linux-kernel - Re: [PATCH 1/2] Export get_user_pages

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Message-ID: <20080730173944.GC28604@cs181140183.pp.htv.fi>
Date:	Wed, 30 Jul 2008 20:39:44 +0300
From:	Adrian Bunk <bunk@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rusty Russell <rusty@...tcorp.com.au>, lguest <lguest@...abs.org>,
	linux-kernel@...r.kernel.org, Nick Piggin <nickpiggin@...oo.com.au>
Subject: Re: [PATCH 1/2] Export get_user_pages_fast

On Wed, Jul 30, 2008 at 10:28:17AM -0700, Andrew Morton wrote:
> On Wed, 30 Jul 2008 20:18:45 +0300 Adrian Bunk <bunk@...nel.org> wrote:
> 
> > > > The export would still only be available on x86 since no other arch 
> > > > would define CONFIG_HAVE_GET_USER_PAGES_FAST.
> > > > 
> > > 
> > > That's presently true in Linus mainline.  The powerpc implementation is
> > > in -mm, but apprarently needs a bit more work.
> > 
> > I still don't get the advantage of your suggestion.
> > 
> > With the powerpc implementation included your suggestion doesn't change 
> > the fact that the export is available only on x86 and powerpc, and if a 
> > driver author mistakenly uses it and only tests it's driver on x86 it 
> > will still break on architectures other than x86 or powerpc.
> 
> On non-CONFIG_HAVE_GET_USER_PAGES_FAST architectures a
> get_user_pages_fast() call will in fact call get_user_pages().
> 
> On CONFIG_HAVE_GET_USER_PAGES_FAST architectures, get_user_pages_fast()
> is a real function.  All architectures which implement that function
> should export it to modules.  Hence it should be exported from within
> generic code.

Are we talking at cross purposes?

I thought you were talking an error due to a missing function.

If you think about an error where the function is present but only the 
EXPORT_SYMBOL is missing then I get your point (although I do not 
consider it a huge problem).

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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