Staging: batman-adv: Aggregate batman packets directly in skb

All originator messages are send through aggregation buffers. Those
buffers can directly be allocated as skb to reduce the cost of
allocation an extra buffer and copying them to a new allocated skb
directly before it gets send.

Now only the skb must be cloned in case of send_packet_to_if as it gets
called by send_packet for each interface. Non-primary ogms must not
cloned at all because they will only send once and the forward_packet
structure is freed by send_outstanding_bat_packet afterwards.

Reported-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/batman-adv/aggregation.c

@@ -39,7 +39,7 @@ static bool can_aggregate_with(struct batman_packet *new_batman_packet,
 			       struct forw_packet *forw_packet)
 {
 	struct batman_packet *batman_packet =
-		(struct batman_packet *)forw_packet->packet_buff;
+		(struct batman_packet *)forw_packet->skb->data;
 	int aggregated_bytes = forw_packet->packet_len + packet_len;
 
 	/**
@@ -106,6 +106,7 @@ static void new_aggregated_packet(unsigned char *packet_buff,
 {
 	struct forw_packet *forw_packet_aggr;
 	unsigned long flags;
+	unsigned char *skb_buff;
 	/* FIXME: each batman_if will be attached to a softif */
 	struct bat_priv *bat_priv = netdev_priv(soft_device);
 
@@ -125,23 +126,22 @@ static void new_aggregated_packet(unsigned char *packet_buff,
 		return;
 	}
 
-	forw_packet_aggr->packet_buff = kmalloc(MAX_AGGREGATION_BYTES,
-						GFP_ATOMIC);
-	if (!forw_packet_aggr->packet_buff) {
+	forw_packet_aggr->skb = dev_alloc_skb(MAX_AGGREGATION_BYTES +
+					      sizeof(struct ethhdr));
+	if (!forw_packet_aggr->skb) {
 		if (!own_packet)
 			atomic_inc(&bat_priv->batman_queue_left);
 		kfree(forw_packet_aggr);
 		return;
 	}
+	skb_reserve(forw_packet_aggr->skb, sizeof(struct ethhdr));
 
 	INIT_HLIST_NODE(&forw_packet_aggr->list);
 
+	skb_buff = skb_put(forw_packet_aggr->skb, packet_len);
 	forw_packet_aggr->packet_len = packet_len;
-	memcpy(forw_packet_aggr->packet_buff,
-	       packet_buff,
-	       forw_packet_aggr->packet_len);
+	memcpy(skb_buff, packet_buff, packet_len);
 
-	forw_packet_aggr->skb = NULL;
 	forw_packet_aggr->own = own_packet;
 	forw_packet_aggr->if_incoming = if_incoming;
 	forw_packet_aggr->num_packets = 0;
@@ -171,8 +171,10 @@ static void aggregate(struct forw_packet *forw_packet_aggr,
 		      int packet_len,
 		      bool direct_link)
 {
-	memcpy((forw_packet_aggr->packet_buff + forw_packet_aggr->packet_len),
-	       packet_buff, packet_len);
+	unsigned char *skb_buff;
+
+	skb_buff = skb_put(forw_packet_aggr->skb, packet_len);
+	memcpy(skb_buff, packet_buff, packet_len);
 	forw_packet_aggr->packet_len += packet_len;
 	forw_packet_aggr->num_packets++;
 

drivers/staging/batman-adv/send.c

@@ -126,14 +126,14 @@ static void send_packet_to_if(struct forw_packet *forw_packet,
 	uint8_t packet_num;
 	int16_t buff_pos;
 	struct batman_packet *batman_packet;
+	struct sk_buff *skb;
 
 	if (batman_if->if_status != IF_ACTIVE)
 		return;
 
 	packet_num = 0;
 	buff_pos = 0;
-	batman_packet = (struct batman_packet *)
-		(forw_packet->packet_buff);
+	batman_packet = (struct batman_packet *)forw_packet->skb->data;
 
 	/* adjust all flags and log packets */
 	while (aggregated_packet(buff_pos,
@@ -165,12 +165,13 @@ static void send_packet_to_if(struct forw_packet *forw_packet,
 			(batman_packet->num_hna * ETH_ALEN);
 		packet_num++;
 		batman_packet = (struct batman_packet *)
-			(forw_packet->packet_buff + buff_pos);
+			(forw_packet->skb->data + buff_pos);
 	}
 
-	send_raw_packet(forw_packet->packet_buff,
-			forw_packet->packet_len,
-			batman_if, broadcast_addr);
+	/* create clone because function is called more than once */
+	skb = skb_clone(forw_packet->skb, GFP_ATOMIC);
+	if (skb)
+		send_skb_packet(skb, batman_if, broadcast_addr);
 }
 
 /* send a batman packet */
@@ -180,7 +181,7 @@ static void send_packet(struct forw_packet *forw_packet)
 	struct bat_priv *bat_priv = netdev_priv(soft_device);
 	struct batman_if *batman_if;
 	struct batman_packet *batman_packet =
-		(struct batman_packet *)(forw_packet->packet_buff);
+		(struct batman_packet *)(forw_packet->skb->data);
 	unsigned char directlink = (batman_packet->flags & DIRECTLINK ? 1 : 0);
 
 	if (!forw_packet->if_incoming) {
@@ -206,10 +207,11 @@ static void send_packet(struct forw_packet *forw_packet)
 			batman_packet->ttl, forw_packet->if_incoming->dev,
 			forw_packet->if_incoming->addr_str);
 
-		send_raw_packet(forw_packet->packet_buff,
-				forw_packet->packet_len,
-				forw_packet->if_incoming,
+		/* skb is only used once and than forw_packet is free'd */
+		send_skb_packet(forw_packet->skb, forw_packet->if_incoming,
 				broadcast_addr);
+		forw_packet->skb = NULL;
+
 		return;
 	}
 
@@ -366,7 +368,6 @@ static void forw_packet_free(struct forw_packet *forw_packet)
 {
 	if (forw_packet->skb)
 		kfree_skb(forw_packet->skb);
-	kfree(forw_packet->packet_buff);
 	kfree(forw_packet);
 }
 
@@ -425,7 +426,6 @@ int add_bcast_packet_to_list(struct sk_buff *skb)
 	skb_reset_mac_header(skb);
 
 	forw_packet->skb = skb;
-	forw_packet->packet_buff = NULL;
 
 	/* how often did we send the bcast packet ? */
 	forw_packet->num_packets = 0;

drivers/staging/batman-adv/types.h

@@ -161,7 +161,6 @@ struct forw_packet {
 	unsigned long send_time;
 	uint8_t own;
 	struct sk_buff *skb;
-	unsigned char *packet_buff;
 	uint16_t packet_len;
 	uint32_t direct_link_flags;
 	uint8_t num_packets;