mac80211: optimise AP stop RCU handling

If there are VLANs, stopping an AP is inefficient as it
calls rcu_barrier() once for each interface (the VLANs
and the AP itself). Optimise this by moving rcu_barrier()
out of the station cleanups and calling it only once for
all interfaces combined.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index be019533b233..908f1153942d 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1010,8 +1010,13 @@ static int ieee80211_stop_ap(struct wiphy *wiphy, struct net_device *dev)
                 kfree_rcu(old_probe_resp, rcu_head);
 
         list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
-                sta_info_flush(vlan);
-        sta_info_flush(sdata);
+                sta_info_flush_defer(vlan);
+        sta_info_flush_defer(sdata);
+        rcu_barrier();
+        list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
+                sta_info_flush_cleanup(vlan);
+        sta_info_flush_cleanup(sdata);
+
         ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED);
 
         drv_stop_ap(sdata->local, sdata);