Re: [PATCH V8 9/9] virtio: Intel IFC VF driver for VDPA

Jason Gunthorpe
2020-03-26T12:17:21Z

On Thu, Mar 26, 2020 at 01:50:53PM +0800, Jason Wang wrote:

> > > + adapter->vdpa.dma_dev = dev;
> > > + ret = vdpa_register_device(&adapter->vdpa);
> > > + if (ret) {
> > > + IFCVF_ERR(adapter->dev, "Failed to register ifcvf to vdpa bus");
> > > + goto err_msix;
> > > + }
> > > +
> > > + return 0;
> > > +
> > > +err_msix:
> > > + put_device(&adapter->vdpa.dev);
> > > + return ret;
> > > +err_alloc:
> > > + pci_free_irq_vectors(pdev);
> > > +err_vectors:
> > > + pci_release_regions(pdev);
> > > +err_regions:
> > > + pci_disable_device(pdev);
> > > +err_enable:
> > > + return ret;
> > > +}
> > I personally don't like seeing goto unwinds with multiple returns, and
> > here I think it is actually a tiny bug.
> >
> > All touches to the PCI device must stop before the driver core
> > remove() returns - so these pci function cannot be in the kref put
> > release function anyhow.
>
>
> I'm not sure I get here. IFCVF held refcnt of its PCI parent, so it looks to
> me it's safe to free PCI resources in vDPA free callback?

The refcnt doesn't prevent the driver core from re-binding the
pci_device to another driver. Then the refcount put would do a
pci_disable_device() after another driver has started

For this reason all touches to a struct pci_device must stop before
remove returns.

Jason