ipv4: Add sysctl knob to control early socket demux

[deliverable/linux.git] / net / ipv4 / ip_input.c

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 93b092c9a3944c59eea4b87dfdd0aed8bff2979b..bca25179cdb9354b3eb53819946a0fad7edb66b1 100644 (file)
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -313,6 +313,8 @@ drop:
        return true;
 }
 
+int sysctl_ip_early_demux __read_mostly = 1;
+
 static int ip_rcv_finish(struct sk_buff *skb)
 {
        const struct iphdr *iph = ip_hdr(skb);
@@ -323,16 +325,18 @@ static int ip_rcv_finish(struct sk_buff *skb)
         *      how the packet travels inside Linux networking.
         */
        if (skb_dst(skb) == NULL) {
-               const struct net_protocol *ipprot;
-               int protocol = iph->protocol;
-               int err;
+               int err = -ENOENT;
 
-               rcu_read_lock();
-               ipprot = rcu_dereference(inet_protos[protocol]);
-               err = -ENOENT;
-               if (ipprot && ipprot->early_demux)
-                       err = ipprot->early_demux(skb);
-               rcu_read_unlock();
+               if (sysctl_ip_early_demux) {
+                       const struct net_protocol *ipprot;
+                       int protocol = iph->protocol;
+
+                       rcu_read_lock();
+                       ipprot = rcu_dereference(inet_protos[protocol]);
+                       if (ipprot && ipprot->early_demux)
+                               err = ipprot->early_demux(skb);
+                       rcu_read_unlock();
+               }
 
                if (err) {
                        err = ip_route_input_noref(skb, iph->daddr, iph->saddr,