linux-kernel - Re: [PATCH] ia64: fix a few section mismatch warnings

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Date:	Fri, 27 Jul 2007 07:49:01 +0200
From:	Sam Ravnborg <sam@...nborg.org>
To:	Al Viro <viro@....linux.org.uk>
Cc:	"Luck, Tony" <tony.luck@...el.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-ia64@...r.kernel.org
Subject: Re: [PATCH] ia64: fix a few section mismatch warnings

On Fri, Jul 27, 2007 at 05:36:14AM +0100, Al Viro wrote:
> On Fri, Jul 27, 2007 at 06:27:44AM +0200, Sam Ravnborg wrote:
> > On Fri, Jul 27, 2007 at 02:18:13AM +0100, Al Viro wrote:
> > > On Thu, Jul 26, 2007 at 11:01:41PM +0200, Sam Ravnborg wrote:
> > >   
> > > > +static void *__init_refok alloc_rte(unsigned long size)
> > > > +{
> > > > +	return alloc_bootmem(size);
> > > > +}
> > > 
> > > That makes no sense at all.  If we ever call that after freeing initmem,
> > > we are screwed, period.  Sounds like __init fodder.
> > 
> > The call site has logic to prevent this from being called after init.
> > And the call site cannot be made __init and to limit the scope of
> > the __init_refok a small function is used.
> > 
> > So unless I mis-understood something the above should be OK.
> 
> Then the call site must be __init_refok, AFAICS.  The point is,
> the callers of alloc_rte() are where the analysis belongs; use of
> __init_refok means that you assert that all calls of __init *from*
> *it* are safe.  Otherwise it just becomes "make modpost STFU and
> let's hope that code is really OK".

The above function is suposed to be used solely from
iosapic_alloc_rte() and not for general use.
And instead of declaring all of iosapic_alloc_rte() as __init_refok
then the single line doing the call to an __init function
was factored out and marked __init.
alloc_rte() can be used from everywhere but the naming suggest
that this is for rte only.

To make it more clear what the function was used for I could have made
it like this:

/*
 * Call site shall make sure this isused only during early init.
 * Use __init_refok to avoid warnings from modpost.
 */ 
static void * __init_refok alloc_rte(unsigned long size)
{
	return alloc_bootmen(sizeof(struct iosapic_rte_info) * size);
}

Would that make the intention more clear?

As for marking all of iosapic_alloc_rte() __init_refok this was not done
because that would then not detect any new __init usage within the function.
That could be done too obviously - it is anyway only 30 loc.

	Sam
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