r1761 - trunk/batman-adv - commits - lists.open-mesh.org

8 Aug 2010

Author: marek
Date: 2010-08-08 15:00:58 +0200 (Sun, 08 Aug 2010)
New Revision: 1761
Modified:
   trunk/batman-adv/routing.c
Log:
batman-adv: Create copy of skb with pre-allocated headroom
We can use skb_cow instead of a handwritten function to test and create
a writable skb buffer. This also allows us to pre-allocate headroom to
be able to send the data without re-allocating the buffer again to add
the ethernet header.
Signed-off-by: Sven Eckelmann sven.eckelmann@gmx.de
Modified: trunk/batman-adv/routing.c
===================================================================

--- trunk/batman-adv/routing.c	2010-08-08 13:00:54 UTC (rev 1760)
+++ trunk/batman-adv/routing.c	2010-08-08 13:00:58 UTC (rev 1761)
@@ -754,7 +754,6 @@
 {
    struct ethhdr *ethhdr;
    unsigned long flags;
-	struct sk_buff *skb_old;
/* drop packet if it has not necessary minimum size */
    if (skb_headlen(skb) < sizeof(struct batman_packet))
@@ -770,19 +769,12 @@
    if (is_bcast(ethhdr->h_source))
    	return NET_RX_DROP;
-	/* TODO: we use headlen instead of "length", because
-	 * only this data is paged in. */
-
    /* create a copy of the skb, if needed, to modify it. */
-	if (!skb_clone_writable(skb, skb_headlen(skb))) {
-		skb_old = skb;
-		skb = skb_copy(skb, GFP_ATOMIC);
-		if (!skb)
-			return NET_RX_DROP;
-		ethhdr = (struct ethhdr *)skb_mac_header(skb);
-		kfree_skb(skb_old);
-	}
+	if (skb_cow(skb, 0) < 0)
+		return NET_RX_DROP;
+	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
    spin_lock_irqsave(&orig_hash_lock, flags);
    receive_aggr_bat_packet(ethhdr,
    			skb->data,
@@ -801,7 +793,6 @@
    struct orig_node *orig_node;
    struct icmp_packet_rr *icmp_packet;
    struct ethhdr *ethhdr;
-	struct sk_buff *skb_old;
    struct batman_if *batman_if;
    int ret;
    unsigned long flags;
@@ -836,17 +827,12 @@
    	spin_unlock_irqrestore(&orig_hash_lock, flags);
/* create a copy of the skb, if needed, to modify it. */
-		skb_old = NULL;
-		if (!skb_clone_writable(skb, icmp_len)) {
-			skb_old = skb;
-			skb = skb_copy(skb, GFP_ATOMIC);
-			if (!skb)
-				return NET_RX_DROP;
-			icmp_packet = (struct icmp_packet_rr *)skb->data;
-			ethhdr = (struct ethhdr *)skb_mac_header(skb);
-			kfree_skb(skb_old);
-		}
+		if (skb_cow(skb, sizeof(struct ethhdr)) < 0)
+			return NET_RX_DROP;
+		icmp_packet = (struct icmp_packet_rr *)skb->data;
+		ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
    	memcpy(icmp_packet->dst, icmp_packet->orig, ETH_ALEN);
    	memcpy(icmp_packet->orig,
    	       bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN);
@@ -869,7 +855,6 @@
    struct orig_node *orig_node;
    struct icmp_packet *icmp_packet;
    struct ethhdr *ethhdr;
-	struct sk_buff *skb_old;
    struct batman_if *batman_if;
    int ret;
    unsigned long flags;
@@ -905,16 +890,12 @@
    	spin_unlock_irqrestore(&orig_hash_lock, flags);
/* create a copy of the skb, if needed, to modify it. */
-		if (!skb_clone_writable(skb, icmp_len)) {
-			skb_old = skb;
-			skb = skb_copy(skb, GFP_ATOMIC);
-			if (!skb)
-				return NET_RX_DROP;
-			icmp_packet = (struct icmp_packet *) skb->data;
-			ethhdr = (struct ethhdr *)skb_mac_header(skb);
-			kfree_skb(skb_old);
-		}
+		if (skb_cow(skb, sizeof(struct ethhdr)) < 0)
+			return NET_RX_DROP;
+		icmp_packet = (struct icmp_packet *) skb->data;
+		ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
    	memcpy(icmp_packet->dst, icmp_packet->orig, ETH_ALEN);
    	memcpy(icmp_packet->orig,
    	       bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN);
@@ -936,7 +917,6 @@
    struct icmp_packet_rr *icmp_packet;
    struct ethhdr *ethhdr;
    struct orig_node *orig_node;
-	struct sk_buff *skb_old;
    struct batman_if *batman_if;
    int hdr_size = sizeof(struct icmp_packet);
    int ret;
@@ -1002,16 +982,12 @@
    	spin_unlock_irqrestore(&orig_hash_lock, flags);
/* create a copy of the skb, if needed, to modify it. */
-		if (!skb_clone_writable(skb, hdr_size)) {
-			skb_old = skb;
-			skb = skb_copy(skb, GFP_ATOMIC);
-			if (!skb)
-				return NET_RX_DROP;
-			icmp_packet = (struct icmp_packet_rr *)skb->data;
-			ethhdr = (struct ethhdr *)skb_mac_header(skb);
-			kfree_skb(skb_old);
-		}
+		if (skb_cow(skb, sizeof(struct ethhdr)) < 0)
+			return NET_RX_DROP;
+		icmp_packet = (struct icmp_packet_rr *)skb->data;
+		ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
    	/* decrement ttl */
    	icmp_packet->ttl--;
@@ -1149,7 +1125,6 @@
    struct orig_node *orig_node;
    struct neigh_node *router;
    struct batman_if *batman_if;
-	struct sk_buff *skb_old;
    uint8_t dstaddr[ETH_ALEN];
    unsigned long flags;
    struct unicast_packet *unicast_packet =
@@ -1185,16 +1160,12 @@
    spin_unlock_irqrestore(&orig_hash_lock, flags);
/* create a copy of the skb, if needed, to modify it. */
-	if (!skb_clone_writable(skb, hdr_size)) {
-		skb_old = skb;
-		skb = skb_copy(skb, GFP_ATOMIC);
-		if (!skb)
-			return NET_RX_DROP;
-		unicast_packet = (struct unicast_packet *) skb->data;
-		ethhdr = (struct ethhdr *)skb_mac_header(skb);
-		kfree_skb(skb_old);
-	}
+	if (skb_cow(skb, sizeof(struct ethhdr)) < 0)
+		return NET_RX_DROP;
+	unicast_packet = (struct unicast_packet *) skb->data;
+	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
    /* decrement ttl */
    unicast_packet->ttl--;

    