Re: [PATCH v15 08/19] media: subdev: Add for_each_active_route() macro

[Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>]

On 09/10/2022 08:38, Dafna Hirschfeld wrote:
> On 03.10.2022 15:18, Tomi Valkeinen wrote:
>> From: Jacopo Mondi <jacopo+renesas@jmondi.org>
>>
>> Add a for_each_active_route() macro to replace the repeated pattern
>> of iterating on the active routes of a routing table.
>>
>> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> ---
>> .clang-format                         |  1 +
>> drivers/media/v4l2-core/v4l2-subdev.c | 20 ++++++++++++++++++++
>> include/media/v4l2-subdev.h           | 13 +++++++++++++
>> 3 files changed, 34 insertions(+)
>>
>> diff --git a/.clang-format b/.clang-format
>> index 1247d54f9e49..31f39ae78f7b 100644
>> --- a/.clang-format
>> +++ b/.clang-format
>> @@ -190,6 +190,7 @@ ForEachMacros:
>>   - 'for_each_active_dev_scope'
>>   - 'for_each_active_drhd_unit'
>>   - 'for_each_active_iommu'
>> +  - 'for_each_active_route'
>>   - 'for_each_aggr_pgid'
>>   - 'for_each_available_child_of_node'
>>   - 'for_each_bench'
>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c 
>> b/drivers/media/v4l2-core/v4l2-subdev.c
>> index 3ae4f39a50e4..1049c07d2e49 100644
>> --- a/drivers/media/v4l2-core/v4l2-subdev.c
>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
>> @@ -1212,6 +1212,26 @@ int v4l2_subdev_set_routing(struct v4l2_subdev 
>> *sd,
>> }
>> EXPORT_SYMBOL_GPL(v4l2_subdev_set_routing);
>>
>> +struct v4l2_subdev_route *
>> +__v4l2_subdev_next_active_route(const struct v4l2_subdev_krouting 
>> *routing,
>> +                struct v4l2_subdev_route *route)
>> +{
>> +    if (route)
>> +        ++route;
>> +    else
>> +        route = &routing->routes[0];
>> +
>> +    for (; route < routing->routes + routing->num_routes; ++route) {
>> +        if (!(route->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
>> +            continue;
>> +
>> +        return route;
>> +    }
>> +
>> +    return NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(__v4l2_subdev_next_active_route);
>> +
>> #endif /* CONFIG_VIDEO_V4L2_SUBDEV_API */
>>
>> #endif /* CONFIG_MEDIA_CONTROLLER */
>> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
>> index 7962e6572bda..89e58208e330 100644
>> --- a/include/media/v4l2-subdev.h
>> +++ b/include/media/v4l2-subdev.h
>> @@ -1435,6 +1435,19 @@ int v4l2_subdev_set_routing(struct v4l2_subdev 
>> *sd,
>>                 struct v4l2_subdev_state *state,
>>                 const struct v4l2_subdev_krouting *routing);
>>
>> +struct v4l2_subdev_route *
>> +__v4l2_subdev_next_active_route(const struct v4l2_subdev_krouting 
>> *routing,
>> +                struct v4l2_subdev_route *route);
>> +
>> +/**
>> + * for_each_active_route - iterate on all active routes of a routing 
>> table
>> + * @routing: The routing table
>> + * @route: The route iterator
>> + */
>> +#define for_each_active_route(routing, route) \
>> +    for ((route) = NULL;                  \
>> +         ((route) = __v4l2_subdev_next_active_route((routing), 
>> (route)));)
> Hi, shouldn't it be something like:
>      for ((route) = NULL; (route) ; (route) = 
> __v4l2_subdev_next_active_route((routing), (route)))

What you suggest would never do anything: you initialize route to NULL, 
and then check if the route is !NULL.

I also find the current version a bit "interesting", but afaics, it 
works correctly.

  Tomi