Re: [PATCH] Input: implement managed polled input devices

[David Herrmann]

Hi

On Tue, Apr 29, 2014 at 5:23 AM, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
> Managed resources are becoming more and more popular in drivers. Let's
> implement managed polled input devices, to complement managed regular input
> devices.
>
> Similarly to managed regular input devices only one new call
> devm_input_allocate_polled_device() is added and the rest of APIs is
> modified to work with both managed and non-managed devices.
>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> ---
>  drivers/input/input-polldev.c | 113 +++++++++++++++++++++++++++++++++++++++++-
>  include/linux/input-polldev.h |   3 ++
>  2 files changed, 115 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/input-polldev.c b/drivers/input/input-polldev.c
> index 4b19190..27961fc 100644
> --- a/drivers/input/input-polldev.c
> +++ b/drivers/input/input-polldev.c
> @@ -176,6 +176,90 @@ struct input_polled_dev *input_allocate_polled_device(void)
>  }
>  EXPORT_SYMBOL(input_allocate_polled_device);
>
> +struct input_polled_devres {
> +       struct input_polled_dev *polldev;
> +};
> +
> +static int devm_input_polldev_match(struct device *dev, void *res, void *data)
> +{
> +       struct input_polled_devres *devres = res;
> +
> +       return devres->polldev == data;
> +}
> +
> +static void devm_input_polldev_release(struct device *dev, void *res)
> +{
> +       struct input_polled_devres *devres = res;
> +       struct input_polled_dev *polldev = devres->polldev;
> +
> +       dev_dbg(dev, "%s: dropping reference/freeing %s\n",
> +               __func__, dev_name(&polldev->input->dev));
> +
> +       input_put_device(polldev->input);
> +       kfree(polldev);
> +}
> +
> +static void devm_input_polldev_unregister(struct device *dev, void *res)
> +{
> +       struct input_polled_devres *devres = res;
> +       struct input_polled_dev *polldev = devres->polldev;
> +
> +       dev_dbg(dev, "%s: unregistering device %s\n",
> +               __func__, dev_name(&polldev->input->dev));
> +       input_unregister_device(polldev->input);
> +
> +       /*
> +        * Note that we are still holding extra reference to the input
> +        * device so it will stick around until devm_input_polldev_release()
> +        * is called.
> +        */
> +}
> +
> +/**
> + * devm_input_allocate_polled_device - allocate managed polled device
> + * @dev: device owning the polled device being created
> + *
> + * Returns prepared &struct input_polled_dev or %NULL.
> + *
> + * Managed polled input devices do not need to be explicitly unregistered
> + * or freed as it will be done automatically when owner device unbinds
> + * from * its driver (or binding fails). Once such managed polled device
> + * is allocated, it is ready to be set up and registered in the same
> + * fashion as regular polled input devices (using
> + * input_register_polled_device() function).
> + *
> + * If you want to manually unregister and free such managed polled devices,
> + * it can be still done by calling input_unregister_polled_device() and
> + * input_free_polled_device(), although it is rarely needed.
> + *
> + * NOTE: the owner device is set up as parent of input device and users
> + * should not override it.
> + */
> +struct input_polled_dev *devm_input_allocate_polled_device(struct device *dev)
> +{
> +       struct input_polled_dev *polldev;
> +       struct input_polled_devres *devres;
> +
> +       devres = devres_alloc(devm_input_polldev_release, sizeof(*devres),
> +                             GFP_KERNEL);
> +       if (!devres)
> +               return NULL;
> +
> +       polldev = input_allocate_polled_device();
> +       if (!polldev) {
> +               devres_free(devres);
> +               return NULL;
> +       }
> +
> +       polldev->input->dev.parent = dev;
> +       polldev->devres_managed = true;
> +
> +       devres->polldev = polldev;
> +       devres_add(dev, devres);
> +
> +       return polldev;
> +}
> +
>  /**
>   * input_free_polled_device - free memory allocated for polled device
>   * @dev: device to free
> @@ -186,7 +270,12 @@ EXPORT_SYMBOL(input_allocate_polled_device);
>  void input_free_polled_device(struct input_polled_dev *dev)
>  {
>         if (dev) {
> -               input_free_device(dev->input);
> +               if (dev->devres_managed)
> +                       WARN_ON(devres_destroy(dev->input->dev.parent,
> +                                               devm_input_polldev_release,
> +                                               devm_input_polldev_match,
> +                                               dev));
> +               input_put_device(dev->input);
>                 kfree(dev);
>         }
>  }
> @@ -204,9 +293,19 @@ EXPORT_SYMBOL(input_free_polled_device);
>   */
>  int input_register_polled_device(struct input_polled_dev *dev)
>  {
> +       struct input_polled_devres *devres = NULL;
>         struct input_dev *input = dev->input;
>         int error;
>
> +       if (dev->devres_managed) {
> +               devres = devres_alloc(devm_input_polldev_unregister,
> +                                     sizeof(*devres), GFP_KERNEL);
> +               if (!devres)
> +                       return -ENOMEM;
> +
> +               devres->polldev = dev;

Your error-paths in this function _must_ free "devres" via devres_free().

With this fixed:
  Reviewed-by: David Herrmann <dh.herrmann@xxxxxxxxx>

Thanks
David

> +       }
> +
>         input_set_drvdata(input, dev);
>         INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
>
> @@ -233,6 +332,12 @@ int input_register_polled_device(struct input_polled_dev *dev)
>          */
>         input_get_device(input);
>
> +       if (dev->devres_managed) {
> +               dev_dbg(input->dev.parent, "%s: registering %s with devres.\n",
> +                       __func__, dev_name(&input->dev));
> +               devres_add(input->dev.parent, devres);
> +       }
> +
>         return 0;
>  }
>  EXPORT_SYMBOL(input_register_polled_device);
> @@ -247,6 +352,12 @@ EXPORT_SYMBOL(input_register_polled_device);
>   */
>  void input_unregister_polled_device(struct input_polled_dev *dev)
>  {
> +       if (dev->devres_managed)
> +               WARN_ON(devres_destroy(dev->input->dev.parent,
> +                                       devm_input_polldev_unregister,
> +                                       devm_input_polldev_match,
> +                                       dev));
> +
>         input_unregister_device(dev->input);
>  }
>  EXPORT_SYMBOL(input_unregister_polled_device);
> diff --git a/include/linux/input-polldev.h b/include/linux/input-polldev.h
> index ce0b724..2465182 100644
> --- a/include/linux/input-polldev.h
> +++ b/include/linux/input-polldev.h
> @@ -48,9 +48,12 @@ struct input_polled_dev {
>
>  /* private: */
>         struct delayed_work work;
> +
> +       bool devres_managed;
>  };
>
>  struct input_polled_dev *input_allocate_polled_device(void);
> +struct input_polled_dev *devm_input_allocate_polled_device(struct device *dev);
>  void input_free_polled_device(struct input_polled_dev *dev);
>  int input_register_polled_device(struct input_polled_dev *dev);
>  void input_unregister_polled_device(struct input_polled_dev *dev);
> --
> 1.9.0
>
>
> --
> Dmitry
> --
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