip_hdr(skb));
 
 	/* FIXME: forward and output firewalls used to be called here.
@@ -1543,8 +1543,7 @@ static int __pim_rcv(struct sk_buff *skb, unsigned int pimlen)
 	skb->protocol = htons(ETH_P_IP);
 	skb->ip_summed = 0;
 	skb->pkt_type = PACKET_HOST;
-	dst_release(skb->dst);
-	skb->dst = NULL;
+	skb_dst_drop(skb);
 	reg_dev->stats.rx_bytes += skb->len;
 	reg_dev->stats.rx_packets++;
 	nf_reset(skb);

net/ipv4/netfilter.c

@@ -12,7 +12,7 @@
 /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
 int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
 {
-	struct net *net = dev_net(skb->dst->dev);
+	struct net *net = dev_net(skb_dst(skb)->dev);
 	const struct iphdr *iph = ip_hdr(skb);
 	struct rtable *rt;
 	struct flowi fl = {};
@@ -41,8 +41,8 @@ int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
 			return -1;
 
 		/* Drop old route. */
-		dst_release(skb->dst);
-		skb->dst = &rt->u.dst;
+		skb_dst_drop(skb);
+		skb_dst_set(skb, &rt->u.dst);
 	} else {
 		/* non-local src, find valid iif to satisfy
 		 * rp-filter when calling ip_route_input. */
@@ -50,7 +50,7 @@ int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
 		if (ip_route_output_key(net, &rt, &fl) != 0)
 			return -1;
 
-		odst = skb->dst;
+		odst = skb_dst(skb);
 		if (ip_route_input(skb, iph->daddr, iph->saddr,
 				   RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
 			dst_release(&rt->u.dst);
@@ -60,18 +60,22 @@ int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
 		dst_release(odst);
 	}
 
-	if (skb->dst->error)
+	if (skb_dst(skb)->error)
 		return -1;
 
 #ifdef CONFIG_XFRM
 	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
-	    xfrm_decode_session(skb, &fl, AF_INET) == 0)
-		if (xfrm_lookup(net, &skb->dst, &fl, skb->sk, 0))
+	    xfrm_decode_session(skb, &fl, AF_INET) == 0) {
+		struct dst_entry *dst = skb_dst(skb);
+		skb_dst_set(skb, NULL);
+		if (xfrm_lookup(net, &dst, &fl, skb->sk, 0))
 			return -1;
+		skb_dst_set(skb, dst);
+	}
 #endif
 
 	/* Change in oif may mean change in hh_len. */
-	hh_len = skb->dst->dev->hard_header_len;
+	hh_len = skb_dst(skb)->dev->hard_header_len;
 	if (skb_headroom(skb) < hh_len &&
 	    pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
 		return -1;
@@ -92,7 +96,7 @@ int ip_xfrm_me_harder(struct sk_buff *skb)
 	if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
 		return -1;
 
-	dst = skb->dst;
+	dst = skb_dst(skb);
 	if (dst->xfrm)
 		dst = ((struct xfrm_dst *)dst)->route;
 	dst_hold(dst);
@@ -100,11 +104,11 @@ int ip_xfrm_me_harder(struct sk_buff *skb)
 	if (xfrm_lookup(dev_net(dst->dev), &dst, &fl, skb->sk, 0) < 0)
 		return -1;
 
-	dst_release(skb->dst);
-	skb->dst = dst;
+	skb_dst_drop(skb);
+	skb_dst_set(skb, dst);
 
 	/* Change in oif may mean change in hh_len. */
-	hh_len = skb->dst->dev->hard_header_len;
+	hh_len = skb_dst(skb)->dev->hard_header_len;
 	if (skb_headroom(skb) < hh_len &&
 	    pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
 		return -1;

net/ipv4/netfilter/ipt_REJECT.c

@@ -108,17 +108,16 @@ static void send_reset(struct sk_buff *oldskb, int hook)
 		addr_type = RTN_LOCAL;
 
