Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r246361 ... bump .Dd for content change.

MFC r246121 ...

Fix a descriptor leak in devd. Clients reading /var/run/devd.pipe can close
their socket connection any time, and devd only notices that when it gets an
error trying to write an event to the client. On a system with no device
change activity, clients could connect and disappear repeatedly without devd
noticing, leading to an ever-growing list of open socket descriptors in devd.

Now devd uses poll(2) looking for POLLHUP on all existing clients every time
a new client connection is established, and also periodically (once a minute)
to proactively find zombie clients and reap the socket descriptors. It also
now has a connection limit, configurable with a new -l <num> command line arg.
When the maximum number of connections is reached it stops accepting new
connections until some current clients drop off.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Add -f option to program's usage(), fix manpage's SYNOPSIS.

Rev 1.15 should have incremented the date on this manual page.

Add a -f configfile option to devd(8), based on a patch submitted by
Wojciech A. Koszek.

Submitted by: Wojciech A. Koszek <dunstan@freebsd.czest.pl>

Scheduled mdoc(7) sweep.

Clarify that devd will only parse files whose names end in .conf.
Prompted by

PR: docs/73668
Submitted by: Dan Pelleg
MFC After: 3 days

mdoc(7) fixes.

Create a unix domain socket and write to it all the events that come
in over the socket.

fix typo: s/Instaed/Instead/

mdoc(7) fixes: Expand contraction.

Implement a two new flags, and change the meaning of another one.
'd': now means don't do daemon().
'D': Debug
'n': Don't wait to process all pending events before calling daemon.

In the past, devd would call daemon immediately. However, this causes
a race. If anything in the boot process depends on configuring the
devices configured by devd, maybe they would be configured in time,
maybe not. Now we don't call daemon until all pending events are
processed, unless -n is specified.

# -n is actually the default for a while due to the select(2) bug in devctl
# that I just fixed to give people a chance to upgrade.

mdoc(7) police: Revision.

devd bugs section is now OBE

english(4) police.

Add BUGS section and note departure of actual implementation from what
is documented so the pioneers will know why it works the way it does.

Try to reword things a bit more to make it clearer.

Reviewed by: imp

- Fix some minor grammar and spelling nits.
- Massage the wording in a few places.
- Put .Nm on lines by itself so it renders correctly.

Reviewed by: imp

devd. A daemon that hooks into the kernel's /dev/devctl to produce
arbitrary commands when devices come and go in the device tree (which is
different than the /dev directory).

This is an initial version. Much of the planned power isn't here.
Instead of doing the full matching, we always run /etc/devd-generic.
/etc/devd.generic will go away at some point, I think.

I'm committing it in this early state so I can start getting feedback
from early adapters.

Approved by: re