net: ipv4: listify ip_rcv_finish

ip_rcv_finish_core(), if it does not drop, sets skb->dst by either early
 demux or route lookup.  The last step, calling dst_input(skb), is left to
 the caller; in the listified case, we split to form sublists with a common
 dst, but then ip_sublist_rcv_finish() just calls dst_input(skb) in a loop.
The next step in listification would thus be to add a list_input() method
 to struct dst_entry.

Early demux is an indirect call based on iph->protocol; this is another
 opportunity for listification which is not taken here (it would require
 slicing up ip_rcv_finish_core() to allow splitting on protocol changes).

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 9142408..24b9b02 100644 (file)
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -307,7 +307,8 @@ drop:
        return true;
 }
 
-static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
+static int ip_rcv_finish_core(struct net *net, struct sock *sk,
+                             struct sk_buff *skb)
 {
        const struct iphdr *iph = ip_hdr(skb);
        int (*edemux)(struct sk_buff *skb);
@@ -393,7 +394,7 @@ static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
                        goto drop;
        }
 
-       return dst_input(skb);
+       return NET_RX_SUCCESS;
 
 drop:
        kfree_skb(skb);
@@ -405,6 +406,15 @@ drop_error:
        goto drop;
 }
 
+static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+       int ret = ip_rcv_finish_core(net, sk, skb);
+
+       if (ret != NET_RX_DROP)
+               ret = dst_input(skb);
+       return ret;
+}
+
 /*
  *     Main IP Receive routine.
  */
@@ -515,15 +525,47 @@ int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
                       ip_rcv_finish);
 }
 
-static void ip_sublist_rcv(struct list_head *head, struct net_device *dev,
-                          struct net *net)
+static void ip_sublist_rcv_finish(struct list_head *head)
 {
        struct sk_buff *skb, *next;
 
+       list_for_each_entry_safe(skb, next, head, list)
+               dst_input(skb);
+}
+
+static void ip_list_rcv_finish(struct net *net, struct sock *sk,
+                              struct list_head *head)
+{
+       struct dst_entry *curr_dst = NULL;
+       struct sk_buff *skb, *next;
+       struct list_head sublist;
+
+       list_for_each_entry_safe(skb, next, head, list) {
+               struct dst_entry *dst;
+
+               if (ip_rcv_finish_core(net, sk, skb) == NET_RX_DROP)
+                       continue;
+
+               dst = skb_dst(skb);
+               if (curr_dst != dst) {
+                       /* dispatch old sublist */
+                       list_cut_before(&sublist, head, &skb->list);
+                       if (!list_empty(&sublist))
+                               ip_sublist_rcv_finish(&sublist);
+                       /* start new sublist */
+                       curr_dst = dst;
+               }
+       }
+       /* dispatch final sublist */
+       ip_sublist_rcv_finish(head);
+}
+
+static void ip_sublist_rcv(struct list_head *head, struct net_device *dev,
+                          struct net *net)
+{
        NF_HOOK_LIST(NFPROTO_IPV4, NF_INET_PRE_ROUTING, net, NULL,
                     head, dev, NULL, ip_rcv_finish);
-       list_for_each_entry_safe(skb, next, head, list)
-               ip_rcv_finish(net, NULL, skb);
+       ip_list_rcv_finish(net, NULL, head);
 }
 
 /* Receive a list of IP packets */