RE: [PATCHv2 2/2] of: fix of_update_property()

["Li.Xiubo@freescale.com" <Li.Xiubo@freescale.com>]

> Subject: Re: [PATCHv2 2/2] of: fix of_update_property()
> 
> On Wed, 22 Jan 2014 13:57:40 +0800, Xiubo Li <Li.Xiubo@freescale.com> wrote:
> > The of_update_property() is intented to update a property in a node
> > and if the property does not exist, will add it.
> >
> > The second search of the property is possibly won't be found, that
> > maybe removed by other thread just before the second search begain.
> >
> > Using the __of_find_property() and __of_add_property() instead and
> > move them into lock operations.
> >
> > Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
> > Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
> 
> I've had to revert this patch. See below...
> 
> > ---
> >  drivers/of/base.c | 36 ++++++++++++++----------------------
> >  1 file changed, 14 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index b86b77a..458072d 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -1573,7 +1573,7 @@ int of_update_property(struct device_node *np, struct
> property *newprop)
> >  {
> >  	struct property **next, *oldprop;
> >  	unsigned long flags;
> > -	int rc, found = 0;
> > +	int rc = 0;
> >
> >  	rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop);
> >  	if (rc)
> > @@ -1582,36 +1582,28 @@ int of_update_property(struct device_node *np,
> struct property *newprop)
> >  	if (!newprop->name)
> >  		return -EINVAL;
> >
> > -	oldprop = of_find_property(np, newprop->name, NULL);
> > -	if (!oldprop)
> > -		return of_add_property(np, newprop);
> > -
> >  	raw_spin_lock_irqsave(&devtree_lock, flags);
> > -	next = &np->properties;
> > -	while (*next) {
> > -		if (*next == oldprop) {
> > -			/* found the node */
> > -			newprop->next = oldprop->next;
> > -			*next = newprop;
> > -			oldprop->next = np->deadprops;
> > -			np->deadprops = oldprop;
> > -			found = 1;
> > -			break;
> > -		}
> > -		next = &(*next)->next;
> > +	oldprop = __of_find_property(np, newprop->name, NULL);
> > +	if (!oldprop) {
> > +		/* add the node */
> > +		rc = __of_add_property(np, newprop);
> > +	} else {
> > +		/* replace the node */
> > +		next = &oldprop;
> 
> Ugh. I just looked closer and the above line is completely broken.
> &oldprop is the address of 'oldprop' on the stack, *not* the address of
> the previous item in the list. The while loop is still required to find it.
> 

Yes, I'll fix this.

Thanks very much.

BRs
Xiubo


> g.
> 
> > +		newprop->next = oldprop->next;
> > +		*next = newprop;
> > +		oldprop->next = np->deadprops;
> > +		np->deadprops = oldprop;
> >  	}
> >  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
> >
> > -	if (!found)
> > -		return -ENODEV;
> > -
> >  #ifdef CONFIG_PROC_DEVICETREE
> >  	/* try to add to proc as well if it was initialized */
> > -	if (np->pde)
> > +	if (!rc && np->pde)
> >  		proc_device_tree_update_prop(np->pde, newprop, oldprop);
> >  #endif /* CONFIG_PROC_DEVICETREE */
> >
> > -	return 0;
> > +	return rc;
> >  }
> >
> >  #if defined(CONFIG_OF_DYNAMIC)
> > --
> > 1.8.4
> >
> >
> 
>