Re: [PATCH 1/2] of: overlay: improve error handling in of_overlay_apply_tree

[Michael Tretter <m.tretter@pengutronix.de>]

On Wed, 21 Sep 2022 08:55:12 +0200, Michael Riesch wrote:
> On 9/5/22 12:07, Michael Riesch wrote:
> > Propagate any error from of_overlay_apply_symbols and let the user
> > know if the provided overlay is not applicable.
> > 
> > Signed-off-by: Michael Riesch <michael.riesch@wolfvision.net>
> > ---
> >  drivers/of/overlay.c | 14 +++++++++-----
> >  1 file changed, 9 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> > index 20a43f5170..20686db511 100644
> > --- a/drivers/of/overlay.c
> > +++ b/drivers/of/overlay.c
> > @@ -115,8 +115,8 @@ static char *of_overlay_fix_path(struct device_node *root,
> >  	return basprintf("%s%s", target->full_name, path_tail);
> >  }
> >  
> > -static void of_overlay_apply_symbols(struct device_node *root,
> > -				     struct device_node *overlay)
> > +static int of_overlay_apply_symbols(struct device_node *root,
> > +				    struct device_node *overlay)
> >  {
> >  	const char *old_path;
> >  	char *new_path;
> > @@ -129,12 +129,12 @@ static void of_overlay_apply_symbols(struct device_node *root,
> >  
> >  	if (!overlay_symbols) {
> >  		pr_debug("overlay doesn't have a __symbols__ node\n");
> > -		return;
> > +		return -EINVAL;
> 
> Come to think of it, do all overlays need to provide a __symbols__ node?
> If not, this check is overly strict.

Overlays don't need a __symbols__ node. It would be only required, if overlays
are stacked and the second overlay refers to nodes of the first overlay by
labels. Having no __symbols__ in the overlay is a success path and the message
is just a debug message.

> 
> >  	}
> >  
> >  	if (!root_symbols) {
> >  		pr_info("root doesn't have a __symbols__ node\n");
> > -		return;
> > +		return -EINVAL;
> 
> Ditto for the root.

I'm not sure what should happen, if the root does not have __symbols__.
Barebox wouldn't be able to copy the __symbols__ of the overlay, but this
still wouldn't be a problem unless overlays are stacked. In the stacking case,
only applying the second overlay should fail.

Maybe, we should add a new __symbols__ node, if the root doesn't have a
__symbols__ node?

> 
> >  	}
> >  
> >  	list_for_each_entry(prop, &overlay_symbols->properties, list) {
> > @@ -148,6 +148,8 @@ static void of_overlay_apply_symbols(struct device_node *root,
> >  			 prop->name, new_path);
> >  		of_property_write_string(root_symbols, prop->name, new_path);
> >  	}
> > +
> > +	return 0;
> >  }
> >  
> >  static int of_overlay_apply_fragment(struct device_node *root,
> > @@ -190,7 +192,9 @@ int of_overlay_apply_tree(struct device_node *root,
> >  		goto out_err;
> >  
> >  	/* Copy symbols from resolved overlay to base device tree */
> > -	of_overlay_apply_symbols(root, resolved);
> > +	err = of_overlay_apply_symbols(root, resolved);
> > +	if (err)
> > +		goto out_err;
> 
> If both checks need to be relaxed, the complete patch should be reverted
> I guess :-/

What did you do to run into this error? What was your expectation?

Michael