On Thu, Aug 14, 2025 at 05:39:37PM +0800, Rui He wrote: > For preconfigured PCI bridge, child bus created on the first scan. > While for some reasons(e.g register mutation), the secondary, and subordiante > register reset to 0 on the second scan, which caused to create > PCI bus twice for the same PCI device. I don't quite follow this. Do you mean something is changing the bridge configuration between the first and second scans? > Following is the related log: > [Wed May 28 20:38:36 CST 2025] pci 0000:0b:01.0: PCI bridge to [bus 0d] > [Wed May 28 20:38:36 CST 2025] pci 0000:0b:05.0: bridge configuration invalid ([bus 00-00]), reconfiguring > [Wed May 28 20:38:36 CST 2025] pci 0000:0b:01.0: PCI bridge to [bus 0e-10] > [Wed May 28 20:38:36 CST 2025] pci 0000:0b:05.0: PCI bridge to [bus 0f-10] Drop the timestamps (since they don't contribute to understanding the problem) and indent the logs a couple spaces. > Here PCI device 000:0b:01.0 assigend to bus 0d and 0e. It looks like the [bus 0f-10] range is assigned to both bridges (0b:01.0 and 0b:05.0), which would definitely be a problem. I'm surprised that we haven't tripped over this before, and I'm curious about how we got here. Can you set CONFIG_DYNAMIC_DEBUG=y, boot with the dyndbg="file drivers/pci/* +p" kernel parameter, and collect the complete dmesg log? > This patch checks if child PCI bus has been created on the second scan > of bridge. If yes, return directly instead of create a new one. > > Signed-off-by: Rui He <rui.he@xxxxxxxxxxxxx> > --- > drivers/pci/probe.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index f41128f91ca76..ec67adbf31738 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -1444,6 +1444,9 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev, > goto out; > } > > + if(pci_has_subordinate(dev)) > + goto out; Follow the coding style, i.e., add a space in "if (pci_..." > /* Clear errors */ > pci_write_config_word(dev, PCI_STATUS, 0xffff); > > -- > 2.43.0 >
