rtnetlink: rtnl_setlink() and rtnl_getlink() changes

rtnl_getlink() & rtnl_setlink() run with RTNL held, we can use
__dev_get_by_index() and __dev_get_by_name() variants and avoid
dev_hold()/dev_put()

Adds to rtnl_getlink() the capability to find a device by its name,
not only by its index.

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

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index eb42873..ba13b09 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -910,9 +910,9 @@ static int rtnl_setlink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
        err = -EINVAL;
        ifm = nlmsg_data(nlh);
        if (ifm->ifi_index > 0)
-               dev = dev_get_by_index(net, ifm->ifi_index);
+               dev = __dev_get_by_index(net, ifm->ifi_index);
        else if (tb[IFLA_IFNAME])
-               dev = dev_get_by_name(net, ifname);
+               dev = __dev_get_by_name(net, ifname);
        else
                goto errout;
 
@@ -922,11 +922,9 @@ static int rtnl_setlink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
        }
 
        if ((err = validate_linkmsg(dev, tb)) < 0)
-               goto errout_dev;
+               goto errout;
 
        err = do_setlink(dev, ifm, tb, ifname, 0);
-errout_dev:
-       dev_put(dev);
 errout:
        return err;
 }
@@ -1154,6 +1152,7 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 {
        struct net *net = sock_net(skb->sk);
        struct ifinfomsg *ifm;
+       char ifname[IFNAMSIZ];
        struct nlattr *tb[IFLA_MAX+1];
        struct net_device *dev = NULL;
        struct sk_buff *nskb;
@@ -1163,19 +1162,23 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
        if (err < 0)
                return err;
 
+       if (tb[IFLA_IFNAME])
+               nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
+
        ifm = nlmsg_data(nlh);
-       if (ifm->ifi_index > 0) {
-               dev = dev_get_by_index(net, ifm->ifi_index);
-               if (dev == NULL)
-                       return -ENODEV;
-       } else
+       if (ifm->ifi_index > 0)
+               dev = __dev_get_by_index(net, ifm->ifi_index);
+       else if (tb[IFLA_IFNAME])
+               dev = __dev_get_by_name(net, ifname);
+       else
                return -EINVAL;
 
+       if (dev == NULL)
+               return -ENODEV;
+
        nskb = nlmsg_new(if_nlmsg_size(dev), GFP_KERNEL);
-       if (nskb == NULL) {
-               err = -ENOBUFS;
-               goto errout;
-       }
+       if (nskb == NULL)
+               return -ENOBUFS;
 
        err = rtnl_fill_ifinfo(nskb, dev, RTM_NEWLINK, NETLINK_CB(skb).pid,
                               nlh->nlmsg_seq, 0, 0);
@@ -1183,11 +1186,8 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
                /* -EMSGSIZE implies BUG in if_nlmsg_size */
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(nskb);
-               goto errout;
-       }
-       err = rtnl_unicast(nskb, net, NETLINK_CB(skb).pid);
-errout:
-       dev_put(dev);
+       } else
+               err = rtnl_unicast(nskb, net, NETLINK_CB(skb).pid);
 
        return err;
 }