On Monday 28 September 2009, Rafael J. Wysocki wrote: > On Monday 28 September 2009, Alex Chiang wrote: > > Hi Xiaotian, > > > > Thanks for the bug report. > > > > * Xiaotian Feng <dfeng@xxxxxxxxxx>: > > > commit 275582 introduces acpi_get_pci_dev(), but pdev->subordinate > > > can be NULL, then a NULL was passed to pci_get_slot, this results > > > the kernel oops when resume from suspend. > > > > > > This patch resolves following kernel oops: > > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 > > > IP: [<ffffffff812217e7>] pci_get_slot+0x4c/0x8c > > > > > > Signed-off-by: Xiaotian Feng <dfeng@xxxxxxxxxx> > > > --- > > > drivers/acpi/pci_root.c | 6 +++++- > > > 1 files changed, 5 insertions(+), 1 deletions(-) > > > > > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c > > > index 3112221..3c35144 100644 > > > --- a/drivers/acpi/pci_root.c > > > +++ b/drivers/acpi/pci_root.c > > > @@ -387,7 +387,11 @@ struct pci_dev *acpi_get_pci_dev(acpi_handle handle) > > > if (!pdev || hnd == handle) > > > break; > > > > > > - pbus = pdev->subordinate; > > > + if (pdev->subordinate) > > > + pbus = pdev->subordinate; > > > + else > > > + pbus = pdev->bus; > > > + > > > > I'm a little confused by this. If we start from the PCI root > > bridge and walk back down the hierarchy, shouldn't everything > > between the root and the device be a P2P bridge? > > Well, if my reading of the code is correct, there's no guarantee that > pci_get_slot() will always return either the right device or a bridge. I should have been more precise. If devfn of node happens to be the same as devfn of a non-bridge device on pbus, the pci_get_slot() will return a valid pointer to it, but pdev->subordinate will be NULL. Is it impossible for some reason? Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
