From: Jakub Kicinski <jakub.kicin...@netronome.com>
Date: Fri, 30 Aug 2019 15:16:04 -0700
> On Fri, 30 Aug 2019 12:31:07 -0700, Shannon Nelson wrote:
>> On 8/29/19 3:52 PM, Jakub Kicinski wrote:
>> > On Thu, 29 Aug 2019 11:27:08 -0700, Shannon Nelson wrote:
>> >> +static void ionic_lif_qcq_deinit(struct ionic_lif *lif, struct ionic_qcq
>> >> *qcq)
>> >> +{
>> >> + struct ionic_dev *idev = &lif->ionic->idev;
>> >> + struct device *dev = lif->ionic->dev;
>> >> +
>> >> + if (!qcq)
>> >> + return;
>> >> +
>> >> + ionic_debugfs_del_qcq(qcq);
>> >> +
>> >> + if (!(qcq->flags & IONIC_QCQ_F_INITED))
>> >> + return;
>> >> +
>> >> + if (qcq->flags & IONIC_QCQ_F_INTR) {
>> >> + ionic_intr_mask(idev->intr_ctrl, qcq->intr.index,
>> >> + IONIC_INTR_MASK_SET);
>> >> + synchronize_irq(qcq->intr.vector);
>> >> + devm_free_irq(dev, qcq->intr.vector, &qcq->napi);
>> > Doesn't free_irq() basically imply synchronize_irq()?
>>
>> The synchronize_irq() waits for any threaded handlers to finish, while
>> free_irq() only waits for HW handling. This helps makes sure we don't
>> have anything still running before we remove resources.
>
> mm.. I'm no IRQ expert but it strikes me as surprising as that'd mean
> every single driver would always have to run synchronize_irq() on
> module exit, no?
>
> I see there is a kthread_stop() in __free_irq(), you sure it doesn't
> wait for threaded IRQs?
I'm pretty sure it does.
