On 11/05/2021 00:32, Tong Zhang wrote: > On Wed, May 5, 2021 at 2:18 AM Hans Verkuil <hverkuil-cisco@xxxxxxxxx> wrote: >> >> On 24/04/2021 02:52, Tong Zhang wrote: >>> the PCI bridge might be NULL, so we'd better check before use it >>> >>> [ 1.870569] RIP: 0010:pcie_bus_link_get_lanes.isra.0+0x26/0x59 [cobalt] >>> [ 1.875880] Call Trace: >>> [ 1.876013] cobalt_probe.cold+0x1be/0xc11 [cobalt] >>> [ 1.876683] pci_device_probe+0x10f/0x1c0 >> >> How did you test this? With some virtualized PCI bus or something? I'm not sure >> how this can happen. >> > Hello Hans, > IMHO bus->self is pci bridge device and we can have a system > configuration that does not have such a bridge, > in this case, bus->self is NULL. That does not answer my question :-) You show a backtrace in the commit message, how did you get that? Regards, Hans > - Tong >> Regards, >> >> Hans >> >>> >>> Signed-off-by: Tong Zhang <ztong0001@xxxxxxxxx> >>> --- >>> drivers/media/pci/cobalt/cobalt-driver.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c >>> index 0695078ef812..5687ed4869ac 100644 >>> --- a/drivers/media/pci/cobalt/cobalt-driver.c >>> +++ b/drivers/media/pci/cobalt/cobalt-driver.c >>> @@ -189,6 +189,8 @@ void cobalt_pcie_status_show(struct cobalt *cobalt) >>> u32 capa; >>> u16 stat, ctrl; >>> >>> + if (!pci_bus_dev) >>> + return; >>> if (!pci_is_pcie(pci_dev) || !pci_is_pcie(pci_bus_dev)) >>> return; >>> >>> @@ -247,6 +249,8 @@ static unsigned pcie_bus_link_get_lanes(struct cobalt *cobalt) >>> struct pci_dev *pci_dev = cobalt->pci_dev->bus->self; >>> u32 link; >>> >>> + if (!pci_dev) >>> + return 0; >>> if (!pci_is_pcie(pci_dev)) >>> return 0; >>> pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &link); >>> >>
