Hi Sakari,

On Thu, Jun 06, 2019 at 04:02:19PM +0300, Sakari Ailus wrote:
> The v4l2_async_notifier_add_fwnode_subdev() did not take a reference of
> the added fwnode, relying on the caller to handle that instead, in essence
> putting the fwnode to be added if there was an error.
>
> As the reference is eventually released during the notifier cleanup, this
> is not intuitive nor logical. Improve this by always getting a reference
> when the function succeeds, and the caller releasing the reference when it
> does not *itself* need it anymore.
>
> Luckily, perhaps, there were just a handful of callers using the function.
>
> Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
> ---
>  drivers/media/platform/am437x/am437x-vpfe.c   |  5 ++---
>  drivers/media/platform/davinci/vpif_capture.c | 16 ++++++++--------
>  drivers/media/platform/qcom/camss/camss.c     |  2 +-
>  drivers/media/platform/xilinx/xilinx-vipp.c   |  2 +-
>  drivers/media/v4l2-core/v4l2-async.c          |  3 ++-
>  drivers/media/v4l2-core/v4l2-fwnode.c         | 23 ++++++-----------------
>  include/media/v4l2-async.h                    |  5 +++--
>  7 files changed, 23 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/media/platform/am437x/am437x-vpfe.c 
> b/drivers/media/platform/am437x/am437x-vpfe.c
> index db263c0ce48e..ccdbd9227955 100644
> --- a/drivers/media/platform/am437x/am437x-vpfe.c
> +++ b/drivers/media/platform/am437x/am437x-vpfe.c
> @@ -2505,10 +2505,9 @@ vpfe_get_pdata(struct vpfe_device *vpfe)
>               pdata->asd[i] = v4l2_async_notifier_add_fwnode_subdev(
>                       &vpfe->notifier, of_fwnode_handle(rem),
>                       sizeof(struct v4l2_async_subdev));
> -             if (IS_ERR(pdata->asd[i])) {
> -                     of_node_put(rem);
> +             of_node_put(rem);
> +             if (IS_ERR(pdata->asd[i]))
>                       goto cleanup;
> -             }
>       }
>
>       of_node_put(endpoint);
> diff --git a/drivers/media/platform/davinci/vpif_capture.c 
> b/drivers/media/platform/davinci/vpif_capture.c
> index 8fdea45ae090..2a0c3f3fb443 100644
> --- a/drivers/media/platform/davinci/vpif_capture.c
> +++ b/drivers/media/platform/davinci/vpif_capture.c
> @@ -1512,6 +1512,7 @@ static struct vpif_capture_config *
>  vpif_capture_get_pdata(struct platform_device *pdev)
>  {
>       struct device_node *endpoint = NULL;
> +     struct device_node *rem = NULL, *rem_ep = NULL;
>       struct vpif_capture_config *pdata;
>       struct vpif_subdev_info *sdinfo;
>       struct vpif_capture_chan_config *chan;
> @@ -1542,7 +1543,6 @@ vpif_capture_get_pdata(struct platform_device *pdev)
>
>       for (i = 0; i < VPIF_CAPTURE_NUM_CHANNELS; i++) {
>               struct v4l2_fwnode_endpoint bus_cfg = { .bus_type = 0 };
> -             struct device_node *rem, *rem_ep;
>               unsigned int flags;
>               int err;
>
> @@ -1565,7 +1565,6 @@ vpif_capture_get_pdata(struct platform_device *pdev)
>                       of_node_put(rem_ep);
>                       goto done;
>               }
> -             of_node_put(rem_ep);
>
>               sdinfo = &pdata->subdev_info[i];
>               chan = &pdata->chan_config[i];
> @@ -1573,10 +1572,8 @@ vpif_capture_get_pdata(struct platform_device *pdev)
>                                           VPIF_CAPTURE_NUM_CHANNELS,
>                                           sizeof(*chan->inputs),
>                                           GFP_KERNEL);
> -             if (!chan->inputs) {
> -                     of_node_put(rem);
> +             if (!chan->inputs)
>                       goto err_cleanup;
> -             }
>
>               chan->input_count++;
>               chan->inputs[i].input.type = V4L2_INPUT_TYPE_CAMERA;
> @@ -1588,6 +1585,7 @@ vpif_capture_get_pdata(struct platform_device *pdev)
>               if (err) {
>                       dev_err(&pdev->dev, "Could not parse the endpoint\n");
>                       of_node_put(rem);
> +                     of_node_put(rem_ep);
>                       goto done;
>               }
>
> @@ -1608,11 +1606,11 @@ vpif_capture_get_pdata(struct platform_device *pdev)
>               pdata->asd[i] = v4l2_async_notifier_add_fwnode_subdev(
>                       &vpif_obj.notifier, of_fwnode_handle(rem_ep),
>                       sizeof(struct v4l2_async_subdev));
> -             if (IS_ERR(pdata->asd[i])) {
> -                     of_node_put(rem);
> +             if (IS_ERR(pdata->asd[i]))
>                       goto err_cleanup;
> -             }
>
> +             of_node_put(rem);
> +             of_node_put(rem_ep);
>       }
>
>  done:
> @@ -1624,6 +1622,8 @@ vpif_capture_get_pdata(struct platform_device *pdev)
>       return pdata;
>
>  err_cleanup:
> +     of_node_put(rem);
> +     of_node_put(rem_ep);
>       of_node_put(endpoint);
>       v4l2_async_notifier_cleanup(&vpif_obj.notifier);
>
> diff --git a/drivers/media/platform/qcom/camss/camss.c 
> b/drivers/media/platform/qcom/camss/camss.c
> index a979f210f441..4ab4a47d34f3 100644
> --- a/drivers/media/platform/qcom/camss/camss.c
