From: Eric Dumazet <edumazet@google.com>
Date: Sun, 29 Jul 2012 21:06:13 +0000 (+0000)
Subject: net: TCP early demux cleanup
X-Git-Tag: v3.6-rc1~30^2~7
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=cca32e4bf999a34ac08d959f351f2b30bcd02460;p=platform%2Fkernel%2Flinux-3.10.git

net: TCP early demux cleanup

early_demux() handlers should be called in RCU context, and as we
use skb_dst_set_noref(skb, dst), caller must not exit from RCU context
before dst use (skb_dst(skb)) or release (skb_drop(dst))

Therefore, rcu_read_lock()/rcu_read_unlock() pairs around
->early_demux() are confusing and not needed :

Protocol handlers are already in an RCU read lock section.
(__netif_receive_skb() does the rcu_read_lock() )

Signed-off-by: Eric Dumazet <edumazet@google.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 981ff1e..f1395a6 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -325,14 +325,12 @@ static int ip_rcv_finish(struct sk_buff *skb)
 		const struct net_protocol *ipprot;
 		int protocol = iph->protocol;
 
-		rcu_read_lock();
 		ipprot = rcu_dereference(inet_protos[protocol]);
 		if (ipprot && ipprot->early_demux) {
 			ipprot->early_demux(skb);
 			/* must reload iph, skb->head might have changed */
 			iph = ip_hdr(skb);
 		}
-		rcu_read_unlock();
 	}
 
 	/*
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 47975e3..a52d864 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -52,11 +52,9 @@ int ip6_rcv_finish(struct sk_buff *skb)
 	if (sysctl_ip_early_demux && !skb_dst(skb)) {
 		const struct inet6_protocol *ipprot;
 
-		rcu_read_lock();
 		ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
 		if (ipprot && ipprot->early_demux)
 			ipprot->early_demux(skb);
-		rcu_read_unlock();
 	}
 	if (!skb_dst(skb))
 		ip6_route_input(skb);