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tcp: increment sk_drops for listeners

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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: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-04-01 08:52:20 -07:00 committed by David S. Miller
parent 532182cd61
commit 9caad86415
5 changed files with 24 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/net/tcp.h
View File

@ -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 */

1
net/core/sock.c
View File

@ -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;

8
net/ipv4/tcp_input.c
View File

@ -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 @@ drop_and_release:
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);

6
net/ipv4/tcp_ipv4.c
View File

@ -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 @@ exit_overflow:
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);

4
net/ipv6/tcp_ipv6.c
View File

@ -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 @@ out_overflow:
out_nonewsk:
dst_release(dst);
out:
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
tcp_listendrop(sk);
return NULL;
}