On Thu, May 21, 2015 at 03:05:03PM +0800, Yijing Wang wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=94361 reported > in ATCA platform, system had unusual pcie topology: > > (root port) (downstream port) (upstream port) > +-1c.0-[02-0a]----00.0-[03-0a]--+-00.0-[04]-- > | +-01.0-[05]-- (downstream port) > | +-02.0-[06]-- > | +-03.0-[07]-- > | +-08.0-[08]-- > | +-09.0-[09]-- > | \-0a.0-[0a]-- > We assumed root port and downstream port always > have external link, and downstream port always has a > upstream port. So in this case, when we allocated > pcie_link_state for downstream port 02:00.0, it try > to get parent bus pcie_link_state, > parent = pdev->bus->parent->self->link_state; > because root bus self is NULL, system will crash here. > > Use pdev->has_secondary_link(introduced in previous patch) > to fix this issue. > > Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx> > --- > drivers/pci/pcie/aspm.c | 7 +++---- > 1 files changed, 3 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > index 7d4fcdc..8830740 100644 > --- a/drivers/pci/pcie/aspm.c > +++ b/drivers/pci/pcie/aspm.c > @@ -561,8 +561,8 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev) > > if (!pci_is_pcie(pdev) || pdev->link_state) > return; > - if (pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT && > - pci_pcie_type(pdev) != PCI_EXP_TYPE_DOWNSTREAM) > + > + if (!pdev->has_secondary_link) > return; > > /* VIA has a strange chipset, root port is under a bridge */ > @@ -723,8 +723,7 @@ static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem, > if (!pci_is_pcie(pdev)) > return; > > - if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT || > - pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM) > + if (pdev->has_secondary_link) > parent = pdev; > if (!parent || !parent->link_state) > return; I think we also have a problem here: 517 static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev) 518 { 519 struct pcie_link_state *link; 520 521 link = kzalloc(sizeof(*link), GFP_KERNEL); 522 if (!link) 523 return NULL; 524 INIT_LIST_HEAD(&link->sibling); 525 INIT_LIST_HEAD(&link->children); 526 INIT_LIST_HEAD(&link->link); 527 link->pdev = pdev; 528 if (pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM) { 529 struct pcie_link_state *parent; 530 parent = pdev->bus->parent->self->link_state; 531 if (!parent) { 532 kfree(link); 533 return NULL; 534 } 535 link->parent = parent; 536 list_add(&link->link, &parent->children); 537 } Before your patch, we could only see Root Ports or Downstream Ports at line 528. Now we may also see Upstream Ports, so I think that test should be changed to "if (pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT)". Without this change, I think we would allocate pcie_link_state for the 03:00.0 Upstream Port in your example, but it would not be connected to the tree of links starting at the 00:1c.0 Root Port. Do you agree? Bjorn -- 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
