MFC r304910, r304912, r304915, r304952, r325019, r328164, r331094, r332664,
r335341-r335345, r335347, r335379-r335380, r335382

r304910:
Introduce cnv man page.

r304912:
Add missed header file for cnv.h .

r304915:
Bump date in the man page.

r304952:
Remove duplicated declaration.

r325019:
Introduce cnvlist_name() and cnvlist_type() functions.

Those function can be used when we are iterating over nvlist to reduce
amount of extra variables we need to declare.

r328164:
libnv: Use mallocarray(9) for the nv_calloc.

r331094:
Fix formatting errors that resulted in apropos(1) output looking weird.

r332664:
Add missing argument in the cnv man page.

r335341:
libnv: change name of cookie from cookiep to cookie.

The name was inconsistent with rest of the library.
No functional change intended.

r335342:
libnv: add const to cookies arguments

r335343:
libnv: Remove nvlist argument from cnvlist_{take,free}_* functions.

All information which are need for those operations is already stored in
the cookie.

We decided not to bump libnv version because this API is not used yet in the
base system.

r335344:
libnv: clean parent in nvlist_array when removing it.

When we are removing element form the nvlist we should also clean parent,
because the array is not a part of the nvlist anymore.

r335345:
libnv: add regression test for r335344.

r335347:
libnv: Add nvlist_append_*_array() family of functions.

The nvlist_append_{bool,number,string,nvlist,descriptor}_array() functions
allows to dynamically extend array stored in the nvlist.

r335379:
Set prev to NULL so its garaunteed to have a value of some kind and
gcc doesn't explode. Feel free to fix this correctly or whatever for
gcc builds.

This *should* quiesce tinderbox after r335347 for the gcc builds.

r335380:
style(9) fix, I was also going to silence gcc.

r335382:
Really fix the style.

MFC r326060:
Clean up the SYSINIT_FLAGS definitions for rwlock(9) and rmlock(9).

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

Reword descriptions of asserting locks held without WITNESS.

This corrects an error in r296947 in that it is not possible to assert
which thread holds a shared (or read) lock, but it is possible to assert
that one is held. Just not very useful.

MFC after: 1 week
Submitted by: wblock, jhb
Reviewed by: kib (earlier version), jhb, wblock
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D5659

Add _NEW flag to mtx(9), sx(9), rmlock(9) and rwlock(9).
A _NEW flag passed to _init_flags() to avoid check for double-init.

Differential Revision: https://reviews.freebsd.org/D1208
Reviewed by: jhb, wblock
MFC after: 1 Month

Document RA_RECURSED and RA_NOTRECURSED.

MFC after: 3 days

Use the defined terms "readers" and "writers" to simplify some text.

Constify arguments for locking KPIs where possible.

This enables locking consumers to pass their own structures around as const and
be able to assert locks embedded into those structures.

Reviewed by: ed, kib, jhb

Add manpages for rw_try_rlock() and rw_try_wlock() functions.

Implement soon-to-be-used rw_unlock() macro.

Add missing .El.

Clean up after previous revision.

Update rwlock(9) manpage adding missing bits about the rw_init_flags()
function, its options and explaining that recursion for writers can be
selectively enabled.

Reported by: rwatson, Skip Ford <skip at menantico dot com>

Add some cross references to locking.9 from related pages.

Allow threads to atomically release rw and sx locks while waiting for an
event. Locking primitives that support this (mtx, rw, and sx) now each
include their own foo_sleep() routine.
- Rename msleep() to _sleep() and change it's 'struct mtx' object to a
'struct lock_object' pointer. _sleep() uses the recently added
lc_unlock() and lc_lock() function pointers for the lock class of the
specified lock to release the lock while the thread is suspended.
- Add wrappers around _sleep() for mutexes (mtx_sleep()), rw locks
(rw_sleep()), and sx locks (sx_sleep()). msleep() still exists and
is now identical to mtx_sleep(), but it is deprecated.
- Rename SLEEPQ_MSLEEP to SLEEPQ_SLEEP.
- Rewrite much of sleep.9 to not be msleep(9) centric.
- Flesh out the 'RETURN VALUES' section in sleep.9 and add an 'ERRORS'
section.
- Add __nonnull(1) to _sleep() and msleep_spin() so that the compiler will
warn if you try to pass a NULL wait channel. The functions already have
a KASSERT to that effect.

Place mtx_destroy() and rw_destroy() right after mtx_init() and rw_init()
to match sx(9) and condvar(9).

- Sort rwlock functions similar to the order in mutex(9).
- Add a missing MLINK.

Update rwlock(9) for rw_wowned().

Revise markup.

Fix typo (s/writeer/writer/).

Document rw_try_upgrade() and rw_downgrade().

Various nits and fixups so that the text reads smoother in several places.
Also, more closely match the prototypes in sys/rwlock.h and add a BUGS
section.

Document read/write locks.

Reviewed by: jhb, ru