net: avoid two atomic ops in ip_rcv_options()

in_dev_get() -> __in_dev_get_rcu() in a rcu protected function.

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

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index d274078b16650009248d3971077c1b3f8bf28f2b..08a3b121f908dc5367f7593c6560bb346b868fdb 100644 (file)
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -293,18 +293,16 @@ static inline int ip_rcv_options(struct sk_buff *skb)
        }
 
        if (unlikely(opt->srr)) {
-               struct in_device *in_dev = in_dev_get(dev);
+               struct in_device *in_dev = __in_dev_get_rcu(dev);
+
                if (in_dev) {
                        if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
                                if (IN_DEV_LOG_MARTIANS(in_dev) &&
                                    net_ratelimit())
                                        printk(KERN_INFO "source route option %pI4 -> %pI4\n",
                                               &iph->saddr, &iph->daddr);
-                               in_dev_put(in_dev);
                                goto drop;
                        }
-
-                       in_dev_put(in_dev);
                }
 
                if (ip_options_rcv_srr(skb))