rt2x00: Don't queue ieee80211 work after USB removal

This prevents the rt2x00 driver from queueing ieee80211 work after the  
USB card has been removed, preventing a kernel panic.

Signed-off-by: Sean Cross <sean@chumby.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c
index 5015448..f02b48a 100644
--- a/drivers/net/wireless/rt2x00/rt2x00usb.c
+++ b/drivers/net/wireless/rt2x00/rt2x00usb.c
@@ -47,6 +47,8 @@
 	    (requesttype == USB_VENDOR_REQUEST_IN) ?
 	    usb_rcvctrlpipe(usb_dev, 0) : usb_sndctrlpipe(usb_dev, 0);
 
+	if (!test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
+		return -ENODEV;
 
 	for (i = 0; i < REGISTER_BUSY_COUNT; i++) {
 		status = usb_control_msg(usb_dev, pipe, request, requesttype,
@@ -60,8 +62,10 @@
 		 * -ENODEV: Device has disappeared, no point continuing.
 		 * All other errors: Try again.
 		 */
-		else if (status == -ENODEV)
+		else if (status == -ENODEV) {
+			clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 			break;
+		}
 	}
 
 	ERROR(rt2x00dev,
@@ -161,6 +165,9 @@
 {
 	unsigned int i;
 
+	if (!test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
+		return -ENODEV;
+
 	for (i = 0; i < REGISTER_BUSY_COUNT; i++) {
 		rt2x00usb_register_read_lock(rt2x00dev, offset, reg);
 		if (!rt2x00_get_field32(*reg, field))