[PATCH] fix PCI bridge swizzle on takara and eiger

This fixes NULL pointer dereference (bus->self) for PCI devices
on the root bus.

Ivan.

arch/alpha/kernel/sys_eiger.c

@@ -194,27 +194,20 @@ eiger_swizzle(struct pci_dev *dev, u8 *pinp)
 	   case 0x0f: bridge_count = 4; break; /* 4 */
 	};
 
-	/*  Check first for the built-in bridges on hose 0. */
-	if (hose->index == 0
-	    && PCI_SLOT(dev->bus->self->devfn) > 20-bridge_count) {
-		slot = PCI_SLOT(dev->devfn);
-	} else {
-		/* Must be a card-based bridge.  */
-		do {
-			/* Check for built-in bridges on hose 0. */
-			if (hose->index == 0
-			    && (PCI_SLOT(dev->bus->self->devfn)
-				> 20 - bridge_count)) {
-                  		slot = PCI_SLOT(dev->devfn);
-				break;
-			}
-			pin = bridge_swizzle(pin, PCI_SLOT(dev->devfn));
-
-			/* Move up the chain of bridges.  */
-			dev = dev->bus->self;
-			/* Slot of the next bridge.  */
+	slot = PCI_SLOT(dev->devfn);
+	while (dev->bus->self) {
+		/* Check for built-in bridges on hose 0. */
+		if (hose->index == 0
+		    && (PCI_SLOT(dev->bus->self->devfn)
+			> 20 - bridge_count)) {
 			slot = PCI_SLOT(dev->devfn);
-		} while (dev->bus->self);
+			break;
+		}
+		/* Must be a card-based bridge.  */
+		pin = bridge_swizzle(pin, PCI_SLOT(dev->devfn));
+
+		/* Move up the chain of bridges.  */
+		dev = dev->bus->self;
 	}
 	*pinp = pin;
 	return slot;

arch/alpha/kernel/sys_takara.c

@@ -231,8 +231,12 @@ takara_swizzle(struct pci_dev *dev, u8 *pinp)
 	int slot = PCI_SLOT(dev->devfn);
 	int pin = *pinp;
 	unsigned int ctlreg = inl(0x500);
-	unsigned int busslot = PCI_SLOT(dev->bus->self->devfn);
+	unsigned int busslot;
 
+	if (!dev->bus->self)
+		return slot;
+
+	busslot = PCI_SLOT(dev->bus->self->devfn);
 	/* Check for built-in bridges.  */
 	if (dev->bus->number != 0
 	    && busslot > 16