On 12/14/2011 12:59 AM, Greg KH wrote:
>
>>>> +static inline int buffer_get_length(struct iio_buffer *buffer)
>>>> +{
>>>> + if (buffer->access->get_length)
>>>> + return buffer->access->get_length(buffer);
>>>> +
>>>> + return -ENOSYS;
>>>
>>> Here you return an error, but why ENOSYS?
>>>
>>> Consistancy is key, and you don't have it here at all. Or if you do, I
>>> sure don't understand it...
>>
>> Well, different types of functions require different semantics. While the
>> previous ones did either return 0 in case of success or a error value in case
>> of an error, buffer_get_length returns an integer value where 0 is a valid
>> value. Since we can't make any meaningful assumptions about the buffer size
>> if
>> the callback is not implemented we return an error value. Why ENOSYS? Because
>> it is the code for 'function not implemented' and is used throughout the
>> kernel
>> in similar situations.
>
> Is the caller always supposed to check this? If so, please mark the
> function as such so the compiler will complain if it isn't.
Marking the function as __must_check doesn't make much sense here. Since it
will either return an error or the buffer length. So you'll always use the
returned result one way or the other.
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