netdev - Re: [PATCH v6 net-next 07/19] ionic: Add basic adminq support

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Date:   Fri, 30 Aug 2019 15:16:04 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Shannon Nelson <snelson@...sando.io>
Cc:     netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH v6 net-next 07/19] ionic: Add basic adminq support

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?