[IPV4]: Replace __in_dev_get with __in_dev_get_rcu/rtnl

The following patch renames __in_dev_get() to __in_dev_get_rtnl() and
introduces __in_dev_get_rcu() to cover the second case.

1) RCU with refcnt should use in_dev_get().
2) RCU without refcnt should use __in_dev_get_rcu().
3) All others must hold RTNL and use __in_dev_get_rtnl().

There is one exception in net/ipv4/route.c which is in fact a pre-existing
race condition.  I've marked it as such so that we remember to fix it.

This patch is based on suggestions and prior work by Suzanne Wood and
Paul McKenney.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 5 deletions

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index ec0e36893b01..b425748f02d7 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -241,7 +241,7 @@ static int arp_constructor(struct neighbour *neigh)
         neigh->type = inet_addr_type(addr);
 
         rcu_read_lock();
-        in_dev = rcu_dereference(__in_dev_get(dev));
+        in_dev = __in_dev_get_rcu(dev);
         if (in_dev == NULL) {
                 rcu_read_unlock();
                 return -EINVAL;
@@ -989,8 +989,8 @@ static int arp_req_set(struct arpreq *r, struct net_device * dev)
                         ipv4_devconf.proxy_arp = 1;
                         return 0;
                 }
-                if (__in_dev_get(dev)) {
-                        __in_dev_get(dev)->cnf.proxy_arp = 1;
+                if (__in_dev_get_rtnl(dev)) {
+                        __in_dev_get_rtnl(dev)->cnf.proxy_arp = 1;
                         return 0;
                 }
                 return -ENXIO;
@@ -1095,8 +1095,8 @@ static int arp_req_delete(struct arpreq *r, struct net_device * dev)
                                 ipv4_devconf.proxy_arp = 0;
                                 return 0;
                         }
-                        if (__in_dev_get(dev)) {
-                                __in_dev_get(dev)->cnf.proxy_arp = 0;
+                        if (__in_dev_get_rtnl(dev)) {
+                                __in_dev_get_rtnl(dev)->cnf.proxy_arp = 0;
                                 return 0;
                         }
                         return -ENXIO;