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Commit cca32e4b authored Jul 29, 2012 by Eric Dumazet Committed by David S. Miller Jul 30, 2012

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>

parent 8bbb1813

net/ipv4/ip_input.c

+0 −2

Original line number	Original line	Diff line number	Diff line
	@@ -325,14 +325,12 @@ static int ip_rcv_finish(struct sk_buff *skb)
	const struct net_protocol *ipprot;		const struct net_protocol *ipprot;
	int protocol = iph->protocol;		int protocol = iph->protocol;

	rcu_read_lock();
	ipprot = rcu_dereference(inet_protos[protocol]);		ipprot = rcu_dereference(inet_protos[protocol]);
	if (ipprot && ipprot->early_demux) {		if (ipprot && ipprot->early_demux) {
	ipprot->early_demux(skb);		ipprot->early_demux(skb);
	/* must reload iph, skb->head might have changed */		/* must reload iph, skb->head might have changed */
	iph = ip_hdr(skb);		iph = ip_hdr(skb);
	}		}
	rcu_read_unlock();
	}		}

	/*		/*

net/ipv6/ip6_input.c

+0 −2

Original line number	Original line	Diff line number	Diff line
	@@ -52,11 +52,9 @@ int ip6_rcv_finish(struct sk_buff *skb)
	if (sysctl_ip_early_demux && !skb_dst(skb)) {		if (sysctl_ip_early_demux && !skb_dst(skb)) {
	const struct inet6_protocol *ipprot;		const struct inet6_protocol *ipprot;

	rcu_read_lock();
	ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);		ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
	if (ipprot && ipprot->early_demux)		if (ipprot && ipprot->early_demux)
	ipprot->early_demux(skb);		ipprot->early_demux(skb);
	rcu_read_unlock();
	}		}
	if (!skb_dst(skb))		if (!skb_dst(skb))
	ip6_route_input(skb);		ip6_route_input(skb);