Re: [PATCH] drivers/ata/libata-eh.c: fix unused variable warning

[Jeff Garzik <jeff@garzik.org>]

On 04/23/2010 10:07 AM, Sergei Shtylyov wrote:
> Hello.
>
> Jeff Garzik wrote:
>
>>>>>> Sorry that the title should be:
>>>>>> "fix uninitialized variable warning"
>>>>>>
>>>>>> not
>>>>>> "fix unused variable warning"
>>>>>>
>>>>>> Need I re-send the patch mail ?
>>>>>
>>>>> Yes, please do so. gcc 4.4.1 generates a spurious warning on it too.
>>>>>
>>>>> Acked-by: Tejun Heo<tj@kernel.org>
>>>>
>>>> It's not a spurious warning. The code failed to fully initialize all
>>>> fields of the ata_taskfile structure, prior to copying the ata_taskfile
>>>> structure into qc->result_tf.
>>>
>>> Hmmmm.... right, I've always thought it was gcc not noticing the
>>> structure is being initialized in ata_eh_read_log_10h() but it
>>> actually is noticing much more, so something like the following is
>>> more appropriate?
>>>
>>> Subject: libata: fully initialize @tf in ata_eh_read_log_10h()
>>>
>>> ata_eh_read_log_10h() filled @tf only partially. It didn't cause any
>>> correctness issues but triggered spruious uninitialized variable
>>> warning. Do ata_tf_init() before filling in @tf.
>>>
>>> Signed-off-by: Tejun Heo<tj@kernel.org>
>>
>> Sorry, I should have also pointed out that a fix went upstream to
>> Linus in the last batch of fixes...
>
> I thought Tejun was fixing a different function, no?

Tejun put the fix in the callee; I put the fix in the caller, who 
instantiated the automatic variable.  Either way, the same region of 
memory gets initialized.

	Jeff