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tcp: Make SYN ACK RTO tunable by BPF programs with TFO

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Instead of the hardcoded TCP_TIMEOUT_INIT, this diff calls tcp_timeout_init
to initiate req->timeout like the non TFO SYN ACK case.

Tested using the following packetdrill script, on a host with a BPF
program that sets the initial connect timeout to 10ms.

`../../common/defaults.sh`

// Initialize connection
    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_TCP, TCP_FASTOPEN, [1], 4) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 < S 0:0(0) win 32792 <mss 1000,sackOK,FO TFO_COOKIE>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
   +.01 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
   +.02 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
   +.04 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
   +.01 < . 1:1(0) ack 1 win 32792

   +0 accept(3, ..., ...) = 4

Signed-off-by: Jie Meng <jmeng@fb.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jie Meng 2022-08-15 13:29:00 -07:00 committed by David S. Miller
parent cfc111d539
commit 8ea731d4c2
2 changed files with 3 additions and 2 deletions
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3
net/ipv4/tcp_fastopen.c
View File

@ -272,8 +272,9 @@ static struct sock *tcp_fastopen_create_child(struct sock *sk,
* The request socket is not added to the ehash
* because it's been added to the accept queue directly.
*/
req->timeout = tcp_timeout_init(child);
inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
TCP_TIMEOUT_INIT, TCP_RTO_MAX);
req->timeout, TCP_RTO_MAX);
refcount_set(&req->rsk_refcnt, 2);

2
net/ipv4/tcp_timer.c
View File

@ -428,7 +428,7 @@ static void tcp_fastopen_synack_timer(struct sock *sk, struct request_sock *req)
if (!tp->retrans_stamp)
tp->retrans_stamp = tcp_time_stamp(tp);
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
req->timeout << req->num_timeout, TCP_RTO_MAX);
}