workqueue: implement mod_delayed_work[_on]()
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>
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@ -390,6 +390,10 @@ extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
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struct delayed_work *work, unsigned long delay);
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extern bool queue_delayed_work(struct workqueue_struct *wq,
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struct delayed_work *work, unsigned long delay);
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extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
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struct delayed_work *dwork, unsigned long delay);
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extern bool mod_delayed_work(struct workqueue_struct *wq,
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struct delayed_work *dwork, unsigned long delay);
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extern void flush_workqueue(struct workqueue_struct *wq);
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extern void drain_workqueue(struct workqueue_struct *wq);
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@ -1413,6 +1413,59 @@ bool queue_delayed_work(struct workqueue_struct *wq,
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}
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EXPORT_SYMBOL_GPL(queue_delayed_work);
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/**
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* mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
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* @cpu: CPU number to execute work on
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* @wq: workqueue to use
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* @dwork: work to queue
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* @delay: number of jiffies to wait before queueing
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*
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* If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
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* modify @dwork's timer so that it expires after @delay. If @delay is
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* zero, @work is guaranteed to be scheduled immediately regardless of its
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* current state.
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*
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* Returns %false if @dwork was idle and queued, %true if @dwork was
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* pending and its timer was modified.
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*
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* This function is safe to call from any context other than IRQ handler.
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* See try_to_grab_pending() for details.
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*/
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bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
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struct delayed_work *dwork, unsigned long delay)
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{
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unsigned long flags;
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int ret;
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do {
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ret = try_to_grab_pending(&dwork->work, true, &flags);
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} while (unlikely(ret == -EAGAIN));
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if (likely(ret >= 0)) {
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__queue_delayed_work(cpu, wq, dwork, delay);
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local_irq_restore(flags);
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}
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/* -ENOENT from try_to_grab_pending() becomes %true */
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return ret;
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}
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EXPORT_SYMBOL_GPL(mod_delayed_work_on);
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/**
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* mod_delayed_work - modify delay of or queue a delayed work
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* @wq: workqueue to use
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* @dwork: work to queue
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* @delay: number of jiffies to wait before queueing
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*
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* mod_delayed_work_on() on local CPU.
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*/
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bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork,
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unsigned long delay)
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{
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return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
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}
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EXPORT_SYMBOL_GPL(mod_delayed_work);
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/**
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* worker_enter_idle - enter idle state
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* @worker: worker which is entering idle state
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