MFC r326276:

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

MFC r308040,308479: nap time between pats is forced to be at most half
of the timeout

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Fix typo.

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Add a new exit-timeout option to watchdogd.

Watchdogd currently disables the watchdog when it exits, such as during
rc.shutdown processing. That leaves the system vulnerable to getting hung
or deadlocked during the shutdown part of a reboot. For embedded systems
it's especially important that the hardware watchdog always be active. It
can also be useful for servers that are administered remotely.

The new -x <seconds> option tells watchdogd to program the watchdog with the
given timeout just before exiting. The -x value can be longer or shorter
than the -t normal time value, to allow for various exceptional conditions
at shutdown such as allowing extra time for buffer flushing.

The exit value is also used internally in the "failsafe" handling (which
used to just disable the watchdog), on the theory that if you're using this
option, "safe" means having the watchdog always running, not disabled.

The default is still to disable the watchdog on exit if -x is not specified.

Differential Revision: https://reviews.freebsd.org/D2556 (timed out)

Add META_MODE support.

Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.

Still need to add real targets under targets/ to build packages.

Differential Revision: D2796
Reviewed by: brooks imp

Convert usr.sbin to LIBADD
Reduce overlinking

Default to use 10 seconds as nap interval instead of 1.

Previously, we have a nap interval of 1 second while we have a timeout of
128 seconds by default, which could be an overkill, and for some hardware
the patting action may be expensive.

Note that the choice of nap interval is still arbitrary. We preferred
a safe value where even when the system is very heavily loaded, the
watchdog should not shoot the system down if it's not really hung.
According to the manual page of Linux's watchdog daemon, the nap interval
time of theirs is 10 seconds, which seems to be a reasonable value --
according to Intel documentation AP-725 (Document Number: 292273-001),
ICH5's maximum timeout is about 37.5 seconds, which the ichwd(4) driver
would set when we requested 128 seconds (although it should probably
feed back this as an error and do not set the timeout). Since that's
the shortest maximum value, 10 seconds seems to be a right choice for
us too.

Discussed with: alfred
MFC after: 1 month

Fix the watchdog/watchdog man pages.

The default timeout is 128 seconds.

MFC after: 1 week

use .Mt to mark up email addresses consistently (part2)

PR: 191174
Submitted by: Franco Fichtner <franco@lastsummer.de>

mdoc: minor paragraph fixes.

Fix bug in r253719: fix command line watchdog disable.

r253719 disallowed watchdog(8) from disabling the watchdog
by breaking the ability to pass 0 as a timeout arg. Fix this.

Apply a casting sledgehammer.

Submitted by: dhw

Fix printf of seconds for systems where time_t is 64 bits.

mdoc and language improvements.

Provide some examples for watchdogd usage.

Fix watchdog pretimeout.

The original API calls for pow2ns, however the new APIs from
Linux call for seconds.

We need to be able to convert to/from 2^Nns to seconds in both
userland and kernel to fix this and properly compare units.

Mark the act_tbl static/const.

This table is only used within this source file and is only accessed
read-only.

MFC after: 1 week

Invert the meaning of -S (added in r247405) and document its meaning. Also,
don't carp about the watchdog command taking too long until after the
watchdog has been patted, and don't carp via warnx(3) unless -S is set
since syslog(3) already logs to standard error otherwise.

Discussed with: alfred
Reviewed by: alfred
Approved by: emaste (co-mentor)

Remove EOL whitespace.

mdoc: begin sentence on new line.

watchdogd(8) and watchdog(4) enhancements.

The following support was added to watchdog(4):
- Support to query the outstanding timeout.
- Support to set a software pre-timeout function watchdog with an 'action'
- Support to set a software only watchdog with a configurable 'action'

'action' can be a mask specifying a single operation or a combination of:
log(9), printf(9), panic(9) and/or kdb_enter(9).

Support the following in watchdogged:
- Support to utilize the new additions to watchdog(4).
- Support to warn if a watchdog script runs for too long.
- Support for "dry run" where we do not actually arm the watchdog,
but only report on our timing.

Sponsored by: iXsystems, Inc.
MFC after: 1 month

Revert accidental regression to previous misspelling.

Approved by: cognet (mentor)

Reduce watchdogd's memory footprint when running daemonized.

