mac80211: mesh gate implementation

In this implementation, a mesh gate is a root node with a certain bit
set in its RANN flags. The mpath to this root node is marked as a path
to a gate, and added to our list of known gates for this if_mesh. Once a
path discovery process fails, we forward the unresolved frames to a
known gate. Thanks to Luis Rodriguez for refactoring and bug fix help.
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/ieee80211.h

@@ -633,6 +633,10 @@ struct ieee80211_rann_ie {
 	u32 rann_metric;
 } __attribute__ ((packed));
 
+enum ieee80211_rann_flags {
+	RANN_FLAG_IS_GATE = 1 << 0,
+};
+
 #define WLAN_SA_QUERY_TR_ID_LEN 2
 
 struct ieee80211_mgmt {

net/mac80211/ieee80211_i.h

@@ -514,6 +514,7 @@ struct ieee80211_if_mesh {
 	struct mesh_config mshcfg;
 	u32 mesh_seqnum;
 	bool accepting_plinks;
+	int num_gates;
 	const u8 *ie;
 	u8 ie_len;
 	enum {

net/mac80211/mesh.c

@@ -545,7 +545,7 @@ void ieee80211_mesh_quiesce(struct ieee80211_sub_if_data *sdata)
 {
 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 
-	/* use atomic bitops in case both timers fire at the same time */
+	/* use atomic bitops in case all timers fire at the same time */
 
 	if (del_timer_sync(&ifmsh->housekeeping_timer))
 		set_bit(TMR_RUNNING_HK, &ifmsh->timers_running);
@@ -752,6 +752,7 @@ void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata)
 	ifmsh->accepting_plinks = true;
 	ifmsh->preq_id = 0;
 	ifmsh->sn = 0;
+	ifmsh->num_gates = 0;
 	atomic_set(&ifmsh->mpaths, 0);
 	mesh_rmc_init(sdata);
 	ifmsh->last_preq = jiffies;

net/mac80211/mesh.h

@@ -81,6 +81,7 @@ enum mesh_deferred_task_flags {
  * @discovery_retries: number of discovery retries
  * @flags: mesh path flags, as specified on &enum mesh_path_flags
  * @state_lock: mesh path state lock
+ * @is_gate: the destination station of this path is a mesh gate
  *
  *
  * The combination of dst and sdata is unique in the mesh path table. Since the
@@ -104,6 +105,7 @@ struct mesh_path {
 	u8 discovery_retries;
 	enum mesh_path_flags flags;
 	spinlock_t state_lock;
+	bool is_gate;
 };
 
 /**
@@ -120,6 +122,9 @@ struct mesh_path {
  *	buckets
  * @mean_chain_len: maximum average length for the hash buckets' list, if it is
  *	reached, the table will grow
+ * @known_gates: list of known mesh gates and their mpaths by the station. The
+ * gate's mpath may or may not be resolved and active.
+ *
  * rcu_head: RCU head to free the table
  */
 struct mesh_table {
@@ -133,6 +138,8 @@ struct mesh_table {
 	int (*copy_node) (struct hlist_node *p, struct mesh_table *newtbl);
 	int size_order;
 	int mean_chain_len;
+	struct hlist_head *known_gates;
+	spinlock_t gates_lock;
 
 	struct rcu_head rcu_head;
 };
@@ -236,6 +243,10 @@ void mesh_path_flush(struct ieee80211_sub_if_data *sdata);
 void mesh_rx_path_sel_frame(struct ieee80211_sub_if_data *sdata,
 		struct ieee80211_mgmt *mgmt, size_t len);
 int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata);
+
+int mesh_path_add_gate(struct mesh_path *mpath);
+int mesh_path_send_to_gates(struct mesh_path *mpath);
+int mesh_gate_num(struct ieee80211_sub_if_data *sdata);
 /* Mesh plinks */
 void mesh_neighbour_update(u8 *hw_addr, u32 rates,
 		struct ieee80211_sub_if_data *sdata,

