linux-kernel - Re: [PATCH] pci: Don't call resume callback for nearly bound devices

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Date:   Mon, 8 Nov 2021 22:36:49 +0100
From:   Robert Święcki <robert@...ecki.net>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Bjorn Helgaas <helgaas@...nel.org>, linux-i2c@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pci: Don't call resume callback for nearly bound devices

Hi all,

> > Here's the call tree:
> >
> >     really_probe
> >       dev->driver = drv;                       # <--
> >       call_driver_probe
> >         dev->bus->probe
> >           pci_device_probe
> >             __pci_device_probe
> >               pci_call_probe
> >                 local_pci_probe
> >                   pm_runtime_get_sync
> >                     ...
> >                     pci_pm_runtime_resume
> >   -                   if (!pci_dev->driver)    # 2a4d9408c9e8 ("PCI: Use to_pci_driver() instead of pci_dev->driver")
> >   +                   if (!to_pci_driver(dev->driver))
> >                         return 0
> >                       pm->runtime_resume
> >                         i2c_dw_pci_resume
> >                           i_dev->init()        # <-- NULL ptr deref
> >   -                 pci_dev->driver = pci_drv  # b5f9c644eb1b ("PCI: Remove struct pci_dev->driver")
> >                   pci_drv->probe
> >                     i2c_dw_pci_probe
>
> I think this analysis is right.
>
> I didn't test this patch, @Robert, maybe you can do this?
>
> Best regards
> Uwe
>
>  drivers/pci/pci-driver.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 1d98c974381c..202533654012 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -1299,7 +1299,7 @@ static int pci_pm_runtime_resume(struct device *dev)
>          */
>         pci_restore_standard_config(pci_dev);
>
> -       if (!to_pci_driver(dev->driver))
> +       if (!device_is_bound(dev))
>                 return 0;
>
>         pci_fixup_device(pci_fixup_resume_early, pci_dev);

Yes, that fixes it. Thanks for the patch.