batman-adv: bcast: queue per interface, if needed

Currently we schedule a broadcast packet like:

3x: [ [(re-)queue] --> for(hard-if): maybe-transmit ]

The intention of queueing a broadcast packet multiple times is to
increase robustness for wireless interfaces. However on interfaces
which we only broadcast on once the queueing induces an unnecessary
penalty. This patch restructures the queueing to be performed on a per
interface basis:

for(hard-if):
- transmit
- if wireless: [queue] --> transmit --> [requeue] --> transmit

Next to the performance benefits on non-wireless interfaces this
should also make it easier to apply alternative strategies for
transmissions on wireless interfaces in the future (for instance sending
via unicast transmissions on wireless interfaces, without queueing in
batman-adv, if appropriate).

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>

1 files changed, 253 insertions, 121 deletions

diff --git a/net/batman-adv/send.c b/net/batman-adv/send.c
index 157abe92d827..07b0ba265472 100644
--- a/net/batman-adv/send.c
+++ b/net/batman-adv/send.c
@@ -737,57 +737,48 @@ void batadv_forw_packet_ogmv1_queue(struct batadv_priv *bat_priv,
 }
 
 /**
- * batadv_add_bcast_packet_to_list() - queue broadcast packet for multiple sends
+ * batadv_forw_bcast_packet_to_list() - queue broadcast packet for transmissions
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: broadcast packet to add
  * @delay: number of jiffies to wait before sending
  * @own_packet: true if it is a self-generated broadcast packet
+ * @if_in: the interface where the packet was received on
+ * @if_out: the outgoing interface to queue on
  *
- * add a broadcast packet to the queue and setup timers. broadcast packets
+ * Adds a broadcast packet to the queue and sets up timers. Broadcast packets
  * are sent multiple times to increase probability for being received.
  *
- * The skb is not consumed, so the caller should make sure that the
- * skb is freed.
- *
  * Return: NETDEV_TX_OK on success and NETDEV_TX_BUSY on errors.
  */
-int batadv_add_bcast_packet_to_list(struct batadv_priv *bat_priv,
-				    const struct sk_buff *skb,
-				    unsigned long delay,
-				    bool own_packet)
+static int batadv_forw_bcast_packet_to_list(struct batadv_priv *bat_priv,
+					    struct sk_buff *skb,
+					    unsigned long delay,
+					    bool own_packet,
+					    struct batadv_hard_iface *if_in,
+					    struct batadv_hard_iface *if_out)
 {
-	struct batadv_hard_iface *primary_if;
 	struct batadv_forw_packet *forw_packet;
-	struct batadv_bcast_packet *bcast_packet;
+	unsigned long send_time = jiffies;
 	struct sk_buff *newskb;
 
-	primary_if = batadv_primary_if_get_selected(bat_priv);
-	if (!primary_if)
-		goto err;
-
 	newskb = skb_copy(skb, GFP_ATOMIC);
-	if (!newskb) {
-		batadv_hardif_put(primary_if);
+	if (!newskb)
 		goto err;
-	}
 
-	forw_packet = batadv_forw_packet_alloc(primary_if, NULL,
+	forw_packet = batadv_forw_packet_alloc(if_in, if_out,
 					       &bat_priv->bcast_queue_left,
 					       bat_priv, newskb);
-	batadv_hardif_put(primary_if);
 	if (!forw_packet)
 		goto err_packet_free;
 
-	/* as we have a copy now, it is safe to decrease the TTL */
-	bcast_packet = (struct batadv_bcast_packet *)newskb->data;
-	bcast_packet->ttl--;
-
 	forw_packet->own = own_packet;
 
 	INIT_DELAYED_WORK(&forw_packet->delayed_work,
 			  batadv_send_outstanding_bcast_packet);
 
-	batadv_forw_packet_bcast_queue(bat_priv, forw_packet, jiffies + delay);
+	send_time += delay ? delay : msecs_to_jiffies(5);
+
+	batadv_forw_packet_bcast_queue(bat_priv, forw_packet, send_time);
 	return NETDEV_TX_OK;
 
