mac80211: cache mesh beacon

Previously, the entire mesh beacon would be generated each
time the beacon timer fired. Instead generate a beacon
head and tail (so the TIM can easily be inserted when mesh
power save is on) when starting a mesh or the MBSS
parameters change.

Also add a mutex for protecting beacon updates and
preventing leaks.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h
index a1bad31..1a1da87 100644
--- a/net/mac80211/mesh.h
+++ b/net/mac80211/mesh.h
@@ -239,10 +239,13 @@
 		struct sta_info *sta, struct sk_buff *skb);
 void ieee80211s_stop(void);
 void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata);
-void ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata);
+int ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata);
 void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata);
 void ieee80211_mesh_root_setup(struct ieee80211_if_mesh *ifmsh);
 const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method);
+/* wrapper for ieee80211_bss_info_change_notify() */
+void ieee80211_mbss_info_change_notify(struct ieee80211_sub_if_data *sdata,
+				       u32 changed);
 
 /* mesh power save */
 u32 ieee80211_mps_local_status_update(struct ieee80211_sub_if_data *sdata);