linux-kernel - Re: [PATCH] introduce __init

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Message-ID: <20070717153236.GB25939@uranus.ravnborg.org>
Date:	Tue, 17 Jul 2007 17:32:36 +0200
From:	Sam Ravnborg <sam@...nborg.org>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Domen Puncer <domen.puncer@...argo.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] introduce __init_exit function annotation

On Tue, Jul 17, 2007 at 05:16:13PM +0200, Takashi Iwai wrote:
> At Tue, 17 Jul 2007 17:14:32 +0200,
> Sam Ravnborg wrote:
> > 
> > On Tue, Jul 17, 2007 at 04:52:12PM +0200, Takashi Iwai wrote:
> > > At Tue, 17 Jul 2007 15:02:30 +0200,
> > > Sam Ravnborg wrote:
> > > > 
> > > > On Tue, Jul 17, 2007 at 10:02:48AM +0200, Domen Puncer wrote:
> > > > > Introduce __init_exit, which is useful ie. for drivers that call
> > > > > cleanup functions when they fail in __init functions.
> > > > 
> > > > This is wrong.
> > > > On arm (just one example of several) the __exit section are discarded
> > > > at buildtime so any reference from __init to __exit will cause the
> > > > linker to error out.
> > > 
> > > Hmm, from what I see, it adds __init to the function.  There is no
> > > reference to __exit.
> > 
> > The cleanup functions are marked __exit in the referenced case.
> 
> My understanding is that it's the very purpose of this patch --
> change the mark from __exit to __init_exit for such clean-up
> functions.

And that is wrong.
See following example:

static void __init foo_init()
{
	if (error)
		foo_exit();
}

static void __exit foo_exit()
{
}

If foo_init is annotated with __init_exit then in the build-in case it
become __init and there is a reference to a non existing function because
functions marked __exit are discarded during link or run-time (depending on arch).

If foo_exit() are marked __init_exit then it becomes __init in the non-module case
which seems coorrect. If this is the intention of the patch then it should
be OK but then this intention should be spelled out.

	Sam
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