 err_packet_free:
@@ -797,9 +788,219 @@ err:
 }
 
 /**
+ * batadv_forw_bcast_packet_if() - forward and queue a broadcast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: broadcast packet to add
+ * @delay: number of jiffies to wait before sending
+ * @own_packet: true if it is a self-generated broadcast packet
+ * @if_in: the interface where the packet was received on
+ * @if_out: the outgoing interface to forward to
+ *
+ * Transmits a broadcast packet on the specified interface either immediately
+ * or if a delay is given after that. Furthermore, queues additional
+ * retransmissions if this interface is a wireless one.
+ *
+ * Return: NETDEV_TX_OK on success and NETDEV_TX_BUSY on errors.
+ */
+static int batadv_forw_bcast_packet_if(struct batadv_priv *bat_priv,
+				       struct sk_buff *skb,
+				       unsigned long delay,
+				       bool own_packet,
+				       struct batadv_hard_iface *if_in,
+				       struct batadv_hard_iface *if_out)
+{
+	unsigned int num_bcasts = if_out->num_bcasts;
+	struct sk_buff *newskb;
+	int ret = NETDEV_TX_OK;
+
+	if (!delay) {
+		newskb = skb_copy(skb, GFP_ATOMIC);
+		if (!newskb)
+			return NETDEV_TX_BUSY;
+
+		batadv_send_broadcast_skb(newskb, if_out);
+		num_bcasts--;
+	}
+
+	/* delayed broadcast or rebroadcasts? */
+	if (num_bcasts >= 1) {
+		BATADV_SKB_CB(skb)->num_bcasts = num_bcasts;
+
+		ret = batadv_forw_bcast_packet_to_list(bat_priv, skb, delay,
+						       own_packet, if_in,
+						       if_out);
+	}
+
+	return ret;
+}
+
+/**
+ * batadv_send_no_broadcast() - check whether (re)broadcast is necessary
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: broadcast packet to check
+ * @own_packet: true if it is a self-generated broadcast packet
+ * @if_out: the outgoing interface checked and considered for (re)broadcast
+ *
+ * Return: False if a packet needs to be (re)broadcasted on the given interface,
+ * true otherwise.
+ */
+static bool batadv_send_no_broadcast(struct batadv_priv *bat_priv,
+				     struct sk_buff *skb, bool own_packet,
+				     struct batadv_hard_iface *if_out)
+{
+	struct batadv_hardif_neigh_node *neigh_node = NULL;
+	struct batadv_bcast_packet *bcast_packet;
+	u8 *orig_neigh;
+	u8 *neigh_addr;
+	char *type;
+	int ret;
+
+	if (!own_packet) {
+		neigh_addr = eth_hdr(skb)->h_source;
+		neigh_node = batadv_hardif_neigh_get(if_out,
+						     neigh_addr);
+	}
+
+	bcast_packet = (struct batadv_bcast_packet *)skb->data;
+	orig_neigh = neigh_node ? neigh_node->orig : NULL;
+
+	ret = batadv_hardif_no_broadcast(if_out, bcast_packet->orig,
+					 orig_neigh);
+
+	if (neigh_node)
+		batadv_hardif_neigh_put(neigh_node);
+
+	/* ok, may broadcast */
+	if (!ret)
+		return false;
+
+	/* no broadcast */
+	switch (ret) {
+	case BATADV_HARDIF_BCAST_NORECIPIENT:
+		type = "no neighbor";
+		break;
+	case BATADV_HARDIF_BCAST_DUPFWD:
+		type = "single neighbor is source";
+		break;
+	case BATADV_HARDIF_BCAST_DUPORIG:
+		type = "single neighbor is originator";
+		break;
+	default:
+		type = "unknown";
+	}
+
+	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+		   "BCAST packet from orig %pM on %s suppressed: %s\n",
+		   bcast_packet->orig,
+		   if_out->net_dev->name, type);
+
+	return true;
+}
+
+/**
+ * __batadv_forw_bcast_packet() - forward and queue a broadcast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: broadcast packet to add
+ * @delay: number of jiffies to wait before sending
+ * @own_packet: true if it is a self-generated broadcast packet
+ *
+ * Transmits a broadcast packet either immediately or if a delay is given
