rt2x00: Properly reserve room for descriptors in skbs.

Instead of fiddling with the skb->data pointer and thereby risking
out of bounds accesses, properly reserve the space needed in an
skb for descriptors.

Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 811844b..889a372 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -1002,6 +1002,13 @@
 void rt2x00queue_map_txskb(struct rt2x00_dev *rt2x00dev, struct sk_buff *skb);
 
 /**
+ * rt2x00queue_unmap_skb - Unmap a skb from DMA.
+ * @rt2x00dev: Pointer to &struct rt2x00_dev.
+ * @skb: The skb to unmap.
+ */
+void rt2x00queue_unmap_skb(struct rt2x00_dev *rt2x00dev, struct sk_buff *skb);
+
+/**
  * rt2x00queue_get_queue - Convert queue index to queue pointer
  * @rt2x00dev: Pointer to &struct rt2x00_dev.
  * @queue: rt2x00 queue index (see &enum data_queue_qid).