MFC r326835: Reduce size of several on-stack string buffers.

Submitted by: Dmitry Luhtionov <dmitryluhtionov@gmail.com>

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

Removed unused malloc types.

Submitted by: Dmitry Luhtionov <dmitryluhtionov@gmail.com>
MFC after: 1 week

Pull in r267961 and r267973 again. Fix for issues reported will follow.

Revert r267961, r267973:

These changes prevent sysctl(8) from returning proper output,
such as:

1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1)
truss: can not get etype: Cannot allocate memory

Extend the meaning of the CTLFLAG_TUN flag to automatically check if
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.

Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.

MFC after: 2 weeks
Sponsored by: Mellanox Technologies

Merge CAM locking changes from the projects/camlock branch to radically
reduce lock congestion and improve SMP scalability of the SCSI/ATA stack,
preparing the ground for the coming next GEOM direct dispatch support.

Replace big per-SIM locks with bunch of smaller ones:
- per-LUN locks to protect device and peripheral drivers state;
- per-target locks to protect list of LUNs on target;
- per-bus locks to protect reference counting;
- per-send queue locks to protect queue of CCBs to be sent;
- per-done queue locks to protect queue of completed CCBs;
- remaining per-SIM locks now protect only HBA driver internals.

While holding LUN lock it is allowed (while not recommended for performance
reasons) to take SIM lock. The opposite acquisition order is forbidden.
All the other locks are leaf locks, that can be taken anywhere, but should
not be cascaded. Many functions, such as: xpt_action(), xpt_done(),
xpt_async(), xpt_create_path(), etc. are no longer require (but allow) SIM
lock to be held.

To keep compatibility and solve cases where SIM lock can't be dropped, all
xpt_async() calls in addition to xpt_done() calls are queued to completion
threads for async processing in clean environment without SIM lock held.

Instead of single CAM SWI thread, used for commands completion processing
before, use multiple (depending on number of CPUs) threads. Load balanced
between them using "hash" of the device B:T:L address.

HBA drivers that can drop SIM lock during completion processing and have
sufficient number of completion threads to efficiently scale to multiple
CPUs can use new function xpt_done_direct() to avoid extra context switch.
Make ahci(4) driver to use this mechanism depending on hardware setup.

Sponsored by: iXsystems, Inc.
MFC after: 2 months

Unify periph invalidation and destruction reporting.
Print message containing device model and serial number on invalidation.

Requested by: glebius
MFC after: 1 week

Disable sending Early R_OK on SiI3726/SiI3826 port multipliers.
With "cached read" HDD testing and multiple ports busy on a SATA
host controller, 3726/3826 PMP will very rarely drop a deferred
R_OK that was intended for the host. Symptom will be all 5 drives
under test will timeout, get reset, and recover.

Submitted by: Rich Futyma <rich.futyma@sanmina.com>
MFC after: 2 weeks

MFprojects/camlock r248894:
Use full freeze while PMP does hard reset. This is only cosmetical change.

Hide SEMB port of the SiI3826 Port Multiplier by default to avoid extra
errors while it tries to talk via I2C to usually missing external SEP.
There is tunable to enable it back when needed.

Remove 'periph == NULL' check from bunch of periph drivers.
This condition can never be true as functions are called from single place
and the checks just pollute the code and confuse Clang Static Analyzer.

Tune and add some missing CAM_DEBUG() points for better consistency.

Add tunable/sysctl kern.cam.pmp.hide_special, controlling whether special
PMP ports such as PMP configuration or SEMB should be exposed or hidden.
These ports were always hidden before as useless and sometimes promatic.
But with updated ses driver supporting SEMB it is no longer so straight.
Keep ports hidden by default to avoid probe request ttimeouts if SEP is
not connected to PMP's SEMB via I2C, that is very often situation.

Mark all SYSCTL_NODEs static that have no corresponding SYSCTL_DECLs.

The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.

Mark MALLOC_DEFINEs static that have no corresponding MALLOC_DECLAREs.

This means that their use is restricted to a single C file.

Remove some used variables.

Found with: Clang Static Analyzer

Improve SATA Asynchronous Notification feature support in CAM:
- make SATA SIMs announce capabilities to handle SDB with Notification bit;
- make PMP driver honor this SIMs capability;
- make SATA XPT to negotiate and enable this feature for ATAPI devices.

