Re: [Xen-devel] [PATCH 2/2] x86/pci: Remove unnecessary check in VF value computation

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.02.14 at 16:49, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 02/18/2014 05:16 AM, Jan Beulich wrote:
>>>>> On 13.02.14 at 10:48, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>>>>>> On 12.02.14 at 22:05, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
>>>> This test is already performed a couple of lines above.
>>> Except that it's the wrong code you remove:
>> No opinion on this alternative at all?
> 
> Sorry Jan, I didn't realize you were waiting for me on this.
> 
> Yes, your version is fine although to be honest I don't see how the 
> original patch had any issues with division by zero since we'd still be 
> inside the 'if (stride)' clause.

It's the very division that this patch removes:

>>> --- a/xen/arch/x86/msi.c
>>> +++ b/xen/arch/x86/msi.c
>>> @@ -635,7 +635,7 @@ static u64 read_pci_mem_bar(u16 seg, u8
>>>               return 0;
>>>           base = pos + PCI_SRIOV_BAR;
>>>           vf -= PCI_BDF(bus, slot, func) + offset;
>>> -        if ( vf < 0 || (vf && vf % stride) )
>>> +        if ( vf < 0 )
>>>               return 0;
>>>           if ( stride )
>>>           {

Which isn't inside the if(stride).

Jan


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