mac80211: move TX info into skb->cb

This patch converts mac80211 and all drivers to have transmit
information and status in skb->cb rather than allocating extra
memory for it and copying all the data around. To make it fit,
a union is used where only data that is necessary for all steps
is kept outside of the union.

A number of fixes were done by Ivo, as well as the rt2x00 part
of this patch.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.h b/drivers/net/wireless/rt2x00/rt2x00queue.h
index c6edc52873c..f263fe422f8 100644
--- a/drivers/net/wireless/rt2x00/rt2x00queue.h
+++ b/drivers/net/wireless/rt2x00/rt2x00queue.h
@@ -105,8 +105,8 @@ enum skb_frame_desc_flags {
 /**
  * struct skb_frame_desc: Descriptor information for the skb buffer
  *
- * This structure is placed over the skb->cb array, this means that
- * this structure should not exceed the size of that array (48 bytes).
+ * This structure is placed over the driver_data array, this means that
+ * this structure should not exceed the size of that array (40 bytes).
  *
  * @flags: Frame flags, see &enum skb_frame_desc_flags.
  * @data: Pointer to data part of frame (Start of ieee80211 header).
@@ -129,10 +129,15 @@ struct skb_frame_desc {
 	struct queue_entry *entry;
 };
 
+/**
+ * get_skb_frame_desc - Obtain the rt2x00 frame descriptor from a sk_buff.
+ * @skb: &struct sk_buff from where we obtain the &struct skb_frame_desc
+ */
 static inline struct skb_frame_desc* get_skb_frame_desc(struct sk_buff *skb)
 {
-	BUILD_BUG_ON(sizeof(struct skb_frame_desc) > sizeof(skb->cb));
-	return (struct skb_frame_desc *)&skb->cb[0];
+	BUILD_BUG_ON(sizeof(struct skb_frame_desc) >
+		     IEEE80211_TX_INFO_DRIVER_DATA_SIZE);
+	return (struct skb_frame_desc *)&IEEE80211_SKB_CB(skb)->driver_data;
 }
 
 /**
@@ -189,12 +194,10 @@ enum txdone_entry_desc_flags {
  * Summary of information that has been read from the TX frame descriptor
  * after the device is done with transmission.
  *
- * @control: Control structure which was used to transmit the frame.
  * @flags: TX done flags (See &enum txdone_entry_desc_flags).
  * @retry: Retry count.
  */
 struct txdone_entry_desc {
-	struct ieee80211_tx_control *control;
 	unsigned long flags;
 	int retry;
 };