Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r258713,262062: add taskqueue_drain_all

MFC r243845:
Document the interpretation of the negative value of ticks for
taskqueue_enqueue_timeout(9).

MFC r243863:
Fix typo.

MFC r233648:
Remove trailing whitespace per mdoc lint warning

Approved by: cperciva (implicit)

MFC r235693:

Typo and mdoc(7) style fixes.

PR: 168117

MFC 228715:
Add a TASK_INITIALIZER() macro that can be used to statically
initialize a task structure.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Ensure that ta_pending doesn't overflow u_short by capping its value at USHRT_MAX.

If it overflows before the taskqueue can run, the task will be
re-added to the taskqueue and cause a loop in the task list.

Reported by: Arnaud Lacombe <lacombar@gmail.com>
Submitted by: Ryan Stone <rysto32@gmail.com>
Reviewed by: jhb
Approved by: re (kib)
MFC after: 1 day

Fix markup.

Approved by: re (hrs)

Document timeout_task.

While there, fix the type of the func argument of INIT_TASK macro,
and use the modern name of the analogous facility from Linux kernel.

Sponsored by: The FreeBSD Foundation
MFC after: 1 month

Add a taskqueue_cancel(9) to cancel a pending task without waiting for
it to run as taskqueue_drain(9) does.

Requested by: hselasky
Original code: jeff
Reviewed by: jhb
MFC after: 2 weeks

Use a safer mechanism for determining if a task is currently running,
that does not rely on the lifetime of pointers being the same. This also
restores the task KBI.

Suggested by: jhb
MFC after: 1 month

Re-expose and briefly document taskqueue_run(9). The function is used
in at least one 3rd party driver.

Requested by: jhb

Spelling fixes.

Fix taskqueue_drain(9) to not have false negatives. For threaded
taskqueues, more than one task can be running simultaneously.

Also make taskqueue_run(9) static to the file, since there are no
consumers in the base kernel and the function signature needs to change
with this fix.

Remove mention of taskqueue_run(9) and taskqueue_run_fast(9) from the
taskqueue(9) man page.

Reviewed by: jhb
Approved by: zml (mentor)

Remove unused taskqueue_find() function.

Reviewed by: dfr
Approved by: re (kib)

Correct typo in the previous commit.

Noticed by: pluknet <pluknet@gmail.com>
Approved by: re (kib, implicit)

Remove OpenSolaris taskq port (it performs very poorly in our kernel) and
replace it with wrappers around our taskqueue(9).
To make it possible implement taskqueue_member() function which returns 1
if the given thread was created by the given taskqueue.

Approved by: re (kib)

It's Friday the 13th, not the 10th and I can't travel in time. Yet.

Add "fast" versions of macros and functions to taskqueue(9) API
description: TASKQUEUE_FAST_DEFINE(9), TASKQUEUE_FAST_DEFINE_THREAD(9),
taskqueue_create_fast(9). They deal with taskqueues intended for use
in fast interrupt handlers.

Approved by: cognet (mentor)
Reviewed by: keramida

Clean out all mentions of struct proc* for it was removed from
taskqueue(9) API more then two years ago.

Approved by: cognet (mentor)

document the call to wakeup after a task has been run...

Approved by: re (hrs)
MFC after: 3 days

Use 'manual page' instead of 'man page' for consistency.

Approved by: re (hrs)

Assorted markup fixes and minor wordsmithing.

Approved by: re

Document taskqueue_drain().

update for recent api changes

Document taskqueue_run_fast(). Markup 'Giant' with ".Va".

Reviewed by: ru

Add a 'SEE ALSO' section.

Scheduled mdoc(7) sweep.

Correct a misspelling, 'task_fn' -> 'task_fn_t'.

Noticed by: sah at softcardsystems dot com
MFC after: 3 days

rearange some code that handles the thread taskqueue so that it is more
generic. Introduce a new define TASKQUEUE_DEFINE_THREAD that takes a
single arg, which is the name of the queue.

Document these changes.

Removed trailing whitespace.

Assorted markup, spelling, and grammar fixes.

Document taskqueue_enqueue_fast()

Fix typo in the last commit.

Pointed out by: njl
MFC after: 3 days

Move dynamic sysctl(8) variable creation for the cd(4) and da(4) drivers
out of cdregister() and daregister(), which are run from interrupt context.

The sysctl code does blocking mallocs (M_WAITOK), which causes problems
if malloc(9) actually needs to sleep.

The eventual fix for this issue will involve moving the CAM probe process
inside a kernel thread. For now, though, I have fixed the issue by moving
dynamic sysctl variable creation for these two drivers to a task queue
running in a kernel thread.

The existing task queues (taskqueue_swi and taskqueue_swi_giant) run in
software interrupt handlers, which wouldn't fix the problem at hand. So I
have created a new task queue, taskqueue_thread, that runs inside a kernel
thread. (It also runs outside of Giant -- clients must explicitly acquire
and release Giant in their taskqueue functions.)

scsi_cd.c: Remove sysctl variable creation code from cdregister(), and
move it to a new function, cdsysctlinit(). Queue
cdsysctlinit() to the taskqueue_thread taskqueue once we
have fully registered the cd(4) driver instance.

scsi_da.c: Remove sysctl variable creation code from daregister(), and
move it to move it to a new function, dasysctlinit().
Queue dasysctlinit() to the taskqueue_thread taskqueue once
we have fully registered the da(4) instance.

taskqueue.h: Declare the new taskqueue_thread taskqueue, update some
comments.

subr_taskqueue.c:
Create the new kernel thread taskqueue. This taskqueue
runs outside of Giant, so any functions queued to it would
need to explicitly acquire/release Giant if they need it.

cd.4: Update the cd(4) man page to talk about the minimum command
size sysctl/loader tunable. Also note that the changer
variables are available as loader tunables as well.

da.4: Update the da(4) man page to cover the retry_count,
default_timeout and minimum_cmd_size sysctl variables/loader
tunables. Remove references to /dev/r???, they aren't used
any longer.

cd.9: Update the cd(9) man page to describe the CD_Q_10_BYTE_ONLY
quirk.

taskqueue.9: Update the taskqueue(9) man page to describe the new thread
task queue, and the taskqueue_swi_giant queue.

MFC after: 3 days

mdoc(7) police: Kill the (now extraneous) empty line. Previously,
.Bd erroneously defaulted to -compact mode in the SYNOPSIS section.

Update function definitions and required include files to reflect
the current state of the system.

Approved by: alfred

mdoc(7) police: Use the new .In macro for #include statements.

mdoc(7) police: remove extraneous .Pp before and/or after .Sh.

mdoc(7) police: Er macro usage cleanup.

Add documentation for taskqueue apis.