arp: RCU change in arp_solicit()

Avoid two atomic ops in arp_solicit()

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

1 files changed, 7 insertions, 5 deletions

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index cf78f41830ca..09ead1baa99e 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -333,11 +333,14 @@ static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
         struct net_device *dev = neigh->dev;
         __be32 target = *(__be32*)neigh->primary_key;
         int probes = atomic_read(&neigh->probes);
-        struct in_device *in_dev = in_dev_get(dev);
+        struct in_device *in_dev;
 
-        if (!in_dev)
+        rcu_read_lock();
+        in_dev = __in_dev_get_rcu(dev);
+        if (!in_dev) {
+                rcu_read_unlock();
                 return;
-
+        }
         switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
         default:
         case 0:         /* By default announce any local IP */
@@ -358,9 +361,8 @@ static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
         case 2:         /* Avoid secondary IPs, get a primary/preferred one */
                 break;
         }
+        rcu_read_unlock();
 
-        if (in_dev)
-                in_dev_put(in_dev);
         if (!saddr)
                 saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);