[PATCH net-next 05/10] decnet: use __dev_get_by_index instead of dev_get_by_index to find interface

Ying Xue
2014-01-14T07:42:40Z

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.xue@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