Messages in this thread Patch in this message |  | | Date | Tue, 15 Aug 2017 12:03:31 -0500 | From | Bjorn Helgaas <> | Subject | Re: [PATCH net RESEND] PCI: fix oops when try to find Root Port for a PCI device |
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On Tue, Aug 15, 2017 at 11:24:48PM +0800, Ding Tianhong wrote: > Eric report a oops when booting the system after applying > the commit a99b646afa8a ("PCI: Disable PCIe Relaxed..."): > ...
> It looks like the pci_find_pcie_root_port() was trying to > find the Root Port for the PCI device which is the Root > Port already, it will return NULL and trigger the problem, > so check the highest_pcie_bridge to fix thie problem.
The problem was actually with a Root Complex Integrated Endpoint that has no upstream PCIe device:
00:05.2 System peripheral: Intel Corporation Device 0e2a (rev 04) Subsystem: Intel Corporation Device 0e2a Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00 DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us ExtTag- RBE- FLReset- DevCtl: Report errors: Correctable- Non-Fatal- Fatal+ Unsupported+ RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+ MaxPayload 128 bytes, MaxReadReq 128 bytes
> Fixes: a99b646afa8a ("PCI: Disable PCIe Relaxed Ordering if unsupported")
This also
Fixes: c56d4450eb68 ("PCI: Turn off Request Attributes to avoid Chelsio T5 Completion erratum")
which added pci_find_pcie_root_port(). Prior to this Relaxed Ordering series, we only used pci_find_pcie_root_port() in a Chelsio quirk that only applied to non-integrated endpoints, so we didn't trip over the bug.
> Reported-by: Eric Dumazet <eric.dumazet@gmail.com> > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> > Signed-off-by: Ding Tianhong <dingtianhong@huawei.com> > --- > drivers/pci/pci.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index af0cc34..7e2022f 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -522,7 +522,8 @@ struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev) > bridge = pci_upstream_bridge(bridge); > } > > - if (pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT) > + if (highest_pcie_bridge && > + pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT) > return NULL; > > return highest_pcie_bridge; > --
I think structuring the fix as follows is a little more readable:
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index af0cc3456dc1..587cd7623ed8 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -522,10 +522,11 @@ struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev) bridge = pci_upstream_bridge(bridge); } - if (pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT) - return NULL; + if (highest_pcie_bridge && + pci_pcie_type(highest_pcie_bridge) == PCI_EXP_TYPE_ROOT_PORT) + return highest_pcie_bridge; - return highest_pcie_bridge; + return NULL; } EXPORT_SYMBOL(pci_find_pcie_root_port);
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