Staging: batman-adv: receive packets directly using skbs

This patch removes the (ugly and racy) packet receiving thread and the
kernel socket usage. Instead, packets are received directly by registering
the ethernet type and handling skbs instead of self-allocated buffers.

Some consequences and comments:

 * we don't copy the payload data when forwarding/sending/receiving data
   anymore. This should boost performance.
 * packets from/to different interfaces can be (theoretically) processed
   simultaneously. Only the big originator hash lock might be in the way.
 * no more polling or sleeping/wakeup/scheduling issues when receiving
   packets
 * this might introduce new race conditions.
 * aggregation and vis code still use packet buffers and are not (yet)
   converted.
 * all spinlocks were converted to irqsave/restore versions to solve
   some lifelock issues when preempted. This might be overkill, some
   of these locks might be reverted later.
 * skb copies are only done if neccesary to avoid overhead

performance differences:

 * we made some "benchmarks" with intel laptops.
 * bandwidth on Gigabit Ethernet increased from ~500 MBit/s to ~920 MBit/s
 * ping latency decresed from ~2ms to ~0.2 ms

I did some tests on my 9 node qemu environment and could confirm that
usual sending/receiving, forwarding, vis, batctl ping etc works.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Acked-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Acked-by: Marek Lindner <lindner_marek@yahoo.de>
Acked-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 109 insertions, 45 deletions

diff --git a/drivers/staging/batman-adv/hard-interface.c b/drivers/staging/batman-adv/hard-interface.c
index 7c885926b16..cc59c307a42 100644
--- a/drivers/staging/batman-adv/hard-interface.c
+++ b/drivers/staging/batman-adv/hard-interface.c
@@ -153,9 +153,6 @@ void hardif_deactivate_interface(struct batman_if *batman_if)
 	if (batman_if->if_active != IF_ACTIVE)
 		return;
 
-	if (batman_if->raw_sock)
-		sock_release(batman_if->raw_sock);
-
 	/**
 	 * batman_if->net_dev has been acquired by dev_get_by_name() in
 	 * proc_interfaces_write() and has to be unreferenced.
@@ -164,9 +161,6 @@ void hardif_deactivate_interface(struct batman_if *batman_if)
 	if (batman_if->net_dev)
 		dev_put(batman_if->net_dev);
 
-	batman_if->raw_sock = NULL;
-	batman_if->net_dev = NULL;
-
 	batman_if->if_active = IF_INACTIVE;
 	active_ifs--;
 
@@ -177,9 +171,6 @@ void hardif_deactivate_interface(struct batman_if *batman_if)
 /* (re)activate given interface. */
 static void hardif_activate_interface(struct batman_if *batman_if)
 {
-	struct sockaddr_ll bind_addr;
-	int retval;
-
 	if (batman_if->if_active != IF_INACTIVE)
 		return;
 
@@ -191,35 +182,8 @@ static void hardif_activate_interface(struct batman_if *batman_if)
 	if (!batman_if->net_dev)
 		goto dev_err;
 
-	retval = sock_create_kern(PF_PACKET, SOCK_RAW,
-				  __constant_htons(ETH_P_BATMAN),
-				  &batman_if->raw_sock);
-
-	if (retval < 0) {
-		printk(KERN_ERR "batman-adv:Can't create raw socket: %i\n",
-			  retval);
-		goto sock_err;
-	}
-
-	bind_addr.sll_family = AF_PACKET;
-	bind_addr.sll_ifindex = batman_if->net_dev->ifindex;
-	bind_addr.sll_protocol = 0;	/* is set by the kernel */
-
-	retval = kernel_bind(batman_if->raw_sock,
-			     (struct sockaddr *)&bind_addr, sizeof(bind_addr));
-
-	if (retval < 0) {
-		printk(KERN_ERR "batman-adv:Can't create bind raw socket: %i\n",
-			  retval);
-		goto bind_err;
-	}
-
 	check_known_mac_addr(batman_if->net_dev->dev_addr);
 
-	batman_if->raw_sock->sk->sk_user_data =
-		batman_if->raw_sock->sk->sk_data_ready;
-	batman_if->raw_sock->sk->sk_data_ready = batman_data_ready;
-
 	addr_to_string(batman_if->addr_str, batman_if->net_dev->dev_addr);
 
 	memcpy(((struct batman_packet *)(batman_if->packet_buff))->orig,
@@ -239,12 +203,7 @@ static void hardif_activate_interface(struct batman_if *batman_if)
 
 	return;
 
-bind_err:
-	sock_release(batman_if->raw_sock);
-sock_err:
-	dev_put(batman_if->net_dev);
 dev_err:
-	batman_if->raw_sock = NULL;
 	batman_if->net_dev = NULL;
 }
 
