batman-adv: gateway election code refactoring

The gateway election mechanism has been a little revised. Now the
gw_election is trigered by an atomic_t flag (gw_reselect) which is set
to 1 in case of election needed, avoding to set curr_gw to NULL.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 7248de2..0350c0c 100644 (file)
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -20,6 +20,7 @@
  */
 
 #include "main.h"
+#include "bat_sysfs.h"
 #include "gateway_client.h"
 #include "gateway_common.h"
 #include "hard-interface.h"
@@ -97,40 +98,19 @@ static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node)
 
 void gw_deselect(struct bat_priv *bat_priv)
 {
-       gw_select(bat_priv, NULL);
+       atomic_set(&bat_priv->gw_reselect, 1);
 }
 
-void gw_election(struct bat_priv *bat_priv)
+static struct gw_node *gw_get_best_gw_node(struct bat_priv *bat_priv)
 {
-       struct hlist_node *node;
-       struct gw_node *gw_node, *curr_gw = NULL, *curr_gw_tmp = NULL;
        struct neigh_node *router;
-       uint8_t max_tq = 0;
+       struct hlist_node *node;
+       struct gw_node *gw_node, *curr_gw = NULL;
        uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
+       uint8_t max_tq = 0;
        int down, up;
 
-       /**
-        * The batman daemon checks here if we already passed a full originator
-        * cycle in order to make sure we don't choose the first gateway we
-        * hear about. This check is based on the daemon's uptime which we
-        * don't have.
-        **/
-       if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)
-               return;
-
-       curr_gw = gw_get_selected_gw_node(bat_priv);
-       if (curr_gw)
-               goto out;
-
        rcu_read_lock();
-       if (hlist_empty(&bat_priv->gw_list)) {
-               bat_dbg(DBG_BATMAN, bat_priv,
-                       "Removing selected gateway - "
-                       "no gateway in range\n");
-               gw_deselect(bat_priv);
-               goto unlock;
-       }
-
        hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
                if (gw_node->deleted)
                        continue;
@@ -139,6 +119,9 @@ void gw_election(struct bat_priv *bat_priv)
                if (!router)
                        continue;
 
+               if (!atomic_inc_not_zero(&gw_node->refcount))
+                       goto next;
+
                switch (atomic_read(&bat_priv->gw_sel_class)) {
                case 1: /* fast connection */
                        gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags,
@@ -151,8 +134,12 @@ void gw_election(struct bat_priv *bat_priv)
 
                        if ((tmp_gw_factor > max_gw_factor) ||
                            ((tmp_gw_factor == max_gw_factor) &&
-                            (router->tq_avg > max_tq)))
-                               curr_gw_tmp = gw_node;
+                            (router->tq_avg > max_tq))) {
+                               if (curr_gw)
+                                       gw_node_free_ref(curr_gw);
+                               curr_gw = gw_node;
+                               atomic_inc(&curr_gw->refcount);
+                       }
                        break;
 
                default: /**
@@ -163,8 +150,12 @@ void gw_election(struct bat_priv *bat_priv)
                          *     soon as a better gateway appears which has
                          *     $routing_class more tq points)
                          **/
-                       if (router->tq_avg > max_tq)
-                               curr_gw_tmp = gw_node;
+                       if (router->tq_avg > max_tq) {
+                               if (curr_gw)
+                                       gw_node_free_ref(curr_gw);
+                               curr_gw = gw_node;
+                               atomic_inc(&curr_gw->refcount);
+                       }
                        break;
                }
 
@@ -174,42 +165,75 @@ void gw_election(struct bat_priv *bat_priv)
                if (tmp_gw_factor > max_gw_factor)
                        max_gw_factor = tmp_gw_factor;
 
+               gw_node_free_ref(gw_node);
+
+next:
                neigh_node_free_ref(router);
        }
+       rcu_read_unlock();
 
-       if (curr_gw != curr_gw_tmp) {
-               router = orig_node_get_router(curr_gw_tmp->orig_node);
-               if (!router)
-                       goto unlock;
+       return curr_gw;
+}
 
