linux-kernel - Re: Calling queue_work() multiple times with the same work

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Date:   Thu, 20 May 2021 13:01:25 -0400
From:   Tejun Heo <tj@...nel.org>
To:     Jason Andryuk <jandryuk@...il.com>
Cc:     Lai Jiangshan <jiangshanlai@...il.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: Calling queue_work() multiple times with the same work_struct

Hello, Jason.

On Thu, May 20, 2021 at 08:39:56AM -0400, Jason Andryuk wrote:
> 1 & 2 look supported from workqueue.h.  Is the 3rd case true and
> guaranteed?  Is it okay to re-use the same work_struct in that case

Yes.

> while it's being executed?  A work_struct function can re-queue

Yes.

> itself, so I hope #3 is supported.

Yes.

> DECLARE_WORK(argo_work, argo_work_fn);
> static struct workqueue_struct *argo_wq = alloc_workqueue("argo_wq",
>                     WQ_UNBOUND | WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_SYSFS, 1);

I don't know what the device is but does it need both HIGHPRI and
CPU_INTENSIVE?

> static void argo_work_fn(struct work_struct *work)
> {
>     argo_interrupt_rx();  /* iterates multiple "rings" */
>     argo_notify();
> }
> 
> static irqreturn_t argo_interrupt(int irq, void *dev_id)
> {
>     queue_work(argo_wq, &argo_work);
> 
>     return IRQ_HANDLED;
> }

Yeah, the above will guarantee that the work function would run at least
once since the last invocation of argo_interrupt().

Thanks.

-- 
tejun