batman-adv: BATMAN_V: introduce per hard-iface OGMv2 queues

In preparation for the OGMv2 packet aggregation, hold OGMv2 packets for
up to BATADV_MAX_AGGREGATION_MS milliseconds (100ms) on per
hard-interface queues, before transmitting.

This allows us to later squash multiple OGMs into a single frame
and transmission for reduced overhead.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/bat_v.c

@@ -79,6 +79,7 @@ static int batadv_v_iface_enable(struct batadv_hard_iface *hard_iface)
 
 static void batadv_v_iface_disable(struct batadv_hard_iface *hard_iface)
 {
+	batadv_v_ogm_iface_disable(hard_iface);
 	batadv_v_elp_iface_disable(hard_iface);
 }
 
@@ -1081,6 +1082,12 @@ void batadv_v_hardif_init(struct batadv_hard_iface *hard_iface)
 	 */
 	atomic_set(&hard_iface->bat_v.throughput_override, 0);
 	atomic_set(&hard_iface->bat_v.elp_interval, 500);
+
+	hard_iface->bat_v.aggr_len = 0;
+	skb_queue_head_init(&hard_iface->bat_v.aggr_list);
+	spin_lock_init(&hard_iface->bat_v.aggr_list_lock);
+	INIT_DELAYED_WORK(&hard_iface->bat_v.aggr_wq,
+			  batadv_v_ogm_aggr_work);
 }
 
 /**

net/batman-adv/bat_v_ogm.c

@@ -17,12 +17,14 @@
 #include <linux/kernel.h>
 #include <linux/kref.h>
 #include <linux/list.h>
+#include <linux/lockdep.h>
 #include <linux/netdevice.h>
 #include <linux/random.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
+#include <linux/spinlock.h>
 #include <linux/stddef.h>
 #include <linux/string.h>
 #include <linux/types.h>
@@ -76,6 +78,20 @@ struct batadv_orig_node *batadv_v_ogm_orig_get(struct batadv_priv *bat_priv,
 	return orig_node;
 }
 
+/**
+ * batadv_v_ogm_start_queue_timer() - restart the OGM aggregation timer
+ * @hard_iface: the interface to use to send the OGM
+ */
+static void batadv_v_ogm_start_queue_timer(struct batadv_hard_iface *hard_iface)
+{
+	unsigned int msecs = BATADV_MAX_AGGREGATION_MS * 1000;
+
+	/* msecs * [0.9, 1.1] */
+	msecs += prandom_u32() % (msecs / 5) - (msecs / 10);
+	queue_delayed_work(batadv_event_workqueue, &hard_iface->bat_v.aggr_wq,
+			   msecs_to_jiffies(msecs / 1000));
+}
+
 /**
  * batadv_v_ogm_start_timer() - restart the OGM sending timer
  * @bat_priv: the bat priv with all the soft interface information
@@ -115,6 +131,104 @@ static void batadv_v_ogm_send_to_if(struct sk_buff *skb,
 	batadv_send_broadcast_skb(skb, hard_iface);
 }
 
