[PATCH net] PCI: fix the return value for the pci_find_pcie_root_port()

On 2017/8/17 21:30, Thierry Reding wrote:

On Thu, Aug 17, 2017 at 08:40:16PM +0800, Ding Tianhong wrote:

quoted

On 2017/8/17 18:51, Thierry Reding wrote:

quoted

On Thu, Aug 17, 2017 at 10:25:30AM +0800, Ding Tianhong wrote:

quoted

The pci_find_pcie_root_port() would return NULL if the given
dev is already a Root Port, it looks like unfriendly to the
PCIe Root Port device, Thierry and Bjorn suggest to let this
function return the given dev under this circumstances.

Fixes: 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI device")
Suggested-by: Thierry Reding <redacted>
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Thierry Reding <redacted>
Signed-off-by: Ding Tianhong <redacted>
---
 drivers/pci/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7e2022f..352bb53 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c

@@ -514,7 +514,7 @@ struct resource *pci_find_resource(struct pci_dev *dev, struct resource *res)
  */
 struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
 {
-	struct pci_dev *bridge, *highest_pcie_bridge = NULL;
+	struct pci_dev *bridge, *highest_pcie_bridge = dev;
 
 	bridge = pci_upstream_bridge(dev);
 	while (bridge && pci_is_pcie(bridge)) {

I think this should actually be this change on top of a revert of commit
0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI
device"). After the above change, the previous fix will have a redundant
check because highest_pcie_bridge will never be NULL.

Let me send out that version to clarify what I mean.

Hi Thierry:

The patch ("PCI: fix oops when try to find Root Port for a PCI device")
has been merge to the linus mainline tree before you found this deficiencies....

I understand that. I'm just saying that there's no point keeping that
change around because it no longer makes sense after we initialize the
highest_pcie_bridge variable to dev.

Ok, NO problem.:)

Thierry