mac80211: mesh gate implementation
authorJavier Cardona <javier@cozybit.com>
Tue, 9 Aug 2011 23:45:08 +0000 (16:45 -0700)
committerJohn W. Linville <linville@tuxdriver.com>
Wed, 24 Aug 2011 17:59:42 +0000 (13:59 -0400)
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
net/mac80211/ieee80211_i.h
net/mac80211/mesh.c
net/mac80211/mesh.h
net/mac80211/mesh_hwmp.c
net/mac80211/mesh_pathtbl.c

index 03cfbf393a6358b4f2907f2bf86dd70880d636d2..37f95f2e10f9606164b441fd0e4622bd01879183 100644 (file)
@@ -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 {
index ea7419050846b42ea6bf8ef44ac6803281ec9346..c204cee1189c4a858ca64c633ff0e8a26fcec453 100644 (file)
@@ -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 {
index ecdde6ce4df0a8727dea8198e8d47235ae0700f0..e120fefb4e4030bb12fbe77c59eb3b13d3843530 100644 (file)
@@ -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;
index 3c7d0f8b376a0b9ca5b267bffab970a84b50bbb4..9d9116e1a9ac0c149781e66603546751d4f43782 100644 (file)
@@ -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,
index abd03473cca40bef17df3b4c07d2b55f6d6d218c..7b517c46100d70e77a43fb05cd98dc583962040c 100644 (file)
@@ -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;
-               mesh_path_flush_pending(mpath);
+               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
index bcf7fee53b2c3196d640ebb2ffecfbc5b1c71a05..75e4b6022b867844829f796268ebb3305985efae 100644 (file)
@@ -66,6 +66,8 @@ static inline struct mesh_table *resize_dereference_mpp_paths(void)
                lockdep_is_held(&pathtbl_resize_lock));
 }
 
+static int mesh_gate_add(struct mesh_table *tbl, struct mesh_path *mpath);
+
 /*
  * CAREFUL -- "tbl" must not be an expression,
  * in particular not an rcu_dereference(), since
@@ -109,6 +111,7 @@ static struct mesh_table *mesh_table_alloc(int size_order)
                        sizeof(newtbl->hash_rnd));
        for (i = 0; i <= newtbl->hash_mask; i++)
                spin_lock_init(&newtbl->hashwlock[i]);
+       spin_lock_init(&newtbl->gates_lock);
 
        return newtbl;
 }
@@ -124,6 +127,7 @@ static void mesh_table_free(struct mesh_table *tbl, bool free_leafs)
 {
        struct hlist_head *mesh_hash;
        struct hlist_node *p, *q;
+       struct mpath_node *gate;
        int i;
 
        mesh_hash = tbl->hash_buckets;
@@ -135,6 +139,17 @@ static void mesh_table_free(struct mesh_table *tbl, bool free_leafs)
                }
                spin_unlock_bh(&tbl->hashwlock[i]);
        }
+       if (free_leafs) {
+               spin_lock_bh(&tbl->gates_lock);
+               hlist_for_each_entry_safe(gate, p, q,
+                                        tbl->known_gates, list) {
+                       hlist_del(&gate->list);
+                       kfree(gate);
+               }
+               kfree(tbl->known_gates);
+               spin_unlock_bh(&tbl->gates_lock);
+       }
+
        __mesh_table_free(tbl);
 }
 
@@ -152,6 +167,7 @@ static int mesh_table_grow(struct mesh_table *oldtbl,
        newtbl->free_node = oldtbl->free_node;
        newtbl->mean_chain_len = oldtbl->mean_chain_len;
        newtbl->copy_node = oldtbl->copy_node;
+       newtbl->known_gates = oldtbl->known_gates;
        atomic_set(&newtbl->entries, atomic_read(&oldtbl->entries));
 
        oldhash = oldtbl->hash_buckets;
@@ -211,6 +227,111 @@ void mesh_path_assign_nexthop(struct mesh_path *mpath, struct sta_info *sta)
        spin_unlock_irqrestore(&mpath->frame_queue.lock, flags);
 }
 
