[dm-devel] dm: remove pointless comparison
Mike Snitzer
snitzer at redhat.com
Tue Jan 7 15:52:52 UTC 2014
On Tue, Jan 07 2014 at 5:39am -0500,
Joe Thornber <thornber at redhat.com> wrote:
> On Mon, Jan 06, 2014 at 10:53:28PM -0500, Mikulas Patocka wrote:
> > Remove pointless comparison in dm_get_from_kobject. The comparison is
> > always true and the compiler optimizes it out anyway.
> >
> > Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
> >
> > ---
> > drivers/md/dm.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > Index: linux-3.13-rc7/drivers/md/dm.c
> > ===================================================================
> > --- linux-3.13-rc7.orig/drivers/md/dm.c 2014-01-07 01:28:27.000000000 +0100
> > +++ linux-3.13-rc7/drivers/md/dm.c 2014-01-07 01:28:39.000000000 +0100
> > @@ -2922,8 +2922,6 @@ struct mapped_device *dm_get_from_kobjec
> > struct mapped_device *md;
> >
> > md = container_of(kobj, struct mapped_device, kobj);
> > - if (&md->kobj != kobj)
> > - return NULL;
>
> What were they trying to check? The compiler?
>
Milan's commit 784aae735d, and the current dm.c code, offers this
comment above dm_get_from_kobject:
/*
* struct mapped_device should not be exported outside of dm.c
* so use this check to verify that kobj is part of md structure
*/
I'm lacking the vision to _know_ why the kobject would suddenly be
outside of the mapped_device without us knowing via code change..
The check does seem overly cautious/useless (if we remove it the above
comment should be removed too).
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