batman-adv: concentrate all curr_gw related rcu operations in select/deselect functions

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 42a8a7b..2acd7a6 100644 (file)
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -43,61 +43,75 @@ static void gw_node_free_ref(struct gw_node *gw_node)
                call_rcu(&gw_node->rcu, gw_node_free_rcu);
 }
 
-struct orig_node *gw_get_selected(struct bat_priv *bat_priv)
+static struct gw_node *gw_get_selected_gw_node(struct bat_priv *bat_priv)
 {
-       struct gw_node *curr_gateway_tmp;
-       struct orig_node *orig_node = NULL;
+       struct gw_node *gw_node;
 
        rcu_read_lock();
-       curr_gateway_tmp = rcu_dereference(bat_priv->curr_gw);
-       if (!curr_gateway_tmp)
-               goto out;
-
-       orig_node = curr_gateway_tmp->orig_node;
-       if (!orig_node)
+       gw_node = rcu_dereference(bat_priv->curr_gw);
+       if (!gw_node)
                goto out;
 
-       if (!atomic_inc_not_zero(&orig_node->refcount))
-               orig_node = NULL;
+       if (!atomic_inc_not_zero(&gw_node->refcount))
+               gw_node = NULL;
 
 out:
        rcu_read_unlock();
-       return orig_node;
+       return gw_node;
 }
 
-void gw_deselect(struct bat_priv *bat_priv)
+struct orig_node *gw_get_selected_orig(struct bat_priv *bat_priv)
 {
        struct gw_node *gw_node;
+       struct orig_node *orig_node = NULL;
 
-       spin_lock_bh(&bat_priv->gw_list_lock);
-       gw_node = rcu_dereference(bat_priv->curr_gw);
-       rcu_assign_pointer(bat_priv->curr_gw, NULL);
-       spin_unlock_bh(&bat_priv->gw_list_lock);
+       gw_node = gw_get_selected_gw_node(bat_priv);
+       if (!gw_node)
+               goto out;
+
+       rcu_read_lock();
+       orig_node = gw_node->orig_node;
+       if (!orig_node)
+               goto unlock;
+
+       if (!atomic_inc_not_zero(&orig_node->refcount))
+               orig_node = NULL;
 
+unlock:
+       rcu_read_unlock();
+out:
        if (gw_node)
                gw_node_free_ref(gw_node);
+       return orig_node;
 }
 
 static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node)
 {
        struct gw_node *curr_gw_node;
 
+       spin_lock_bh(&bat_priv->gw_list_lock);
+
        if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
                new_gw_node = NULL;
 
-       spin_lock_bh(&bat_priv->gw_list_lock);
-       curr_gw_node = rcu_dereference(bat_priv->curr_gw);
+       curr_gw_node = bat_priv->curr_gw;
        rcu_assign_pointer(bat_priv->curr_gw, new_gw_node);
-       spin_unlock_bh(&bat_priv->gw_list_lock);
 
        if (curr_gw_node)
                gw_node_free_ref(curr_gw_node);
+
+       spin_unlock_bh(&bat_priv->gw_list_lock);
+}
+
+void gw_deselect(struct bat_priv *bat_priv)
+{
+       gw_select(bat_priv, NULL);
 }
 
 void gw_election(struct bat_priv *bat_priv)
 {
        struct hlist_node *node;
-       struct gw_node *gw_node, *curr_gw, *curr_gw_tmp = NULL;
+       struct gw_node *gw_node, *curr_gw = NULL, *curr_gw_tmp = NULL;
        struct neigh_node *router;
        uint8_t max_tq = 0;
        uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
@@ -112,25 +126,17 @@ void gw_election(struct bat_priv *bat_priv)
        if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)
                return;
 
