PCI: Don't enable decoding if BAR hasn't been assigned an address

Don't enable memory or I/O decoding if we haven't assigned or claimed the
BAR's resource.

If we enable decoding for a BAR that hasn't been assigned an address, we'll
likely cause bus conflicts. This declines to enable decoding for resources
with IORESOURCE_UNSET.

Note that drivers can use pci_enable_device_io() or pci_enable_device_mem()
if they only care about specific types of BARs. In that case, we don't
bother checking whether the corresponding resources are assigned or
claimed.

Signed-off-by: Bjorn Helgaas <[e-mail]>

drivers/pci/setup-res.c

···
 				(!(r->flags & IORESOURCE_ROM_ENABLE)))
 			continue;
 
+		if (r->flags & IORESOURCE_UNSET) {
+			dev_err(&dev->dev, "can't enable device: BAR %d %pR not assigned\n",
+				i, r);
+			return -EINVAL;
+		}
+
 		if (!r->parent) {
-			dev_err(&dev->dev, "device not available "
-				"(can't reserve %pR)\n", r);
+			dev_err(&dev->dev, "can't enable device: BAR %d %pR not claimed\n",
+				i, r);
 			return -EINVAL;
 		}