+ * after that. Furthermore, queues additional retransmissions on wireless
+ * interfaces.
+ *
+ * This call clones the given skb, hence the caller needs to take into
+ * account that the data segment of the given skb might not be
+ * modifiable anymore.
+ *
+ * Return: NETDEV_TX_OK on success and NETDEV_TX_BUSY on errors.
+ */
+static int __batadv_forw_bcast_packet(struct batadv_priv *bat_priv,
+				      struct sk_buff *skb,
+				      unsigned long delay,
+				      bool own_packet)
+{
+	struct batadv_hard_iface *hard_iface;
+	struct batadv_hard_iface *primary_if;
+	int ret = NETDEV_TX_OK;
+
+	primary_if = batadv_primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		return NETDEV_TX_BUSY;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
+		if (hard_iface->soft_iface != bat_priv->soft_iface)
+			continue;
+
+		if (!kref_get_unless_zero(&hard_iface->refcount))
+			continue;
+
+		if (batadv_send_no_broadcast(bat_priv, skb, own_packet,
+					     hard_iface)) {
+			batadv_hardif_put(hard_iface);
+			continue;
+		}
+
+		ret = batadv_forw_bcast_packet_if(bat_priv, skb, delay,
+						  own_packet, primary_if,
+						  hard_iface);
+		batadv_hardif_put(hard_iface);
+
+		if (ret == NETDEV_TX_BUSY)
+			break;
+	}
+	rcu_read_unlock();
+
+	batadv_hardif_put(primary_if);
+	return ret;
+}
+
+/**
+ * batadv_forw_bcast_packet() - forward and queue a broadcast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: broadcast packet to add
+ * @delay: number of jiffies to wait before sending
+ * @own_packet: true if it is a self-generated broadcast packet
+ *
+ * Transmits a broadcast packet either immediately or if a delay is given
+ * after that. Furthermore, queues additional retransmissions on wireless
+ * interfaces.
+ *
+ * Return: NETDEV_TX_OK on success and NETDEV_TX_BUSY on errors.
+ */
+int batadv_forw_bcast_packet(struct batadv_priv *bat_priv,
+			     struct sk_buff *skb,
+			     unsigned long delay,
+			     bool own_packet)
+{
+	return __batadv_forw_bcast_packet(bat_priv, skb, delay, own_packet);
+}
+
+/**
+ * batadv_send_bcast_packet() - send and queue a broadcast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: broadcast packet to add
+ * @delay: number of jiffies to wait before sending
+ * @own_packet: true if it is a self-generated broadcast packet
+ *
+ * Transmits a broadcast packet either immediately or if a delay is given
+ * after that. Furthermore, queues additional retransmissions on wireless
+ * interfaces.
+ *
+ * Consumes the provided skb.
+ */
+void batadv_send_bcast_packet(struct batadv_priv *bat_priv,
+			      struct sk_buff *skb,
+			      unsigned long delay,
+			      bool own_packet)
+{
+	__batadv_forw_bcast_packet(bat_priv, skb, delay, own_packet);
+	consume_skb(skb);
+}
+
+/**
  * batadv_forw_packet_bcasts_left() - check if a retransmission is necessary
  * @forw_packet: the forwarding packet to check
- * @hard_iface: the interface to check on
  *
  * Checks whether a given packet has any (re)transmissions left on the provided
  * interface.
@@ -811,28 +1012,20 @@ err:
  * Return: True if (re)transmissions are left, false otherwise.
  */
 static bool
-batadv_forw_packet_bcasts_left(struct batadv_forw_packet *forw_packet,
-			       struct batadv_hard_iface *hard_iface)
+batadv_forw_packet_bcasts_left(struct batadv_forw_packet *forw_packet)
 {
-	unsigned int max;
-
-	if (hard_iface)
-		max = hard_iface->num_bcasts;
-	else
-		max = BATADV_NUM_BCASTS_MAX;
-
-	return BATADV_SKB_CB(forw_packet->skb)->num_bcasts < max;
+	return BATADV_SKB_CB(forw_packet->skb)->num_bcasts;
 }
 
