mac80211: use RCU for TX aggregation

Currently we allocate some memory for each TX
aggregation session and additionally keep a
state bitmap indicating the state it is in.
By using RCU to protect the pointer, moving
the state into the structure and some locking
trickery we can avoid locking when the TX agg
session is fully operational.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index c426c57..06d8e00 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -246,14 +246,12 @@
 	}
 
 	for (i = 0; i < STA_TID_NUM; i++) {
-		/* timer_to_tid must be initialized with identity mapping to
-		 * enable session_timer's data differentiation. refer to
-		 * sta_rx_agg_session_timer_expired for useage */
+		/*
+		 * timer_to_tid must be initialized with identity mapping
+		 * to enable session_timer's data differentiation. See
+		 * sta_rx_agg_session_timer_expired for usage.
+		 */
 		sta->timer_to_tid[i] = i;
-		/* tx */
-		sta->ampdu_mlme.tid_state_tx[i] = HT_AGG_STATE_IDLE;
-		sta->ampdu_mlme.tid_tx[i] = NULL;
-		sta->ampdu_mlme.addba_req_num[i] = 0;
 	}
 	skb_queue_head_init(&sta->ps_tx_buf);
 	skb_queue_head_init(&sta->tx_filtered);