> +++ b/drivers/media/platform/qcom/camss/camss.c
> @@ -486,9 +486,9 @@ static int camss_of_parse_ports(struct camss *camss)
>
>               asd = v4l2_async_notifier_add_fwnode_subdev(
>                       &camss->notifier, remote, sizeof(*csd));
> +             fwnode_handle_put(remote);
>               if (IS_ERR(asd)) {
>                       ret = PTR_ERR(asd);
> -                     fwnode_handle_put(remote);
>                       goto err_cleanup;
>               }
>
> diff --git a/drivers/media/platform/xilinx/xilinx-vipp.c 
> b/drivers/media/platform/xilinx/xilinx-vipp.c
> index 41df417153bd..d788f4870a23 100644
> --- a/drivers/media/platform/xilinx/xilinx-vipp.c
> +++ b/drivers/media/platform/xilinx/xilinx-vipp.c
> @@ -392,9 +392,9 @@ static int xvip_graph_parse_one(struct 
> xvip_composite_device *xdev,
>               asd = v4l2_async_notifier_add_fwnode_subdev(
>                       &xdev->notifier, remote,
>                       sizeof(struct xvip_graph_entity));
> +             fwnode_handle_put(remote);
>               if (IS_ERR(asd)) {
>                       ret = PTR_ERR(asd);
> -                     fwnode_handle_put(remote);
>                       goto err_notifier_cleanup;
>               }
>       }
> diff --git a/drivers/media/v4l2-core/v4l2-async.c 
> b/drivers/media/v4l2-core/v4l2-async.c
> index 304969ff3191..dc4e83b4f6ba 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -596,10 +596,11 @@ v4l2_async_notifier_add_fwnode_subdev(struct 
> v4l2_async_notifier *notifier,
>               return ERR_PTR(-ENOMEM);
>
>       asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> -     asd->match.fwnode = fwnode;
> +     asd->match.fwnode = fwnode_handle_get(fwnode);
>
>       ret = v4l2_async_notifier_add_subdev(notifier, asd);
>       if (ret) {
> +             fwnode_handle_put(fwnode);
>               kfree(asd);
>               return ERR_PTR(ret);
>       }
> diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c 
> b/drivers/media/v4l2-core/v4l2-fwnode.c
> index 810b6584b522..b48725824580 100644
> --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> @@ -780,23 +780,17 @@ static int v4l2_fwnode_reference_parse(struct device 
> *dev,
>               asd = v4l2_async_notifier_add_fwnode_subdev(notifier,
>                                                           args.fwnode,
>                                                           sizeof(*asd));
> +             fwnode_handle_put(args.fwnode);
>               if (IS_ERR(asd)) {
> -                     ret = PTR_ERR(asd);
>                       /* not an error if asd already exists */
> -                     if (ret == -EEXIST) {
> -                             fwnode_handle_put(args.fwnode);
> +                     if (PTR_ERR(asd) == -EEXIST)
>                               continue;
> -                     }
>
> -                     goto error;
> +                     return PTR_ERR(asd);
>               }
>       }
>
>       return 0;
> -
> -error:
> -     fwnode_handle_put(args.fwnode);
> -     return ret;
>  }
>
>  /*
> @@ -1085,22 +1079,17 @@ v4l2_fwnode_reference_parse_int_props(struct device 
> *dev,
>
>               asd = v4l2_async_notifier_add_fwnode_subdev(notifier, fwnode,
>                                                           sizeof(*asd));
> +             fwnode_handle_put(fwnode);
>               if (IS_ERR(asd)) {
>                       /* not an error if asd already exists */
> -                     if (PTR_ERR(asd) == -EEXIST) {
> -                             fwnode_handle_put(fwnode);
> +                     if (PTR_ERR(asd) == -EEXIST)
>                               continue;
> -                     }
>
> -                     goto error;
> +                     return PTR_ERR(asd);
>               }
>       }
>
>       return PTR_ERR(fwnode) == -ENOENT ? 0 : PTR_ERR(fwnode);
> -
> -error:
> -     fwnode_handle_put(fwnode);
> -     return PTR_ERR(fwnode);
>  }
>
>  int v4l2_async_notifier_parse_fwnode_sensor_common(struct device *dev,
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index 1497bda66c3b..b9141ffa188a 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -175,8 +175,9 @@ int v4l2_async_notifier_add_subdev(struct 
> v4l2_async_notifier *notifier,
>   *                the driver's async sub-device struct, i.e. both
>   *                begin at the same memory address.
>   *
> - * Allocate a fwnode-matched asd of size asd_struct_size, and add it
> - * to the notifiers @asd_list.
> + * Allocate a fwnode-matched asd of size asd_struct_size, and add it to the
> + * notifiers @asd_list. The function also gets a reference of the fwnode 
> which
> + * is released later at notifier cleanup time.

I would add that, as a consequence, the caller need to put their local
references as soon as they don't need them anymore (possibly just
after calling this function).

That apart
Reviewed-by: Jacopo Mondi <jacopo+rene...@jmondi.org>

Thanks
   j

>   */
>  struct v4l2_async_subdev *
>  v4l2_async_notifier_add_fwnode_subdev(struct v4l2_async_notifier *notifier,
> --
> 2.11.0
>

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