This feature allows supporting SATA ATAPI devices to inform system about
some events happened, that may require attention. In my case this allows
LG GH22LS50 SATA DVR-RW drive to report tray open/close events. Events
reported to CAM in form of AC_SCSI_AEN async. Further they could be used
as a hints for checking device status and reporting media change to upper
layers, for example, via spoiling mechanism of GEOM.

Fix double free on error.

Found with: Coverity Prevent(tm)
CID: 4573

Make SATA XPT negotiate and enable some additional SATA features, such as:
- device initiated power management (some devices support only this way);
- Automatic Partial to Slumber Transition (more power saving);
- DMA auto-activation (expected to slightly improve performance).
More features could be added later, when hardware supports.

- Use separate buffer for identify data fetching. We can't use main buffer
here if device already running, as data need to be formatted before use.
- Remove some saved_ccb variables. They are unused now.

MFp4: Large set of CAM inprovements.

- Unify bus reset/probe sequence. Whenever bus attached at boot or later,
CAM will automatically reset and scan it. It allows to remove duplicate
code from many drivers.
- Any bus, attached before CAM completed it's boot-time initialization,
will equally join to the process, delaying boot if needed.
- New kern.cam.boot_delay loader tunable should help controllers that
are still unable to register their buses in time (such as slow USB/
PCCard/ CardBus devices), by adding one more event to wait on boot.
- To allow synchronization between different CAM levels, concept of
requests priorities was extended. Priorities now split between several
"run levels". Device can be freezed at specified level, allowing higher
priority requests to pass. For example, no payload requests allowed,
until PMP driver enable port. ATA XPT negotiate transfer parameters,
periph driver configure caching and so on.
- Frozen requests are no more counted by request allocation scheduler.
It fixes deadlocks, when frozen low priority payload requests occupying
slots, required by higher levels to manage theit execution.
- Two last changes were holding proper ATA reinitialization and error
recovery implementation. Now it is done: SATA controllers and Port
Multipliers now implement automatic hot-plug and should correctly
recover from timeouts and bus resets.
- Improve SCSI error recovery for devices on buses without automatic sense
reporting, such as ATAPI or USB. For example, it allows CAM to wait, while
CD drive loads disk, instead of immediately return error status.
- Decapitalize diagnostic messages and make them more readable and sensible.
- Teach PMP driver to limit maximum speed on fan-out ports.
- Make boot wait for PMP scan completes, and make rescan more reliable.
- Fix pass driver, to return CCB to user level in case of error.
- Increase number of retries in cd driver, as device may return several UAs.

MFp4;
- Cleanup kernel messages, mostly PMP.
- Took references on devices, while PMP reinitializes them, to not let them
go and distort freeze reference counting.

MFp4:
- Extend XPT-SIM transfer settings control API. Now it allows to report to
SATA SIM number of tags supported by each device, implement ATA mode and
SATA revision negotiation for both SATA and PATA SIMs.
- Make ahci(4) and siis(4) to use submitted maximum tag number, when
scheduling requests. It allows to support NCQ on devices with lower tags
count then controller supports.
- Make PMP driver to report attached devices connection speeds.
- Implement ATA mode negotiation between user settings, device and
controller capabilities.

Disable PortMultiplier Async Notifications for time of ports reset.
They are useless at that time, but confuse Marvell AHCI.

Add quirk for SiI57XX Port Multipliers, to hide extra port.

MFp4:
- Reduce code duplication in ATA XPT and PMP driver.
- Move PIO size setting from ada driver to ATA XPT. It is XPT business
to negotiate transfer details. ada driver is now stateless.
- Report PIO size to SIM. It is required for correct PATA SIM operation.
- Tune PMP scan timings. It workarounds some problems with SiI.
- If reset hapens during PMP initialization - restart it.
- Introduce early-initialized periph drivers, which are used during initial
scan process. Use it for xpt, probe, aprobe and pmp. It gives pmp chance
to finish scan before mountroot and numerate devices in right order.

MFp4:
Move Port Multiplier support code out of ATA XPT into pmp periph driver.
This is convinient, as PMP itself is a bus target and has own state.