linux-kernel - Re: [External] Re: [RFC 0/1] PCI: Fix pci devices double register WARNING in the kernel starting process

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Message-ID: <CAKmKDKm_5TXKafWVVMoRdj8Zp=up7YXQ=-CMO=VDHg6KLw-dTQ@mail.gmail.com>
Date: Fri, 4 Jul 2025 15:41:46 +0800
From: He Shuan <heshuan@...edance.com>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: Sunil V L <sunilvl@...tanamicro.com>, bhelgaas@...gle.com, cuiyunhui@...edance.com, 
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [External] Re: [RFC 0/1] PCI: Fix pci devices double register
 WARNING in the kernel starting process

Hi Mani,

Thanks for your comments.

>But in your case, looks like the PCI device is available somehow before
>pci_proc_init() gets executed. Now, it is not very clear to me how the device
>becomes available at this point. It might be due to some other issue. But in
>anycase, I think we need to get rid of calling pci_proc_attach_device() from
>pci_proc_init() as I don't see a reason to call this function from two
>different places. pci_bus_add_device() should be the one calling this function
>as it is the one adding the PCI device.
Got it. I need to figure out why the PCI device is available already before
pci_proc_init() is executed. (Actually I didn't change too much source code yet,
basically running my test based on the upstream code).

>Ironically, I do see a similar pattern for sysfs also. Maybe there is (or was) a
>reason to create these files from two different places?
Yes, I see the sysfs register confusion (pci_create_sysfs_dev_files) from
pci_sysfs_init() and pci_bus_add_device() as well. There do have concurrence
protection through pci_bus_add_device() paths, so I agree that function
pci_proc_attach_device and pci_create_sysfs_dev_files should be called
from pci_bus_add_devices().

Anyway, it appears there is a great deal of work/effort needed before
making this part clear. :(

Bests,
Shuan