Re: [Xen-devel] xl/SR-IOV: disposition of VFs when PF disappears?

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Oct 28, 2014 at 04:25:16PM +0000, Jan Beulich wrote:
> >>> On 28.10.14 at 16:18, <JBeulich@xxxxxxxx> wrote:
> > That flag doesn't inhibit the PF driver unloading. It only suppresses
> > it freeing the VFs in that process (and afaics nothing will ever allow
> > them to be released subsequently in that case). I'm about to test a
> > change to pciback (it's building right now).
> 
> Attached a raw patch for you or anyone else to comment on from
> a conceptual perspective. The main thing probably is to determine
> whether any further serialization needs to be added.
> 
> Jan
> 

> --- sle12.orig/drivers/xen/xen-pciback/pci_stub.c
> +++ sle12/drivers/xen/xen-pciback/pci_stub.c
> @@ -1502,6 +1502,44 @@ parse_error:
>  fs_initcall(pcistub_init);
>  #endif
>  
> +#ifdef CONFIG_PCI_IOV
> +static int pci_stub_notifier(struct notifier_block *nb,
> +                          unsigned long action, void *data)
> +{
> +     struct device *dev = data;
> +     struct pci_dev *pdev = to_pci_dev(dev);
> +
> +     switch (action) {
> +     case BUS_NOTIFY_UNBIND_DRIVER:
> +             for (;;) {
> +                     struct pcistub_device *psdev;
> +                     unsigned long flags;
> +                     bool found = false;
> +
> +                     spin_lock_irqsave(&pcistub_devices_lock, flags);
> +
> +                     list_for_each_entry(psdev, &pcistub_devices, dev_list)
> +                             if (!psdev->pdev && psdev->dev != pdev
> +                                 && pci_physfn(psdev->dev) == pdev) {
> +                                     found = true;
> +                                     break;
> +                             }
> +                     spin_unlock_irqrestore(&pcistub_devices_lock, flags);

There are existing functions in the PCI back driver to find an device based
on the 'struct pci_dev'.

That should make this piece of code much simpler by just looking for it
and if found call the 'device_release_driver'.

However I am not entirely sure what ought to be done if the VF is
in _use_ ? Should we still do it?

> +                     if (!found)
> +                             break;
> +                     device_release_driver(&psdev->dev->dev);
> +             }
> +             break;
> +     }
> +
> +     return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block pci_stub_nb = {
> +     .notifier_call = pci_stub_notifier,
> +};
> +#endif
> +
>  static int __init xen_pcibk_init(void)
>  {
>       int err;
> @@ -1523,6 +1561,10 @@ static int __init xen_pcibk_init(void)
>       err = xen_pcibk_xenbus_register();
>       if (err)
>               pcistub_exit();
> +#ifdef CONFIG_PCI_IOV
> +     else
> +             bus_register_notifier(&pci_bus_type, &pci_stub_nb);
> +#endif
>  
>       return err;
>  }


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