tcp_create_openreq_child() is essentially cloning a listener, then must initialize some fields that can not be inherited.
Listeners are either fresh sockets, or sockets that came through tcp_disconnect() after a session that dirtied many fields. By moving code to tcp_disconnect(), we can shorten time taken to create a clone, since tcp_disconnect() operation is very unlikely. Eric Dumazet (11): tcp: do not set snd_ssthresh in tcp_create_openreq_child() tcp: move icsk_rto init to tcp_disconnect() tcp: do not clear packets_out in tcp_create_openreq_child() tcp: do not clear srtt_us in tcp_create_openreq_child tcp: move mdev_us init to tcp_disconnect() tcp: move snd_cwnd & snd_cwnd_cnt init to tcp_disconnect() tcp: do not clear urg_data in tcp_create_openreq_child tcp: move retrans_out,sacked_out,tlp_high_seq,last_oow_ack_time init to tcp_disconnect() tcp: move app_limited init to tcp_disconnect() tcp: move tp->rack init to tcp_disconnect() tcp: move rx_opt & syn_data_acked init to tcp_disconnect() net/ipv4/tcp.c | 21 ++++++++++++++++++++- net/ipv4/tcp_minisocks.c | 34 ---------------------------------- 2 files changed, 20 insertions(+), 35 deletions(-) -- 2.20.1.321.g9e740568ce-goog