The following call chain we can identify that dn_cache_getroute() is
protected under rtnl_lock. So if we use __dev_get_by_index() instead
of dev_get_by_index() to find interface handlers in it, this would help
us avoid to change interface reference counter.

rtnetlink_rcv()
  rtnl_lock()
    netlink_rcv_skb()
      dn_cache_getroute()
  rtnl_unlock()

Signed-off-by: Ying Xue <ying....@windriver.com>
---
 net/decnet/dn_route.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index ad2efa5..22390e4 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1666,12 +1666,12 @@ static int dn_cache_getroute(struct sk_buff *in_skb, 
struct nlmsghdr *nlh)
 
        if (fld.flowidn_iif) {
                struct net_device *dev;
-               if ((dev = dev_get_by_index(&init_net, fld.flowidn_iif)) == 
NULL) {
+               dev = __dev_get_by_index(&init_net, fld.flowidn_iif);
+               if (!dev) {
                        kfree_skb(skb);
                        return -ENODEV;
                }
                if (!dev->dn_ptr) {
-                       dev_put(dev);
                        kfree_skb(skb);
                        return -ENODEV;
                }
@@ -1693,8 +1693,6 @@ static int dn_cache_getroute(struct sk_buff *in_skb, 
struct nlmsghdr *nlh)
                err = dn_route_output_key((struct dst_entry **)&rt, &fld, 0);
        }
 
-       if (skb->dev)
-               dev_put(skb->dev);
        skb->dev = NULL;
        if (err)
                goto out_free;
-- 
1.7.9.5

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