tipc: eliminate redundant buffer cloning at transmission

Since all packet transmitters (link, bcast, discovery) are now sending
consumable buffer clones to the bearer layer, we can remove the
redundant buffer cloning that is perfomed in the lower level functions
tipc_l2_send_msg() and tipc_udp_send_msg().
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/bearer.c

@@ -414,10 +414,9 @@ void tipc_disable_l2_media(struct tipc_bearer *b)
  * @b_ptr: the bearer through which the packet is to be sent
  * @dest: peer destination address
  */
-int tipc_l2_send_msg(struct net *net, struct sk_buff *buf,
+int tipc_l2_send_msg(struct net *net, struct sk_buff *skb,
 		     struct tipc_bearer *b, struct tipc_media_addr *dest)
 {
-	struct sk_buff *clone;
 	struct net_device *dev;
 	int delta;
 
@@ -425,23 +424,19 @@ int tipc_l2_send_msg(struct net *net, struct sk_buff *buf,
 	if (!dev)
 		return 0;
 
-	clone = skb_clone(buf, GFP_ATOMIC);
-	if (!clone)
-		return 0;
-
-	delta = dev->hard_header_len - skb_headroom(buf);
+	delta = dev->hard_header_len - skb_headroom(skb);
 	if ((delta > 0) &&
-	    pskb_expand_head(clone, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
-		kfree_skb(clone);
+	    pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
+		kfree_skb(skb);
 		return 0;
 	}
 
-	skb_reset_network_header(clone);
-	clone->dev = dev;
-	clone->protocol = htons(ETH_P_TIPC);
-	dev_hard_header(clone, dev, ETH_P_TIPC, dest->value,
-			dev->dev_addr, clone->len);
-	dev_queue_xmit(clone);
+	skb_reset_network_header(skb);
+	skb->dev = dev;
+	skb->protocol = htons(ETH_P_TIPC);
+	dev_hard_header(skb, dev, ETH_P_TIPC, dest->value,
+			dev->dev_addr, skb->len);
+	dev_queue_xmit(skb);
 	return 0;
 }
 
@@ -491,8 +486,6 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
 	if (likely(b))
 		b->media->send_msg(net, skb, b, dest);
 	rcu_read_unlock();
-	/* Until we remove cloning in tipc_l2_send_msg(): */
-	kfree_skb(skb);
 }
 
 /* tipc_bearer_xmit() -send buffer to destination over bearer
@@ -514,8 +507,6 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id,
 		skb_queue_walk_safe(xmitq, skb, tmp) {
 			__skb_dequeue(xmitq);
 			b->media->send_msg(net, skb, b, dst);
-			/* Until we remove cloning in tipc_l2_send_msg(): */
-			kfree_skb(skb);
 		}
 	}
 	rcu_read_unlock();
@@ -541,8 +532,6 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id,
 			msg_set_mc_netid(hdr, net_id);
 			__skb_dequeue(xmitq);
 			b->media->send_msg(net, skb, b, &b->bcast_addr);
-			/* Until we remove cloning in tipc_l2_send_msg(): */
-			kfree_skb(skb);
 		}
 	}
 	rcu_read_unlock();

net/tipc/udp_media.c

@@ -155,14 +155,12 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 	struct udp_bearer *ub;
 	struct udp_media_addr *dst = (struct udp_media_addr *)&dest->value;
 	struct udp_media_addr *src = (struct udp_media_addr *)&b->addr.value;
-	struct sk_buff *clone;
 	struct rtable *rt;
 
 	if (skb_headroom(skb) < UDP_MIN_HEADROOM)
 		pskb_expand_head(skb, UDP_MIN_HEADROOM, 0, GFP_ATOMIC);
 
-	clone = skb_clone(skb, GFP_ATOMIC);
-	skb_set_inner_protocol(clone, htons(ETH_P_TIPC));
+	skb_set_inner_protocol(skb, htons(ETH_P_TIPC));
 	ub = rcu_dereference_rtnl(b->media_ptr);
 	if (!ub) {
 		err = -ENODEV;
@@ -172,7 +170,7 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 		struct flowi4 fl = {
 			.daddr = dst->ipv4.s_addr,
 			.saddr = src->ipv4.s_addr,
-			.flowi4_mark = clone->mark,
+			.flowi4_mark = skb->mark,
 			.flowi4_proto = IPPROTO_UDP
 		};
 		rt = ip_route_output_key(net, &fl);
@@ -181,7 +179,7 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 			goto tx_error;
 		}
 		ttl = ip4_dst_hoplimit(&rt->dst);
-		err = udp_tunnel_xmit_skb(rt, ub->ubsock->sk, clone,
+		err = udp_tunnel_xmit_skb(rt, ub->ubsock->sk, skb,
 					  src->ipv4.s_addr,
 					  dst->ipv4.s_addr, 0, ttl, 0,
 					  src->udp_port, dst->udp_port,
@@ -204,7 +202,7 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 		if (err)
 			goto tx_error;
 		ttl = ip6_dst_hoplimit(ndst);
-		err = udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, clone,
+		err = udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, skb,
 					   ndst->dev, &src->ipv6,
 					   &dst->ipv6, 0, ttl, src->udp_port,
 					   dst->udp_port, false);
@@ -213,7 +211,7 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 	return err;
 
 tx_error:
-	kfree_skb(clone);
+	kfree_skb(skb);
 	return err;
 }