linux-kernel - Re: [PATCH] PCI: Remove redudant calls to pci_create_sysfs_dev_files() and pci_proc_attach

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Message-ID: <d2ty2hr5jqmlqwkdnd252ctix4xqmxtonx6wqyq3oj5f3j3cpf@yuibbj5owarp>
Date: Wed, 23 Jul 2025 19:10:22 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Lukas Wunner <lukas@...ner.de>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>, 
	bhelgaas@...gle.com, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Shuan He <heshuan@...edance.com>, kwilczynski@...nel.org
Subject: Re: [PATCH] PCI: Remove redudant calls to
 pci_create_sysfs_dev_files() and pci_proc_attach_device()

On Wed, Jul 23, 2025 at 02:55:28PM GMT, Lukas Wunner wrote:
> On Wed, Jul 23, 2025 at 04:41:24PM +0530, Manivannan Sadhasivam wrote:
> > Both pci_create_sysfs_dev_files() and pci_proc_attach_device() are called
> > from pci_bus_add_device(). Calling these APIs from other places is prone to
> > a race condition as nothing prevents the callers from racing against
> > each other.
> > 
> > Moreover, the proper place to create SYSFS and PROCFS entries is during
> > the 'pci_dev' creation. So there is no real need to call these APIs
> > elsewhere.
> 
> The raison d'être for the call to pci_create_sysfs_dev_files() in
> pci_sysfs_init() is that PCI_ROM_RESOURCEs may appear after device
> enumeration but before the late_initcall stage:
> 
> https://lore.kernel.org/r/20231019200110.GA1410324@bhelgaas/
> 
> Your patch will regress those platforms.
> 

Ok, thanks for the pointer. I was not aware of this issue.

> The proper solution is to make the resource files in sysfs static
> and call sysfs_update_group() from pci_sysfs_init().
> 
> Krzysztof has an old branch where he started working on this:
> 
> https://github.com/kwilczynski/linux/commits/kwilczynski/sysfs-static-resource-attributes/
> 

I had a chat with Krzysztof offline and he promised me that he will revive this
effort (thanks Krzysztof!).

- Mani

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