[libvirt] [PATCH 11/24] hostdev: Remove redundant check
John Ferlan
jferlan at redhat.com
Thu Mar 10 17:35:03 UTC 2016
On 03/10/2016 12:21 PM, Andrea Bolognani wrote:
> On Thu, 2016-03-10 at 12:01 -0500, John Ferlan wrote:
>> On 03/07/2016 12:24 PM, Andrea Bolognani wrote:
>>>
>>> If 'last_processed_hostdev_vf != -1' is false then, since the
>>> loop counter 'i' starts at 0, 'i <= last_processed_hostdev_vf'
>>> can't possibly be true and the loop body will never be executed.
>>>
>>> Hence, the first check is completely redundant and can be safely
>>> removed.
>>> ---
>>> src/util/virhostdev.c | 3 +--
>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>> Premise understood; however, Coverity has an issue...
>
> Well, that's a first :P
>
>> Way back here:
>>
>> 507 virPCIDeviceListPtr pcidevs = NULL;
>>
>> (1) Event var_tested_neg: Assigning: "last_processed_hostdev_vf" = a negative value.
>> Also see events: [negative_returns]
>>
>> 508 int last_processed_hostdev_vf = -1;
>>
>>
>> Eventually we enter this loop:
>>
>> for (i = 0; i < nhostdevs; i++) {
>> virDomainHostdevDefPtr hostdev = hostdevs[i];
>> if (!virHostdevIsPCINetDevice(hostdev))
>> continue;
>> if (virHostdevNetConfigReplace(hostdev, uuid,
>> mgr->stateDir) < 0) {
>> goto resetvfnetconfig;
>> }
>> last_processed_hostdev_vf = i;
>> }
>>
>> If for some reason we "continue" (or not) and eventually "goto resetvfnetconfig;"
>> before ever setting last_processed_hostdev_vf, then we get to the goto.,..
>>
>>> resetvfnetconfig:
>>> - for (i = 0;
>>> - last_processed_hostdev_vf != -1 && i <= last_processed_hostdev_vf; i++)
>> and last_processed_hostdev_vf still == -1
>>
>> So that check needs to be there - perhaps just add an:
>>
>> if (last_processed_hostdev_vf > -1) {
>> }
>
> I fail to see how this is a problem: if last_processed_hostdev_vf
> has never been assigned a value after being declared, then the
> rewritten loop would be equivalent to
>
> for (i = 0; i <= -1; i++) { ... }
>
> which means the loop body will never be executed, just as
> expected. Am I missing something?
size_t i;
Coverity says:
(60) Event negative_returns: Using unsigned variable
"last_processed_hostdev_vf" in a loop exit condition.
John
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