Re: [PATCH v2 1/1] Guard pci_create_sysfs_dev_files with atomic value

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On 16.03.23 14:16, Alexander Stein wrote:

But isn't the root bridge discovered by the driver (pci-imx6 in this case) for
that? And the driver probe path eventually calls into the sysfs file creation.
I compared the file creation to usb, as this is a discoverable bus as well.
There is no special initialization regarding sysfs.

If you discover a bus system you always have the option of creating of virtual
hotplug event for the root hub or host controller.
But for PCI that is a bad design choice. USB is different.

If, for some reason, the device enumeration for PCI bus during imx6_pcie_probe
is delayed after pci_sysfs_init initcall, this initcall essentially does
nothing, no devices or busses to iterate. Which means the complete pcie sysfs

On your specific system. You cannot use that as a model for all systems.

creation is done from bridge probe path. There is no reason to iterate over
discovered PCIe devices/busses separately.

If there is no other PCI device, the loop is a nop. But otherwise it is necessary.

So technically the device is not probed from within a initcall but a
kthread. It is set to be probed asynchronous in imx6_pcie_driver.

That may be the problem, respectively that system is incomplete
You are registering a PCI bridge. The PCI subsystem should be
done setting up when you run. That is just a simple dependency.

Is there such an dependency in the first place? I can't see anything, even the
late_initcall to pci_resource_alignment_sysfs_init is a different matter.

On your hardware, yes. In the kernel, no.
That is the very point. The kernel is missing a way to represent a dependency.


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