tcp: do not set queue_mapping on SYNACK

At the time of commit fff326990789 ("tcp: reflect SYN queue_mapping into
SYNACK packets") we had little ways to cope with SYN floods.

We no longer need to reflect incoming skb queue mappings, and instead
can pick a TX queue based on cpu cooking the SYNACK, with normal XPS
affinities.

Note that all SYNACK retransmits were picking TX queue 0, this no longer
is a win given that SYNACK rtx are now distributed on all cpus.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 2 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 9c68cf3762c4..30dd45c1f568 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -821,7 +821,6 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
                               struct flowi *fl,
                               struct request_sock *req,
-                              u16 queue_mapping,
                               struct tcp_fastopen_cookie *foc,
                                   bool attach_req)
 {
@@ -839,7 +838,6 @@ static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
         if (skb) {
                 __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);
 
-                skb_set_queue_mapping(skb, queue_mapping);
                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
                                             ireq->ir_rmt_addr,
                                             ireq->opt);