net: TCP early demux cleanup (cca32e4b) · Commits · 戴 / test

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>

net/ipv4/ip_input.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -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();
		}

		/*

net/ipv6/ip6_input.c

+0 −2

Original line number	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)) {
		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);

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