+static void prepare_for_gate(struct sk_buff *skb, char *dst_addr,
+                            struct mesh_path *gate_mpath)
+{
+       struct ieee80211_hdr *hdr;
+       struct ieee80211s_hdr *mshdr;
+       int mesh_hdrlen, hdrlen;
+       char *next_hop;
+
+       hdr = (struct ieee80211_hdr *) skb->data;
+       hdrlen = ieee80211_hdrlen(hdr->frame_control);
+       mshdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);
+
+       if (!(mshdr->flags & MESH_FLAGS_AE)) {
+               /* size of the fixed part of the mesh header */
+               mesh_hdrlen = 6;
+
+               /* make room for the two extended addresses */
+               skb_push(skb, 2 * ETH_ALEN);
+               memmove(skb->data, hdr, hdrlen + mesh_hdrlen);
+
+               hdr = (struct ieee80211_hdr *) skb->data;
+
+               /* we preserve the previous mesh header and only add
+                * the new addreses */
+               mshdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);
+               mshdr->flags = MESH_FLAGS_AE_A5_A6;
+               memcpy(mshdr->eaddr1, hdr->addr3, ETH_ALEN);
+               memcpy(mshdr->eaddr2, hdr->addr4, ETH_ALEN);
+       }
+
+       /* update next hop */
+       hdr = (struct ieee80211_hdr *) skb->data;
+       rcu_read_lock();
+       next_hop = rcu_dereference(gate_mpath->next_hop)->sta.addr;
+       memcpy(hdr->addr1, next_hop, ETH_ALEN);
+       rcu_read_unlock();
+       memcpy(hdr->addr3, dst_addr, ETH_ALEN);
+}
+
+/**
+ *
+ * mesh_path_move_to_queue - Move or copy frames from one mpath queue to another
+ *
+ * This function is used to transfer or copy frames from an unresolved mpath to
+ * a gate mpath.  The function also adds the Address Extension field and
+ * updates the next hop.
+ *
+ * If a frame already has an Address Extension field, only the next hop and
+ * destination addresses are updated.
+ *
+ * The gate mpath must be an active mpath with a valid mpath->next_hop.
+ *
+ * @mpath: An active mpath the frames will be sent to (i.e. the gate)
+ * @from_mpath: The failed mpath
+ * @copy: When true, copy all the frames to the new mpath queue.  When false,
+ * move them.
+ */
+static void mesh_path_move_to_queue(struct mesh_path *gate_mpath,
+                                   struct mesh_path *from_mpath,
+                                   bool copy)
+{
+       struct sk_buff *skb, *cp_skb;
+       struct sk_buff_head gateq, failq;
+       unsigned long flags;
+       int num_skbs;
+
+       BUG_ON(gate_mpath == from_mpath);
+       BUG_ON(!gate_mpath->next_hop);
+
+       __skb_queue_head_init(&gateq);
+       __skb_queue_head_init(&failq);
+
+       spin_lock_irqsave(&from_mpath->frame_queue.lock, flags);
+       skb_queue_splice_init(&from_mpath->frame_queue, &failq);
+       spin_unlock_irqrestore(&from_mpath->frame_queue.lock, flags);
+
+       num_skbs = skb_queue_len(&failq);
+
+       while (num_skbs--) {
+               skb = __skb_dequeue(&failq);
+               if (copy)
+                       cp_skb = skb_copy(skb, GFP_ATOMIC);
+
+               prepare_for_gate(skb, gate_mpath->dst, gate_mpath);
+               __skb_queue_tail(&gateq, skb);
+
+               if (copy && cp_skb)
+                       __skb_queue_tail(&failq, cp_skb);
+       }
+
+       spin_lock_irqsave(&gate_mpath->frame_queue.lock, flags);
+       skb_queue_splice(&gateq, &gate_mpath->frame_queue);
+       mpath_dbg("Mpath queue for gate %pM has %d frames\n",
+                       gate_mpath->dst,
+                       skb_queue_len(&gate_mpath->frame_queue));
+       spin_unlock_irqrestore(&gate_mpath->frame_queue.lock, flags);
+
+       if (!copy)
+               return;
+
+       spin_lock_irqsave(&from_mpath->frame_queue.lock, flags);
+       skb_queue_splice(&failq, &from_mpath->frame_queue);
+       spin_unlock_irqrestore(&from_mpath->frame_queue.lock, flags);
+}
+
 
