diff options
| author | Eric Dumazet <edumazet@google.com> | 2016-04-13 22:05:39 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-04-15 16:45:44 -0400 |
| commit | b3d051477cf94e9d71d6acadb8a90de15237b9c1 (patch) | |
| tree | 59009bc698f472b31b15059972e6904cd9272d32 /net/ipv4/tcp_input.c | |
| parent | ac18dd9e842294377dbaf1e8d169493567a81fa1 (diff) | |
| download | linux-b3d051477cf94e9d71d6acadb8a90de15237b9c1.tar.bz2 | |
tcp: do not mess with listener sk_wmem_alloc
When removing sk_refcnt manipulation on synflood, I missed that
using skb_set_owner_w() was racy, if sk->sk_wmem_alloc had already
transitioned to 0.
We should hold sk_refcnt instead, but this is a big deal under attack.
(Doing so increase performance from 3.2 Mpps to 3.8 Mpps only)
In this patch, I chose to not attach a socket to syncookies skb.
Performance is now 5 Mpps instead of 3.2 Mpps.
Following patch will remove last known false sharing in
tcp_rcv_state_process()
Fixes: 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 983f04c11177..7ea7034af83f 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6327,7 +6327,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, } if (fastopen_sk) { af_ops->send_synack(fastopen_sk, dst, &fl, req, - &foc, false); + &foc, TCP_SYNACK_FASTOPEN); /* Add the child socket directly into the accept queue */ inet_csk_reqsk_queue_add(sk, req, fastopen_sk); sk->sk_data_ready(sk); @@ -6337,8 +6337,9 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, tcp_rsk(req)->tfo_listener = false; if (!want_cookie) inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT); - af_ops->send_synack(sk, dst, &fl, req, - &foc, !want_cookie); + af_ops->send_synack(sk, dst, &fl, req, &foc, + !want_cookie ? TCP_SYNACK_NORMAL : + TCP_SYNACK_COOKIE); if (want_cookie) { reqsk_free(req); return 0; |