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

[Jason Gunthorpe <jgg@mellanox.com>]

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