On Thu, Nov 26, 2015 at 8:54 AM, SF Markus Elfring
<elfring@xxxxxxxxxxxxxxxxxxxxx> wrote:
>>> I interpreted the eventual passing of a null pointer to the rbd_dev_destroy()
>>> function as an indication for further source code adjustments.
>>
>> If all error paths could be adjusted so that NULL pointers are never passed in,
>> destroy functions wouldn't need to have a NULL check, would they?
>
> How do you think about to clarify corresponding implementation details a bit more?
>
> * Why was the function "rbd_dev_probe_parent" implemented in the way
> that it relies on a sanity check in the function "rbd_dev_destroy" then?
Because it's not a bad thing? What's wrong with an init to NULL,
a possible assignment, in this case from rbd_dev_create(), and an
unconditional rbd_dev_destroy()?
The NULL check in rbd_dev_destroy() is not a sanity check, it's
a feature. It's not there to "fixup" callers that pass NULL - it's
there because it is _expected_ that some callers will pass NULL.
> * How are the chances to restructure the source code a bit (like changing a few
> jump labels) so that it should also work without an extra function call
> during error handling there?
As I said in my reply to Dan, the problem with rbd_dev_probe_parent()
is the calling code which expects it to call unparent if ->parent_spec.
This makes it stand out and confuses people, but can't be fixed without
refactoring a bunch of other code.
The extra function call is *not* a problem.
Thanks,
Ilya
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