Re: [PATCH v6 2/2] media: i2c: Add driver for ST VD56G3 camera sensor

[Sakari Ailus]

Hi Sylvain,

On Fri, May 02, 2025 at 09:39:27PM +0200, Sylvain Petinot wrote:
> Hi Sakari,
> 
> Le 02/05/2025 à 00:20, Sakari Ailus a écrit :
> > Hi Sylvain,
> > 
> > On Wed, Apr 30, 2025 at 04:19:14PM +0200, Sylvain Petinot wrote:
> > > > > +static int vd56g3_subdev_init(struct vd56g3 *sensor)
> > > > > +{
> > > > > +	int ret;
> > > > > +
> > > > > +	/* Init remaining sub device ops */
> > > > > +	sensor->sd.internal_ops = &vd56g3_internal_ops;
> > > > > +	sensor->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > > > > +	sensor->sd.entity.ops = &vd56g3_subdev_entity_ops;
> > > > > +
> > > > > +	/* Init source pad */
> > > > > +	sensor->pad.flags = MEDIA_PAD_FL_SOURCE;
> > > > > +	sensor->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> > > > > +	ret = media_entity_pads_init(&sensor->sd.entity, 1, &sensor->pad);
> > > > > +	if (ret) {
> > > > > +		dev_err(sensor->dev, "Failed to init media entity : %d", ret);
> > > > > +		return ret;
> > > > > +	}
> > > > > +
> > > > > +	/* Init controls */
> > > > > +	ret = vd56g3_init_controls(sensor);
> > > > > +	if (ret) {
> > > > > +		dev_err(sensor->dev, "Controls initialization failed %d", ret);
> > > > > +		goto err_media;
> > > > > +	}
> > > > > +
> > > > > +	/* Init vd56g3 struct : default resolution + raw8 */
> > > > > +	sensor->sd.state_lock = sensor->ctrl_handler.lock;
> > > > > +	ret = v4l2_subdev_init_finalize(&sensor->sd);
> > > > > +	if (ret) {
> > > > > +		dev_err(sensor->dev, "subdev init error: %d", ret);
> > > > > +		goto err_ctrls;
> > > > > +	}
> > > > > +
> > > > > +	return vd56g3_update_controls(sensor);
> > > > 
> > > > You're not holding the control handler's lock in the above call.
> > > 
> > > If your comment is related to the fact that 'vd56g3_update_controls() can
> > > fail and that we do not free control handler not cleanup media entity, it's
> > > fixed in V7.
> > 
> > It's not. The access to the control handler is serialised by a mutex and
> > you're not holding that mutex whilst calling vd56g3_update_controls() here.
> > The same issue exists in accessing sub-device state.
> > 
> 
> I'm sorry, I missed that ...
> That should be better with something like :
> 
> 	state = v4l2_subdev_lock_and_get_active_state(&sensor->sd);
> 	ret = vd56g3_update_controls(sensor);
> 	v4l2_subdev_unlock_state(state);

Correct.

> 
> I'll prepare and push a V8.

Thanks!

-- 
Regards,

Sakari Ailus