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 <eduma...@google.com>
---
include/net/tcp.h | 13 +++++++++++++
net/core/sock.c | 1 +
net/ipv4/tcp_input.c | 8 +++++---
net/ipv4/tcp_ipv4.c | 6 +++---
net/ipv6/tcp_ipv6.c | 4 ++--
5 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index b91370f61be6..0da2e6fcc7aa 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1846,4 +1846,17 @@ 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 */
diff --git a/net/core/sock.c b/net/core/sock.c
index 238a94f879ca..62918344ff2b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1524,6 +1524,7 @@ 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;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d994d358ccbe..f2445cabf734 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6350,8 +6350,10 @@ 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;
@@ -6361,7 +6363,7 @@ 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);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 059a98f5e7e1..f3ce0afe70aa 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -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);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 5fa8fea394c9..7cde1b6fdda3 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -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;
}
--
2.8.0.rc3.226.g39d4020
