On Wed, Oct 13, 2021 at 12:26:42PM +0300, Andy Shevchenko wrote:

On Wed, Oct 13, 2021 at 2:33 AM Bjorn Helgaas [off-list ref] wrote:

quoted

On Mon, Oct 04, 2021 at 02:59:24PM +0200, Uwe Kleine-König wrote:

quoted

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.

It's a bit unusual. Other to_*_dev() are not NULL-aware IIRC.

It is a little unusual.  I only found three of 77 that are NULL-aware:

  to_moxtet_driver()
  to_siox_driver()
  to_spi_driver()

It seems worthwhile to me because it makes the patch and the resulting
code significantly cleaner.  Here's one example without the NULL
check:

  @@ -493,12 +493,15 @@ static void pci_device_remove(struct device *dev)
   static void pci_device_shutdown(struct device *dev)
   {
          struct pci_dev *pci_dev = to_pci_dev(dev);
  -       struct pci_driver *drv = pci_dev->driver;

          pm_runtime_resume(dev);

  -       if (drv && drv->shutdown)
  -               drv->shutdown(pci_dev);
  +       if (pci_dev->dev.driver) {
  +               struct pci_driver *drv = to_pci_driver(pci_dev->dev.driver);
  +
  +               if (drv->shutdown)
  +                       drv->shutdown(pci_dev);
  +       }

  static void pci_device_shutdown(struct device *dev)
  {
    struct pci_dev *pci_dev = to_pci_dev(dev);

    pm_runtime_resume(dev);

    if (pci_dev->dev.driver) {
      struct pci_driver *drv = to_pci_driver(pci_dev->dev.driver);

      if (drv->shutdown)
        drv->shutdown(pci_dev);
    }

and here's the same thing with the NULL check:

  @@ -493,7 +493,7 @@ static void pci_device_remove(struct device *dev)
   static void pci_device_shutdown(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);

  static void pci_device_shutdown(struct device *dev)
  {
    struct pci_dev *pci_dev = to_pci_dev(dev);
    struct pci_driver *drv = to_pci_driver(dev->driver);

    pm_runtime_resume(dev);

    if (drv && drv->shutdown)
      drv->shutdown(pci_dev);

quoted

 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;

quoted

+       for (id = drv ? drv->id_table : NULL; id && id->vendor; id++)
+               if (id->vendor == vendor && id->device == device)

quoted

+                       break;

return true;

quoted

        return id && id->vendor;

return false;

Good cleanup for a follow-up patch, but doesn't seem directly related
to the objective here.  The current patch is:

  @@ -80,7 +80,7 @@ static struct resource video_rom_resource = {
    */
   static bool match_id(struct pci_dev *pdev, unsigned short vendor, unsigned short device)
   {
  -       struct pci_driver *drv = pdev->driver;
  +       struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
          const struct pci_device_id *id;

          if (pdev->vendor == vendor && pdev->device == device)

quoted

        device_lock(&vf_dev->dev);
-       if (vf_dev->dev.driver) {
+       if (to_pci_driver(vf_dev->dev.driver)) {

Hmm...

Yeah, it could be either of:

  if (to_pci_driver(vf_dev->dev.driver))
  if (vf_dev->dev.driver)

I went back and forth on that and went with to_pci_driver() on the
theory that we were testing the pci_driver * before and the patch is
more of a mechanical change and easier to review if we test the
pci_driver * after.

quoted

+               if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0

quoted

+                   && pci_dev->current_state != PCI_UNKNOWN) {

Can we keep && on the previous line?

I think this is in pci_legacy_suspend(), and I didn't touch that line.
It shows up in the interdiff because without the NULL check in
to_pci_driver(), we had to indent this code another level.  With the
NULL check, we don't need that extra indentation.

quoted

+                       pci_WARN_ONCE(pci_dev, pci_dev->current_state != prev,
+                                     "PCI PM: Device state not saved by %pS\n",
+                                     drv->suspend);
                }

...

quoted

+       return drv && drv->resume ?
+                       drv->resume(pci_dev) : pci_pm_reenable_device(pci_dev);

One line?

I don't think I touched that line.

quoted

+       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?

quoted

        device_lock(&dev->dev);
+       pdrv = to_pci_driver(dev->dev.driver);
        if (!pci_dev_set_io_state(dev, state) ||
-               !dev->dev.driver ||
-               !(pdrv = to_pci_driver(dev->dev.driver))->err_handler ||

quoted

+               !pdrv ||
+               !pdrv->err_handler ||

One line now?

quoted

                !pdrv->err_handler->error_detected) {

Or this and the previous line?

Could, but the "dev->driver" to "to_pci_driver(dev->dev.driver)"
changes are the heart of this patch, and I don't like to clutter it
with unrelated changes.

quoted

-       result = PCI_ERS_RESULT_NONE;

        pcidev = pci_get_domain_bus_and_slot(domain, bus, devfn);
        if (!pcidev || !pcidev->dev.driver) {
                dev_err(&pdev->xdev->dev, "device or AER driver is NULL\n");
                pci_dev_put(pcidev);
-               return result;
+               return PCI_ERS_RESULT_NONE;
        }
        pdrv = to_pci_driver(pcidev->dev.driver);

What about splitting the conditional to two with clear error message
in each and use pci_err() in the second one?

Could possibly be cleaned up.  Felt like feature creep so I didn't.

quoted

                default:
                        dev_err(&pdev->xdev->dev,
-                               "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.

Bjorn