 /**
  * mesh_path_lookup - look up a path in the mesh path table
@@ -310,6 +431,109 @@ struct mesh_path *mesh_path_lookup_by_idx(int idx, struct ieee80211_sub_if_data
        return NULL;
 }
 
+static void mesh_gate_node_reclaim(struct rcu_head *rp)
+{
+       struct mpath_node *node = container_of(rp, struct mpath_node, rcu);
+       kfree(node);
+}
+
+/**
+ * mesh_gate_add - mark mpath as path to a mesh gate and add to known_gates
+ * @mesh_tbl: table which contains known_gates list
+ * @mpath: mpath to known mesh gate
+ *
+ * Returns: 0 on success
+ *
+ */
+static int mesh_gate_add(struct mesh_table *tbl, struct mesh_path *mpath)
+{
+       struct mpath_node *gate, *new_gate;
+       struct hlist_node *n;
+       int err;
+
+       rcu_read_lock();
+       tbl = rcu_dereference(tbl);
+
+       hlist_for_each_entry_rcu(gate, n, tbl->known_gates, list)
+               if (gate->mpath == mpath) {
+                       err = -EEXIST;
+                       goto err_rcu;
+               }
+
+       new_gate = kzalloc(sizeof(struct mpath_node), GFP_ATOMIC);
+       if (!new_gate) {
+               err = -ENOMEM;
+               goto err_rcu;
+       }
+
+       mpath->is_gate = true;
+       mpath->sdata->u.mesh.num_gates++;
+       new_gate->mpath = mpath;
+       spin_lock_bh(&tbl->gates_lock);
+       hlist_add_head_rcu(&new_gate->list, tbl->known_gates);
+       spin_unlock_bh(&tbl->gates_lock);
+       rcu_read_unlock();
+       mpath_dbg("Mesh path (%s): Recorded new gate: %pM. %d known gates\n",
+                 mpath->sdata->name, mpath->dst,
+                 mpath->sdata->u.mesh.num_gates);
+       return 0;
+err_rcu:
+       rcu_read_unlock();
+       return err;
+}
+
+/**
+ * mesh_gate_del - remove a mesh gate from the list of known gates
+ * @tbl: table which holds our list of known gates
+ * @mpath: gate mpath
+ *
+ * Returns: 0 on success
+ *
+ * Locking: must be called inside rcu_read_lock() section
+ */
+static int mesh_gate_del(struct mesh_table *tbl, struct mesh_path *mpath)
+{
+       struct mpath_node *gate;
+       struct hlist_node *p, *q;
+
+       tbl = rcu_dereference(tbl);
+
+       hlist_for_each_entry_safe(gate, p, q, tbl->known_gates, list)
+               if (gate->mpath == mpath) {
+                       spin_lock_bh(&tbl->gates_lock);
+                       hlist_del_rcu(&gate->list);
+                       call_rcu(&gate->rcu, mesh_gate_node_reclaim);
+                       spin_unlock_bh(&tbl->gates_lock);
+                       mpath->sdata->u.mesh.num_gates--;
+                       mpath->is_gate = false;
+                       mpath_dbg("Mesh path (%s): Deleted gate: %pM. "
+                                 "%d known gates\n", mpath->sdata->name,
+                                 mpath->dst, mpath->sdata->u.mesh.num_gates);
+                       break;
+               }
+
+       return 0;
+}
+
+/**
+ *
+ * mesh_path_add_gate - add the given mpath to a mesh gate to our path table
+ * @mpath: gate path to add to table
+ */
+int mesh_path_add_gate(struct mesh_path *mpath)
+{
+       return mesh_gate_add(mesh_paths, mpath);
+}
+
+/**
+ * mesh_gate_num - number of gates known to this interface
+ * @sdata: subif data
+ */
+int mesh_gate_num(struct ieee80211_sub_if_data *sdata)
+{
+       return sdata->u.mesh.num_gates;
+}
+
 /**
  * mesh_path_add - allocate and add a new path to the mesh path table
  * @addr: destination address of the path (ETH_ALEN length)
@@ -655,6 +879,8 @@ int mesh_path_del(u8 *addr, struct ieee80211_sub_if_data *sdata)
                if (mpath->sdata == sdata &&
                    memcmp(addr, mpath->dst, ETH_ALEN) == 0) {
                        spin_lock_bh(&mpath->state_lock);
+                       if (mpath->is_gate)
+                               mesh_gate_del(tbl, mpath);
                        mpath->flags |= MESH_PATH_RESOLVING;
                        hlist_del_rcu(&node->list);
                        call_rcu(&node->rcu, mesh_path_node_reclaim);
@@ -687,6 +913,58 @@ void mesh_path_tx_pending(struct mesh_path *mpath)
                                &mpath->frame_queue);
 }
 
