arp: RCU changes

Avoid two atomic ops in arp_fwd_proxy()

Avoid two atomic ops in arp_process()

Valid optims since arp_rcv() is run under rcu_read_lock()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 7 deletions

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index f094b75810db..917d2d66162e 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -545,10 +545,10 @@ static inline int arp_fwd_proxy(struct in_device *in_dev,
 
         /* place to check for proxy_arp for routes */
 
-        if ((out_dev = in_dev_get(rt->u.dst.dev)) != NULL) {
+        out_dev = __in_dev_get_rcu(rt->u.dst.dev);
+        if (out_dev)
                 omi = IN_DEV_MEDIUM_ID(out_dev);
-                in_dev_put(out_dev);
-        }
+
         return (omi != imi && omi != -1);
 }
 
@@ -741,7 +741,7 @@ void arp_send(int type, int ptype, __be32 dest_ip,
 static int arp_process(struct sk_buff *skb)
 {
         struct net_device *dev = skb->dev;
-        struct in_device *in_dev = in_dev_get(dev);
+        struct in_device *in_dev = __in_dev_get_rcu(dev);
         struct arphdr *arp;
         unsigned char *arp_ptr;
         struct rtable *rt;
@@ -890,7 +890,6 @@ static int arp_process(struct sk_buff *skb)
                                         arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
                                 } else {
                                         pneigh_enqueue(&arp_tbl, in_dev->arp_parms, skb);
-                                        in_dev_put(in_dev);
                                         return 0;
                                 }
                                 goto out;
@@ -936,8 +935,6 @@ static int arp_process(struct sk_buff *skb)
         }
 
 out:
-        if (in_dev)
-                in_dev_put(in_dev);
         consume_skb(skb);
         return 0;
 }