On Thu, 17 Apr 2014 09:32:16 -0500, Rob Herring <robherring2@xxxxxxxxx> wrote:
> On Thu, Apr 17, 2014 at 2:48 AM, Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx> 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.
>
> I have a fix in my tree from Guenter which handles the race of the
> property being removed. However, your change will be needed when we
> have overlays and the node itself can be removed. So this is 3.16
> material and will need to be rebased on Guenter's fix.
I didn't think Guenter's patch actually fixed a race. It only fixed a
double checking of the oldprop pointer. Do I have it wrong?
g.
>
> Rob
>
> >
> > Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>
> > ---
> > drivers/of/base.c | 18 +++++++-----------
> > 1 file changed, 7 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index be2861d..06623d0c 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -1767,7 +1767,7 @@ int of_update_property(struct device_node *np, struct property *newprop)
> > {
> > struct property **next, *oldprop;
> > unsigned long flags;
> > - int rc, found = 0;
> > + int rc;
> >
> > rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop);
> > if (rc)
> > @@ -1776,20 +1776,19 @@ 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 new node */
> > + rc = __of_add_property(np, newprop);
> > + } else while (*next) {
> > + /* found the node and then replace it */
> > 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;
> > @@ -1803,9 +1802,6 @@ 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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