mac80211: set mesh formation field properly

Cap max peerings at 63 in accordance with IEEE-2012 8.4.2.100.7.
Triggers a beacon regeneration every time the number of peerings changes.
Previously this would only happen if the "accepting peerings" bit changed.

Signed-off-by: Jacob Minshall <jacob@cozybit.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/linux/ieee80211.h

@@ -146,6 +146,7 @@ static inline u16 ieee80211_sn_sub(u16 sn1, u16 sn2)
 #define IEEE80211_MAX_RTS_THRESHOLD	2353
 #define IEEE80211_MAX_AID		2007
 #define IEEE80211_MAX_TIM_LEN		251
+#define IEEE80211_MAX_MESH_PEERINGS	63
 /* Maximum size for the MA-UNITDATA primitive, 802.11 standard section
    6.2.1.1.2.
 

net/mac80211/mesh.c

@@ -274,8 +274,7 @@ int mesh_add_meshconf_ie(struct ieee80211_sub_if_data *sdata,
 	*pos++ = ifmsh->mesh_auth_id;
 	/* Mesh Formation Info - number of neighbors */
 	neighbors = atomic_read(&ifmsh->estab_plinks);
-	/* Number of neighbor mesh STAs or 15 whichever is smaller */
-	neighbors = (neighbors > 15) ? 15 : neighbors;
+	neighbors = min_t(int, neighbors, IEEE80211_MAX_MESH_PEERINGS);
 	*pos++ = neighbors << 1;
 	/* Mesh capability */
 	*pos = IEEE80211_MESHCONF_CAPAB_FORWARDING;

net/mac80211/mesh.h

@@ -324,14 +324,14 @@ static inline
 u32 mesh_plink_inc_estab_count(struct ieee80211_sub_if_data *sdata)
 {
 	atomic_inc(&sdata->u.mesh.estab_plinks);
-	return mesh_accept_plinks_update(sdata);
+	return mesh_accept_plinks_update(sdata) | BSS_CHANGED_BEACON;
 }
 
 static inline
 u32 mesh_plink_dec_estab_count(struct ieee80211_sub_if_data *sdata)
 {
 	atomic_dec(&sdata->u.mesh.estab_plinks);
-	return mesh_accept_plinks_update(sdata);
+	return mesh_accept_plinks_update(sdata) | BSS_CHANGED_BEACON;
 }
 
 static inline int mesh_plink_free_count(struct ieee80211_sub_if_data *sdata)