+/**
+ * mesh_path_send_to_gates - sends pending frames to all known mesh gates
+ *
+ * @mpath: mesh path whose queue will be emptied
+ *
+ * If there is only one gate, the frames are transferred from the failed mpath
+ * queue to that gate's queue.  If there are more than one gates, the frames
+ * are copied from each gate to the next.  After frames are copied, the
+ * mpath queues are emptied onto the transmission queue.
+ */
+int mesh_path_send_to_gates(struct mesh_path *mpath)
+{
+       struct ieee80211_sub_if_data *sdata = mpath->sdata;
+       struct hlist_node *n;
+       struct mesh_table *tbl;
+       struct mesh_path *from_mpath = mpath;
+       struct mpath_node *gate = NULL;
+       bool copy = false;
+       struct hlist_head *known_gates;
+
+       rcu_read_lock();
+       tbl = rcu_dereference(mesh_paths);
+       known_gates = tbl->known_gates;
+       rcu_read_unlock();
+
+       if (!known_gates)
+               return -EHOSTUNREACH;
+
+       hlist_for_each_entry_rcu(gate, n, known_gates, list) {
+               if (gate->mpath->sdata != sdata)
+                       continue;
+
+               if (gate->mpath->flags & MESH_PATH_ACTIVE) {
+                       mpath_dbg("Forwarding to %pM\n", gate->mpath->dst);
+                       mesh_path_move_to_queue(gate->mpath, from_mpath, copy);
+                       from_mpath = gate->mpath;
+                       copy = true;
+               } else {
+                       mpath_dbg("Not forwarding %p\n", gate->mpath);
+                       mpath_dbg("flags %x\n", gate->mpath->flags);
+               }
+       }
+
+       hlist_for_each_entry_rcu(gate, n, known_gates, list)
+               if (gate->mpath->sdata == sdata) {
+                       mpath_dbg("Sending to %pM\n", gate->mpath->dst);
+                       mesh_path_tx_pending(gate->mpath);
+               }
+
+       return (from_mpath == mpath) ? -EHOSTUNREACH : 0;
+}
+
 /**
  * mesh_path_discard_frame - discard a frame whose path could not be resolved
  *
@@ -804,6 +1082,9 @@ int mesh_pathtbl_init(void)
        tbl_path->free_node = &mesh_path_node_free;
        tbl_path->copy_node = &mesh_path_node_copy;
        tbl_path->mean_chain_len = MEAN_CHAIN_LEN;
+       tbl_path->known_gates = kzalloc(sizeof(struct hlist_head), GFP_ATOMIC);
+       INIT_HLIST_HEAD(tbl_path->known_gates);
+
 
        tbl_mpp = mesh_table_alloc(INIT_PATHS_SIZE_ORDER);
        if (!tbl_mpp) {
@@ -813,6 +1094,9 @@ int mesh_pathtbl_init(void)
        tbl_mpp->free_node = &mesh_path_node_free;
        tbl_mpp->copy_node = &mesh_path_node_copy;
        tbl_mpp->mean_chain_len = MEAN_CHAIN_LEN;
+       /* XXX: not needed */
+       tbl_mpp->known_gates = kzalloc(sizeof(struct hlist_head), GFP_ATOMIC);
+       INIT_HLIST_HEAD(tbl_mpp->known_gates);
 
        /* Need no locking since this is during init */
        RCU_INIT_POINTER(mesh_paths, tbl_path);