Re: [PATCH v7 10/18] v4l: async: Introduce macros for calling async ops callbacks

[Hans Verkuil]

On 09/03/2017 07:49 PM, Sakari Ailus wrote:
> Add two macros to call async operations callbacks. Besides simplifying
> callbacks, this allows async notifiers to have no ops set, i.e. it can be
> left NULL.
> 
> Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
> ---
>  drivers/media/v4l2-core/v4l2-async.c | 19 +++++++------------
>  include/media/v4l2-async.h           |  8 ++++++++
>  2 files changed, 15 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-async.c 
> b/drivers/media/v4l2-core/v4l2-async.c
> index 810f5e0273dc..91d04f00b4e4 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -107,16 +107,13 @@ static int v4l2_async_test_notify(struct 
> v4l2_async_notifier *notifier,
>  {
>       int ret;
>  
> -     if (notifier->ops->bound) {
> -             ret = notifier->ops->bound(notifier, sd, asd);
> -             if (ret < 0)
> -                     return ret;
> -     }
> +     ret = v4l2_async_notifier_call_int_op(notifier, bound, sd, asd);

Hmm, I think this is rather ugly. We only have three ops, so why not make
three macros:

        v4l2_async_notifier_call_bound/unbind/complete?

Much cleaner than _int_op(...bound...).

Regards,

        Hans

> +     if (ret < 0)
> +             return ret;
>  
>       ret = v4l2_device_register_subdev(notifier->v4l2_dev, sd);
>       if (ret < 0) {
> -             if (notifier->ops->unbind)
> -                     notifier->ops->unbind(notifier, sd, asd);
> +             v4l2_async_notifier_call_void_op(notifier, unbind, sd, asd);
>               return ret;
>       }
>  
> @@ -129,7 +126,7 @@ static int v4l2_async_test_notify(struct 
> v4l2_async_notifier *notifier,
>       list_move(&sd->async_list, &notifier->done);
>  
>       if (list_empty(&notifier->waiting) && notifier->ops->complete)
> -             return notifier->ops->complete(notifier);
> +             return v4l2_async_notifier_call_int_op(notifier, complete);
>  
>       return 0;
>  }
> @@ -232,8 +229,7 @@ void v4l2_async_notifier_unregister(struct 
> v4l2_async_notifier *notifier)
>               /* If we handled USB devices, we'd have to lock the parent too 
> */
>               device_release_driver(d);
>  
> -             if (notifier->ops->unbind)
> -                     notifier->ops->unbind(notifier, sd, sd->asd);
> +             v4l2_async_notifier_call_void_op(notifier, unbind, sd, sd->asd);
>  
>               /*
>                * Store device at the device cache, in order to call
> @@ -344,8 +340,7 @@ void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
>  
>       v4l2_async_cleanup(sd);
>  
> -     if (notifier->ops->unbind)
> -             notifier->ops->unbind(notifier, sd, sd->asd);
> +     v4l2_async_notifier_call_void_op(notifier, unbind, sd, sd->asd);
>  
>       mutex_unlock(&list_lock);
>  }
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index 3c48f8b66d12..c3e001e0d1f1 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -95,6 +95,14 @@ struct v4l2_async_notifier_operations {
>                      struct v4l2_async_subdev *asd);
>  };
>  
> +#define v4l2_async_notifier_call_int_op(n, op, ...)                  \
> +     (((n)->ops && (n)->ops->op) ? (n)->ops->op(n, ## __VA_ARGS__) : 0)
> +#define v4l2_async_notifier_call_void_op(n, op, ...)  \
> +     do {                                             \
> +             if ((n)->ops && (n)->ops->op)            \
> +                     (n)->ops->op(n, ## __VA_ARGS__); \
> +     } while (false)
> +
>  /**
>   * struct v4l2_async_notifier - v4l2_device notifier data
>   *
>