src/sys/kern/subr_sleepqueue.c, branch releng/14.3 FreeBSD source tree sleepqueue: Fix the comment for sleepq_switch() 2024-11-19T14:15:07+00:00 Mark Johnston markj@FreeBSD.org 2024-11-12T01:57:24+00:00 b9f9be5d92a345a52e1dedffb5fdd2e7b6bbc2e2 The comment from mi_switch() applies here. PR: 279708 Fixes: 686bcb5c14ab ("schedlock 4/4") MFC after: 1 week (cherry picked from commit 1030ee9128373e7819e5d4a45475ad8cda24fec9) 
The comment from mi_switch() applies here.

PR:		279708
Fixes:		686bcb5c14ab ("schedlock 4/4")
MFC after:	1 week

(cherry picked from commit 1030ee9128373e7819e5d4a45475ad8cda24fec9)
sys: Remove $FreeBSD$: one-line .c pattern 2023-08-16T17:54:36+00:00 Warner Losh imp@FreeBSD.org 2023-08-16T17:54:36+00:00 685dc743dc3b5645e34836464128e1c0558b404b Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/ 
Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/
spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD 2023-05-12T16:44:03+00:00 Warner Losh imp@FreeBSD.org 2023-05-10T15:40:58+00:00 4d846d260e2b9a3d4d0a701462568268cbfe7a5b The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch up to that fact and revert to their recommended match of BSD-2-Clause. Discussed with: pfg MFC After: 3 days Sponsored by: Netflix 
The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with:		pfg
MFC After:		3 days
Sponsored by:		Netflix
sleepq_set_timeout_sbt(): correct comment to not talk about ticks 2022-08-20T17:33:17+00:00 Konstantin Belousov kib@FreeBSD.org 2022-08-12T00:35:45+00:00 f835be58226a058c56d305455ec78c4d6f11b9fc It is sbt now. Also, explain what flags are. Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 3 days Differential revision: https://reviews.freebsd.org/D36207 
It is sbt now.  Also, explain what flags are.

Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Differential revision:	https://reviews.freebsd.org/D36207
sleepq_check_ast_sc_locked(): update comment 2022-08-20T17:33:17+00:00 Konstantin Belousov kib@FreeBSD.org 2022-08-12T00:19:36+00:00 da39a100dbfe60da6512a8b230386b1105c42445 The relock order is important not only for a signal delivery, but also for the suspension requests. Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 3 days Differential revision: https://reviews.freebsd.org/D36207 
The relock order is important not only for a signal delivery, but also
for the suspension requests.

Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Differential revision:	https://reviews.freebsd.org/D36207
AST: rework 2022-08-02T18:11:09+00:00 Konstantin Belousov kib@FreeBSD.org 2022-07-18T16:39:17+00:00 c6d31b8306eb708441c61c33bcf886ecad268a16 Make most AST handlers dynamically registered. This allows to have subsystem-specific handler source located in the subsystem files, instead of making subr_trap.c aware of it. For instance, signal delivery code on return to userspace is now moved to kern_sig.c. Also, it allows to have some handlers designated as the cleanup (kclear) type, which are called both at AST and on thread/process exit. For instance, ast(), exit1(), and NFS server no longer need to be aware about UFS softdep processing. The dynamic registration also allows third-party modules to register AST handlers if needed. There is one caveat with loadable modules: the code does not make any effort to ensure that the module is not unloaded before all threads processed through AST handler in it. In fact, this is already present behavior for hwpmc.ko and ufs.ko. I do not think it is worth the efforts and the runtime overhead to try to fix it. Reviewed by: markj Tested by: emaste (arm64), pho Discussed with: jhb Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D35888 
Make most AST handlers dynamically registered.  This allows to have
subsystem-specific handler source located in the subsystem files,
instead of making subr_trap.c aware of it.  For instance, signal
delivery code on return to userspace is now moved to kern_sig.c.

Also, it allows to have some handlers designated as the cleanup (kclear)
type, which are called both at AST and on thread/process exit.  For
instance, ast(), exit1(), and NFS server no longer need to be aware
about UFS softdep processing.