@@ -318,6 +277,7 @@ int hardif_add_interface(char *dev, int if_num)
 	struct batman_if *batman_if;
 	struct batman_packet *batman_packet;
 	struct orig_node *orig_node;
+	unsigned long flags;
 	HASHIT(hashit);
 
 	batman_if = kmalloc(sizeof(struct batman_if), GFP_KERNEL);
@@ -327,7 +287,6 @@ int hardif_add_interface(char *dev, int if_num)
 		return -1;
 	}
 
-	batman_if->raw_sock = NULL;
 	batman_if->net_dev = NULL;
 
 	if ((if_num == 0) && (num_hna > 0))
@@ -375,17 +334,17 @@ int hardif_add_interface(char *dev, int if_num)
 
 	/* resize all orig nodes because orig_node->bcast_own(_sum) depend on
 	 * if_num */
-	spin_lock(&orig_hash_lock);
+	spin_lock_irqsave(&orig_hash_lock, flags);
 
 	while (hash_iterate(orig_hash, &hashit)) {
 		orig_node = hashit.bucket->data;
 		if (resize_orig(orig_node, if_num) == -1) {
-			spin_unlock(&orig_hash_lock);
+			spin_unlock_irqrestore(&orig_hash_lock, flags);
 			goto out;
 		}
 	}
 
-	spin_unlock(&orig_hash_lock);
+	spin_unlock_irqrestore(&orig_hash_lock, flags);
 
 	if (!hardif_is_interface_up(batman_if->dev))
 		printk(KERN_ERR "batman-adv:Not using interface %s (retrying later): interface not active\n", batman_if->dev);
@@ -443,6 +402,111 @@ out:
 	return NOTIFY_DONE;
 }
 
+/* find batman interface by netdev. assumes rcu_read_lock on */
+static struct batman_if *find_batman_if(struct net_device *dev)
+{
+	struct batman_if *batman_if;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(batman_if, &if_list, list) {
+		if (batman_if->net_dev == dev) {
+			rcu_read_unlock();
+			return batman_if;
+		}
+	}
+	rcu_read_unlock();
+	return NULL;
+}
+
+
+/* receive a packet with the batman ethertype coming on a hard
+ * interface */
+int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
+	struct packet_type *ptype, struct net_device *orig_dev)
+{
+	struct batman_packet *batman_packet;
+	struct batman_if *batman_if;
+	struct net_device_stats *stats;
+	int ret;
+
+    skb = skb_share_check(skb, GFP_ATOMIC);
+
+    if (skb == NULL)
+		goto err_free;
+
+	/* packet should hold at least type and version */
+	if (unlikely(skb_headlen(skb) < 2))
+		goto err_free;
+
+	/* expect a valid ethernet header here. */
+	if (unlikely(skb->mac_len != sizeof(struct ethhdr)
+				|| !skb_mac_header(skb)))
+		goto err_free;
+
+	batman_if = find_batman_if(skb->dev);
+	if (!batman_if)
+		goto err_free;
+
+    stats = &skb->dev->stats;
+    stats->rx_packets++;
+    stats->rx_bytes += skb->len;
+
+	batman_packet = (struct batman_packet *)skb->data;
+
+	if (batman_packet->version != COMPAT_VERSION) {
+		bat_dbg(DBG_BATMAN,
+			"Drop packet: incompatible batman version (%i)\n",
+			batman_packet->version);
+		goto err_free;
+	}
+
+	/* all receive handlers return whether they received or reused
+	 * the supplied skb. if not, we have to free the skb. */
+
+	switch (batman_packet->packet_type) {
+		/* batman originator packet */
+	case BAT_PACKET:
+		ret = recv_bat_packet(skb, batman_if);
+		break;
+
+		/* batman icmp packet */
+	case BAT_ICMP:
+		ret = recv_icmp_packet(skb);
+		break;
+
+		/* unicast packet */
+	case BAT_UNICAST:
+		ret = recv_unicast_packet(skb);
+		break;
+
+		/* broadcast packet */
+	case BAT_BCAST:
+		ret = recv_bcast_packet(skb);
+		break;
+
+		/* vis packet */
+	case BAT_VIS:
+		ret = recv_vis_packet(skb);
+		break;
+	default:
+		ret = NET_RX_DROP;
+	}
+	if (ret == NET_RX_DROP)
+		kfree_skb(skb);
+
+	/* return NET_RX_SUCCESS in any case as we
+	 * most probably dropped the packet for
+	 * routing-logical reasons. */
+
+	return NET_RX_SUCCESS;
+
+err_free:
+    kfree_skb(skb);
+    return NET_RX_DROP;
+
+}
+
+
 struct notifier_block hard_if_notifier = {
 	.notifier_call = hard_if_event,
 };