linux-kernel - Re: [patch 16/17] Immediate Values

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Message-ID: <20080411011647.GA2785@Krystal>
Date:	Thu, 10 Apr 2008 21:16:47 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	akpm@...ux-foundation.org, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, Andi Kleen <andi@...stfloor.org>,
	Adrian Bunk <bunk@...sta.de>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Christoph Hellwig <hch@...radead.org>, akpm@...l.org
Subject: Re: [patch 16/17] Immediate Values - Documentation

* Rusty Russell (rusty@...tcorp.com.au) wrote:
> On Thursday 10 April 2008 01:08:45 Mathieu Desnoyers wrote:
> > If you have to read the immediate values from a function declared as
> > __init or __exit, you should explicitly use _imv_read(), which will fall
> > back on a global variable read. Failing to do so will leave a reference to
> > the __init section after it is freed (it would generate a modpost
> > warning).
> 
> That's a real usability wart.  Couldn't we skip these in the patching loop if 
> required and revert so noone can make this mistake?
> 

Yeah, I know :(

Well, only if we can find a way to detect the macro is put within a init
or exit section. Is there some assembly trickery that would permit us to
do that ?

Otherwise, given the memory freed from the init section could be reused
later by the kernel, I don't see how we can detect the pointer leads to
a freed init section and, say, a module.

Mathieu

> Thanks,
> Rusty.

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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