The dynamic registration also allows third-party modules to register AST
handlers if needed.  There is one caveat with loadable modules: the
code does not make any effort to ensure that the module is not unloaded
before all threads processed through AST handler in it.  In fact, this
is already present behavior for hwpmc.ko and ufs.ko.  I do not think it
is worth the efforts and the runtime overhead to try to fix it.

Reviewed by:	markj
Tested by:	emaste (arm64), pho
Discussed with:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D35888
sleepqueue: Annotate sleepq_max_depth as static 2022-02-14T15:06:47+00:00 Mark Johnston markj@FreeBSD.org 2022-02-14T14:41:07+00:00 852ff943b9c23d40e36ebe5f82112f7bce4537c9 MFC after: 1 week Sponsored by: The FreeBSD Foundation 
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
sleepqueue: Address a lock order reversal 2022-02-14T15:06:47+00:00 Mark Johnston markj@FreeBSD.org 2022-02-14T14:38:53+00:00 893be9d8ac161c4cc96e9f3f12f1260355dd123b After commit 74cf7cae4d22 ("softclock: Use dedicated ithreads for running callouts."), there is a lock order reversal between the per-CPU callout lock and the scheduler lock. softclock_thread() locks callout lock then the scheduler lock, when preparing to switch off-CPU, and sleepq_remove_thread() stops the timed sleep callout while potentially holding a scheduler lock. In the latter case, it's the thread itself that's locked, and if the thread is sleeping then its lock will be a sleepqueue lock, but if it's still in the process of going to sleep it'll be a scheduler lock. We could perhaps change softclock_thread() to try to acquire locks in the opposite order, but that'd require dropping and re-acquiring the callout lock, which seems expensive for an operation that will happen quite frequently. We can instead perhaps avoid stopping the td_slpcallout callout if the thread is still going to sleep, which is what this patch does. This will result in a spurious call to sleepq_timeout(), but some counters suggest that this is very rare. PR: 261198 Fixes: 74cf7cae4d22 ("softclock: Use dedicated ithreads for running callouts.") Reported and tested by: thj Reviewed by: kib Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D34204 
After commit 74cf7cae4d22 ("softclock: Use dedicated ithreads for
running callouts."), there is a lock order reversal between the per-CPU
callout lock and the scheduler lock.  softclock_thread() locks callout
lock then the scheduler lock, when preparing to switch off-CPU, and
sleepq_remove_thread() stops the timed sleep callout while potentially
holding a scheduler lock.  In the latter case, it's the thread itself
that's locked, and if the thread is sleeping then its lock will be a
sleepqueue lock, but if it's still in the process of going to sleep
it'll be a scheduler lock.

We could perhaps change softclock_thread() to try to acquire locks in
the opposite order, but that'd require dropping and re-acquiring the
callout lock, which seems expensive for an operation that will happen
quite frequently.  We can instead perhaps avoid stopping the
td_slpcallout callout if the thread is still going to sleep, which is
what this patch does.  This will result in a spurious call to
sleepq_timeout(), but some counters suggest that this is very rare.

PR:		261198
Fixes:		74cf7cae4d22 ("softclock: Use dedicated ithreads for running callouts.")
Reported and tested by:	thj
Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D34204
When queuing ignored signal, only abort target thread' sleep if it is inside sigwait() 2021-10-06T14:05:22+00:00 Konstantin Belousov kib@FreeBSD.org 2021-10-03T02:03:59+00:00 9b86d3e5de1997ed8d3153d4530bcb981e6602b9 Reported and tested by: trasz Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D32252 
Reported and tested by:	trasz
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D32252
When sending ignored signal, arrange for zero return code from sleep 2021-10-06T14:05:22+00:00 Konstantin Belousov kib@FreeBSD.org 2021-10-01T06:59:02+00:00 f17eb93d5540ec2bf422d96195820bba5021fa9c Otherwise consumers get unexpected EINTR errors without seeing a properly discarded signal. Reported and tested by: trasz Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D32252 
Otherwise consumers get unexpected EINTR errors without seeing
a properly discarded signal.

Reported and tested by:	trasz
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D32252