Query on workqueue

Query on workqueue

[Victor Ascroft]

Hello,

Is it ok to use wait_for_completion in a workqueue? 

static void my_work(struct work_struct *work)
{

	while (true)
	{
		wait_for_completion(completion);
		
		// Do something here

		reinit_completion(completion);
		enable_irq(irq);
	}
}

static irqreturn_t my_irq_handler(int irq, void *dev)
{
	disable_irq(irq);

	complete(completion);

	return IRQ_HANDLED;
}

Something like the above is what I have. Is it a correct way to 
do things or complete idiotic brainfart. Workqueues can sleep so
I thought of the above code, but, was not sure.

And I am not using _interruptible or _interruptible_timeout because
I absolutely want it to wait for the IRQ. Now as such though this 
works I get stack traces with hung task complaining and I have
to set /proc/sys/kernel/hung_task_timeout_secs to 0. And were the IRQ
not generated I do get NMI watchdog hang.

I will accept I have only little knowledge of these things.

Regards,
Victor.

Query on workqueue

[Dave Tian]

If you have to wait for the IRQ to be finished, do NOT use work queue, which belongs to bottom half. Just write your own IRQ handler, do sth there and register your handler.

-daveti


> On Jan 13, 2015, at 8:51 AM, Victor Ascroft <victorascroft@gmail.com> wrote:
> 
> Hello,
> 
> Is it ok to use wait_for_completion in a workqueue? 
> 
> static void my_work(struct work_struct *work)
> {
> 
> 	while (true)
> 	{
> 		wait_for_completion(completion);
> 		
> 		// Do something here
> 
> 		reinit_completion(completion);
> 		enable_irq(irq);
> 	}
> }
> 
> static irqreturn_t my_irq_handler(int irq, void *dev)
> {
> 	disable_irq(irq);
> 
> 	complete(completion);
> 
> 	return IRQ_HANDLED;
> }
> 
> Something like the above is what I have. Is it a correct way to 
> do things or complete idiotic brainfart. Workqueues can sleep so
> I thought of the above code, but, was not sure.
> 
> And I am not using _interruptible or _interruptible_timeout because
> I absolutely want it to wait for the IRQ. Now as such though this 
> works I get stack traces with hung task complaining and I have
> to set /proc/sys/kernel/hung_task_timeout_secs to 0. And were the IRQ
> not generated I do get NMI watchdog hang.
> 
> I will accept I have only little knowledge of these things.
> 
> Regards,
> Victor.
> 
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Query on workqueue

[Richard Maciel Costa]

Hi Victor,

I don't think it's a good idea to block an entire IRQ line for so much time
(i.e. until a work queue runs), unless you're sure you're the sole user of
it.

How about you try a more traditional approach and make the IRQ handler
schedule a work queue after it completes?

Or, if you need to run as fast as possible, why don't you create a tasklet?
Remember that you can't sleep in this case.

- Richard

2015-01-13 11:51 GMT-02:00 Victor Ascroft <victorascroft@gmail.com>:

> Hello,
>
> Is it ok to use wait_for_completion in a workqueue?
>
> static void my_work(struct work_struct *work)
> {
>
>         while (true)
>         {
>                 wait_for_completion(completion);
>
>                 // Do something here
>
>                 reinit_completion(completion);
>                 enable_irq(irq);
>         }
> }
>
> static irqreturn_t my_irq_handler(int irq, void *dev)
> {
>         disable_irq(irq);
>
>         complete(completion);
>
>         return IRQ_HANDLED;
> }
>
> Something like the above is what I have. Is it a correct way to
> do things or complete idiotic brainfart. Workqueues can sleep so
> I thought of the above code, but, was not sure.
>
> And I am not using _interruptible or _interruptible_timeout because
> I absolutely want it to wait for the IRQ. Now as such though this
> works I get stack traces with hung task complaining and I have
> to set /proc/sys/kernel/hung_task_timeout_secs to 0. And were the IRQ
> not generated I do get NMI watchdog hang.
>
> I will accept I have only little knowledge of these things.
>
> Regards,
> Victor.
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
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