Hung sessions

[rrs]

Summary

Michael Tuexen as came up with a test case where rack ends with a stuck session. It rotates
around the TCP-FO. The problem is a return(0) and not a walk through the normal just-return
path.. special for SYN-Sent/SYN-Rcvd and FO.

This change fixes that. The attached program is a reproducer that Michael sent me. With the
fix the session now is no longer stuck.

Test Plan

michaels_stuck_tcp.c870 BDownload

[tuexen]

Except for the whitespace issue, I'm fine with it.

FreeBSD/sys/netinet/tcp_stacks/rack.c

12122 ↗

(On Diff #71719)

Are the trailing whitespaces intended?

[rrs]

Looks like BBR has the same issue, and we need to strip trailing emacs presents too :)

[rrs]

Opps used the wrong goto label...

[rrs]

Let's also fix the accounting panic that skyzaller is finding here too. When we are in a front
state and have a SYN outstanding that should count in the ctf_outstanding size. Also if
we have sent a FIN same thing.

[rrs]

And even yet another issue thanks to skyzaller in bbr.. the rc_lost when doing TCP-FO was incorrect in rxt timers.

[rrs]

One little other niggle that I noticed, we should not do a goto again if the SYN bit is set ...

[rrs]

We should not ever do GP measurements until we are established

[tuexen]

This change is committed in r361080.