[B.A.T.M.A.N.] [PATCHv4 4/4] batman-adv: roaming handling mechanism redesign

Antonio Quartulli
2012-09-23T20:38:37Z

This patch allows clients to roam multiple times within the same
originator-interval.

To enable this new feature two key aspects that have been introduced:
1) packets are always directed to the node that was originally
serving the roamed client which will then re-route the data
to the correct destination at any point in time;
2) the client flags handling mechanism has been properly modified
in order to allow multiple roamings withinin the same orig-int.
Therefore flags are now set properly even in this scenario.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
---
translation-table.c | 160 ++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 123 insertions(+), 37 deletions(-)

diff --git a/translation-table.c b/translation-table.c
index 919bc41..1f5ad91 100644
--- a/translation-table.c
+++ b/translation-table.c
@@ -238,6 +238,20 @@ static int batadv_tt_local_init(struct batadv_priv *bat_priv)
return 0;
}

+static void batadv_tt_global_free(struct batadv_priv *bat_priv,
+ struct batadv_tt_global_entry *tt_global,
+ const char *message)
+{
+ batadv_dbg(BATADV_DBG_TT, bat_priv,
+ "Deleting global tt entry %pM: %s\n",
+ tt_global->common.addr, message);
+
+ batadv_hash_remove(bat_priv->tt.global_hash, batadv_compare_tt,
+ batadv_choose_orig, tt_global->common.addr);
+ batadv_tt_global_entry_free_ref(tt_global);
+
+}
+
void batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
int ifindex)
{
@@ -248,14 +262,39 @@ void batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
struct hlist_node *node;
struct batadv_tt_orig_list_entry *orig_entry;
int hash_added;
+ bool roamed_back = false;

tt_local = batadv_tt_local_hash_find(bat_priv, addr);
+ tt_global = batadv_tt_global_hash_find(bat_priv, addr);

if (tt_local) {
tt_local->last_seen = jiffies;
- /* possibly unset the BATADV_TT_CLIENT_PENDING flag */
- tt_local->common.flags &= ~BATADV_TT_CLIENT_PENDING;
- goto out;
+ if (tt_local->common.flags & BATADV_TT_CLIENT_PENDING) {
+ batadv_dbg(BATADV_DBG_TT, bat_priv,
+ "Re-adding pending client %pM\n", addr);
+ /* whatever the reason why the PENDING flag was set,
+ * this is a client which was enqueued to be removed in
+ * this orig_interval. Since it popped up again, the
+ * flag can be reset like it was never enqueued
+ */
+ tt_local->common.flags &= ~BATADV_TT_CLIENT_PENDING;
+ goto add_event;
+ }
+
+ if (tt_local->common.flags & BATADV_TT_CLIENT_ROAM) {
+ batadv_dbg(BATADV_DBG_TT, bat_priv,
+ "Roaming client %pM came back to its original location\n",
+ addr);
+ /* the ROAM flag is set because this client roamed away
+ * and the node got a roaming_advertisement message. Now
+ * that the client popped up again at its original
+ * location such flag can be unset
+ */
+ tt_local->common.flags &= ~BATADV_TT_CLIENT_ROAM;
+ roamed_back = true;
+ goto check_roaming;
+ }
+ goto check_roaming;
}

tt_local = kmalloc(sizeof(*tt_local), GFP_ATOMIC);
@@ -294,11 +333,10 @@ void batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
goto out;
}

+add_event:
batadv_tt_local_event(bat_priv, addr, tt_local->common.flags);

