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Commit 9caad864 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: increment sk_drops for listeners 



Goal: packets dropped by a listener are accounted for.

This adds tcp_listendrop() helper, and clears sk_drops in sk_clone_lock()
so that children do not inherit their parent drop count.

Note that we no longer increment LINUX_MIB_LISTENDROPS counter when
sending a SYNCOOKIE, since the SYN packet generated a SYNACK.
We already have a separate LINUX_MIB_SYNCOOKIESSENT

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 532182cd

include/net/tcp.h

+13 −0
Original line number Diff line number Diff line
@@ -1836,4 +1836,17 @@ static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 
		tp->data_segs_in += segs_in;

}



/*

 * TCP listen path runs lockless.

 * We forced "struct sock" to be const qualified to make sure

 * we don't modify one of its field by mistake.

 * Here, we increment sk_drops which is an atomic_t, so we can safely

 * make sock writable again.

 */

static inline void tcp_listendrop(const struct sock *sk)

{

	atomic_inc(&((struct sock *)sk)->sk_drops);

	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);

}



#endif	/* _TCP_H */

net/core/sock.c

+1 −0
Original line number Diff line number Diff line
@@ -1525,6 +1525,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) 
		newsk->sk_dst_cache	= NULL;

		newsk->sk_wmem_queued	= 0;

		newsk->sk_forward_alloc = 0;

		atomic_set(&newsk->sk_drops, 0);

		newsk->sk_send_head	= NULL;

		newsk->sk_userlocks	= sk->sk_userlocks & ~SOCK_BINDPORT_LOCK;

net/ipv4/tcp_input.c

+5 −3
Original line number Diff line number Diff line
@@ -6339,8 +6339,10 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, 
			inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);

		af_ops->send_synack(sk, dst, &fl, req,

				    &foc, !want_cookie);

		if (want_cookie)

			goto drop_and_free;

		if (want_cookie) {

			reqsk_free(req);

			return 0;

		}

	}

	reqsk_put(req);

	return 0;
@@ -6350,7 +6352,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, 
drop_and_free:

	reqsk_free(req);

drop:

	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);

	tcp_listendrop(sk);

	return 0;

}

EXPORT_SYMBOL(tcp_conn_request);

net/ipv4/tcp_ipv4.c

+3 −3
Original line number Diff line number Diff line
@@ -329,7 +329,7 @@ void tcp_req_err(struct sock *sk, u32 seq, bool abort) 
		 * errors returned from accept().

		 */

		inet_csk_reqsk_queue_drop(req->rsk_listener, req);

		NET_INC_STATS_BH(net, LINUX_MIB_LISTENDROPS);

		tcp_listendrop(req->rsk_listener);

	}

	reqsk_put(req);

}
@@ -1246,7 +1246,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 
				&tcp_request_sock_ipv4_ops, sk, skb);



drop:

	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);

	tcp_listendrop(sk);

	return 0;

}

EXPORT_SYMBOL(tcp_v4_conn_request);
@@ -1348,7 +1348,7 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 
exit_nonewsk:

	dst_release(dst);

exit:

	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);

	tcp_listendrop(sk);

	return NULL;

put_and_exit:

	inet_csk_prepare_forced_close(newsk);

net/ipv6/tcp_ipv6.c

+2 −2
Original line number Diff line number Diff line
@@ -964,7 +964,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb) 
				&tcp_request_sock_ipv6_ops, sk, skb);



drop:

	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);

	tcp_listendrop(sk);

	return 0; /* don't send reset */

}
@@ -1169,7 +1169,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff * 
out_nonewsk:

	dst_release(dst);

out:

	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);

	tcp_listendrop(sk);

	return NULL;

}