The patch titled
Subject: kthread: allow to modify delayed kthread work
has been added to the -mm tree. Its filename is
kthread-allow-to-modify-delayed-kthread-work.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kthread-allow-to-modify-delayed-kthread-work.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kthread-allow-to-modify-delayed-kthread-work.patch
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------------------------------------------------------
From: Petr Mladek <pmladek@xxxxxxxx>
Subject: kthread: allow to modify delayed kthread work
There are situations when we need to modify the delay of a delayed kthread
work. For example, when the work depends on an event and the initial delay
means a timeout. Then we want to queue the work immediately when the event
happens.
This patch implements kthread_mod_delayed_work() as inspired workqueues.
It cancels the timer, removes the work from any worker list and queues it
again with the given timeout.
A very special case is when the work is being canceled at the same time.
It might happen because of the regular kthread_cancel_delayed_work_sync()
or by another kthread_mod_delayed_work(). In this case, we do nothing and
let the other operation win. This should not normally happen as the caller
is supposed to synchronize these operations a reasonable way.
Link: http://lkml.kernel.org/r/1470754545-17632-11-git-send-email-pmladek@xxxxxxxx
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Jiri Kosina <jkosina@xxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kthread.h | 4 ++
kernel/kthread.c | 53 ++++++++++++++++++++++++++++++++++++++
2 files changed, 57 insertions(+)
diff -puN include/linux/kthread.h~kthread-allow-to-modify-delayed-kthread-work include/linux/kthread.h
--- a/include/linux/kthread.h~kthread-allow-to-modify-delayed-kthread-work
+++ a/include/linux/kthread.h
@@ -168,6 +168,10 @@ bool kthread_queue_delayed_work(struct k
struct kthread_delayed_work *dwork,
unsigned long delay);
+bool kthread_mod_delayed_work(struct kthread_worker *worker,
+ struct kthread_delayed_work *dwork,
+ unsigned long delay);
+
void kthread_flush_work(struct kthread_work *work);
void kthread_flush_worker(struct kthread_worker *worker);
diff -puN kernel/kthread.c~kthread-allow-to-modify-delayed-kthread-work kernel/kthread.c
--- a/kernel/kthread.c~kthread-allow-to-modify-delayed-kthread-work
+++ a/kernel/kthread.c
@@ -972,6 +972,59 @@ static bool __kthread_cancel_work(struct
return false;
}
+/**
+ * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
+ * @worker: kthread worker to use
+ * @dwork: kthread delayed work to queue
+ * @delay: number of jiffies to wait before queuing
+ *
+ * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
+ * modify @dwork's timer so that it expires after @delay. If @delay is zero,
+ * @work is guaranteed to be queued immediately.
+ *
+ * Return: %true if @dwork was pending and its timer was modified,
+ * %false otherwise.
+ *
+ * A special case is when the work is being canceled in parallel.
+ * It might be caused either by the real kthread_cancel_delayed_work_sync()
+ * or yet another kthread_mod_delayed_work() call. We let the other command
+ * win and return %false here. The caller is supposed to synchronize these
+ * operations a reasonable way.
+ *
+ * This function is safe to call from any context including IRQ handler.
+ * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
+ * for details.
+ */
+bool kthread_mod_delayed_work(struct kthread_worker *worker,
+ struct kthread_delayed_work *dwork,
+ unsigned long delay)
+{
+ struct kthread_work *work = &dwork->work;
+ unsigned long flags;
+ int ret = false;
+
+ spin_lock_irqsave(&worker->lock, flags);
+
+ /* Do not bother with canceling when never queued. */
+ if (!work->worker)
+ goto fast_queue;
+
+ /* Work must not be used with >1 worker, see kthread_queue_work() */
+ WARN_ON_ONCE(work->worker != worker);
+
+ /* Do not fight with another command that is canceling this work. */
+ if (work->canceling)
+ goto out;
+
+ ret = __kthread_cancel_work(work, true, &flags);
+fast_queue:
+ __kthread_queue_delayed_work(worker, dwork, delay);
+out:
+ spin_unlock_irqrestore(&worker->lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kthread_mod_delayed_work);
+
static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork)
{
struct kthread_worker *worker = work->worker;
_
Patches currently in -mm which might be from pmladek@xxxxxxxx are
kthread-rename-probe_kthread_data-to-kthread_probe_data.patch
kthread-kthread-worker-api-cleanup.patch
kthread-smpboot-do-not-park-in-kthread_create_on_cpu.patch
kthread-allow-to-call-__kthread_create_on_node-with-va_list-args.patch
kthread-add-kthread_create_worker.patch
kthread-add-kthread_destroy_worker.patch
kthread-detect-when-a-kthread-work-is-used-by-more-workers.patch
kthread-initial-support-for-delayed-kthread-work.patch
kthread-allow-to-cancel-kthread-work.patch
kthread-allow-to-modify-delayed-kthread-work.patch
kthread-better-support-freezable-kthread-workers.patch
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