-       rcu_read_lock();
-       curr_gw = rcu_dereference(bat_priv->curr_gw);
-       if (curr_gw) {
-               rcu_read_unlock();
-               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)) {
-
-               if (curr_gw) {
-                       rcu_read_unlock();
-                       bat_dbg(DBG_BATMAN, bat_priv,
-                               "Removing selected gateway - "
-                               "no gateway in range\n");
-                       gw_deselect(bat_priv);
-               } else
-                       rcu_read_unlock();
-
-               return;
+               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) {
@@ -182,7 +188,7 @@ void gw_election(struct bat_priv *bat_priv)
        if (curr_gw != curr_gw_tmp) {
                router = orig_node_get_router(curr_gw_tmp->orig_node);
                if (!router)
-                       goto out;
+                       goto unlock;
 
                if ((curr_gw) && (!curr_gw_tmp))
                        bat_dbg(DBG_BATMAN, bat_priv,
@@ -207,8 +213,11 @@ void gw_election(struct bat_priv *bat_priv)
                gw_select(bat_priv, curr_gw_tmp);
        }
 
-out:
+unlock:
        rcu_read_unlock();
+out:
+       if (curr_gw)
+               gw_node_free_ref(curr_gw);
 }
 
 void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node)
@@ -217,7 +226,7 @@ void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node)
        struct neigh_node *router_gw = NULL, *router_orig = NULL;
        uint8_t gw_tq_avg, orig_tq_avg;
 
-       curr_gw_orig = gw_get_selected(bat_priv);
+       curr_gw_orig = gw_get_selected_orig(bat_priv);
        if (!curr_gw_orig)
                goto deselect;
 
@@ -299,7 +308,11 @@ void gw_node_update(struct bat_priv *bat_priv,
                    struct orig_node *orig_node, uint8_t new_gwflags)
 {
        struct hlist_node *node;
-       struct gw_node *gw_node;
+       struct gw_node *gw_node, *curr_gw;
+
+       curr_gw = gw_get_selected_gw_node(bat_priv);
+       if (!curr_gw)
+               goto out;
 
        rcu_read_lock();
        hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
@@ -320,22 +333,26 @@ void gw_node_update(struct bat_priv *bat_priv,
                                "Gateway %pM removed from gateway list\n",
                                orig_node->orig);
 
-                       if (gw_node == rcu_dereference(bat_priv->curr_gw)) {
-                               rcu_read_unlock();
-                               gw_deselect(bat_priv);
-                               return;
-                       }
+                       if (gw_node == curr_gw)
+                               goto deselect;
                }
 
-               rcu_read_unlock();
-               return;
+               goto unlock;
        }
-       rcu_read_unlock();
 
        if (new_gwflags == 0)
-               return;
+               goto unlock;
 
        gw_node_add(bat_priv, orig_node, new_gwflags);
+       goto unlock;
+
+deselect:
+       gw_deselect(bat_priv);
+unlock:
+       rcu_read_unlock();
+out:
+       if (curr_gw)
+               gw_node_free_ref(curr_gw);
 }
 
 void gw_node_delete(struct bat_priv *bat_priv, struct orig_node *orig_node)
@@ -345,9 +362,12 @@ void gw_node_delete(struct bat_priv *bat_priv, struct orig_node *orig_node)
 
 void gw_node_purge(struct bat_priv *bat_priv)
 {
-       struct gw_node *gw_node;
+       struct gw_node *gw_node, *curr_gw;
        struct hlist_node *node, *node_tmp;
        unsigned long timeout = 2 * PURGE_TIMEOUT * HZ;
+       char do_deselect = 0;
+
+       curr_gw = gw_get_selected_gw_node(bat_priv);
 
        spin_lock_bh(&bat_priv->gw_list_lock);
 
@@ -358,15 +378,21 @@ void gw_node_purge(struct bat_priv *bat_priv)
                    atomic_read(&bat_priv->mesh_state) == MESH_ACTIVE)
                        continue;
 
-               if (rcu_dereference(bat_priv->curr_gw) == gw_node)
-                       gw_deselect(bat_priv);
+               if (curr_gw == gw_node)
+                       do_deselect = 1;
 
                hlist_del_rcu(&gw_node->list);
                gw_node_free_ref(gw_node);
        }
 
