linux-kernel - Re: [PATCH v2] device property: fix of node refcount leak in fwnode_graph_get_next

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Message-ID: <Y3zHF8rdguSaavo1@smile.fi.intel.com>
Date:   Tue, 22 Nov 2022 14:56:55 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Yang Yingliang <yangyingliang@...wei.com>
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        djrscally@...il.com, heikki.krogerus@...ux.intel.com,
        sakari.ailus@...ux.intel.com, gregkh@...uxfoundation.org,
        rafael@...nel.org
Subject: Re: [PATCH v2] device property: fix of node refcount leak in
 fwnode_graph_get_next_endpoint()

On Tue, Nov 22, 2022 at 02:54:36PM +0200, Andy Shevchenko wrote:
> On Tue, Nov 22, 2022 at 08:00:39PM +0800, Yang Yingliang wrote:

One more thing below.

...

> >  fwnode_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
> >  			       struct fwnode_handle *prev)
> >  {
> > +	struct fwnode_handle *ep, *port_parent = NULL;
> >  	const struct fwnode_handle *parent;
> > -	struct fwnode_handle *ep;
> >  
> >  	/*
> >  	 * If this function is in a loop and the previous iteration returned
> >  	 * an endpoint from fwnode->secondary, then we need to use the secondary
> >  	 * as parent rather than @fwnode.
> >  	 */
> > -	if (prev)
> > -		parent = fwnode_graph_get_port_parent(prev);
> > -	else
> > +	if (prev) {
> > +		port_parent = fwnode_graph_get_port_parent(prev);
> > +		parent = port_parent;
> > +	} else {
> >  		parent = fwnode;
> > +	}
> >  	if (IS_ERR_OR_NULL(parent))
> >  		return NULL;
> >  
> >  	ep = fwnode_call_ptr_op(parent, graph_get_next_endpoint, prev);
> > -	if (ep)

> > +	if (ep) {
> > +		fwnode_handle_put(port_parent);
> >  		return ep;
> > +	}

	if (ep)
		goto out;

> > -	return fwnode_graph_get_next_endpoint(parent->secondary, NULL);
> > +	ep = fwnode_graph_get_next_endpoint(parent->secondary, NULL);

out:

> > +	fwnode_handle_put(port_parent);
> > +	return ep;
> 
> It seems too complicated for the simple fix.
> 
> As I said, just drop const qualifier and add fwnode_handle_get() in the 'else'
> branch. This will allow you to drop if (prev) at the end.

-- 
With Best Regards,
Andy Shevchenko