linux-kernel - Re: [PATCH V3 11/21] pci, acpi: Move ACPI host bridge device companion assignment to core code.

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: <20160120142243.GB13437@red-moon>
Date:	Wed, 20 Jan 2016 14:22:43 +0000
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	Tomasz Nowicki <tn@...ihalf.com>
Cc:	bhelgaas@...gle.com, arnd@...db.de, will.deacon@....com,
	catalin.marinas@....com, rjw@...ysocki.net, hanjun.guo@...aro.org,
	okaya@...eaurora.org, jiang.liu@...ux.intel.com,
	Stefano.Stabellini@...citrix.com,
	robert.richter@...iumnetworks.com, mw@...ihalf.com,
	Liviu.Dudau@....com, ddaney@...iumnetworks.com, tglx@...utronix.de,
	wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
	msalter@...hat.com, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
	jchandra@...adcom.com, jcm@...hat.com
Subject: Re: [PATCH V3 11/21] pci, acpi: Move ACPI host bridge device
 companion assignment to core code.

On Wed, Jan 20, 2016 at 02:40:08PM +0100, Tomasz Nowicki wrote:

[...]

> >>>>+	/* Root bridge device needs to be sure of parent ACPI type */
> >>>>+	ACPI_COMPANION_SET(&device->dev, device);
> >>>
> >>>I do not understand why the code above is needed, can you elaborate
> >>>please ?
> >>>
> >>
> >>This makes sure that device->dev can be identified as ACPI device,
> >>so we can use to_acpi_device_node() and assign companion safely
> >>below.
> >
> >I do not follow. If you refer to the fwnode handle type, that is
> >already set by ACPI core code (before acpi_pci_root_add() is called,
> >in acpi_init_device_object()).
> 
> acpi_init_device_object() sets ACPI fwnode handle type only for
> "device", but not for "device->dev" which is what is passed as an
> argument to pci_create_root_bus().
> 
> Without ACPI_COMPANION_SET(&device->dev, device) here, no one can be
> sure if we have ACPI device in pci_create_root_bus().

Ok, got it. The question is whether this should be done in ACPI
core instead (is there a reason why it should *not* be done ?), but I
now understand your point.

Thanks,
Lorenzo