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

Rename the dtrace-* man pages to dtrace_* for consistency with other
subsection man pages (e.g. geom_*, mac_*, snd_*).

Add manual pages for the io, ip, proc, sched, tcp and udp DTrace providers.
The format of these pages is somewhat experimental, so they may be subject
to further tweaking.

Differential Revision: https://reviews.freebsd.org/D2170
Reviewed by: bcr, rpaulo
MFC after: 2 weeks

SDT(9): add a section on SDT providers, mentioning the "sdt" provider.
Add examples demonstrating how one can list available providers and the
DTrace probes provided by a provider.

Differential Revision: https://reviews.freebsd.org/D2166
Reviewed by: rpaulo
MFC after: 2 weeks

Don't specify a function name in the example SDT(9) probe. As with the
module component, it is a bug that the SDT(9) KPI allows one to specify the
function component of an SDT probe. Currently, the module component is
filled in automatically if left unset; this is not yet true for the function
component, but will be addressed by some ongoing work.

MFC after: 3 days

Remove sys/types.h include as per style (9)

SDT requries sys/param.h due to use of NULL

Reported by: Garrett
Sponsored by: Multiplay

Add dtrace probe support for zfs SET_ERROR(..)

MFC after: 1 week
Sponsored by: Multiplay

use .Mt to mark up email addresses consistently (part6)

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

Update the SDT(9) examples to reflect the removal of the sname parameter
in r258622.

MFC after: 3 days

dtrace sdt: remove the ugly sname parameter of SDT_PROBE_DEFINE

In its stead use the Solaris / illumos approach of emulating '-' (dash)
in probe names with '__' (two consecutive underscores).

Reviewed by: markj
MFC after: 3 weeks

Update the SDT(9) man page with the macros added in 254468. Also change the
existing examples to not pass an mbuf as a probe argument. There's no
obvious reason to have it there, and it doesn't really jibe with the example
added in this revision.

MFC after: 1 week

mdoc: remove superfluous paragraph macros.

Add a man page for the SDT_* macros, which can be used to define new static
DTrace probes and providers in kernel code.

MFC after: 1 week