netdev - [PATCH IPV6 v2 3/4] ipv6: ip6_finish

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Message-ID: <b6286d9c-13fc-00ef-8306-c2215c7dd417@virtuozzo.com>
Date:   Fri, 9 Jul 2021 12:05:35 +0300
From:   Vasily Averin <vvs@...tuozzo.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH IPV6 v2 3/4] ipv6: ip6_finish_output2 refactoring

Commonly used dereferences was replaced by variables.

Signed-off-by: Vasily Averin <vvs@...tuozzo.com>
---
 net/ipv6/ip6_output.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 9418802..9ae3baa 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -83,9 +83,11 @@ 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;
 
@@ -94,18 +96,17 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
 		skb = skb_expand_head(skb, delta);
 
 	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
@@ -116,7 +117,7 @@ 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);
@@ -125,9 +126,7 @@ 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;
@@ -142,10 +141,10 @@ 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);
@@ -154,7 +153,7 @@ 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;
 }
-- 
1.8.3.1