-               if ((curr_gw) && (!curr_gw_tmp))
-                       bat_dbg(DBG_BATMAN, bat_priv,
-                               "Removing selected gateway - "
-                               "no gateway in range\n");
-               else if ((!curr_gw) && (curr_gw_tmp))
-                       bat_dbg(DBG_BATMAN, bat_priv,
-                               "Adding route to gateway %pM "
-                               "(gw_flags: %i, tq: %i)\n",
-                               curr_gw_tmp->orig_node->orig,
-                               curr_gw_tmp->orig_node->gw_flags,
-                               router->tq_avg);
-               else
-                       bat_dbg(DBG_BATMAN, bat_priv,
-                               "Changing route to gateway %pM "
-                               "(gw_flags: %i, tq: %i)\n",
-                               curr_gw_tmp->orig_node->orig,
-                               curr_gw_tmp->orig_node->gw_flags,
-                               router->tq_avg);
+void gw_election(struct bat_priv *bat_priv)
+{
+       struct gw_node *curr_gw = NULL, *next_gw = NULL;
+       struct neigh_node *router = NULL;
 
-               neigh_node_free_ref(router);
-               gw_select(bat_priv, curr_gw_tmp);
+       /**
+        * The batman daemon checks here if we already passed a full originator
+        * cycle in order to make sure we don't choose the first gateway we
+        * hear about. This check is based on the daemon's uptime which we
+        * don't have.
+        **/
+       if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)
+               goto out;
+
+       if (!atomic_dec_not_zero(&bat_priv->gw_reselect))
+               goto out;
+
+       curr_gw = gw_get_selected_gw_node(bat_priv);
+
+       next_gw = gw_get_best_gw_node(bat_priv);
+
+       if (curr_gw == next_gw)
+               goto out;
+
+       if (next_gw) {
+               router = orig_node_get_router(next_gw->orig_node);
+               if (!router) {
+                       gw_deselect(bat_priv);
+                       goto out;
+               }
        }
 
-unlock:
-       rcu_read_unlock();
+       if ((curr_gw) && (!next_gw)) {
+               bat_dbg(DBG_BATMAN, bat_priv,
+                       "Removing selected gateway - no gateway in range\n");
+       } else if ((!curr_gw) && (next_gw)) {
+               bat_dbg(DBG_BATMAN, bat_priv,
+                       "Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
+                       next_gw->orig_node->orig,
+                       next_gw->orig_node->gw_flags,
+                       router->tq_avg);
+       } else {
+               bat_dbg(DBG_BATMAN, bat_priv,
+                       "Changing route to gateway %pM "
+                       "(gw_flags: %i, tq: %i)\n",
+                       next_gw->orig_node->orig,
+                       next_gw->orig_node->gw_flags,
+                       router->tq_avg);
+       }
+
+       gw_select(bat_priv, next_gw);
+
 out:
        if (curr_gw)
                gw_node_free_ref(curr_gw);
+       if (next_gw)
+               gw_node_free_ref(next_gw);
+       if (router)
+               neigh_node_free_ref(router);
 }
 
 void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node)

diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index c2b06b7..e367e69 100644 (file)
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -113,6 +113,7 @@ int mesh_init(struct net_device *soft_iface)
        if (vis_init(bat_priv) < 1)
                goto err;
 
+       atomic_set(&bat_priv->gw_reselect, 0);
        atomic_set(&bat_priv->mesh_state, MESH_ACTIVE);
        goto end;
 

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 11e8569..85cf122 100644 (file)
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -201,6 +201,7 @@ struct bat_priv {
        struct delayed_work orig_work;
        struct delayed_work vis_work;
        struct gw_node __rcu *curr_gw;  /* rcu protected pointer */
+       atomic_t gw_reselect;
        struct hard_iface __rcu *primary_if;  /* rcu protected pointer */
        struct vis_info *my_vis_info;
 };