Re: [PATCH 3/3] target: Minor sparse warning fixes and annotations

[Joe Eykholt <joe.eykholt@gmail.com>]

On 1/24/11 1:33 PM, Nicholas A. Bellinger wrote:
> On Mon, 2011-01-24 at 14:56 -0600, James Bottomley wrote:
>> On Mon, 2011-01-24 at 12:37 -0800, Nicholas A. Bellinger wrote:
>>> -#define TASK_CMD(task) ((struct se_cmd *)task->task_se_cmd)
>>> -#define TASK_DEV(task) ((struct se_device *)task->se_dev)
>>> +#define TASK_CMD(task) ((task)->task_se_cmd)
>>> +#define TASK_DEV(task) ((task)->se_dev)
Part of the problem with the old code is that task was not parenthesized,
so if TASK_CMD() were used with an expression, you might not get what
you want.  If you did TASK_CMD(p + 5), for example, you would get

     ((struct se_cmd *)p + 5->task_se_cmd)

Which wouldn't compile, but maybe other examples would compile and
would cause strange problems.   So, it's a bad macro as it is.
Just my 2 cents.

      Cheers,
      Joe

>>> If sparse is objecting to things like this then sparse needs fixing:
>>> It's decreasing typesafety.  the things being cast are void * ... they'd
>>> be depositable into any pointer whatsoever without the cast.  With the
>>> cast in the #define, we pick up pointer mismatches (as we should).
>>> Without it, we don't.  As long as the define is always a specific type,
>>> it *should* cast to it.
>>>
>
> Hmmm, good point..  In that case I will go ahead and drop this part of
> the patch.
>
> Thanks!
>
> --nab
>