2013-06-12 15:54-0600, Bjorn Helgaas: > [+cc linux-pci, Myron, Joe] I'll remember it. > On Wed, Jun 12, 2013 at 11:21 AM, Radim Krčmář <rkrcmar@xxxxxxxxxx> wrote: > > Hello, > > > > as a consequence of hitting a NULL dereference bug[1] while downstream > > aspm is setting up link_state, I started to wonder why is the code > > skipping its parent bus in favour of grandparent's link_state.[2] > > > > Is this right? (I have no device to test on ...) No, pcie_link_state covers both upstream and downstream port, so we skip upstream port of current device. Must the "parent device" (grandparent) have valid "->self"? (qemu allows even topologies without the upstream port, so it does not count for much ...) > > Thanks. > > > > --- > > 1: https://bugzilla.redhat.com/show_bug.cgi?id=972381 > > The bug is hit because "pdev->bus->parent" has NULL "->parent" and thus > > NULL "->self". > > 2: "pdev = bus->self", so "pdev->bus->parent == bus->parent->parent" > > > > > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > > index 403a443..d58e282 100644 > > --- a/drivers/pci/pcie/aspm.c > > +++ b/drivers/pci/pcie/aspm.c > > @@ -527,7 +527,7 @@ static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev) > > link->pdev = pdev; > > if (pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM) { > > struct pcie_link_state *parent; > > - parent = pdev->bus->parent->self->link_state; > > + parent = pdev->bus->self->link_state; > > if (!parent) { > > kfree(link); > > return NULL; -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
