From: Tejun Heo <tj@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org,
padovan@profusion.mobi, marcel@holtmann.org,
peterz@infradead.org, mingo@redhat.com, davem@davemloft.net,
dougthompson@xmission.com, ibm-acpi@hmh.eng.br, cbou@mail.ru,
rui.zhang@intel.com, tomi.valkeinen@ti.com
Subject:
Date: Fri, 3 Aug 2012 10:43:45 -0700 [thread overview]
Message-ID: <1344015839-21800-1-git-send-email-tj@kernel.org> (raw)
delayed_work has been annoyingly missing the mechanism to modify timer
of a pending delayed_work - ie. mod_timer() counterpart. delayed_work
users have been working around this using several methods - using an
explicit timer + work item, messing directly with delayed_work->timer,
and canceling before re-queueing, all of which are error-prone and/or
ugly.
Gustavo Padovan posted a RFC implementation[1] of mod_delayed_work() a
while back but it wasn't complete. To properly implement
mod_delayed_work[_on](), it should be able to steal pending work items
which may be on timer or worklist or anywhere inbetween. This is
similar to what __cancel_work_timer() does but it turns out that there
are a lot of holes around this area and try_to_grab_pending() needs
considerable amount of work to be used for other purposes too.
This patchset improves canceling and try_to_grab_pending(), use it to
implement mod_delayed_work[_on](), convert easy ones, and drop
__cancel_delayed_work_sync() which doesn't have relevant users
afterwards.
Changes from the first take[L] are,
* All updated patches rolled into the series and Acked-by's added.a
* Tomi Valkeinen pointed out that mod_delayed_work() can't be called
from IRQ handlers and thus can't replace __cancel_delayed_work()
users. __cancel_delayed_work() users dropped from conversion. This
will be handled by a future patchset.
* Ensuring preemtion is disabled across PENDING manipulation doesn't
make try_to_grab_pending() safe to use from bh context and making it
impossible to replace even cancel_delayed_work() users. Whole patch
series updated so that IRQ is disabled across PENDING manipulation
instead. As most operations had to grab gcwq->lock anyway, this
doesn't add extra IRQ toggling.
* try_to_grab_pending() and __cancel_work_timer() updated to take bool
@is_dwork instead of @timer and disable IRQ on successful return.
This patchset contains the following fourteen patches.
0001-workqueue-reorder-queueing-functions-so-that-_on-var.patch
0002-workqueue-make-queueing-functions-return-bool.patch
0003-workqueue-add-missing-smp_wmb-in-process_one_work.patch
0004-workqueue-disable-irq-while-manipulating-PENDING.patch
0005-workqueue-set-delayed_work-timer-function-on-initial.patch
0006-workqueue-unify-local-CPU-queueing-handling.patch
0007-workqueue-fix-zero-delay-handling-of-queue_delayed_w.patch
0008-workqueue-move-try_to_grab_pending-upwards.patch
0009-workqueue-introduce-WORK_OFFQ_FLAG_.patch
0010-workqueue-factor-out-__queue_delayed_work-from-queue.patch
0011-workqueue-reorganize-try_to_grab_pending-and-__cance.patch
0012-workqueue-mark-a-work-item-being-canceled-as-such.patch
0013-workqueue-implement-mod_delayed_work-_on.patch
0014-workqueue-use-mod_delayed_work-instead-of-cancel-que.patch
0001-0003 are preparatory.
0004 removes the possibility of cancel_sync spinning for extended
period of time while another task holding PENDING is preempted or
interrupted.
0005-0007 clean up local queueing handling.
0008-0011 prepare for try_to_grab_pending() improvements.
0012 makes try_to_grab_pending() distinguish transient failure which
can be safely busy-retried and failure because the work item is being
canceled, which may take arbitrary amount of time.
0013 uses the improved try_to_grab_pending() to implement
mod_delayed_work[_on]().
0014 converts cancel + queue sequences to mod_delayed_work().
This patchset is also available at the following git branch.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git review-wq-mod_delayed
If nobody objects, I'd like to route this series through wq/for-3.7.
Changes to other subsystems are fairly localized and conflicts, if
they occur, shouldn't be too painful to handle.
