nl80211/mac80211: mesh: add mesh path change count to mpath info

Expose path change count to destination in mpath info

Signed-off-by: Julan Hsu <julanhsu@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -1746,7 +1746,8 @@ static void mpath_set_pinfo(struct mesh_path *mpath, u8 *next_hop,
 			MPATH_INFO_DISCOVERY_TIMEOUT |
 			MPATH_INFO_DISCOVERY_RETRIES |
 			MPATH_INFO_FLAGS |
-			MPATH_INFO_HOP_COUNT;
+			MPATH_INFO_HOP_COUNT |
+			MPATH_INFO_PATH_CHANGE;
 
 	pinfo->frame_qlen = mpath->frame_queue.qlen;
 	pinfo->sn = mpath->sn;
@@ -1767,6 +1768,7 @@ static void mpath_set_pinfo(struct mesh_path *mpath, u8 *next_hop,
 	if (mpath->flags & MESH_PATH_RESOLVED)
 		pinfo->flags |= NL80211_MPATH_FLAG_RESOLVED;
 	pinfo->hop_count = mpath->hop_count;
+	pinfo->path_change_count = mpath->path_change_count;
 }
 
 static int ieee80211_get_mpath(struct wiphy *wiphy, struct net_device *dev,

net/mac80211/mesh.h

@@ -94,6 +94,7 @@ enum mesh_deferred_task_flags {
  * @last_preq_to_root: Timestamp of last PREQ sent to root
  * @is_root: the destination station of this path is a root node
  * @is_gate: the destination station of this path is a mesh gate
+ * @path_change_count: the number of path changes to destination
  *
  *
  * The dst address is unique in the mesh path table. Since the mesh_path is
@@ -124,6 +125,7 @@ struct mesh_path {
 	unsigned long last_preq_to_root;
 	bool is_root;
 	bool is_gate;
+	u32 path_change_count;
 };
 
 /**

net/mac80211/mesh_hwmp.c

@@ -479,6 +479,8 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 		}
 
 		if (fresh_info) {
+			if (rcu_access_pointer(mpath->next_hop) != sta)
+				mpath->path_change_count++;
 			mesh_path_assign_nexthop(mpath, sta);
 			mpath->flags |= MESH_PATH_SN_VALID;
 			mpath->metric = new_metric;
@@ -523,6 +525,8 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 		}
 
 		if (fresh_info) {
+			if (rcu_access_pointer(mpath->next_hop) != sta)
+				mpath->path_change_count++;
 			mesh_path_assign_nexthop(mpath, sta);
 			mpath->metric = last_hop_metric;
 			mpath->exp_time = time_after(mpath->exp_time, exp_time)