Re: [Xen-devel] [PATCH v8 5/9] PCI: Add pci_iomap_wc() variants

["Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx>]

On Thu, Jun 25, 2015 at 8:09 AM, Borislav Petkov <bp@xxxxxxx> wrote:
>> +void __iomem *pci_iomap_wc_range(struct pci_dev *dev,
>> +                              int bar,
>> +                              unsigned long offset,
>> +                              unsigned long maxlen)
>> +{
>> +     resource_size_t start = pci_resource_start(dev, bar);
>> +     resource_size_t len = pci_resource_len(dev, bar);
>> +     unsigned long flags = pci_resource_flags(dev, bar);
>> +
>> +     if (len <= offset || !start)
>> +             return NULL;
>> +     len -= offset;
>> +     start += offset;
>> +     if (maxlen && len > maxlen)
>> +             len = maxlen;
>> +     if (flags & IORESOURCE_IO)
>> +             return NULL;
>
> I've moved this check at the beginning of the function so that we bail
> out before doing the computations above it.

That indeed looks like a good optimization.

 Luis

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