Although this ends up adding ~130 LOC, it contains a lot more
documentation, converted only the apparent ones, and IMHO is
worthwhile to have regardless as it removes an annoyance which is
pretty easy to encounter while using delayed_work.
Thanks.
block/genhd.c | 6
drivers/edac/edac_mc.c | 17
drivers/infiniband/core/addr.c | 4
drivers/infiniband/hw/nes/nes_hw.c | 6
drivers/infiniband/hw/nes/nes_nic.c | 5
drivers/net/wireless/ipw2x00/ipw2100.c | 8
drivers/net/wireless/zd1211rw/zd_usb.c | 3
drivers/platform/x86/thinkpad_acpi.c | 20
drivers/power/charger-manager.c | 9
drivers/power/ds2760_battery.c | 9
drivers/power/jz4740-battery.c | 6
drivers/thermal/thermal_sys.c | 15
fs/afs/callback.c | 4
fs/afs/server.c | 10
fs/afs/vlocation.c | 14
fs/nfs/nfs4renewd.c | 3
include/linux/workqueue.h | 47 +-
kernel/workqueue.c | 732 ++++++++++++++++++++-------------
net/core/dst.c | 4
net/rfkill/input.c | 3
20 files changed, 526 insertions(+), 399 deletions(-)
--
tejun
[1] http://thread.gmane.org/gmane.linux.kernel/1159922
[L] http://thread.gmane.org/gmane.linux.kernel/1334546
next reply other threads:[~2012-08-03 17:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-03 17:43 Tejun Heo [this message]
2012-08-03 17:43 ` [PATCH 01/14] workqueue: reorder queueing functions so that _on() variants are on top Tejun Heo
2012-08-03 17:43 ` [PATCH 02/14] workqueue: make queueing functions return bool Tejun Heo
2012-08-03 17:43 ` [PATCH 03/14] workqueue: add missing smp_wmb() in process_one_work() Tejun Heo
2012-08-03 17:43 ` [PATCH 04/14] workqueue: disable irq while manipulating PENDING Tejun Heo
2012-08-03 17:43 ` [PATCH 05/14] workqueue: set delayed_work->timer function on initialization Tejun Heo
2012-08-03 17:43 ` [PATCH 06/14] workqueue: unify local CPU queueing handling Tejun Heo
2012-08-03 17:43 ` [PATCH 07/14] workqueue: fix zero @delay handling of queue_delayed_work_on() Tejun Heo
2012-08-03 17:43 ` [PATCH 08/14] workqueue: move try_to_grab_pending() upwards Tejun Heo
2012-08-03 17:43 ` [PATCH 09/14] workqueue: introduce WORK_OFFQ_FLAG_* Tejun Heo
2012-08-03 17:43 ` [PATCH 10/14] workqueue: factor out __queue_delayed_work() from queue_delayed_work_on() Tejun Heo
2012-08-03 17:43 ` [PATCH 11/14] workqueue: reorganize try_to_grab_pending() and __cancel_timer_work() Tejun Heo
2012-08-03 17:43 ` [PATCH 12/14] workqueue: mark a work item being canceled as such Tejun Heo
2012-08-03 17:43 ` [PATCH 13/14] workqueue: implement mod_delayed_work[_on]() Tejun Heo
2012-08-03 17:43 ` [PATCH 14/14] workqueue: use mod_delayed_work() instead of cancel + queue Tejun Heo
2012-08-03 17:45 ` $SUBJ should have been "[PATCHSET] workqueue: implement mod_delayed_work[_on](), take#2" Tejun Heo
2012-08-08 16:39 ` your mail Tejun Heo
2012-08-13 13:27 ` [PATCH 14/14] workqueue: use mod_delayed_work() instead of cancel + queue David Howells
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1344015839-21800-1-git-send-email-tj@kernel.org \
--to=tj@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=cbou@mail.ru \
--cc=davem@davemloft.net \
--cc=dougthompson@xmission.com \
--cc=ibm-acpi@hmh.eng.br \
--cc=linux-kernel@vger.kernel.org \
--cc=marcel@holtmann.org \
--cc=mingo@redhat.com \
--cc=padovan@profusion.mobi \
--cc=peterz@infradead.org \
--cc=rui.zhang@intel.com \
--cc=tomi.valkeinen@ti.com \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).