tipc: tipc_udp_recv() cleanup vs rcu verbs (4109a2c3) · Commits · 戴 / test

First thing tipc_udp_recv() does is to use rcu_dereference_sk_user_data(), and this is really hinting we already own rcu_read_lock() from the caller (UDP stack). No need to add another rcu_read_lock()/rcu_read_unlock() pair. Also use rcu_dereference() instead of rcu_dereference_rtnl() in the data path. Signed-off-by:

Eric Dumazet <edumazet@google.com> Cc: Jon Maloy <jon.maloy@ericsson.com> Cc: Ying Xue <ying.xue@windriver.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/tipc/udp_media.c

+3 −6

Original line number	Diff line number	Diff line
		@@ -354,10 +354,9 @@ static int tipc_udp_recv(struct sock sk, struct sk_buff skb)
		skb_pull(skb, sizeof(struct udphdr));
		hdr = buf_msg(skb);

		rcu_read_lock();
		b = rcu_dereference_rtnl(ub->bearer);
		b = rcu_dereference(ub->bearer);
		if (!b)
		goto rcu_out;
		goto out;

		if (b && test_bit(0, &b->up)) {
		tipc_rcv(sock_net(sk), skb, b);
		@@ -368,11 +367,9 @@ static int tipc_udp_recv(struct sock sk, struct sk_buff skb)
		if (unlikely(msg_user(hdr) == LINK_CONFIG)) {
		err = tipc_udp_rcast_disc(b, skb);
		if (err)
		goto rcu_out;
		goto out;
		}

		rcu_out:
		rcu_read_unlock();
		out:
		kfree_skb(skb);
		return 0;

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