This uses the recently-added jemalloc(3) feature of setting the lg_chunk
tuning option to zero to request that memory be allocated in the smallest
chunks possible. Without this option, the default is to initally map 8MB,
and then the mlockall() call wires that entire allocation even though the
program only uses a few Kbytes of it at runtime.

PR: bin/173332
Approved by: cognet (mentor)

Spelling: exitting -> exiting

MFC after: 2 weeks

Replace log(3) with flsll(3) for watchdogd(8) and drop libm dependency.

MFC after: 2 weeks

- It's also need to lock current memory.

Approved by: kib (mentor)
MFC after: 1 week

- Don't allow watchdogd(8) to be swapped out.
On machines with huge amount of swap and high IO activity,
watchdogd(8) may wait for a swap memory longer than timeout and
sometimes fires.

Approved by: kib (mentor)
MFC after: 1 week

Protect the watchdog daemon against swap OOM killer. This is similar to
SVN r199804 which added protection to sshd, cron, syslogd, and inetd.

Staticify local variables.

While I'm there also add a 'static' keyword for a function to make it
consistent with prototype.

Reviewed by: phk
MFC after: 3 months

The last big commit: let usr.sbin/ use WARNS=6 by default.

ANSIfy almost all applications that use WARNS=6.

I was considering committing all these patches one by one, but as
discussed with brooks@, there is no need to do this. If we ever
need/want to merge these changes back, it is still possible to do this
per application.

Don't hide an error if the initial attempt to program a watchdog from
within watchdogd(8) fails. This is also consistent with watchdog(8).

Don't exit from watchdogd on receiving a signal if we cannot stop the watchdog.
That'll require -KILL. This avoids resetting your system on one of the
watchdogs that you cannot disable.

Markup fixes.

Document that the default timeout is 16 seconds

Fix usage().

Submitted by: Adrian Steinmann <ast@marabu.ch>

Report any errors we might see when disabling the watchdog.

Complain about extra arguments so people don't get surprised
if they type "watchdog 0"

Pidfiles should be created with permission preventing users from opening
them for reading. When user can open file for reading, he can also
flock(2) it, which can lead to confusions.

Pointed out by: green

Use pidfile(3) in watchdogd(8).

When disarming a watchdog by using an interval of WD_TO_NEVER a non-zero
return value of the ioctl doesn't indicate that the command has failed
so don't let watchdog(8) return an error in this case.

MFC after: 3 days

Sort sections.

Disable memory locking that could keep watchdogd from deadlocking itself
if the swap subsystem failed.

Requested by: phk

Now that mlockall(2) is unbroken, use it to keep watchdogd(8) permanently
out of swap.

mdoc(7) fixes.

Document -d flag

Assorted markup, grammar, and spelling fixes.

Bump the copyright year since I forgot last time.

Update comments to reflect changes made by phk. Also no longer need
<sys/sysctl.h>.

mdoc(7) janitor:
- Sort SEE ALSO by section number.
- Remove redundant ','.

mdoc(7) janitor:
- Remove EOL whitespace.
- Expand contracted words.
- Correct usage of .Fl macro.
- Use complete argument to -width.
- Remove redundant ','.

Rename the WATCHDOG option to SW_WATCHDOG and make it use the
generic watchdoc(9) interface.

Make watchdogd(8) perform as watchdog(8) as well, and make it
possible to specify a check command to run, timeout and sleep
periods.

Update watchdog(4) to talk about the generic interface and add
new watchdog(8) page.

style.Makefile(5):
Use WARNS?= instead of WARNS=.

o style(9) fixes
- Reordered #includes
- Only include <sys/types.h>, not it and <sys/cdefs.h>
o style.Makefile(5) fixes
- No SRCS= line when only one src file with same name as program
o Use warn()/errx() instead of fprintf()
- Integrated patch from Philippe Charnier <charnier@xp11.frmug.org>

Approved by: jeff (mentor)

Unbreak this for alpha and friends.

Double pointy hat to me, or something.

o Fix typo.

Submitted by: smkelly

- Add a software watchdog facility.

This commit has two pieces. One half is the watchdog kernel code which lives
primarily in hardclock() in sys/kern/kern_clock.c. The other half is a userland
daemon which, when run, will keep the watchdog from firing while the userland
is intact and functioning.

Approved by: jeff (mentor)