From: David Howells <dhowells@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: dhowells@redhat.com, linux-kernel@vger.kernel.org,
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,
Jens Axboe <axboe@kernel.dk>, Jiri Kosina <jkosina@suse.cz>,
David Airlie <airlied@linux.ie>,
Roland Dreier <roland@kernel.org>,
"John W. Linville" <linville@tuxdriver.com>,
Len Brown <len.brown@intel.com>,
"J. Bruce Fields" <bfields@fieldses.org>,
Johannes Berg <johannes@sipsolutions.net>
Subject: Re: [PATCH 14/14] workqueue: use mod_delayed_work() instead of cancel + queue
Date: Mon, 13 Aug 2012 14:27:57 +0100 [thread overview]
Message-ID: <8393.1344864477@warthog.procyon.org.uk> (raw)
In-Reply-To: <1344015839-21800-15-git-send-email-tj@kernel.org>
Tejun Heo <tj@kernel.org> wrote:
> Convert delayed_work users doing cancel_delayed_work() followed by
> queue_delayed_work() to mod_delayed_work().
>
> Most conversions are straight-forward. Ones worth mentioning are,
>
> * drivers/edac/edac_mc.c: edac_mc_workq_setup() converted to always
> use mod_delayed_work() and cancel loop in
> edac_mc_reset_delay_period() is dropped.
>
> * drivers/platform/x86/thinkpad_acpi.c: No need to remember whether
> watchdog is active or not. @fan_watchdog_active and related code
> dropped.
>
> * drivers/power/charger-manager.c: Seemingly a lot of
> delayed_work_pending() abuse going on here.
> [delayed_]work_pending() are unsynchronized and racy when used like
> this. I converted one instance in fullbatt_handler(). Please
> conver the rest so that it invokes workqueue APIs for the intended
> target state rather than trying to game work item pending state
> transitions. e.g. if timer should be modified - call
> mod_delayed_work(), canceled - call cancel_delayed_work[_sync]().
>
> * drivers/thermal/thermal_sys.c: thermal_zone_device_set_polling()
> simplified. Note that round_jiffies() calls in this function are
> meaningless. round_jiffies() work on absolute jiffies not delta
> delay used by delayed_work.
>
> v2: Tomi pointed out that __cancel_delayed_work() users can't be
> safely converted to mod_delayed_work(). They could be calling it
> from irq context and if that happens while delayed_work_timer_fn()
> is running, it could deadlock. __cancel_delayed_work() users are
> dropped.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
prev parent reply other threads:[~2012-08-13 13:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-03 17:43 Tejun Heo
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 ` David Howells [this message]
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