Request for comments/discussion on listen queue overflow logging

[Matt Joras]

Hello,

Some of you may have noticed a review I posed on Phabricator:
https://reviews.freebsd.org/D11725. The general problem this is trying
to solve is the lack of information about which application's listen
queue has overflowed. As mentioned in the review, there is no good way
to implement this where the message is currently logged, as it is at the
generic socket layer. The approach I take in the review is to construct
an additional more verbose log message (the TCP 4-tuple) at call point
of sonewconn in the syncache code.

I'd appreciate any feedback on the review or suggestions of alternative
approaches. An approach I did think about, but discarded, was to add a
protocol function to struct protosw, something like int
pr_getsockdescr(struct socket *, char *, size_t) which would fill in a
"human-readable" description of the socket based on whatever is appropriate.

Thanks,

Matt Joras