Hello,
On Mon, Jan 25, 2016 at 04:44:57PM +0100, Petr Mladek wrote:
> +/*
> + * Returns true when there is a pending operation for this work.
> + * In particular, it checks if the work is:
> + * - queued
> + * - a timer is running to queue this delayed work
> + *
> + * This function must be called with locked work.
> + */
> +static inline bool kthread_work_pending(const struct kthread_work *work)
> +{
> + return !list_empty(&work->node) ||
> + (work->timer && timer_active(work->timer));
> +}
Why not just put the work item on a separate list so that
lits_empty(&work->node) is always enough? IOW, put delayed work items
on timers on worker->delayed or sth.
> +/*
> + * Queue @work right into the worker queue.
> + */
> +static void __queue_kthread_work(struct kthread_worker *worker,
> + struct kthread_work *work)
> +{
> + insert_kthread_work(worker, work, &worker->work_list);
> +}
Does this really need to be an inline function? This sort of one
liner helpers tend to be obfuscating more than anything else.
> @@ -756,6 +779,121 @@ bool queue_kthread_work(struct kthread_worker *worker,
> }
> EXPORT_SYMBOL_GPL(queue_kthread_work);
>
> +static bool try_lock_kthread_work(struct kthread_work *work)
> +{
> + struct kthread_worker *worker;
> + int ret = false;
> +
> +try_again:
> + worker = work->worker;
> +
> + if (!worker)
> + goto out;
return false;
> +
> + spin_lock(&worker->lock);
> + if (worker != work->worker) {
> + spin_unlock(&worker->lock);
> + goto try_again;
> + }
return true;
> + ret = true;
> +
> +out:
> + return ret;
> +}
Stop building unnecessary structures. Keep it simple.
> +static inline void unlock_kthread_work(struct kthread_work *work)
> +{
> + spin_unlock(&work->worker->lock);
> +}
Ditto. Just open code it. It doesn't add anything.
> +/**
> + * delayed_kthread_work_timer_fn - callback that queues the associated delayed
> + * kthread work when the timer expires.
> + * @__data: pointer to the data associated with the timer
> + *
> + * The format of the function is defined by struct timer_list.
> + * It should have been called from irqsafe timer with irq already off.
> + */
> +void delayed_kthread_work_timer_fn(unsigned long __data)
> +{
> + struct delayed_kthread_work *dwork =
> + (struct delayed_kthread_work *)__data;
> + struct kthread_work *work = &dwork->work;
> +
> + if (!try_lock_kthread_work(work))
Can you please explain why try_lock is necessary here? That's the
most important and non-obvious thing going on here and there's no
explanation of that at all.
Thanks.
--
tejun
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