mac80211: simplify station/aggregation code

A number of places use RCU locking for accessing
the station list, even though they do not need
to. Use mutex locking instead to prepare for the
locking changes I want to make. The mlme code is
also using a WLAN_STA_DISASSOC flag that has the
same meaning as WLAN_STA_BLOCK_BA, so use that.

While doing so, combine places where we loop
over stations twice, and optimise away some of
the loops by checking if the hardware supports
aggregation at all first.

Also fix a more theoretical race condition: right
now we could resume, set up an aggregation session,
and right after tear it down again due to the code
that is needed for hardware reconfiguration here.
Also mark add a comment to that code marking it as
a workaround.

Finally, remove a pointless aggregation disabling
loop when an interface is stopped, directly after
that we remove all stations from it which will also
disable all aggregation sessions that may still be
active, and does so in a race-free way unlike the
current loop that doesn't block new sessions.

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

1 files changed, 0 insertions, 13 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 1afa9ec81fe8..906fc2be0cfb 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -339,7 +339,6 @@ static int ieee80211_stop(struct net_device *dev)
 {
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
         struct ieee80211_local *local = sdata->local;
-        struct sta_info *sta;
         unsigned long flags;
         struct sk_buff *skb, *tmp;
         u32 hw_reconf_flags = 0;
@@ -356,18 +355,6 @@ static int ieee80211_stop(struct net_device *dev)
         ieee80211_work_purge(sdata);
 
         /*
-         * Now delete all active aggregation sessions.
-         */
-        rcu_read_lock();
-
-        list_for_each_entry_rcu(sta, &local->sta_list, list) {
-                if (sta->sdata == sdata)
-                        ieee80211_sta_tear_down_BA_sessions(sta);
-        }
-
-        rcu_read_unlock();
-
-        /*
          * Remove all stations associated with this interface.
          *
          * This must be done before calling ops->remove_interface()