Re: [PATCH v16 19/32] v4l: async: Ensure only unique fwnodes are registered to notifiers

Sakari Ailus
2017-10-27T10:06:09Z

Hi Niklas,

On Fri, Oct 27, 2017 at 11:52:27AM +0200, Niklas Söderlund wrote:
> Hi Sakari,
>
> Thanks for your patch.
>
> On 2017-10-26 10:53:29 +0300, Sakari Ailus wrote:
> > While registering a notifier, check that each newly added fwnode is
> > unique, and return an error if it is not. Also check that a newly added
> > notifier does not have the same fwnodes twice.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > Acked-by: Hans Verkuil <hans.verkuil-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
> > ---
> > drivers/media/v4l2-core/v4l2-async.c | 82 +++++++++++++++++++++++++++++++++---
> > 1 file changed, 77 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > index ed539c4fd5dc..b4e88eef195f 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -308,8 +308,71 @@ static void v4l2_async_notifier_unbind_all_subdevs(
> > notifier->parent = NULL;
> > }
> >
> > +/* See if an fwnode can be found in a notifier's lists. */
> > +static bool __v4l2_async_notifier_fwnode_has_async_subdev(
> > + struct v4l2_async_notifier *notifier, struct fwnode_handle *fwnode)
> > +{
> > + struct v4l2_async_subdev *asd;
> > + struct v4l2_subdev *sd;
> > +
> > + list_for_each_entry(asd, &notifier->waiting, list) {
> > + if (asd->match_type != V4L2_ASYNC_MATCH_FWNODE)
> > + continue;
> > +
> > + if (asd->match.fwnode.fwnode == fwnode)
> > + return true;
> > + }
> > +
> > + list_for_each_entry(sd, &notifier->done, async_list) {
> > + if (WARN_ON(!sd->asd))
> > + continue;
> > +
> > + if (sd->asd->match_type != V4L2_ASYNC_MATCH_FWNODE)
> > + continue;
> > +
> > + if (sd->asd->match.fwnode.fwnode == fwnode)
> > + return true;
> > + }
> > +
> > + return false;
> > +}
> > +
> > +/*
> > + * Find out whether an async sub-device was set up for an fwnode already or
> > + * whether it exists in a given notifier before @this_index.
> > + */
> > +static bool v4l2_async_notifier_fwnode_has_async_subdev(
> > + struct v4l2_async_notifier *notifier, struct fwnode_handle *fwnode,
> > + unsigned int this_index)
> > +{
> > + unsigned int j;
> > +
> > + lockdep_assert_held(&list_lock);
> > +
> > + /* Check that an fwnode is not being added more than once. */
> > + for (j = 0; j < this_index; j++) {
> > + struct v4l2_async_subdev *asd = notifier->subdevs[this_index];
> > + struct v4l2_async_subdev *other_asd = notifier->subdevs[j];
> > +
> > + if (other_asd->match_type == V4L2_ASYNC_MATCH_FWNODE &&
> > + asd->match.fwnode.fwnode ==
> > + other_asd->match.fwnode.fwnode)
> > + return true;
> > + }
> > +
> > + /* Check than an fwnode did not exist in other notifiers. */
> > + list_for_each_entry(notifier, &notifier_list, list)
> > + if (__v4l2_async_notifier_fwnode_has_async_subdev(
> > + notifier, fwnode))
> > + return true;
> > +
> > + return false;
> > +}
> > +
> > static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > {
> > + struct device *dev =
> > + notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL;
> > struct v4l2_async_subdev *asd;
> > int ret;
> > int i;
> > @@ -320,6 +383,8 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > INIT_LIST_HEAD(&notifier->waiting);
> > INIT_LIST_HEAD(&notifier->done);
> >
> > + mutex_lock(&list_lock);
> > +
> > for (i = 0; i < notifier->num_subdevs; i++) {
> > asd = notifier->subdevs[i];
> >
> > @@ -327,19 +392,25 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > case V4L2_ASYNC_MATCH_CUSTOM:
> > case V4L2_ASYNC_MATCH_DEVNAME:
> > case V4L2_ASYNC_MATCH_I2C:
> > + break;
> > case V4L2_ASYNC_MATCH_FWNODE:
> > + if (v4l2_async_notifier_fwnode_has_async_subdev(
> > + notifier, asd->match.fwnode.fwnode, i)) {
> > + dev_err(dev,
> > + "fwnode has already been registered or in notifier's subdev list\n");
> > + ret = -EEXIST;
> > + goto out_unlock;
>
> You store the error code in ret before the jump, but in the out_unlock
> path ret is not considered and 0 is always returned.
>
> > + }
> > break;
> > default:
> > - dev_err(notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL,
> > - "Invalid match type %u on %p\n",
> > + dev_err(dev, "Invalid match type %u on %p\n",
> > asd->match_type, asd);
> > - return -EINVAL;
> > + ret = -EINVAL;
> > + goto out_unlock;
>
> Same here.

Good catch! How about this change on top of the patch? It makes return
value checks a little bit safer, too.

diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
index b4e88eef195f..a33a68e5417b 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -412,12 +412,13 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
}

ret = v4l2_async_notifier_try_all_subdevs(notifier);
- if (ret)
+ if (ret < 0)
goto err_unbind;

ret = v4l2_async_notifier_try_complete(notifier);
- if (ret)
+ if (ret < 0)
goto err_unbind;
+ ret = 0;

/* Keep also completed notifiers on the list */
list_add(&notifier->list, &notifier_list);
@@ -425,7 +426,7 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
out_unlock:
mutex_unlock(&list_lock);

- return 0;
+ return ret;

err_unbind:
/*

>
> > }
> > list_add_tail(&asd->list, &notifier->waiting);
> > }
> >
> > - mutex_lock(&list_lock);
> > -
> > ret = v4l2_async_notifier_try_all_subdevs(notifier);
> > if (ret)
> > goto err_unbind;
> > @@ -351,6 +422,7 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > /* Keep also completed notifiers on the list */
> > list_add(&notifier->list, &notifier_list);
> >
> > +out_unlock:
> > mutex_unlock(&list_lock);
> >
> > return 0;

--
Sakari Ailus
e-mail: sakari.ailus-X3B1VOXEql0@public.gmane.org
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