On Mon, 28 Mar 2022 08:47:39 +0530, Viresh Kumar wrote:
> > diff --git a/drivers/opp/debugfs.c b/drivers/opp/debugfs.c
> > index 596c185b5dda..a4476985e4ce 100644
> > --- a/drivers/opp/debugfs.c
> > +++ b/drivers/opp/debugfs.c
> > @@ -187,14 +187,19 @@ void opp_debug_register(struct opp_device *opp_dev, struct opp_table *opp_table)
> > static void opp_migrate_dentry(struct opp_device *opp_dev,
> > struct opp_table *opp_table)
> > {
> > - struct opp_device *new_dev;
> > + struct opp_device *new_dev = NULL, *iter;
> > const struct device *dev;
> > struct dentry *dentry;
> >
> > /* Look for next opp-dev */
> > - list_for_each_entry(new_dev, &opp_table->dev_list, node)
> > - if (new_dev != opp_dev)
> > + list_for_each_entry(iter, &opp_table->dev_list, node)
> > + if (iter != opp_dev) {
> > + new_dev = iter;
> > break;
> > + }
> > +
> > + if (!new_dev)
> > + return;
>
> I think you missed this check in the parent function ?
>
> if (!list_is_singular(&opp_table->dev_list)) {
>
>
> i.e. this bug can never happen.
>
No. the conditon to call opp_migrate_dentry(opp_dev, opp_table); is:
if (!list_is_singular(&opp_table->dev_list)),
while list_is_singlular is: !list_empty(head) && (head->next == head->prev);
so the condition is: list_empty(head) || (head->next != head->prev)
if the list is empty, the bug can be triggered.
--
Xiaomeng Tong
