callout: retire callout_async_drain()

This function was used only in TCP before 446ccdd08e2a. It was born in
pain in 2016 to plug different complex panics in TCP timers. It wasn't
warmly accepted

callout: retire callout_async_drain()

This function was used only in TCP before 446ccdd08e2a. It was born in
pain in 2016 to plug different complex panics in TCP timers. It wasn't
warmly accepted in phabricator by all of the reviewers and my recollection
of overall agreement was that "if you need this KPI, then you'd better fix
your code to not need it". However, the function served its duty well all
the way to FreeBSD 14. But now that TCP doesn't need it anymore, let's
retire it to reduce complexity of callout code and also to avoid its
further use.

Reviewed by: jhb, markj, kib, rrs
Differential Revision: https://reviews.freebsd.org/D43546

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sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl s

sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

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sys: Remove $FreeBSD$: one-line .h pattern

Remove /^\s*\*+\s*\$FreeBSD\$.*$\n/

callout: Remove the CS_EXECUTING flag

It is now unused.

MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34626

Remove struct callout_handle. Should have gone with r355732.

Allow pause_sbt() to catch signals during sleep by passing C_CATCH flag.
Define pause_sig() function macro helper similarly to other kernel functions
which catch signals. Update outdated function des

Allow pause_sbt() to catch signals during sleep by passing C_CATCH flag.
Define pause_sig() function macro helper similarly to other kernel functions
which catch signals. Update outdated function description.

Discussed with: kib@
MFC after: 1 week
Sponsored by: Mellanox Technologies

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sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

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Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96

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Extract the calculation of the callout fire time into the new function
callout_when(9). See the man page update for the description of the
intended use.

Tested by: pho
Reviewed by: jhb, bjk (man pa

Extract the calculation of the callout fire time into the new function
callout_when(9). See the man page update for the description of the
intended use.

Tested by: pho
Reviewed by: jhb, bjk (man page updates)
Sponsored by: The FreeBSD Foundation
MFC after: 1 month
X-Differential revision: https://reviews.freebsd.org/D7137

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The paradigm of a callout is that it has three consequent states:
not scheduled -> scheduled -> running -> not scheduled. The API and the
manual page assume that, some comments in the code assume tha

The paradigm of a callout is that it has three consequent states:
not scheduled -> scheduled -> running -> not scheduled. The API and the
manual page assume that, some comments in the code assume that, and looks
like some contributors to the code also did. The problem is that this
paradigm isn't true. A callout can be scheduled and running at the same
time, which makes API description ambigouous. In such case callout_stop()
family of functions/macros should return 1 and 0 at the same time, since it
successfully unscheduled future callout but the current one is running.
Before this change we returned 1 in such a case, with an exception that
if running callout was migrating we returned 0, unless CS_MIGRBLOCK was
specified.

With this change, we now return 0 in case if future callout was unscheduled,
but another one is still in action, indicating to API users that resources
are not yet safe to be freed.

However, the sleepqueue code relies on getting 1 return code in that case,
and there already was CS_MIGRBLOCK flag, that covered one of the edge cases.
In the new return path we will also use this flag, to keep sleepqueue safe.

Since the flag CS_MIGRBLOCK doesn't block migration and now isn't limited to
migration edge case, rename it to CS_EXECUTING.

This change fixes panics on a high loaded TCP server.

Reviewed by: jch, hselasky, rrs, kib
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7042

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If callout_stop_safe() noted that the callout is currently executing,
but next invocation is cancelled while migrating,
sleepq_check_timeout() needs to be informed that the callout is
stopped. Other

If callout_stop_safe() noted that the callout is currently executing,
but next invocation is cancelled while migrating,
sleepq_check_timeout() needs to be informed that the callout is
stopped. Otherwise the thread switches off CPU and never become
runnable, since running callout could have already raced with us,
while the migrating and cancelled callout could be one which is
expected to set TDP_TIMOFAIL flag for us. This contradicts with the
expected behaviour of callout_stop() for other callers, which
e.g. decrement references from the callout callbacks.

Add a new flag CS_MIGRBLOCK requesting report of the situation as
'successfully stopped'.

Reviewed by: jhb (previous version)
Tested by: cognet, pho
PR: 200992
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D5221

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Add new async_drain to the callout system. This is so-far not used but
should be used by TCP for sure in its cleanup of the IN-PCB (will be coming shortly).

Sponsored by: Netflix Inc.
Differential R

Add new async_drain to the callout system. This is so-far not used but
should be used by TCP for sure in its cleanup of the IN-PCB (will be coming shortly).

Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D4076

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Revert r287780 until more developers have their say.