 	/* ip_route_me_harder expects skb->dst to be set */
-	dst_hold(oldskb->dst);
-	nskb->dst = oldskb->dst;
+	skb_dst_set(nskb, dst_clone(skb_dst(oldskb)));
 
 	if (ip_route_me_harder(nskb, addr_type))
 		goto free_nskb;
 
-	niph->ttl	= dst_metric(nskb->dst, RTAX_HOPLIMIT);
+	niph->ttl	= dst_metric(skb_dst(nskb), RTAX_HOPLIMIT);
 	nskb->ip_summed = CHECKSUM_NONE;
 
 	/* "Never happens" */
-	if (nskb->len > dst_mtu(nskb->dst))
+	if (nskb->len > dst_mtu(skb_dst(nskb)))
 		goto free_nskb;
 
 	nf_ct_attach(nskb, oldskb);

net/ipv4/netfilter/nf_nat_standalone.c

@@ -167,10 +167,9 @@ nf_nat_in(unsigned int hooknum,
 
 	ret = nf_nat_fn(hooknum, skb, in, out, okfn);
 	if (ret != NF_DROP && ret != NF_STOLEN &&
-	    daddr != ip_hdr(skb)->daddr) {
-		dst_release(skb->dst);
-		skb->dst = NULL;
-	}
+	    daddr != ip_hdr(skb)->daddr)
+		skb_dst_drop(skb);
+
 	return ret;
 }
 

net/ipv4/raw.c

@@ -343,7 +343,7 @@ static int raw_send_hdrinc(struct sock *sk, void *from, size_t length,
 
 	skb->priority = sk->sk_priority;
 	skb->mark = sk->sk_mark;
-	skb->dst = dst_clone(&rt->u.dst);
+	skb_dst_set(skb, dst_clone(&rt->u.dst));
 
 	skb_reset_network_header(skb);
 	iph = ip_hdr(skb);

net/ipv4/route.c

@@ -1118,7 +1118,7 @@ restart:
 			if (rp)
 				*rp = rth;
 			else
-				skb->dst = &rth->u.dst;
+				skb_dst_set(skb, &rth->u.dst);
 			return 0;
 		}
 
@@ -1217,7 +1217,7 @@ restart:
 	if (rp)
 		*rp = rt;
 	else
-		skb->dst = &rt->u.dst;
+		skb_dst_set(skb, &rt->u.dst);
 	return 0;
 }
 
@@ -2251,7 +2251,7 @@ int ip_route_input(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 			dst_use(&rth->u.dst, jiffies);
 			RT_CACHE_STAT_INC(in_hit);
 			rcu_read_unlock();
-			skb->dst = &rth->u.dst;
+			skb_dst_set(skb, &rth->u.dst);
 			return 0;
 		}
 		RT_CACHE_STAT_INC(in_hlist_search);
@@ -2934,7 +2934,7 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr* nlh, void
 	if (err)
 		goto errout_free;
 
-	skb->dst = &rt->u.dst;
+	skb_dst_set(skb, &rt->u.dst);
 	if (rtm->rtm_flags & RTM_F_NOTIFY)
 		rt->rt_flags |= RTCF_NOTIFY;
 
@@ -2975,15 +2975,15 @@ int ip_rt_dump(struct sk_buff *skb,  struct netlink_callback *cb)
 				continue;
 			if (rt_is_expired(rt))
 				continue;
-			skb->dst = dst_clone(&rt->u.dst);
+			skb_dst_set(skb, dst_clone(&rt->u.dst));
 			if (rt_fill_info(net, skb, NETLINK_CB(cb->skb).pid,
 					 cb->nlh->nlmsg_seq, RTM_NEWROUTE,
 					 1, NLM_F_MULTI) <= 0) {
-				dst_release(xchg(&skb->dst, NULL));
+				skb_dst_drop(skb);
 				rcu_read_unlock_bh();
 				goto done;
 			}
-			dst_release(xchg(&skb->dst, NULL));
+			skb_dst_drop(skb);
 		}
 		rcu_read_unlock_bh();
 	}

net/ipv4/tcp_ipv4.c

@@ -590,7 +590,7 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
 	arg.csumoffset = offsetof(struct tcphdr, check) / 2;
 	arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
 