-
        spin_unlock_bh(&bat_priv->gw_list_lock);
+
+       /* gw_deselect() needs to acquire the gw_list_lock */
+       if (do_deselect)
+               gw_deselect(bat_priv);
+
+       if (curr_gw)
+               gw_node_free_ref(curr_gw);
 }
 
 /**
@@ -385,22 +411,22 @@ static int _write_buffer_text(struct bat_priv *bat_priv,
        if (!router)
                goto out;
 
-       rcu_read_lock();
-       curr_gw = rcu_dereference(bat_priv->curr_gw);
+       curr_gw = gw_get_selected_gw_node(bat_priv);
 
        ret = seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %3i - %i%s/%i%s\n",
-                      (curr_gw == gw_node ? "=>" : "  "),
-                      gw_node->orig_node->orig,
-                      router->tq_avg, router->addr,
-                      router->if_incoming->net_dev->name,
-                      gw_node->orig_node->gw_flags,
-                      (down > 2048 ? down / 1024 : down),
-                      (down > 2048 ? "MBit" : "KBit"),
-                      (up > 2048 ? up / 1024 : up),
-                      (up > 2048 ? "MBit" : "KBit"));
+                        (curr_gw == gw_node ? "=>" : "  "),
+                        gw_node->orig_node->orig,
+                        router->tq_avg, router->addr,
+                        router->if_incoming->net_dev->name,
+                        gw_node->orig_node->gw_flags,
+                        (down > 2048 ? down / 1024 : down),
+                        (down > 2048 ? "MBit" : "KBit"),
+                        (up > 2048 ? up / 1024 : up),
+                        (up > 2048 ? "MBit" : "KBit"));
 
-       rcu_read_unlock();
        neigh_node_free_ref(router);
+       if (curr_gw)
+               gw_node_free_ref(curr_gw);
 out:
        return ret;
 }
@@ -459,6 +485,7 @@ int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb)
        struct iphdr *iphdr;
        struct ipv6hdr *ipv6hdr;
        struct udphdr *udphdr;
+       struct gw_node *curr_gw;
        unsigned int header_len = 0;
 
        if (atomic_read(&bat_priv->gw_mode) == GW_MODE_OFF)
@@ -523,12 +550,11 @@ int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb)
        if (atomic_read(&bat_priv->gw_mode) == GW_MODE_SERVER)
                return -1;
 
-       rcu_read_lock();
-       if (!rcu_dereference(bat_priv->curr_gw)) {
-               rcu_read_unlock();
+       curr_gw = gw_get_selected_gw_node(bat_priv);
+       if (!curr_gw)
                return 0;
-       }
-       rcu_read_unlock();
 
+       if (curr_gw)
+               gw_node_free_ref(curr_gw);
        return 1;
 }

diff --git a/net/batman-adv/gateway_client.h b/net/batman-adv/gateway_client.h
index 97c31d1..1ce8c60 100644 (file)
--- a/net/batman-adv/gateway_client.h
+++ b/net/batman-adv/gateway_client.h
@@ -24,7 +24,7 @@
 
 void gw_deselect(struct bat_priv *bat_priv);
 void gw_election(struct bat_priv *bat_priv);
-struct orig_node *gw_get_selected(struct bat_priv *bat_priv);
+struct orig_node *gw_get_selected_orig(struct bat_priv *bat_priv);
 void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node);
 void gw_node_update(struct bat_priv *bat_priv,
                    struct orig_node *orig_node, uint8_t new_gwflags);

diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c
index 19f84bd..d46acc8 100644 (file)
--- a/net/batman-adv/unicast.c
+++ b/net/batman-adv/unicast.c
@@ -289,7 +289,7 @@ int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
 
        /* get routing information */
        if (is_multicast_ether_addr(ethhdr->h_dest)) {
-               orig_node = (struct orig_node *)gw_get_selected(bat_priv);
+               orig_node = (struct orig_node *)gw_get_selected_orig(bat_priv);
                if (orig_node)
                        goto find_router;
        }