Differential Revision: https://reviews.freebsd.org/D3521
Requested by: gnn

Implement callout_drain_async(), inspired by the projects/hps_head
branch.

This function is used to drain a callout via a callback instead of
blocking the caller until the drain is complete. Refer t

Implement callout_drain_async(), inspired by the projects/hps_head
branch.

This function is used to drain a callout via a callback instead of
blocking the caller until the drain is complete. Refer to the
callout_drain_async() manual page for a detailed description.

Limitation: If a lock is used with the callout, the callout can only
be drained asynchronously one time unless the callout_init_mtx()
function is called again. This limitation is not present in
projects/hps_head and will require more invasive changes to the
timeout code, which was not in the scope of this patch.

Differential Revision: https://reviews.freebsd.org/D3521
Reviewed by: wblock
MFC after: 1 month

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CALLOUT_MPSAFE has lost its meaning since r141428, i.e., for more than ten
years for head. However, it is continuously misused as the mpsafe argument
for callout_init(9). Deprecate the flag and cle

CALLOUT_MPSAFE has lost its meaning since r141428, i.e., for more than ten
years for head. However, it is continuously misused as the mpsafe argument
for callout_init(9). Deprecate the flag and clean up callout_init() calls
to make them more consistent.

Differential Revision: https://reviews.freebsd.org/D2613
Reviewed by: jhb
MFC after: 2 weeks

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Adopt jhb's suggested changes, updated comments and callout_migration() moving
to kern/kern_timeout.c

This does *not* address his -1 -> NOCPU comment.

Sponsored by: Netflix Inc.

Change the callout to supply -1 to indicate we are not changing
CPU, also add protection against invalid CPU's as well as
split c_flags and c_iflags so that if a user plays with the active
flag (the

Change the callout to supply -1 to indicate we are not changing
CPU, also add protection against invalid CPU's as well as
split c_flags and c_iflags so that if a user plays with the active
flag (the one expected to be played with by callers in MPSAFE) without
a lock, it won't adversely affect the callout system by causing a corrupt
list. This also means that all callers need to use the macros and *not*
play with the falgs directly (like netgraph used to).

Differential Revision: htts://reviews.freebsd.org/D1894
Reviewed by: .. timed out but looked at by jhb, imp, adrian hselasky
tested by hiren and netflix.
Sponsored by: Netflix Inc.

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This fixes two conditions that can incur when migration
is being done in the callout code and harmonizes the macro
use.:
1) The callout_active() will lie. Basically if a migration
is occuring and

This fixes two conditions that can incur when migration
is being done in the callout code and harmonizes the macro
use.:
1) The callout_active() will lie. Basically if a migration
is occuring and the callout is about to expire and the
migration has been deferred, the callout_active will no
longer return true until after the migration. This confuses
and breaks callers that are doing callout_init(&c, 1); such
as TCP.
2) The migration code had a bug in it where when migrating, if
a two calls to callout_reset came in and they both collided with
the callout on the wheel about to run, then the second call to
callout_reset would corrupt the list the callout wheel uses
putting the callout thread into a endless loop.
3) Per imp, I have fixed all the macro occurance in the code that
were for the most part being ignored.

Phabricator D1711 and looked at by lstewart and jhb and sbruno.
Reviewed by: kostikbel, imp, adrian, hselasky
MFC after: 3 days
Sponsored by: Netflix Inc.

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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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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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whitespace and cosmetic changes in callout_reset family of macros

- add parentheses around macro parameters for consistent style
- remove redundant parentheses around an expression
- use tab before

whitespace and cosmetic changes in callout_reset family of macros

- add parentheses around macro parameters for consistent style
- remove redundant parentheses around an expression
- use tab before a line continuation symbol

Differential Revision: https://reviews.freebsd.org/D1161 (partial)
Reviewed by: markj
MFC after: 1 week

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callout(9): add sbt flavors of callout_schedule

Differential Revision: https://reviews.freebsd.org/D1161 (partial)
Reviewed by: jhb, markj
MFC after: 1 week

Add a missing brace to callout_init_rm() to fix syntax.

MFC after: 1 week

Fix the build and fix style.

Pointy-hat to: davide

Introduce callout_init_rm() so that callouts can be used in conjunction
with rmlocks. This works only with non-sleepable rm because handlers run
in SWI context. While here, document the new KPI in th

Introduce callout_init_rm() so that callouts can be used in conjunction
with rmlocks. This works only with non-sleepable rm because handlers run
in SWI context. While here, document the new KPI in the timeout(9)
manpage.

Requested by: adrian, scottl
Reviewed by: mav, remko(manpage)

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