Re: [PATCH] uio: add irq control support to uio_pci_generic

Michael S. Tsirkin
2015-04-16T07:43:28Z

On Wed, Apr 15, 2015 at 09:59:34AM -0700, Stephen Hemminger wrote:
> The driver already supported INTX interrupts but had no in kernel
> function to enable and disable them.
>
> It is possible for userspace to do this by accessing PCI config
> directly, but this racy

How is it racy? We have userspace using this interface,
if there's a race I want to fix it.

> and better handled by same mechanism
> that already exists in kernel.
>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
>
>
> --- a/drivers/uio/uio_pci_generic.c 2015-04-15 08:50:15.543900681 -0700
> +++ b/drivers/uio/uio_pci_generic.c 2015-04-15 09:00:01.658609786 -0700
> @@ -53,6 +53,18 @@ static irqreturn_t irqhandler(int irq, s
> return IRQ_HANDLED;
> }
>
> +static int irqcontrol(struct uio_info *info, s32 irq_on)
> +{
> + struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
> + struct pci_dev *pdev = gdev->pdev;
> +
> + pci_cfg_access_lock(pdev);
> + pci_intx(pdev, irq_on);
> + pci_cfg_access_unlock(pdev);
> +
> + return 0;
> +}
> +
> static int probe(struct pci_dev *pdev,
> const struct pci_device_id *id)
> {
> @@ -89,6 +101,7 @@ static int probe(struct pci_dev *pdev,
> gdev->info.irq = pdev->irq;
> gdev->info.irq_flags = IRQF_SHARED;
> gdev->info.handler = irqhandler;
> + gdev->info.irqcontrol = irqcontrol;
> gdev->pdev = pdev;
>
> err = uio_register_device(&pdev->dev, &gdev->info);