Finish merging from head, messed up in previous attempt

Catch up with head, primarily for the 1.14.4.0 firmware.

Merge ^/head r285924 through r286421.

Don't modify curthread->td_locks unless INVARIANTS is enabled.

This field is only used in a KASSERT that verifies that no locks are held
when returning to user mode. Moreover, the td_locks accountin

Don't modify curthread->td_locks unless INVARIANTS is enabled.

This field is only used in a KASSERT that verifies that no locks are held
when returning to user mode. Moreover, the td_locks accounting is only
correct when LOCK_DEBUG > 0, which is implied by INVARIANTS.

Reviewed by: jhb
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D3205

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Merge from HEAD

Merge ^/head r277327 through r277718.

MFhead @ r277555

Revert for r277213:

FreeBSD developers need more time to review patches in the surrounding
areas like the TCP stack which are using MPSAFE callouts to restore
distribution of callouts on multiple CP

Revert for r277213:

FreeBSD developers need more time to review patches in the surrounding
areas like the TCP stack which are using MPSAFE callouts to restore
distribution of callouts on multiple CPUs.

Bump the __FreeBSD_version instead of reverting it.

Suggested by: kmacy, adrian, glebius and kib
Differential Revision: https://reviews.freebsd.org/D1438

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MFhead @ r277403

Reintegrate head: r274132-r277384

Sponsored by: The FreeBSD Foundation

Major callout subsystem cleanup and rewrite:
- Close a migration race where callout_reset() failed to set the
CALLOUT_ACTIVE flag.
- Callout callback functions are now allowed to be protected by

Major callout subsystem cleanup and rewrite:
- Close a migration race where callout_reset() failed to set the
CALLOUT_ACTIVE flag.
- Callout callback functions are now allowed to be protected by
spinlocks.
- Switching the callout CPU number cannot always be done on a
per-callout basis. See the updated timeout(9) manual page for more
information.
- The timeout(9) manual page has been updated to reflect how all the
functions inside the callout API are working. The manual page has
been made function oriented to make it easier to deduce how each of
the functions making up the callout API are working without having
to first read the whole manual page. Group all functions into a
handful of sections which should give a quick top-level overview
when the different functions should be used.
- The CALLOUT_SHAREDLOCK flag and its functionality has been removed
to reduce the complexity in the callout code and to avoid problems
about atomically stopping callouts via callout_stop(). If someone
needs it, it can be re-added. From my quick grep there are no
CALLOUT_SHAREDLOCK clients in the kernel.
- A new callout API function named "callout_drain_async()" has been
added. See the updated timeout(9) manual page for a complete
description.
- Update the callout clients in the "kern/" folder to use the callout
API properly, like cv_timedwait(). Previously there was some custom
sleepqueue code in the callout subsystem, which has been removed,
because we now allow callouts to be protected by spinlocks. This
allows us to tear down the callout like done with regular mutexes,
and a "td_slpmutex" has been added to "struct thread" to atomically
teardown the "td_slpcallout". Further the "TDF_TIMOFAIL" and
"SWT_SLEEPQTIMO" states can now be completely removed. Currently
they are marked as available and will be cleaned up in a follow up
commit.
- Bump the __FreeBSD_version to indicate kernel modules need
recompilation.
- There has been several reports that this patch "seems to squash a
serious bug leading to a callout timeout and panic".

Kernel build testing: all architectures were built
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D1438
Sponsored by: Mellanox Technologies
Reviewed by: jhb, adrian, sbruno and emaste

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Reintegrate head revisions r273096-r277147

Sponsored by: The FreeBSD Foundation

Sync to HEAD@r274766

Merge from head@274682

Do not try to dereference thread pointer when the value is not a pointer.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Sync to HEAD@r274095.

Add a new thread state "spinning" to schedgraph and add tracepoints at the
start and stop of spinning waits in lock primitives.

Followup to r273966. Fix the build with ADAPTIVE_LOCKMGRS kernel option.

Note that the option is currently not used in any in-tree kernel
configs, including LINTs.

Sponsored by: The FreeBSD Founda

Followup to r273966. Fix the build with ADAPTIVE_LOCKMGRS kernel option.

Note that the option is currently not used in any in-tree kernel
configs, including LINTs.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

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Fix two issues with lockmgr(9) LK_CAN_SHARE() test, which determines
whether the shared request for already shared-locked lock could be
granted. Both problems result in the exclusive locker starvati

Fix two issues with lockmgr(9) LK_CAN_SHARE() test, which determines
whether the shared request for already shared-locked lock could be
granted. Both problems result in the exclusive locker starvation.

The concurrent exclusive request is indicated by either
LK_EXCLUSIVE_WAITERS or LK_EXCLUSIVE_SPINNERS flags. The reverse
condition, i.e. no exclusive waiters, must check that both flags are
cleared.

Add a flag LK_NODDLKTREAT for shared lock request to indicate that
current thread guarantees that it does not own the lock in shared
mode. This turns back the exclusive lock starvation avoidance code;
see man page update for detailed description.

Use LK_NODDLKTREAT when doing lookup(9).

Reported and tested by: pho
No objections from: attilio
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

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IFC @r271694

Sync to HEAD@r271160.

Add function and wrapper to switch lockmgr and vnode lock back to
auto-promotion of shared to exclusive.

Tested by: hrs, pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Merge head

IFC @264767

Merge head up to r262222 (last merge was incomplete).