linux-kernel - Re: [PATCH 2/2] clk: Move init fields from clk to clk

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 for Android: free password hash cracker in your pocket

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

Message-ID: <CAJOA=zOKE7hyvvjB3HLh_iAX8HGCbFQtUHijU3BM+0r+9-b72A@mail.gmail.com>
Date:	Wed, 11 Apr 2012 13:17:20 -0700
From:	"Turquette, Mike" <mturquette@...com>
To:	Saravana Kannan <skannan@...eaurora.org>
Cc:	Sascha Hauer <s.hauer@...gutronix.de>,
	Andrew Lunn <andrew@...n.ch>,
	Grant Likely <grant.likely@...retlab.ca>,
	Jamie Iles <jamie@...ieiles.com>,
	Jeremy Kerr <jeremy.kerr@...onical.com>,
	Magnus Damm <magnus.damm@...il.com>,
	Deepak Saxena <dsaxena@...aro.org>,
	linux-arm-kernel@...ts.infradead.org,
	Arnd Bergman <arnd.bergmann@...aro.org>,
	linux-arm-msm@...r.kernel.org,
	Rob Herring <rob.herring@...xeda.com>,
	Russell King <linux@....linux.org.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	Richard Zhao <richard.zhao@...aro.org>,
	Shawn Guo <shawn.guo@...escale.com>,
	Paul Walmsley <paul@...an.com>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Shawn Guo <shawn.guo@...aro.org>
Subject: Re: [PATCH 2/2] clk: Move init fields from clk to clk_hw

On Wed, Apr 11, 2012 at 12:57 PM, Saravana Kannan
<skannan@...eaurora.org> wrote:
> On 04/11/2012 10:59 AM, Turquette, Mike wrote:
>> On Thu, Apr 5, 2012 at 6:30 PM, Saravana Kannan<skannan@...eaurora.org>
>> My only concern with this series is that platform clock code will
>> access struct clk_hw members without the appropriate lock held (namely
>> prepare_lock).  I'm a bit worried that there might be a case where
>> some clock code access clk_hw->name when clk_hw has somehow been
>> destroyed/altered (e.g. if clk_put every finally gets implemented...).
>>  Besides clk_put are there any real instances where this might happen?
>
> This problem is true for any struct/field marked as __init_data. So, I don't
> think this is a real problem. If someone is stupid enough to mark their data
> as __init_data and access them later, then there is not much we can do.
> Also, I believe the compiler throws out some warning when you try to access
> __init_data from non-init code.

I'm referring to platform clock code accessing clk_hw->name or
clk_hw->parent_names AFTER the core code has copied the initialization
data.  So this isn't an __initdata problem as much as it is a design
issue with exposing some members of struct clk_hw.  I think that this
is basically OK since the benefits of not having to use so many
helpers functions in platform clock code is obvious and if a platform
gets bitten by this then they will learn the hard way to honor the
locking semantics outlined in Documentation/clk.txt

>> I'll be pushing my fixes branch out to the list soon.  Do you want to
>> rebase this change on top of it taking into account the __initdata
>> bits?
>
> I thought it might be easier for you to base your changes on top of my
> patch. But I can try to rebase mine on top of your changes. Hopefully your
> fixes aren't crazy big/complex.

I don't think the fixes are a big deal, especially in the core code.

> This is a busy week for me at work. I will try to send a patch in a day or
> two.

OK.  I might take a swing at it myself if I have time.

Regards,
Mike
--
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/