-	net = dev_net(skb->dst->dev);
+	net = dev_net(skb_dst(skb)->dev);
 	ip_send_reply(net->ipv4.tcp_sock, skb,
 		      &arg, arg.iov[0].iov_len);
 
@@ -617,7 +617,7 @@ static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
 			];
 	} rep;
 	struct ip_reply_arg arg;
-	struct net *net = dev_net(skb->dst->dev);
+	struct net *net = dev_net(skb_dst(skb)->dev);
 
 	memset(&rep.th, 0, sizeof(struct tcphdr));
 	memset(&arg, 0, sizeof(arg));

net/ipv4/tcp_output.c

@@ -2202,7 +2202,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 	/* Reserve space for headers. */
 	skb_reserve(skb, MAX_TCP_HEADER);
 
-	skb->dst = dst_clone(dst);
+	skb_dst_set(skb, dst_clone(dst));
 
 	mss = dst_metric(dst, RTAX_ADVMSS);
 	if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss)

net/ipv4/udp.c

@@ -328,7 +328,7 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
 	if (unlikely(sk = skb_steal_sock(skb)))
 		return sk;
 	else
-		return __udp4_lib_lookup(dev_net(skb->dst->dev), iph->saddr, sport,
+		return __udp4_lib_lookup(dev_net(skb_dst(skb)->dev), iph->saddr, sport,
 					 iph->daddr, dport, inet_iif(skb),
 					 udptable);
 }
@@ -1237,7 +1237,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 	struct sock *sk;
 	struct udphdr *uh;
 	unsigned short ulen;
-	struct rtable *rt = (struct rtable*)skb->dst;
+	struct rtable *rt = skb_rtable(skb);
 	__be32 saddr, daddr;
 	struct net *net = dev_net(skb->dev);
 

net/ipv4/xfrm4_input.c

@@ -23,7 +23,7 @@ int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
 
 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
 {
-	if (skb->dst == NULL) {
+	if (skb_dst(skb) == NULL) {
 		const struct iphdr *iph = ip_hdr(skb);
 
 		if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,

net/ipv4/xfrm4_mode_tunnel.c

@@ -28,7 +28,7 @@ static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
  */
 static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 {
-	struct dst_entry *dst = skb->dst;
+	struct dst_entry *dst = skb_dst(skb);
 	struct iphdr *top_iph;
 	int flags;
 
@@ -41,7 +41,7 @@ static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 	top_iph->ihl = 5;
 	top_iph->version = 4;
 
-	top_iph->protocol = xfrm_af2proto(skb->dst->ops->family);
+	top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
 
 	/* DS disclosed */
 	top_iph->tos = INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb)->tos,

net/ipv4/xfrm4_output.c

@@ -29,7 +29,7 @@ static int xfrm4_tunnel_check_size(struct sk_buff *skb)
 	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
 		goto out;
 
-	dst = skb->dst;
+	dst = skb_dst(skb);
 	mtu = dst_mtu(dst);
 	if (skb->len > mtu) {
 		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
@@ -72,7 +72,7 @@ EXPORT_SYMBOL(xfrm4_prepare_output);
 static int xfrm4_output_finish(struct sk_buff *skb)
 {
 #ifdef CONFIG_NETFILTER
-	if (!skb->dst->xfrm) {
+	if (!skb_dst(skb)->xfrm) {
 		IPCB(skb)->flags |= IPSKB_REROUTED;
 		return dst_output(skb);
 	}
@@ -87,6 +87,6 @@ static int xfrm4_output_finish(struct sk_buff *skb)
 int xfrm4_output(struct sk_buff *skb)
 {
 	return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb,
-			    NULL, skb->dst->dev, xfrm4_output_finish,
+			    NULL, skb_dst(skb)->dev, xfrm4_output_finish,
 			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 }