Re: [Xen-devel] [PATCH v2 1/4] xen/MSI-X: latch MSI-X table writes

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.12.15 at 13:41, <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> On Tue, 24 Nov 2015, Jan Beulich wrote:
>> @@ -332,6 +334,13 @@ static int xen_pt_msix_update_one(XenPCI
>>  
>>      pirq = entry->pirq;
> 
> I know that in your opinion is superfluous, nonetheless could you please
> add 2-3 lines of in-code comment right here, to explain what you are
> doing with the check?  Something like:
> 
> /*
>  * Update the entry addr and data to the latest values only when the
>  * entry is masked or they are all masked, as required by the spec.
>  * Addr and data changes while the MSI-X entry is unmasked will be
>  * delayed until the next masking->unmasking.
>  */
> 
> 
>> +    if (pirq == XEN_PT_UNASSIGNED_PIRQ || s->msix->maskall ||
>> +        (vec_ctrl & PCI_MSIX_ENTRY_CTRL_MASKBIT)) {
>> +        entry->addr = entry->latch(LOWER_ADDR) |
>> +                      ((uint64_t)entry->latch(UPPER_ADDR) << 32);
>> +        entry->data = entry->latch(DATA);
>> +    }

Adding a comment like this is fine of course, namely if it helps
acceptance.

Jan


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