bonding: remove packet cloning in recv_probe()

Cloning all packets in input path have a significant cost.

Use skb_header_pointer()/skb_copy_bits() instead of pskb_may_pull() so
that recv_probe handlers (bond_3ad_lacpdu_recv / bond_arp_rcv /
rlb_arp_recv ) dont touch input skb.

bond_handle_frame() can avoid the skb_clone()/dev_kfree_skb()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
Cc: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 17 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 2ee8cf9e8a3b..9e2301eef386 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1444,8 +1444,8 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
 	struct sk_buff *skb = *pskb;
 	struct slave *slave;
 	struct bonding *bond;
-	int (*recv_probe)(struct sk_buff *, struct bonding *,
-				struct slave *);
+	int (*recv_probe)(const struct sk_buff *, struct bonding *,
+			  struct slave *);
 	int ret = RX_HANDLER_ANOTHER;
 
 	skb = skb_share_check(skb, GFP_ATOMIC);
@@ -1462,15 +1462,10 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
 
 	recv_probe = ACCESS_ONCE(bond->recv_probe);
 	if (recv_probe) {
-		struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
-
-		if (likely(nskb)) {
-			ret = recv_probe(nskb, bond, slave);
-			dev_kfree_skb(nskb);
-			if (ret == RX_HANDLER_CONSUMED) {
-				consume_skb(skb);
-				return ret;
-			}
+		ret = recv_probe(skb, bond, slave);
+		if (ret == RX_HANDLER_CONSUMED) {
+			consume_skb(skb);
+			return ret;
 		}
 	}
 
@@ -2737,25 +2732,31 @@ static void bond_validate_arp(struct bonding *bond, struct slave *slave, __be32
 	}
 }
 
-static int bond_arp_rcv(struct sk_buff *skb, struct bonding *bond,
-			 struct slave *slave)
+static int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
+			struct slave *slave)
 {
-	struct arphdr *arp;
+	struct arphdr *arp = (struct arphdr *)skb->data;
 	unsigned char *arp_ptr;
 	__be32 sip, tip;
+	int alen;
 
 	if (skb->protocol != __cpu_to_be16(ETH_P_ARP))
 		return RX_HANDLER_ANOTHER;
 
 	read_lock(&bond->lock);
+	alen = arp_hdr_len(bond->dev);
 
 	pr_debug("bond_arp_rcv: bond %s skb->dev %s\n",
 		 bond->dev->name, skb->dev->name);
 
-	if (!pskb_may_pull(skb, arp_hdr_len(bond->dev)))
-		goto out_unlock;
+	if (alen > skb_headlen(skb)) {
+		arp = kmalloc(alen, GFP_ATOMIC);
+		if (!arp)
+			goto out_unlock;
+		if (skb_copy_bits(skb, 0, arp, alen) < 0)
+			goto out_unlock;
+	}
 
-	arp = arp_hdr(skb);
 	if (arp->ar_hln != bond->dev->addr_len ||
 	    skb->pkt_type == PACKET_OTHERHOST ||
 	    skb->pkt_type == PACKET_LOOPBACK ||
@@ -2790,6 +2791,8 @@ static int bond_arp_rcv(struct sk_buff *skb, struct bonding *bond,
 
 out_unlock:
 	read_unlock(&bond->lock);
+	if (arp != (struct arphdr *)skb->data)
+		kfree(arp);
 	return RX_HANDLER_ANOTHER;
 }