- /* remove address from global hash if present */
- tt_global = batadv_tt_global_hash_find(bat_priv, addr);
-
+check_roaming:
/* Check whether it is a roaming! */
if (tt_global) {
/* These node are probably going to update their tt table */
@@ -309,12 +347,19 @@ void batadv_tt_local_add(struct net_device *soft_iface, const uint8_t *addr,
orig_entry->orig_node);
}
rcu_read_unlock();
- /* The global entry has to be marked as ROAMING and
- * has to be kept for consistency purpose
- */
- tt_global->common.flags |= BATADV_TT_CLIENT_ROAM;
- tt_global->roam_at = jiffies;
+ if (roamed_back) {
+ batadv_tt_global_free(bat_priv, tt_global,
+ "Roaming canceled");
+ tt_global = NULL;
+ } else {
+ /* The global entry has to be marked as ROAMING and
+ * has to be kept for consistency purpose
+ */
+ tt_global->common.flags |= BATADV_TT_CLIENT_ROAM;
+ tt_global->roam_at = jiffies;
+ }
}
+
out:
if (tt_local)
batadv_tt_local_entry_free_ref(tt_local);
@@ -508,13 +553,28 @@ uint16_t batadv_tt_local_remove(struct batadv_priv *bat_priv,
curr_flags = tt_local_entry->common.flags;

flags = BATADV_TT_CLIENT_DEL;
+ /* if this global entry addition is due to a roaming, the node has to
+ * mark the local entry as "roamed" in order to correctly reroute
+ * packets later
+ */
if (roaming) {
flags |= BATADV_TT_CLIENT_ROAM;
/* mark the local client as ROAMed */
tt_local_entry->common.flags |= BATADV_TT_CLIENT_ROAM;
}

- batadv_tt_local_set_pending(bat_priv, tt_local_entry, flags, message);
+ if (!(tt_local_entry->common.flags & BATADV_TT_CLIENT_NEW)) {
+ batadv_tt_local_set_pending(bat_priv, tt_local_entry, flags,
+ message);
+ goto out;
+ }
+ /* if this client has been added right now, it is possible to
+ * immediately purge it
+ */
+ batadv_tt_local_event(bat_priv, tt_local_entry->common.addr,
+ curr_flags | BATADV_TT_CLIENT_DEL);
+ hlist_del_rcu(&tt_local_entry->common.hash_entry);
+ batadv_tt_local_entry_free_ref(tt_local_entry);

out:
if (tt_local_entry)
@@ -724,12 +784,22 @@ int batadv_tt_global_add(struct batadv_priv *bat_priv,
uint8_t ttvn)
{
struct batadv_tt_global_entry *tt_global_entry = NULL;
+ struct batadv_tt_local_entry *tt_local_entry = NULL;
int ret = 0;
int hash_added;
struct batadv_tt_common_entry *common;
uint16_t local_flags;

tt_global_entry = batadv_tt_global_hash_find(bat_priv, tt_addr);
+ tt_local_entry = batadv_tt_local_hash_find(bat_priv, tt_addr);
+
+ /* if the node already has a local client for this entry, it has to wait
+ * for a roaming advertisement instead of manually messing up the global
+ * table
+ */
+ if ((flags & BATADV_TT_CLIENT_TEMP) && tt_local_entry &&
+ !(tt_local_entry->common.flags & BATADV_TT_CLIENT_NEW))
+ goto out;

if (!tt_global_entry) {
tt_global_entry = kzalloc(sizeof(*tt_global_entry), GFP_ATOMIC);
@@ -764,19 +834,39 @@ int batadv_tt_global_add(struct batadv_priv *bat_priv,
goto out_remove;
}
} else {
+ common = &tt_global_entry->common;
/* If there is already a global entry, we can use this one for
* our processing.
- * But if we are trying to add a temporary client we can exit
- * directly because the temporary information should never
- * override any already known client state (whatever it is)
+ * But if we are trying to add a temporary client then here are
+ * two options at this point:
+ * 1) the global client is not a temporary client: the global
+ * client has to be left as it is, temporary information
+ * should never override any already known client state
+ * 2) the global client is a temporary client: purge the
+ * originator list and add the new one orig_entry
*/
- if (flags & BATADV_TT_CLIENT_TEMP)
- goto out;
+ if (flags & BATADV_TT_CLIENT_TEMP) {
+ if (!(common->flags & BATADV_TT_CLIENT_TEMP))
+ goto out;
+ if (batadv_tt_global_entry_has_orig(tt_global_entry,
+ orig_node))
+ goto out_remove;
+ batadv_tt_global_del_orig_list(tt_global_entry);
+ goto add_orig_entry;
+ }

