net: ipv4: ipmr: Split ipmr_queue_xmit() in two

Some of the work of ipmr_queue_xmit() is specific to IPMR forwarding, and
should not take place on the output path. In order to allow reuse of the
common parts, split the function into two: the ipmr_prepare_xmit() helper
that takes care of the common bits, and the ipmr_queue_fwd_xmit(), which
invokes the former and encapsulates the whole forwarding algorithm.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/4e8db165572a4f8bd29a723a801e854e9d20df4d.1750113335.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 29 insertions, 16 deletions

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index d2ac630bea3a..74d45fd5d11e 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1853,8 +1853,8 @@ static bool ipmr_forward_offloaded(struct sk_buff *skb, struct mr_table *mrt,
 
 /* Processing handlers for ipmr_forward, under rcu_read_lock() */
 
-static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
-			    int in_vifi, struct sk_buff *skb, int vifi)
+static int ipmr_prepare_xmit(struct net *net, struct mr_table *mrt,
+			     struct sk_buff *skb, int vifi)
 {
 	const struct iphdr *iph = ip_hdr(skb);
 	struct vif_device *vif = &mrt->vif_table[vifi];
@@ -1865,7 +1865,7 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
 
 	vif_dev = vif_dev_read(vif);
 	if (!vif_dev)
-		goto out_free;
+		return -1;
 
 	if (vif->flags & VIFF_REGISTER) {
 		WRITE_ONCE(vif->pkt_out, vif->pkt_out + 1);
@@ -1873,12 +1873,9 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
 		DEV_STATS_ADD(vif_dev, tx_bytes, skb->len);
 		DEV_STATS_INC(vif_dev, tx_packets);
 		ipmr_cache_report(mrt, skb, vifi, IGMPMSG_WHOLEPKT);
-		goto out_free;
+		return -1;
 	}
 
-	if (ipmr_forward_offloaded(skb, mrt, in_vifi, vifi))
-		goto out_free;
-
 	if (vif->flags & VIFF_TUNNEL) {
 		rt = ip_route_output_ports(net, &fl4, NULL,
 					   vif->remote, vif->local,
@@ -1886,7 +1883,7 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
 					   IPPROTO_IPIP,
 					   iph->tos & INET_DSCP_MASK, vif->link);
 		if (IS_ERR(rt))
-			goto out_free;
+			return -1;
 		encap = sizeof(struct iphdr);
 	} else {
 		rt = ip_route_output_ports(net, &fl4, NULL, iph->daddr, 0,
@@ -1894,7 +1891,7 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
 					   IPPROTO_IPIP,
 					   iph->tos & INET_DSCP_MASK, vif->link);
 		if (IS_ERR(rt))
-			goto out_free;
+			return -1;
 	}
 
 	if (skb->len+encap > dst_mtu(&rt->dst) && (ntohs(iph->frag_off) & IP_DF)) {
@@ -1904,14 +1901,14 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
 		 */
 		IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 		ip_rt_put(rt);
-		goto out_free;
+		return -1;
 	}
 
 	encap += LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len;
 
 	if (skb_cow(skb, encap)) {
 		ip_rt_put(rt);
-		goto out_free;
+		return -1;
 	}
 
 	WRITE_ONCE(vif->pkt_out, vif->pkt_out + 1);
@@ -1931,6 +1928,22 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt,
 		DEV_STATS_ADD(vif_dev, tx_bytes, skb->len);
 	}
 
+	return 0;
+}
+
+static void ipmr_queue_fwd_xmit(struct net *net, struct mr_table *mrt,
+				int in_vifi, struct sk_buff *skb, int vifi)
+{
+	struct rtable *rt;
+
+	if (ipmr_forward_offloaded(skb, mrt, in_vifi, vifi))
+		goto out_free;
+
+	if (ipmr_prepare_xmit(net, mrt, skb, vifi))
+		goto out_free;
+
+	rt = skb_rtable(skb);
+
 	IPCB(skb)->flags |= IPSKB_FORWARDED;
 
 	/* RFC1584 teaches, that DVMRP/PIM router must deliver packets locally
@@ -2062,8 +2075,8 @@ forward:
 				struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 
 				if (skb2)
-					ipmr_queue_xmit(net, mrt, true_vifi,
-							skb2, psend);
+					ipmr_queue_fwd_xmit(net, mrt, true_vifi,
+							    skb2, psend);
 			}
 			psend = ct;
 		}
@@ -2074,10 +2087,10 @@ last_forward:
 			struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 
 			if (skb2)
-				ipmr_queue_xmit(net, mrt, true_vifi, skb2,
-						psend);
+				ipmr_queue_fwd_xmit(net, mrt, true_vifi, skb2,
+						    psend);
 		} else {
-			ipmr_queue_xmit(net, mrt, true_vifi, skb, psend);
+			ipmr_queue_fwd_xmit(net, mrt, true_vifi, skb, psend);
 			return;
 		}
 	}