net/mac80211/mesh_hwmp.c

@@ -696,6 +696,7 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 	u8 *orig_addr;
 	u32 orig_sn, metric;
 	u32 interval = cpu_to_le32(IEEE80211_MESH_RANN_INTERVAL);
+	bool root_is_gate;
 
 	ttl = rann->rann_ttl;
 	if (ttl <= 1) {
@@ -704,12 +705,19 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 	}
 	ttl--;
 	flags = rann->rann_flags;
+	root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
 	orig_addr = rann->rann_addr;
 	orig_sn = rann->rann_seq;
 	hopcount = rann->rann_hopcount;
 	hopcount++;
 	metric = rann->rann_metric;
-	mhwmp_dbg("received RANN from %pM\n", orig_addr);
+
+	/*  Ignore our own RANNs */
+	if (memcmp(orig_addr, sdata->vif.addr, ETH_ALEN) == 0)
+		return;
+
+	mhwmp_dbg("received RANN from %pM (is_gate=%d)", orig_addr,
+			root_is_gate);
 
 	rcu_read_lock();
 	mpath = mesh_path_lookup(orig_addr, sdata);
@@ -721,9 +729,16 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 			sdata->u.mesh.mshstats.dropped_frames_no_route++;
 			return;
 		}
-		mesh_queue_preq(mpath,
-				PREQ_Q_F_START | PREQ_Q_F_REFRESH);
 	}
+
+	if ((!(mpath->flags & (MESH_PATH_ACTIVE | MESH_PATH_RESOLVING)) ||
+	     time_after(jiffies, mpath->exp_time - 1*HZ)) &&
+	     !(mpath->flags & MESH_PATH_FIXED)) {
+		mhwmp_dbg("%s time to refresh root mpath %pM", sdata->name,
+							       orig_addr);
+		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
+	}
+
 	if (mpath->sn < orig_sn) {
 		mesh_path_sel_frame_tx(MPATH_RANN, flags, orig_addr,
 				       cpu_to_le32(orig_sn),
@@ -733,6 +748,9 @@ static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 				       0, sdata);
 		mpath->sn = orig_sn;
 	}
+	if (root_is_gate)
+		mesh_path_add_gate(mpath);
+
 	rcu_read_unlock();
 }
 
@@ -994,25 +1012,32 @@ void mesh_path_timer(unsigned long data)
 {
 	struct mesh_path *mpath = (void *) data;
 	struct ieee80211_sub_if_data *sdata = mpath->sdata;
+	int ret;
 
 	if (sdata->local->quiescing)
 		return;
 
 	spin_lock_bh(&mpath->state_lock);
 	if (mpath->flags & MESH_PATH_RESOLVED ||
-			(!(mpath->flags & MESH_PATH_RESOLVING)))
+			(!(mpath->flags & MESH_PATH_RESOLVING))) {
 		mpath->flags &= ~(MESH_PATH_RESOLVING | MESH_PATH_RESOLVED);
-	else if (mpath->discovery_retries < max_preq_retries(sdata)) {
+		spin_unlock_bh(&mpath->state_lock);
+	} else if (mpath->discovery_retries < max_preq_retries(sdata)) {
 		++mpath->discovery_retries;
 		mpath->discovery_timeout *= 2;
+		spin_unlock_bh(&mpath->state_lock);
 		mesh_queue_preq(mpath, 0);
 	} else {
 		mpath->flags = 0;
 		mpath->exp_time = jiffies;
+		spin_unlock_bh(&mpath->state_lock);
+		if (!mpath->is_gate && mesh_gate_num(sdata) > 0) {
+			ret = mesh_path_send_to_gates(mpath);
+			if (ret)
+				mhwmp_dbg("no gate was reachable");
+		} else
 			mesh_path_flush_pending(mpath);
 	}
-
-	spin_unlock_bh(&mpath->state_lock);
 }
 
 void