Subject: Re: [PATCH 3/5] of/device: Make of_get_next_child() check status properties

From: Michael Ellerman <[email-masked]>
Date: Thu, 09 Dec 2010 12:33:22 +1100

On Wed, 2010-12-08 at 15:01 -0600, Scott Wood wrote:
> On Wed, 8 Dec 2010 11:29:44 -0800
> Deepak Saxena <[email-masked]> wrote:
> 
> > We only return the next child if the device is available.
> > 
> > Signed-off-by: Hollis Blanchard <[email-masked]>
> > Signed-off-by: Deepak Saxena <[email-masked]>
> > ---
> >  drivers/of/base.c |    4 +++-
> >  1 files changed, 3 insertions(+), 1 deletions(-)
> > 
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index 5d269a4..81b2601 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -321,6 +321,8 @@ struct device_node *of_get_next_parent(struct device_node *node)
> >   *
> >   *	Returns a node pointer with refcount incremented, use
> >   *	of_node_put() on it when done.
> > + *
> > + *	Does not return nodes marked unavailable by a status property.
> >   */
> >  struct device_node *of_get_next_child(const struct device_node *node,
> >  	struct device_node *prev)
> > @@ -330,7 +332,7 @@ struct device_node *of_get_next_child(const struct device_node *node,
> >  	read_lock(&devtree_lock);
> >  	next = prev ? prev->sibling : node->child;
> >  	for (; next; next = next->sibling)
> > -		if (of_node_get(next))
> > +		if (of_device_is_available(next) && of_node_get(next))
> >  			break;
> >  	of_node_put(prev);
> >  	read_unlock(&devtree_lock);
> 
> This seems like too low-level a place to put this.  Some code may know
> how to un-disable a device in certain situations, or it may be part of
> debug code trying to dump the whole device tree, etc.  Looking
> further[1], I see a raw version of this function, but not other things
> like of_find_compatible_node.

Yeah I agree. I think we'll eventually end up with __ versions of all or
lots of them. Not to mention there might be cases you've missed where
code expects to see unavailable nodes. The right approach is to add
_new_ routines that don't return unavailable nodes, and convert code
that you know wants to use them.

cheers