ipv4: avoid two atomic ops in ip_rt_redirect()

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

[ Fix build with CONFIG_IP_ROUTE_VERBOSE disabled. -DaveM ]

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

1 files changed, 3 insertions, 7 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 7b8eacd5ac26..883b5c7195ac 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1343,11 +1343,12 @@ static void rt_del(unsigned hash, struct rtable *rt)
         spin_unlock_bh(rt_hash_lock_addr(hash));
 }
 
+/* called in rcu_read_lock() section */
 void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
                     __be32 saddr, struct net_device *dev)
 {
         int i, k;
-        struct in_device *in_dev = in_dev_get(dev);
+        struct in_device *in_dev = __in_dev_get_rcu(dev);
         struct rtable *rth, **rthp;
         __be32  skeys[2] = { saddr, 0 };
         int  ikeys[2] = { dev->ifindex, 0 };
@@ -1383,7 +1384,6 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
 
                         rthp=&rt_hash_table[hash].chain;
 
-                        rcu_read_lock();
                         while ((rth = rcu_dereference(*rthp)) != NULL) {
                                 struct rtable *rt;
 
@@ -1405,12 +1405,10 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
                                         break;
 
                                 dst_hold(&rth->u.dst);
-                                rcu_read_unlock();
 
                                 rt = dst_alloc(&ipv4_dst_ops);
                                 if (rt == NULL) {
                                         ip_rt_put(rth);
-                                        in_dev_put(in_dev);
                                         return;
                                 }
 
@@ -1463,12 +1461,10 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
                                         ip_rt_put(rt);
                                 goto do_next;
                         }
-                        rcu_read_unlock();
                 do_next:
                         ;
                 }
         }
-        in_dev_put(in_dev);
         return;
 
 reject_redirect:
@@ -1479,7 +1475,7 @@ reject_redirect:
                        &old_gw, dev->name, &new_gw,
                        &saddr, &daddr);
 #endif
-        in_dev_put(in_dev);
+        ;
 }
 
 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)