Re: [REVIEW PATCH for v3.15 1/4] v4l2-subdev.h: fix sparse error with v4l2_subdev_notify

[Hans Verkuil <hverkuil@xs4all.nl>]

On 03/17/2014 12:44 PM, Laurent Pinchart wrote:
> Hi Hans,
> 
> Thank you for the patch.
> 
> On Saturday 15 March 2014 14:08:00 Hans Verkuil wrote:
>> From: Hans Verkuil <hans.verkuil@cisco.com>
>>
>> The notify function is a void function, yet the v4l2_subdev_notify
>> define uses it in a ? : construction, which causes sparse warnings.
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
>> ---
>>  include/media/v4l2-subdev.h | 8 +++++---
>>  1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
>> index 28f4d8c..0fbf669 100644
>> --- a/include/media/v4l2-subdev.h
>> +++ b/include/media/v4l2-subdev.h
>> @@ -692,9 +692,11 @@ void v4l2_subdev_init(struct v4l2_subdev *sd,
>>  		(sd)->ops->o->f((sd) , ##args) : -ENOIOCTLCMD))
>>
>>  /* Send a notification to v4l2_device. */
>> -#define v4l2_subdev_notify(sd, notification, arg)			   \
>> -	((!(sd) || !(sd)->v4l2_dev || !(sd)->v4l2_dev->notify) ? -ENODEV : \
>> -	 (sd)->v4l2_dev->notify((sd), (notification), (arg)))
>> +#define v4l2_subdev_notify(sd, notification, arg)				\
>> +	do {									\
>> +		if ((sd) && (sd)->v4l2_dev && (sd)->v4l2_dev->notify)		\
>> +			(sd)->v4l2_dev->notify((sd), (notification), (arg));	\
>> +	} while (0)
> 
> The construct would prevent using v4l2_subdev_notify() as an expression. What 
> about turning the macro into an inline function instead ?

How can you use a void function in an expression anyway? That was the whole point
of the sparse error.

Regards,

	Hans

> 
>>  #define v4l2_subdev_has_op(sd, o, f) \
>>  	((sd)->ops->o && (sd)->ops->o->f)
>