Subject: Re: [PATCH v6 00/11] PCI: Drop duplicated tracking of a pci_dev's bound driver

From: Bjorn Helgaas <[email-masked]>
Date: Wed, 13 Oct 2021 05:54:28 -0500

On Wed, Oct 13, 2021 at 10:51:31AM +0200, Uwe Kleine-König wrote:
> On Tue, Oct 12, 2021 at 06:32:12PM -0500, Bjorn Helgaas wrote:
> > On Mon, Oct 04, 2021 at 02:59:24PM +0200, Uwe Kleine-König wrote:
> > > Hello,
> > > 
> > > this is v6 of the quest to drop the "driver" member from struct pci_dev
> > > which tracks the same data (apart from a constant offset) as dev.driver.
> > 
> > I like this a lot and applied it to pci/driver for v5.16, thanks!
> > 
> > I split some of the bigger patches apart so they only touched one
> > driver or subsystem at a time.  I also updated to_pci_driver() so it
> > returns NULL when given NULL, which makes some of the validations
> > quite a bit simpler, especially in the PM code in pci-driver.c.
> 
> OK.
> 
> > Full interdiff from this v6 series:
> > 
> > diff --git a/arch/x86/kernel/probe_roms.c b/arch/x86/kernel/probe_roms.c
> > index deaaef6efe34..36e84d904260 100644
> > --- a/arch/x86/kernel/probe_roms.c
> > +++ b/arch/x86/kernel/probe_roms.c
> > @@ -80,17 +80,15 @@ static struct resource video_rom_resource = {
> >   */
> >  static bool match_id(struct pci_dev *pdev, unsigned short vendor, unsigned short device)
> >  {
> > +	struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
> >  	const struct pci_device_id *id;
> >  
> >  	if (pdev->vendor == vendor && pdev->device == device)
> >  		return true;
> >  
> > -	if (pdev->dev.driver) {
> > -		struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
> > -		for (id = drv->id_table; id && id->vendor; id++)
> > -			if (id->vendor == vendor && id->device == device)
> > -				break;
> > -	}
> > +	for (id = drv ? drv->id_table : NULL; id && id->vendor; id++)
> > +		if (id->vendor == vendor && id->device == device)
> > +			break;
> >  
> >  	return id && id->vendor;
> >  }
> > diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
> > index d997c9c3ebb5..7eb3706cf42d 100644
> > --- a/drivers/misc/cxl/guest.c
> > +++ b/drivers/misc/cxl/guest.c
> > @@ -20,38 +20,38 @@ static void pci_error_handlers(struct cxl_afu *afu,
> >  				pci_channel_state_t state)
> >  {
> >  	struct pci_dev *afu_dev;
> > +	struct pci_driver *afu_drv;
> > +	struct pci_error_handlers *err_handler;
> 
> These two could be moved into the for loop (where afu_drv was with my
> patch already). This is also possible in a few other drivers.

That's true, they could.  I tried to follow the prevailing style in
the file.  At least in cxl, I didn't see any other cases of
declarations being in the minimal scope like that.

Bjorn