Query on workqueue

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 [off-list ref]:

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.

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