+/**
+ * batadv_v_ogm_len() - OGMv2 packet length
+ * @skb: the OGM to check
+ *
+ * Return: Length of the given OGMv2 packet, including tvlv length, excluding
+ * ethernet header length.
+ */
+static unsigned int batadv_v_ogm_len(struct sk_buff *skb)
+{
+	struct batadv_ogm2_packet *ogm_packet;
+
+	ogm_packet = (struct batadv_ogm2_packet *)skb->data;
+	return BATADV_OGM2_HLEN + ntohs(ogm_packet->tvlv_len);
+}
+
+/**
+ * batadv_v_ogm_queue_left() - check if given OGM still fits aggregation queue
+ * @skb: the OGM to check
+ * @hard_iface: the interface to use to send the OGM
+ *
+ * Caller needs to hold the hard_iface->bat_v.aggr_list_lock.
+ *
+ * Return: True, if the given OGMv2 packet still fits, false otherwise.
+ */
+static bool batadv_v_ogm_queue_left(struct sk_buff *skb,
+				    struct batadv_hard_iface *hard_iface)
+{
+	unsigned int max = min_t(unsigned int, hard_iface->net_dev->mtu,
+				 BATADV_MAX_AGGREGATION_BYTES);
+	unsigned int ogm_len = batadv_v_ogm_len(skb);
+
+	lockdep_assert_held(&hard_iface->bat_v.aggr_list_lock);
+
+	return hard_iface->bat_v.aggr_len + ogm_len <= max;
+}
+
+/**
+ * batadv_v_ogm_aggr_list_free - free all elements in an aggregation queue
+ * @hard_iface: the interface holding the aggregation queue
+ *
+ * Empties the OGMv2 aggregation queue and frees all the skbs it contained.
+ *
+ * Caller needs to hold the hard_iface->bat_v.aggr_list_lock.
+ */
+static void batadv_v_ogm_aggr_list_free(struct batadv_hard_iface *hard_iface)
+{
+	struct sk_buff *skb;
+
+	lockdep_assert_held(&hard_iface->bat_v.aggr_list_lock);
+
+	while ((skb = skb_dequeue(&hard_iface->bat_v.aggr_list)))
+		kfree_skb(skb);
+
+	hard_iface->bat_v.aggr_len = 0;
+}
+
+/**
+ * batadv_v_ogm_aggr_send() - flush & send aggregation queue
+ * @hard_iface: the interface with the aggregation queue to flush
+ *
+ * Caller needs to hold the hard_iface->bat_v.aggr_list_lock.
+ */
+static void batadv_v_ogm_aggr_send(struct batadv_hard_iface *hard_iface)
+{
+	struct sk_buff *skb;
+
+	lockdep_assert_held(&hard_iface->bat_v.aggr_list_lock);
+
+	while ((skb = skb_dequeue(&hard_iface->bat_v.aggr_list))) {
+		hard_iface->bat_v.aggr_len -= batadv_v_ogm_len(skb);
+		batadv_v_ogm_send_to_if(skb, hard_iface);
+	}
+}
+
+/**
+ * batadv_v_ogm_queue_on_if() - queue a batman ogm on a given interface
+ * @skb: the OGM to queue
+ * @hard_iface: the interface to queue the OGM on
+ */
+static void batadv_v_ogm_queue_on_if(struct sk_buff *skb,
+				     struct batadv_hard_iface *hard_iface)
+{
+	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
+
+	if (!atomic_read(&bat_priv->aggregated_ogms)) {
+		batadv_v_ogm_send_to_if(skb, hard_iface);
+		return;
+	}
+
+	spin_lock_bh(&hard_iface->bat_v.aggr_list_lock);
+	if (!batadv_v_ogm_queue_left(skb, hard_iface))
+		batadv_v_ogm_aggr_send(hard_iface);
+
+	hard_iface->bat_v.aggr_len += batadv_v_ogm_len(skb);
+	skb_queue_tail(&hard_iface->bat_v.aggr_list, skb);
+	spin_unlock_bh(&hard_iface->bat_v.aggr_list_lock);
+}
+
 /**
  * batadv_v_ogm_send() - periodic worker broadcasting the own OGM
  * @work: work queue item
@@ -210,7 +324,7 @@ static void batadv_v_ogm_send(struct work_struct *work)
 			break;
 		}
 
-		batadv_v_ogm_send_to_if(skb_tmp, hard_iface);
+		batadv_v_ogm_queue_on_if(skb_tmp, hard_iface);
 		batadv_hardif_put(hard_iface);
 	}
 	rcu_read_unlock();
@@ -223,6 +337,27 @@ static void batadv_v_ogm_send(struct work_struct *work)
 	return;
 }
 
