MFC r344855 (by jhb):

Drop "All rights reserved" from my copyright statements.

Reviewed by: rgrimes
Differential Revision: https://reviews.freebsd.org/D19485

Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

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

Drop the 3rd clause from all 3 clause BSD licenses where I am the sole
holder to convert them to 2 clause BSD licenses.

MFC after: 1 week

Tweak comments.

In collabouration with: alc

Merge r242395,242483 from mutex implementation:
give rwlock(9) the ability to crunch different type of structures, with
the only constraint that they have a lock cookie named rw_lock.
This name, then, becames reserved from the struct that wants to use
the rwlock(9) KPI and other locking primitives cannot reuse it for
their members.

Namely such structs are the current struct rwlock and the new struct
rwlock_padalign. The new structure will define an object which has the
same layout of a struct rwlock but will be allocated in areas aligned
to the cache line size and will be as big as a cache line.

For further details check comments on above mentioned revisions.

Reviewed by: jimharris, jeff

- Embed the recursion counter for any locking primitive directly in the
lock_object, using an unified field called lo_data.
- Replace lo_type usage with the w_name usage and at init time pass the
lock "type" directly to witness_init() from the parent lock init
function. Handle delayed initialization before than
witness_initialize() is called through the witness_pendhelp structure.
- Axe out LO_ENROLLPEND as it is not really needed. The case where the
mutex init delayed wants to be destroyed can't happen because
witness_destroy() checks for witness_cold and panic in case.
- In enroll(), if we cannot allocate a new object from the freelist,
notify that to userspace through a printf().
- Modify the depart function in order to return nothing as in the current
CVS version it always returns true and adjust callers accordingly.
- Fix the witness_addgraph() argument name prototype.
- Remove unuseful code from itismychild().

This commit leads to a shrinked struct lock_object and so smaller locks,
in particular on amd64 where 2 uintptr_t (16 bytes per-primitive) are
gained.

Reviewed by: jhb

Introduce a new rwlocks initialization function: rw_init_flags.
This is very similar to sx_init_flags: it initializes the rwlock using
special flags passed as third argument (RW_DUPOK, RW_NOPROFILE,
RW_NOWITNESS, RW_QUIET, RW_RECURSE).
Among these, the most important new feature is probabilly that rwlocks
can be acquired recursively now (for both shared and exclusive paths).

Because of the recursion counter, the ABI is changed.

Tested by: Timothy Redaelli <drizzt@gufi.org>
Reviewed by: jhb
Approved by: jeff (mentor)
Approved by: re

Rename the 'mtx_object', 'rw_object', and 'sx_object' members of mutexes,
rwlocks, and sx locks to 'lock_object'.

Fix a typo and match the copyright on rwlock.h.

Add _rwlock.h, apparently missed from the rwlock.h commit.