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

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Tue, Apr 29, 2014 at 08:09:39AM +0200, David Herrmann wrote:
> Hi
> 
> On Tue, Apr 29, 2014 at 5:23 AM, Dmitry Torokhov
> <dmitry.torokhov@gmail.com> 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@gmail.com>
> > ---
> >  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().

Indeed.

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

Thanks David!

-- 
Dmitry