 /**
- * batadv_forw_packet_bcasts_inc() - increment retransmission counter of a
+ * batadv_forw_packet_bcasts_dec() - decrement retransmission counter of a
  *  packet
- * @forw_packet: the packet to increase the counter for
+ * @forw_packet: the packet to decrease the counter for
  */
 static void
-batadv_forw_packet_bcasts_inc(struct batadv_forw_packet *forw_packet)
+batadv_forw_packet_bcasts_dec(struct batadv_forw_packet *forw_packet)
 {
-	BATADV_SKB_CB(forw_packet->skb)->num_bcasts++;
+	BATADV_SKB_CB(forw_packet->skb)->num_bcasts--;
 }
 
 /**
@@ -843,30 +1036,30 @@ batadv_forw_packet_bcasts_inc(struct batadv_forw_packet *forw_packet)
  */
 bool batadv_forw_packet_is_rebroadcast(struct batadv_forw_packet *forw_packet)
 {
-	return BATADV_SKB_CB(forw_packet->skb)->num_bcasts > 0;
+	unsigned char num_bcasts = BATADV_SKB_CB(forw_packet->skb)->num_bcasts;
+
+	return num_bcasts != forw_packet->if_outgoing->num_bcasts;
 }
 
+/**
+ * batadv_send_outstanding_bcast_packet() - transmit a queued broadcast packet
+ * @work: work queue item
+ *
+ * Transmits a queued broadcast packet and if necessary reschedules it.
+ */
 static void batadv_send_outstanding_bcast_packet(struct work_struct *work)
 {
-	struct batadv_hard_iface *hard_iface;
-	struct batadv_hardif_neigh_node *neigh_node;
-	struct delayed_work *delayed_work;
+	unsigned long send_time = jiffies + msecs_to_jiffies(5);
 	struct batadv_forw_packet *forw_packet;
-	struct batadv_bcast_packet *bcast_packet;
-	struct sk_buff *skb1;
-	struct net_device *soft_iface;
+	struct delayed_work *delayed_work;
 	struct batadv_priv *bat_priv;
-	unsigned long send_time = jiffies + msecs_to_jiffies(5);
+	struct sk_buff *skb1;
 	bool dropped = false;
-	u8 *neigh_addr;
-	u8 *orig_neigh;
-	int ret = 0;
 
 	delayed_work = to_delayed_work(work);
 	forw_packet = container_of(delayed_work, struct batadv_forw_packet,
 				   delayed_work);
-	soft_iface = forw_packet->if_incoming->soft_iface;
-	bat_priv = netdev_priv(soft_iface);
+	bat_priv = netdev_priv(forw_packet->if_incoming->soft_iface);
 
 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING) {
 		dropped = true;
@@ -878,76 +1071,15 @@ static void batadv_send_outstanding_bcast_packet(struct work_struct *work)
 		goto out;
 	}
 
-	bcast_packet = (struct batadv_bcast_packet *)forw_packet->skb->data;
-
-	/* rebroadcast packet */
-	rcu_read_lock();
-	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
-		if (hard_iface->soft_iface != soft_iface)
-			continue;
-
-		if (!batadv_forw_packet_bcasts_left(forw_packet, hard_iface))
-			continue;
-
-		if (forw_packet->own) {
-			neigh_node = NULL;
-		} else {
-			neigh_addr = eth_hdr(forw_packet->skb)->h_source;
-			neigh_node = batadv_hardif_neigh_get(hard_iface,
-							     neigh_addr);
-		}
-
-		orig_neigh = neigh_node ? neigh_node->orig : NULL;
-
-		ret = batadv_hardif_no_broadcast(hard_iface, bcast_packet->orig,
-						 orig_neigh);
-
-		if (ret) {
-			char *type;
-
-			switch (ret) {
-			case BATADV_HARDIF_BCAST_NORECIPIENT:
-				type = "no neighbor";
-				break;
-			case BATADV_HARDIF_BCAST_DUPFWD:
-				type = "single neighbor is source";
-				break;
-			case BATADV_HARDIF_BCAST_DUPORIG:
-				type = "single neighbor is originator";
-				break;
-			default:
-				type = "unknown";
-			}
-
-			batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "BCAST packet from orig %pM on %s suppressed: %s\n",
-				   bcast_packet->orig,
-				   hard_iface->net_dev->name, type);
-
-			if (neigh_node)
-				batadv_hardif_neigh_put(neigh_node);
-
-			continue;
-		}
-
-		if (neigh_node)
-			batadv_hardif_neigh_put(neigh_node);
-
-		if (!kref_get_unless_zero(&hard_iface->refcount))
-			continue;
-
-		/* send a copy of the saved skb */
-		skb1 = skb_clone(forw_packet->skb, GFP_ATOMIC);
-		if (skb1)
-			batadv_send_broadcast_skb(skb1, hard_iface);
-
-		batadv_hardif_put(hard_iface);
-	}
-	rcu_read_unlock();
+	/* send a copy of the saved skb */
+	skb1 = skb_copy(forw_packet->skb, GFP_ATOMIC);
+	if (!skb1)
+		goto out;
 
-	batadv_forw_packet_bcasts_inc(forw_packet);
+	batadv_send_broadcast_skb(skb1, forw_packet->if_outgoing);
+	batadv_forw_packet_bcasts_dec(forw_packet);
 
-	/* if we still have some more bcasts to send */
-	if (batadv_forw_packet_bcasts_left(forw_packet, NULL)) {
+	if (batadv_forw_packet_bcasts_left(forw_packet)) {
 		batadv_forw_packet_bcast_queue(bat_priv, forw_packet,
 					       send_time);
 		return;