Re: [PATCH 1/2] v4l2-ioctl: simplify code

[Hans Verkuil <hverkuil@xs4all.nl>]

On 03/14/2016 01:42 PM, Niklas Söderlund wrote:
> Hi Hans,
> 
> On 2016-02-29 11:16:39 +0100, Hans Verkuil wrote:
>> From: Hans Verkuil <hans.verkuil@cisco.com>
>>
>> Instead of a big if at the beginning, just check if g_selection == NULL
>> and call the cropcap op immediately and return the result.
>>
>> No functional changes in this patch.
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
>> ---
>>  drivers/media/v4l2-core/v4l2-ioctl.c | 44 ++++++++++++++++++------------------
>>  1 file changed, 22 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
>> index 86c4c19..67dbb03 100644
>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>> @@ -2157,33 +2157,33 @@ static int v4l_cropcap(const struct v4l2_ioctl_ops *ops,
>>  				struct file *file, void *fh, void *arg)
>>  {
>>  	struct v4l2_cropcap *p = arg;
>> +	struct v4l2_selection s = { .type = p->type };
>> +	int ret;
>>  
>> -	if (ops->vidioc_g_selection) {
>> -		struct v4l2_selection s = { .type = p->type };
>> -		int ret;
>> +	if (ops->vidioc_g_selection == NULL)
>> +		return ops->vidioc_cropcap(file, fh, p);
> 
> I might be missing something but is there a guarantee 
> ops->vidioc_cropcap is not NULL here?

There is, either vidioc_g_selection or vidioc_cropcap will always be
non-NULL. Since g_selection == NULL it follows that cropcap != NULL.

But I admit that it isn't exactly obvious since the test that ensures
this is in determine_valid_ioctls() in v4l2-dev.c.

Regards,

	Hans