mac80211: change RX aggregation locking

To prepare for allowing drivers to sleep in
ampdu_action, change the locking in the RX
aggregation code to use a mutex, so that it
would already allow drivers to sleep. But
explicitly disable BHs around the callback
for now since the TX part cannot yet sleep,
and drivers' locking might require it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/iface.c

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 9f00d3f..490be2f 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -740,7 +740,7 @@
 			   mgmt->u.action.category == WLAN_CATEGORY_BACK) {
 			int len = skb->len;
 
-			rcu_read_lock();
+			mutex_lock(&local->sta_mtx);
 			sta = sta_info_get(sdata, mgmt->sa);
 			if (sta) {
 				switch (mgmt->u.action.u.addba_req.action_code) {
@@ -761,7 +761,7 @@
 					break;
 				}
 			}
-			rcu_read_unlock();
+			mutex_unlock(&local->sta_mtx);
 		} else if (ieee80211_is_data_qos(mgmt->frame_control)) {
 			struct ieee80211_hdr *hdr = (void *)mgmt;
 			/*
@@ -781,7 +781,7 @@
 			 * a block-ack session was active. That cannot be
 			 * right, so terminate the session.
 			 */
-			rcu_read_lock();
+			mutex_lock(&local->sta_mtx);
 			sta = sta_info_get(sdata, mgmt->sa);
 			if (sta) {
 				u16 tid = *ieee80211_get_qos_ctl(hdr) &
@@ -791,7 +791,7 @@
 					sta, tid, WLAN_BACK_RECIPIENT,
 					WLAN_REASON_QSTA_REQUIRE_SETUP);
 			}
-			rcu_read_unlock();
+			mutex_unlock(&local->sta_mtx);
 		} else switch (sdata->vif.type) {
 		case NL80211_IFTYPE_STATION:
 			ieee80211_sta_rx_queued_mgmt(sdata, skb);