RE: [PATCH] of: fix of_update_property [v2]

[Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On Wed, 2 Apr 2014 05:29:53 +0000, "Li.Xiubo-KZfg59tc24xl57MIdRCFDg@public.gmane.org" <Li.Xiubo-KZfg59tc24xl57MIdRCFDg@public.gmane.org> wrote:
> 
> 
> > > @@ -1776,25 +1776,26 @@ 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) {
> > > +	oldprop = __of_find_property(np, newprop->name, NULL);
> > > +	if (!oldprop) {
> > > +		/* add the node */
> > > +		rc = __of_add_property(np, newprop);
> > > +	} else {
> > 
> > if you changed this line to:
> > 	} else while (*next) {
> > then most of the other changes go away. You don't need the separate
> > while loop 
> 
> Yes, I will fix this.
> 
> 
> > and the function remains largely identical aside from moving
> > the __of_find_property() into the spinlock.
> >
> 
> But, from the following codes, we can see that, if oldprop !=  NULL 
> Meaning that we have found it, and should just do the updatation later:
> +++++++++++++++
> 	oldprop = of_find_property(np, newprop->name, NULL);
> 	if (!oldprop)
> 		return of_add_property(np, newprop);
> ---------------
> 
> 
>  
> > >  			/* found the node */
> > >  			newprop->next = oldprop->next;
> > >  			*next = newprop;
> > >  			oldprop->next = np->deadprops;
> > >  			np->deadprops = oldprop;
> > > -			found = 1;
> 
> And why the 'found' flag is here is that the oldprop maybe removed
> just before the spin_lock and after of_find_property().
> 
> And so use and move __of_find_property() and __of_add_property() into
> the spinlock could avoid this...

Isn't that what I said?

g.

> 
> 
> Thanks,
> --
> 
> BRs,
> Xiubo
> 
> 
> > > -			break;
> > >  		}
> > > -		next = &(*next)->next;
> > >  	}
> > >  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
> > > +
> > >  	if (rc)
> > >  		return rc;
> > >
> > > @@ -1803,9 +1804,6 @@ int of_update_property(struct device_node *np, struct
> > property *newprop)
> > >  		sysfs_remove_bin_file(&np->kobj, &oldprop->attr);
> > >  	__of_add_property_sysfs(np, newprop);
> > >
> > > -	if (!found)
> > > -		return -ENODEV;
> > > -
> > >  	return 0;
> > >  }
> > >
> > > --
> > > 1.8.4
> > >
> > >
> > 
> > 
> 

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