/* if the client was temporary added before receiving the first
* OGM announcing it, we have to clear the TEMP flag
*/
- tt_global_entry->common.flags &= ~BATADV_TT_CLIENT_TEMP;
+ common->flags &= ~BATADV_TT_CLIENT_TEMP;
+
+ /* if this is a normal add, possibly unset the ROAM flag. This
+ * flag could have been set before because the client was
+ * roaming, but now that the node got the ADD event, the flag
+ * can be unset
+ */
+ if (!(flags & BATADV_TT_CLIENT_ROAM))
+ common->flags &= ~BATADV_TT_CLIENT_ROAM;

/* If there is the BATADV_TT_CLIENT_ROAM flag set, there is only
* one originator left in the list and we previously received a
@@ -785,18 +875,19 @@ int batadv_tt_global_add(struct batadv_priv *bat_priv,
* We should first delete the old originator before adding the
* new one.
*/
- if (tt_global_entry->common.flags & BATADV_TT_CLIENT_ROAM) {
+ if (common->flags & BATADV_TT_CLIENT_ROAM) {
batadv_tt_global_del_orig_list(tt_global_entry);
- tt_global_entry->common.flags &= ~BATADV_TT_CLIENT_ROAM;
+ common->flags &= ~BATADV_TT_CLIENT_ROAM;
tt_global_entry->roam_at = 0;
}
}
+add_orig_entry:
/* add the new orig_entry (if needed) or update it */
batadv_tt_global_orig_entry_add(tt_global_entry, orig_node, ttvn);

batadv_dbg(BATADV_DBG_TT, bat_priv,
"Creating new global tt entry: %pM (via %pM)\n",
- tt_global_entry->common.addr, orig_node->orig);
+ common->addr, orig_node->orig);
ret = 1;

out_remove:
@@ -804,12 +895,20 @@ out_remove:
/* remove address from local hash if present */
local_flags = batadv_tt_local_remove(bat_priv, tt_addr,
"global tt received",
- flags & BATADV_TT_CLIENT_ROAM);
+ !!(flags & BATADV_TT_CLIENT_ROAM));
tt_global_entry->common.flags |= local_flags & BATADV_TT_CLIENT_WIFI;

+ if (!(flags & BATADV_TT_CLIENT_ROAM))
+ /* this is a normal global add. Therefore the client is not in a
+ * roaming state anymore.
+ */
+ tt_global_entry->common.flags &= ~BATADV_TT_CLIENT_ROAM;
+
out:
if (tt_global_entry)
batadv_tt_global_entry_free_ref(tt_global_entry);
+ if (tt_local_entry)
+ batadv_tt_local_entry_free_ref(tt_local_entry);
return ret;
}

@@ -927,20 +1026,6 @@ batadv_tt_global_del_orig_entry(struct batadv_priv *bat_priv,
spin_unlock_bh(&tt_global_entry->list_lock);
}

-static void batadv_tt_global_free(struct batadv_priv *bat_priv,
- struct batadv_tt_global_entry *tt_global,
- const char *message)
-{
- batadv_dbg(BATADV_DBG_TT, bat_priv,
- "Deleting global tt entry %pM: %s\n",
- tt_global->common.addr, message);
-
- batadv_hash_remove(bat_priv->tt.global_hash, batadv_compare_tt,
- batadv_choose_orig, tt_global->common.addr);
- batadv_tt_global_entry_free_ref(tt_global);
-
-}
-
/* If the client is to be deleted, we check if it is the last origantor entry
* within tt_global entry. If yes, we set the BATADV_TT_CLIENT_ROAM flag and the
* timer, otherwise we simply remove the originator scheduled for deletion.
@@ -1204,7 +1289,8 @@ struct batadv_orig_node *batadv_transtable_search(struct batadv_priv *bat_priv,

if (src && atomic_read(&bat_priv->ap_isolation)) {
tt_local_entry = batadv_tt_local_hash_find(bat_priv, src);
- if (!tt_local_entry)
+ if (!tt_local_entry ||
+ (tt_local_entry->common.flags & BATADV_TT_CLIENT_PENDING))
goto out;
}

--
1.7.12