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batman-adv: roaming handling mechanism redesign
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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>
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Antonio Quartulli committed Nov 14, 2012
1 parent be73b48 commit 068ee6e
Showing 1 changed file with 118 additions and 39 deletions.
157 changes: 118 additions & 39 deletions net/batman-adv/translation-table.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand All @@ -248,14 +262,38 @@ 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;
}

tt_local = kmalloc(sizeof(*tt_local), GFP_ATOMIC);
Expand Down Expand Up @@ -294,13 +332,14 @@ 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 whether it is a roaming! */
if (tt_global) {
check_roaming:
/* Check whether it is a roaming, but don't do anything if the roaming
* process has already been handled
*/
if (tt_global && !(tt_global->common.flags & BATADV_TT_CLIENT_ROAM)) {
/* These node are probably going to update their tt table */
head = &tt_global->orig_list;
rcu_read_lock();
Expand All @@ -309,12 +348,19 @@ 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);
Expand Down Expand Up @@ -508,13 +554,28 @@ 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)
Expand Down Expand Up @@ -724,12 +785,22 @@ 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);
Expand Down Expand Up @@ -764,19 +835,31 @@ 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 there is the BATADV_TT_CLIENT_ROAM flag set, there is only
* one originator left in the list and we previously received a
Expand All @@ -785,31 +868,40 @@ 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:

/* 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;
}

Expand Down Expand Up @@ -927,20 +1019,6 @@ 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.
Expand Down Expand Up @@ -1204,7 +1282,8 @@ 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;
}

Expand Down

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