linux-kernel - Re: [PATCH v7 4/6] pci: Introduce a domain number for pci_host

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: <CAErSpo6u7kr+QdnhAXBo20izg-DNHR4zHT+kRvq34whp68RJCQ@mail.gmail.com>
Date:	Thu, 10 Apr 2014 07:50:52 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linux-pci <linux-pci@...r.kernel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	linaro-kernel <linaro-kernel@...ts.linaro.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	LAKML <linux-arm-kernel@...ts.infradead.org>,
	Tanmay Inamdar <tinamdar@....com>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [PATCH v7 4/6] pci: Introduce a domain number for pci_host_bridge.

On Thu, Apr 10, 2014 at 2:00 AM, Arnd Bergmann <arnd@...db.de> wrote:
> On Wednesday 09 April 2014 21:48:14 Bjorn Helgaas wrote:
>> On Wed, Apr 9, 2014 at 7:27 PM, Liviu Dudau <liviu@...au.co.uk> wrote:
>> > On Wed, Apr 09, 2014 at 08:02:41AM -0600, Bjorn Helgaas wrote:
>> >> >>   struct pci_host_bridge {
>> >> >>     int domain;
>> >> >>     int node;
>> >> >>     struct device *dev;
>> >> >>     struct pci_ops *ops;
>> >> >>     struct list_head resources;
>> >> >>     void *sysdata;
>> >> >>     struct pci_bus *bus;  /* filled in by core, not by arch */
>> >> >>     ... /* other existing contents managed by core */
>> >> >>   };
>> >> >>
>> >> >>   struct pci_bus *pci_scan_host_bridge(struct pci_host_bridge *bridge);
>> >> >
>> >> > I'm really reluctant to give the arches more rope to hang themselves.
>> >>
>> >> If you mean the sysdata pointer is rope to hang themselves, I think it
>> >> would be great it we didn't need sysdata at all.  But I think it would
>> >> be a huge amount of work to get rid of it completely, and keeping it
>> >> would let us work at that incrementally.
>> >
>> > Agree. But then your suggestion was to wrap sysdata inside another structure,
>> > which to me constitutes additional rope.
>>
>> I'll ponder this more, but I don't see your point here yet.  The arch
>> already supplies a sysdata pointer to pci_scan_root_bus(), and we
>> stash it in every struct pci_bus already.  My idea was just to pass it
>> in differently, as a structure member rather than a separate argument.
>>  (And I'm not completely attached to my proposal; it was only to
>> illustrate my concern about the explosion of interfaces if we have to
>> add *_domain(), *_node(), etc.)
>
> As a minor variation of your suggestion, how about passing in a pointer
> to struct pci_host_bridge, and embed that within its own private
> structure? I think this is closer to how a lot of other subsystems
> do the abstraction.

I'm not sure I'm following you; you mean the arch-specific sysdata
structure would contain a pointer to struct pci_host_bridge?

I have to admit that I'm not up on how other subsystems handle this
sort of abstraction.  Do you have any pointers to good examples that I
can study?

Bjorn
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/