[PATCH] yenta oops fix

In some cases, especially on modern laptops with a lot of PCI and
cardbus bridges, we're unable to assign correct secondary/subordinate
bus numbers to all cardbus bridges due to BIOS limitations unless
we are using "pci=assign-busses" boot option.
So some cardbus controllers may not have attached subordinate pci_bus
structure, and yenta driver must cope with it - just ignore such cardbus
bridges.

For example, see https://bugzilla.novell.com/show_bug.cgi?id=113778

Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/pcmcia/yenta_socket.c

@@ -1045,7 +1045,18 @@ static int __devinit yenta_probe (struct pci_dev *dev, const struct pci_device_i
 {
 	struct yenta_socket *socket;
 	int ret;
-	
+
+	/*
+	 * If we failed to assign proper bus numbers for this cardbus
+	 * controller during PCI probe, its subordinate pci_bus is NULL.
+	 * Bail out if so.
+	 */
+	if (!dev->subordinate) {
+		printk(KERN_ERROR "Yenta: no bus associated with %s!\n",
+			pci_name(dev));
+		return -ENODEV;
+	}
+
 	socket = kmalloc(sizeof(struct yenta_socket), GFP_KERNEL);
 	if (!socket)
 		return -ENOMEM;