linux-kernel - Re: [PATCH] staging: Disable lustre file system for MIPS, SH, and XTENSA

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Date:	Mon, 9 Sep 2013 13:06:10 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Christoph Hellwig <hch@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	driverdevel <devel@...verdev.osuosl.org>,
	Peng Tao <tao.peng@....com>, Peng Tao <bergwolf@...il.com>
Subject: Re: [PATCH] staging: Disable lustre file system for MIPS, SH, and
 XTENSA

On Mon, Sep 09, 2013 at 09:11:25PM +0200, Geert Uytterhoeven wrote:
> On Mon, Sep 9, 2013 at 7:22 PM, Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
> > On Mon, Sep 09, 2013 at 10:08:19AM -0700, Guenter Roeck wrote:
> >> On Mon, Sep 09, 2013 at 09:39:02AM -0700, Greg Kroah-Hartman wrote:
> >> > On Mon, Sep 09, 2013 at 06:40:12AM -0700, Christoph Hellwig wrote:
> >> > > On Sun, Sep 08, 2013 at 06:59:45PM -0700, Greg Kroah-Hartman wrote:
> >> > > > Can't we just export the functions for those arches?  Surely lutre
> >> > > > isn't the first/only driver that needs this?
> >> > >
> >> > > Lustre is.  These are core mm helpers, and lustre uses them to
> >> > > reimplement another core VM function.  It then uses it to access
> >> > > userspace environment variable.
> >> > >
> >> > > In short all this code should be nuked, and no new symbols should be
> >> > > exported.
> >> >
> >> > Ugh, you are right, the lustre code needs to be fixed here.
> >> >
> >> Given that, should I send another patch marking it as BROKEN again ?
> >
> > Well, on those arches it's "broken", so I'll dig up your original patch
> > on this thread.  It's just "normal" for staging drivers to duplicate
> > core code, it needs to be fixed up before it can be merged into the
> > kernel tree, so no need to do anything special.
> 
> It's not only broken on MIPS, SH, and XTENSA, but also on at least parisc
> and m68k[*].
> 
> It's no longer broken on sparc64, as the missing export already got
> into mainline.
> In light of the above, perhaps that should be reverted?
> 
Agreed.

> [*] Why does m68k allmodconfig still succeed on kissb???
>     It does fail for me, as m68k's copy_from_user_page() calls
>     flush_icache_user_range(), which is not exported.
> 
I don't see a build failure in m68k:allmodconfig either.

flush_icache_user_range() is called from copy_to_user_page(), not from
copy_from_user_page(). copy_from_user_page() calls flush_cache_page()
which calls __flush_cache_030(). The first is inline, the second is
assembler, so I would expect it to work. Which doesn't answer
the question why it fails for you.

powerpc and frm export flush_icache_user_range(). Wonder if that is really
necessary or points to other abuses.

On parisc I currently only test defconfig. I'll check if allmodconfig passes
in 3.10 and/or 3.11; if yes I'll add it to my test suite.

Guenter
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