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

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Oct 13, 2021 at 04:23:09PM +0300, Andy Shevchenko wrote:
> On Wed, Oct 13, 2021 at 06:33:56AM -0500, Bjorn Helgaas wrote:
> > On Wed, Oct 13, 2021 at 12:26:42PM +0300, Andy Shevchenko wrote:
> > > On Wed, Oct 13, 2021 at 2:33 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > > On Mon, Oct 04, 2021 at 02:59:24PM +0200, Uwe Kleine-König wrote:

> > > > +       return drv && drv->resume ?
> > > > +                       drv->resume(pci_dev) : pci_pm_reenable_device(pci_dev);
> > > 
> > > One line?
> > 
> > I don't think I touched that line.
> 
> Then why they are both in + section?

They're both in the + section of the interdiff because Uwe's v6 patch
looks like this:

  static int pci_legacy_resume(struct device *dev)
  {
          struct pci_dev *pci_dev = to_pci_dev(dev);
  -       return drv && drv->resume ?
  -                       drv->resume(pci_dev) : pci_pm_reenable_device(pci_dev);
  +       if (pci_dev->dev.driver) {
  +               struct pci_driver *drv = to_pci_driver(pci_dev->dev.driver);
  +
  +               if (drv->resume)
  +                       return drv->resume(pci_dev);
  +       }
  +
  +       return pci_pm_reenable_device(pci_dev);

and my revision looks like this:

   static int pci_legacy_resume(struct device *dev)
   {
	  struct pci_dev *pci_dev = to_pci_dev(dev);
  -       struct pci_driver *drv = pci_dev->driver;
  +       struct pci_driver *drv = to_pci_driver(dev->driver);

so compared to Uwe's v6, I restored that section to the original code.
My goal here was to make the patch as simple and easy to review as
possible.

> > > > +       struct pci_driver *drv = to_pci_driver(dev->dev.driver);
> > > >         const struct pci_error_handlers *err_handler =
> > > > -                       dev->dev.driver ? to_pci_driver(dev->dev.driver)->err_handler : NULL;
> > > > +                       drv ? drv->err_handler : NULL;
> > > 
> > > Isn't dev->driver == to_pci_driver(dev->dev.driver)?
> > 
> > Yes, I think so, but not sure what you're getting at here, can you
> > elaborate?
> 
> Getting pointer from another pointer seems waste of resources, why we
> can't simply
> 
> 	struct pci_driver *drv = dev->driver;

I think this is in pci_dev_save_and_disable(), and "dev" here is a
struct pci_dev *.  We're removing the dev->driver member.  Let me know
if I'm still missing something.

> > > > -                               "bad request in aer recovery "
> > > > -                               "operation!\n");
> > > > +                               "bad request in AER recovery operation!\n");

> > > Stray change? Or is it in a separate patch in your tree?
> > 
> > Could be skipped.  The string now fits on one line so I combined it to
> > make it more greppable.
> 
> This is inconsistency in your changes, in one case you are objecting of
> doing something close to the changed lines, in the other you are doing
> unrelated change.

You're right, this didn't make much sense in that patch.  I moved the
line join to the previous patch, which unindented this section and
made space for this to fit on one line.  Here's the revised commit:

  https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/commit/?id=34ab316d7287