On Thu, Apr 28, 2022 at 04:28:53PM +0200, Greg Kroah-Hartman wrote:
> In acpi_get_pci_dev(), the debugging message for when a PCI bridge is
> not found uses a pointer to a pci device whose reference has just been
> dropped. The chance that this really is a device that is now been
> removed from the system is almost impossible to happen, but to be safe,
> let's print out the debugging message based on the acpi root device
> which we do have a valid reference to at the moment.
This code was added by 497fb54f578e ("ACPI / PCI: Fix NULL pointer
dereference in acpi_get_pci_dev() (rev. 2)"). Not sure if it's worth
a Fixes: tag.
acpi_get_pci_dev() is used by only five callers, three of which are
video/backlight related. I'm always skeptical of one-off interfaces
like this, but I don't know enough to propose any refactoring or other
alternatives.
I'll leave this for Rafael, but if I were applying I would silently
touch up the subject to match convention:
PCI/ACPI: Do not reference PCI device after it has been released
> Cc: Bjorn Helgaas <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: Len Brown <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Reported-by: whitehat002 <[email protected]>
> Signed-off-by: Greg Kroah-Hartman <[email protected]>
> ---
> drivers/acpi/pci_root.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 6f9e75d14808..ecda378dbc09 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -303,7 +303,8 @@ struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
> * case pdev->subordinate will be NULL for the parent.
> */
> if (!pbus) {
> - dev_dbg(&pdev->dev, "Not a PCI-to-PCI bridge\n");
> + dev_dbg(&root->device->dev,
> + "dev %d, function %d is not a PCI-to-PCI bridge\n", dev, fn);
This should use "%02x.%d" to be consistent with the dev_set_name() in
pci_setup_device().
> pdev = NULL;
> break;
> }
> --
> 2.36.0
>
On Thu, Apr 28, 2022 at 10:58:58AM -0500, Bjorn Helgaas wrote:
> On Thu, Apr 28, 2022 at 04:28:53PM +0200, Greg Kroah-Hartman wrote:
> > In acpi_get_pci_dev(), the debugging message for when a PCI bridge is
> > not found uses a pointer to a pci device whose reference has just been
> > dropped. The chance that this really is a device that is now been
> > removed from the system is almost impossible to happen, but to be safe,
> > let's print out the debugging message based on the acpi root device
> > which we do have a valid reference to at the moment.
>
> This code was added by 497fb54f578e ("ACPI / PCI: Fix NULL pointer
> dereference in acpi_get_pci_dev() (rev. 2)"). Not sure if it's worth
> a Fixes: tag.
Can't hurt, I'll add it for the v2 based on this review.
>
> acpi_get_pci_dev() is used by only five callers, three of which are
> video/backlight related. I'm always skeptical of one-off interfaces
> like this, but I don't know enough to propose any refactoring or other
> alternatives.
>
> I'll leave this for Rafael, but if I were applying I would silently
> touch up the subject to match convention:
>
> PCI/ACPI: Do not reference PCI device after it has been released
Much simpler, thanks.
>
> > Cc: Bjorn Helgaas <[email protected]>
> > Cc: "Rafael J. Wysocki" <[email protected]>
> > Cc: Len Brown <[email protected]>
> > Cc: [email protected]
> > Cc: [email protected]
> > Reported-by: whitehat002 <[email protected]>
> > Signed-off-by: Greg Kroah-Hartman <[email protected]>
> > ---
> > drivers/acpi/pci_root.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > index 6f9e75d14808..ecda378dbc09 100644
> > --- a/drivers/acpi/pci_root.c
> > +++ b/drivers/acpi/pci_root.c
> > @@ -303,7 +303,8 @@ struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
> > * case pdev->subordinate will be NULL for the parent.
> > */
> > if (!pbus) {
> > - dev_dbg(&pdev->dev, "Not a PCI-to-PCI bridge\n");
> > + dev_dbg(&root->device->dev,
> > + "dev %d, function %d is not a PCI-to-PCI bridge\n", dev, fn);
>
> This should use "%02x.%d" to be consistent with the dev_set_name() in
> pci_setup_device().
Ah, missed that, will change it and send out a new version tomorrow.
thanks for the quick review.
greg k-h