From b3d051477cf94e9d71d6acadb8a90de15237b9c1 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 13 Apr 2016 22:05:39 -0700 Subject: 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 Signed-off-by: David S. Miller --- net/ipv6/tcp_ipv6.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/ipv6') diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 0e621bc1ae11..800265c7fd3f 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -439,7 +439,7 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst, struct flowi *fl, struct request_sock *req, struct tcp_fastopen_cookie *foc, - bool attach_req) + enum tcp_synack_type synack_type) { struct inet_request_sock *ireq = inet_rsk(req); struct ipv6_pinfo *np = inet6_sk(sk); @@ -452,7 +452,7 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst, IPPROTO_TCP)) == NULL) goto done; - skb = tcp_make_synack(sk, dst, req, foc, attach_req); + skb = tcp_make_synack(sk, dst, req, foc, synack_type); if (skb) { __tcp_v6_send_check(skb, &ireq->ir_v6_loc_addr, -- cgit v1.2.3