Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[deliverable/linux.git] / net / batman-adv / bat_v_elp.c

diff --git a/net/batman-adv/bat_v_elp.c b/net/batman-adv/bat_v_elp.c
index 8376730ebd6987984a1f98625198677929d59fd3..3844e7efd0b0d4d7f61f0cdaee144f761c2499f2 100644 (file)
--- a/net/batman-adv/bat_v_elp.c
+++ b/net/batman-adv/bat_v_elp.c
@@ -164,6 +164,69 @@ void batadv_v_elp_throughput_metric_update(struct work_struct *work)
        batadv_hardif_neigh_put(neigh);
 }
 
+/**
+ * batadv_v_elp_wifi_neigh_probe - send link probing packets to a neighbour
+ * @neigh: the neighbour to probe
+ *
+ * Sends a predefined number of unicast wifi packets to a given neighbour in
+ * order to trigger the throughput estimation on this link by the RC algorithm.
+ * Packets are sent only if there there is not enough payload unicast traffic
+ * towards this neighbour..
+ *
+ * Return: True on success and false in case of error during skb preparation.
+ */
+static bool
+batadv_v_elp_wifi_neigh_probe(struct batadv_hardif_neigh_node *neigh)
+{
+       struct batadv_hard_iface *hard_iface = neigh->if_incoming;
+       struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
+       unsigned long last_tx_diff;
+       struct sk_buff *skb;
+       int probe_len, i;
+       int elp_skb_len;
+
+       /* this probing routine is for Wifi neighbours only */
+       if (!batadv_is_wifi_netdev(hard_iface->net_dev))
+               return true;
+
+       /* probe the neighbor only if no unicast packets have been sent
+        * to it in the last 100 milliseconds: this is the rate control
+        * algorithm sampling interval (minstrel). In this way, if not
+        * enough traffic has been sent to the neighbor, batman-adv can
+        * generate 2 probe packets and push the RC algorithm to perform
+        * the sampling
+        */
+       last_tx_diff = jiffies_to_msecs(jiffies - neigh->bat_v.last_unicast_tx);
+       if (last_tx_diff <= BATADV_ELP_PROBE_MAX_TX_DIFF)
+               return true;
+
+       probe_len = max_t(int, sizeof(struct batadv_elp_packet),
+                         BATADV_ELP_MIN_PROBE_SIZE);
+
+       for (i = 0; i < BATADV_ELP_PROBES_PER_NODE; i++) {
+               elp_skb_len = hard_iface->bat_v.elp_skb->len;
+               skb = skb_copy_expand(hard_iface->bat_v.elp_skb, 0,
+                                     probe_len - elp_skb_len,
+                                     GFP_ATOMIC);
+               if (!skb)
+                       return false;
+
+               /* Tell the skb to get as big as the allocated space (we want
+                * the packet to be exactly of that size to make the link
+                * throughput estimation effective.
+                */
+               skb_put(skb, probe_len - hard_iface->bat_v.elp_skb->len);
+
+               batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+                          "Sending unicast (probe) ELP packet on interface %s to %pM\n",
+                          hard_iface->net_dev->name, neigh->addr);
+
+               batadv_send_skb_packet(skb, hard_iface, neigh->addr);
+       }
+
+       return true;
+}
+
 /**
  * batadv_v_elp_periodic_work - ELP periodic task per interface
  * @work: work queue item
@@ -227,6 +290,12 @@ static void batadv_v_elp_periodic_work(struct work_struct *work)
         */
        rcu_read_lock();
        hlist_for_each_entry_rcu(hardif_neigh, &hard_iface->neigh_list, list) {
+               if (!batadv_v_elp_wifi_neigh_probe(hardif_neigh))
+                       /* if something goes wrong while probing, better to stop
+                        * sending packets immediately and reschedule the task
+                        */
+                       break;
+
                if (!kref_get_unless_zero(&hardif_neigh->refcount))
                        continue;