linux-kernel - Re: [RESEND PATCH v7 1/1] PCI/sysfs: Expose PCIe device serial number

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Message-ID: <20250917121620.GA792199@rocinante>
Date: Wed, 17 Sep 2025 21:16:20 +0900
From: Krzysztof Wilczyński <kwilczynski@...nel.org>
To: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Cc: Keith Busch <kbusch@...nel.org>, Bjorn Helgaas <helgaas@...nel.org>,
	Matthew Wood <thepacketgeek@...il.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Mario Limonciello <superm1@...nel.org>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [RESEND PATCH v7 1/1] PCI/sysfs: Expose PCIe device serial number

Hi Thomas,

> > > It's a waste of resources to provide a handle just to say the capability
> > > doesn't exist when the handle could just not exist instead.
> > 
> > I haven't checked how the kernfs side looks like, admittedly, but I think
> > whether an attribute is visible or not, it does not unload and/or de-allocate
> > any space for the accompanying kernfs object...  So, the resources saving
> > here might not be in any way significant.
> 
> If I read the sysfs code correctly (create_files() in fs/sysfs/group.c),
> the kernfs node should not even be allocated for invisible files.

Good to know!  I wasn't sure and did look...  I stand corrected now.

Thank you for taking the time to check this.  Much appreciated. :)

Thank you!

	Krzysztof