s390/pci: recognize name clashes with uids

When uid checking is enabled firmware guarantees uniqueness of the uids
and we use them for device enumeration. Tests have shown that uid checking
can be toggled at runtime. This is unfortunate since it can lead to name
clashes.

Recognize these name clashes by allocating bits in zpci_domain even for
firmware provided ids.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/pci/pci.c

@@ -736,6 +736,16 @@ static int zpci_alloc_domain(struct zpci_dev *zdev)
 {
 	if (zpci_unique_uid) {
 		zdev->domain = (u16) zdev->uid;
+		if (zdev->domain >= ZPCI_NR_DEVICES)
+			return 0;
+
+		spin_lock(&zpci_domain_lock);
+		if (test_bit(zdev->domain, zpci_domain)) {
+			spin_unlock(&zpci_domain_lock);
+			return -EEXIST;
+		}
+		set_bit(zdev->domain, zpci_domain);
+		spin_unlock(&zpci_domain_lock);
 		return 0;
 	}
 
@@ -752,7 +762,7 @@ static int zpci_alloc_domain(struct zpci_dev *zdev)
 
 static void zpci_free_domain(struct zpci_dev *zdev)
 {
-	if (zpci_unique_uid)
+	if (zdev->domain >= ZPCI_NR_DEVICES)
 		return;
 
 	spin_lock(&zpci_domain_lock);