linux-kernel - Re: [PATCH v2 02/10] sysfs: introduce callback attribute_group::bin

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241106200513.GB174958@rocinante>
Date: Thu, 7 Nov 2024 05:05:13 +0900
From: Krzysztof Wilczyński <kw@...ux.com>
To: Thomas Weißschuh <linux@...ssschuh.net>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
	Davidlohr Bueso <dave@...olabs.net>,
	Jonathan Cameron <jonathan.cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Alison Schofield <alison.schofield@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Ira Weiny <ira.weiny@...el.com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	Xinhui Pan <Xinhui.Pan@....com>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
	Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
	Tudor Ambarus <tudor.ambarus@...aro.org>,
	Pratyush Yadav <pratyush@...nel.org>,
	Michael Walle <mwalle@...nel.org>,
	Miquel Raynal <miquel.raynal@...tlin.com>,
	Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>,
	Naveen Krishna Chatradhi <naveenkrishna.chatradhi@....com>,
	Carlos Bilbao <carlos.bilbao.osdev@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	"David E. Box" <david.e.box@...ux.intel.com>,
	"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	Richard Henderson <richard.henderson@...aro.org>,
	Matt Turner <mattst88@...il.com>,
	Frederic Barrat <fbarrat@...ux.ibm.com>,
	Andrew Donnellan <ajd@...ux.ibm.com>, Arnd Bergmann <arnd@...db.de>,
	Logan Gunthorpe <logang@...tatee.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
	Dan Williams <dan.j.williams@...el.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-cxl@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org, linux-rdma@...r.kernel.org,
	linux-mtd@...ts.infradead.org, platform-driver-x86@...r.kernel.org,
	linux-scsi@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-alpha@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-hyperv@...r.kernel.org
Subject: Re: [PATCH v2 02/10] sysfs: introduce callback
 attribute_group::bin_size

Hello,

> Several drivers need to dynamically calculate the size of an binary
> attribute. Currently this is done by assigning attr->size from the
> is_bin_visible() callback.
> 
> This has drawbacks:
> * It is not documented.
> * A single attribute can be instantiated multiple times, overwriting the
>   shared size field.
> * It prevents the structure to be moved to read-only memory.
> 
> Introduce a new dedicated callback to calculate the size of the
> attribute.

Would it be possible to have a helper that when run against a specific
kobject reference, then it would refresh or re-run the size callbacks?

We have an use case where we resize BARs on demand via sysfs, and currently
the only way to update the size of each resource sysfs object is to remove
and added them again, which is a bit crude, and can also be unsafe.

Hence the question.

There exist the sysfs_update_groups(), but the BAR resource sysfs objects
are currently, at least not yet, added to any attribute group.

Thank you!

	Krzysztof