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,
Tejun Heo <tj@kernel.org>
Subject: [PATCH 13/14] workqueue: implement mod_delayed_work[_on]()
Date: Fri, 3 Aug 2012 10:43:58 -0700 [thread overview]
Message-ID: <1344015839-21800-14-git-send-email-tj@kernel.org> (raw)
In-Reply-To: <1344015839-21800-1-git-send-email-tj@kernel.org>
Workqueue was lacking a mechanism to modify the timeout of an already
pending delayed_work. 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.
This patch implements mod_delayed_work[_on]() which behaves similarly
to mod_timer() - if the delayed_work is idle, it's queued with the
given delay; otherwise, its timeout is modified to the new value.
Zero @delay guarantees immediate execution.
v2: Updated to reflect try_to_grab_pending() changes. Now safe to be
called from bh context.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
---
include/linux/workqueue.h | 4 +++
kernel/workqueue.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 57 insertions(+), 0 deletions(-)
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 5f4aeaa..2000030 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -390,6 +390,10 @@ extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
struct delayed_work *work, unsigned long delay);
extern bool queue_delayed_work(struct workqueue_struct *wq,
struct delayed_work *work, unsigned long delay);
+extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
+ struct delayed_work *dwork, unsigned long delay);
+extern bool mod_delayed_work(struct workqueue_struct *wq,
+ struct delayed_work *dwork, unsigned long delay);
extern void flush_workqueue(struct workqueue_struct *wq);
extern void drain_workqueue(struct workqueue_struct *wq);
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index b4a4e05..41ae2c0 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1414,6 +1414,59 @@ bool queue_delayed_work(struct workqueue_struct *wq,
EXPORT_SYMBOL_GPL(queue_delayed_work);
/**
+ * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
+ * @cpu: CPU number to execute work on
+ * @wq: workqueue to use
+ * @dwork: work to queue
+ * @delay: number of jiffies to wait before queueing
+ *
+ * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
+ * modify @dwork's timer so that it expires after @delay. If @delay is
+ * zero, @work is guaranteed to be scheduled immediately regardless of its
+ * current state.
+ *
+ * Returns %false if @dwork was idle and queued, %true if @dwork was
+ * pending and its timer was modified.
+ *
+ * This function is safe to call from any context other than IRQ handler.
+ * See try_to_grab_pending() for details.
+ */
+bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
+ struct delayed_work *dwork, unsigned long delay)
+{
+ unsigned long flags;
+ int ret;
+
+ do {
+ ret = try_to_grab_pending(&dwork->work, true, &flags);
+ } while (unlikely(ret == -EAGAIN));
+
+ if (likely(ret >= 0)) {
+ __queue_delayed_work(cpu, wq, dwork, delay);
+ local_irq_restore(flags);
+ }
+
+ /* -ENOENT from try_to_grab_pending() becomes %true */
+ return ret;
+}
+EXPORT_SYMBOL_GPL(mod_delayed_work_on);
+
+/**
+ * mod_delayed_work - modify delay of or queue a delayed work
+ * @wq: workqueue to use
+ * @dwork: work to queue
+ * @delay: number of jiffies to wait before queueing
+ *
+ * mod_delayed_work_on() on local CPU.
+ */
+bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork,
+ unsigned long delay)
+{
+ return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
+}
+EXPORT_SYMBOL_GPL(mod_delayed_work);
+
+/**
* worker_enter_idle - enter idle state
* @worker: worker which is entering idle state
*
--
1.7.7.3
next prev parent reply other threads:[~2012-08-03 17:45 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 ` Tejun Heo [this message]
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
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