+/**
+ * batadv_v_ogm_aggr_work() - OGM queue periodic task per interface
+ * @work: work queue item
+ *
+ * Emits aggregated OGM message in regular intervals.
+ */
+void batadv_v_ogm_aggr_work(struct work_struct *work)
+{
+	struct batadv_hard_iface_bat_v *batv;
+	struct batadv_hard_iface *hard_iface;
+
+	batv = container_of(work, struct batadv_hard_iface_bat_v, aggr_wq.work);
+	hard_iface = container_of(batv, struct batadv_hard_iface, bat_v);
+
+	spin_lock_bh(&hard_iface->bat_v.aggr_list_lock);
+	batadv_v_ogm_aggr_send(hard_iface);
+	spin_unlock_bh(&hard_iface->bat_v.aggr_list_lock);
+
+	batadv_v_ogm_start_queue_timer(hard_iface);
+}
+
 /**
  * batadv_v_ogm_iface_enable() - prepare an interface for B.A.T.M.A.N. V
  * @hard_iface: the interface to prepare
@@ -235,11 +370,25 @@ int batadv_v_ogm_iface_enable(struct batadv_hard_iface *hard_iface)
 {
 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 
+	batadv_v_ogm_start_queue_timer(hard_iface);
 	batadv_v_ogm_start_timer(bat_priv);
 
 	return 0;
 }
 
+/**
+ * batadv_v_ogm_iface_disable() - release OGM interface private resources
+ * @hard_iface: interface for which the resources have to be released
+ */
+void batadv_v_ogm_iface_disable(struct batadv_hard_iface *hard_iface)
+{
+	cancel_delayed_work_sync(&hard_iface->bat_v.aggr_wq);
+
+	spin_lock_bh(&hard_iface->bat_v.aggr_list_lock);
+	batadv_v_ogm_aggr_list_free(hard_iface);
+	spin_unlock_bh(&hard_iface->bat_v.aggr_list_lock);
+}
+
 /**
  * batadv_v_ogm_primary_iface_set() - set a new primary interface
  * @primary_iface: the new primary interface
@@ -382,7 +531,7 @@ static void batadv_v_ogm_forward(struct batadv_priv *bat_priv,
 		   if_outgoing->net_dev->name, ntohl(ogm_forward->throughput),
 		   ogm_forward->ttl, if_incoming->net_dev->name);
 
-	batadv_v_ogm_send_to_if(skb, if_outgoing);
+	batadv_v_ogm_queue_on_if(skb, if_outgoing);
 
 out:
 	if (orig_ifinfo)

net/batman-adv/bat_v_ogm.h

@@ -11,10 +11,13 @@
 
 #include <linux/skbuff.h>
 #include <linux/types.h>
+#include <linux/workqueue.h>
 
 int batadv_v_ogm_init(struct batadv_priv *bat_priv);
 void batadv_v_ogm_free(struct batadv_priv *bat_priv);
+void batadv_v_ogm_aggr_work(struct work_struct *work);
 int batadv_v_ogm_iface_enable(struct batadv_hard_iface *hard_iface);
+void batadv_v_ogm_iface_disable(struct batadv_hard_iface *hard_iface);
 struct batadv_orig_node *batadv_v_ogm_orig_get(struct batadv_priv *bat_priv,
 					       const u8 *addr);
 void batadv_v_ogm_primary_iface_set(struct batadv_hard_iface *primary_iface);

net/batman-adv/types.h

@@ -117,6 +117,18 @@ struct batadv_hard_iface_bat_v {
 	/** @elp_wq: workqueue used to schedule ELP transmissions */
 	struct delayed_work elp_wq;
 
+	/** @aggr_wq: workqueue used to transmit queued OGM packets */
+	struct delayed_work aggr_wq;
+
+	/** @aggr_list: queue for to be aggregated OGM packets */
+	struct sk_buff_head aggr_list;
+
+	/** @aggr_len: size of the OGM aggregate (excluding ethernet header) */
+	unsigned int aggr_len;
+
+	/** @aggr_list_lock: protects aggr_list */
+	spinlock_t aggr_list_lock;
+
 	/**
 	 * @throughput_override: throughput override to disable link
 	 *  auto-detection