From: Dan Smith <da...@us.ibm.com>

This is the kernel equivalent of "ip link del $name" and matches the
existing rtnl_newlink() equivalent of "ip link add $name".  It factors
out the message creation and dispatch code a little further into
rtnl_do() before adding the new function.

Cc: net...@vger.kernel.org
Signed-off-by: Dan Smith <da...@us.ibm.com>
---
 net/checkpoint_dev.c |   86 +++++++++++++++++++++++++++++++++++++++++--------
 1 files changed, 72 insertions(+), 14 deletions(-)

diff --git a/net/checkpoint_dev.c b/net/checkpoint_dev.c
index 34a6bdb..5097011 100644
--- a/net/checkpoint_dev.c
+++ b/net/checkpoint_dev.c
@@ -475,22 +475,49 @@ static struct sk_buff *new_link_msg(new_link_fn fn, void 
*data, char *name)
        return skb;
 }
 
-static struct net_device *rtnl_newlink(new_link_fn fn, void *data, char *name)
+static struct sk_buff *del_link_msg(char *name)
+{
+       int ret = -ENOMEM;
+       int flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_ACK;
+       struct nlmsghdr *nlh;
+       struct sk_buff *skb;
+       struct ifinfomsg *ifm;
+
+       skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+       if (!skb)
+               return ERR_PTR(-ENOMEM);
+
+       nlh = nlmsg_put(skb, 0, 0, RTM_DELLINK, sizeof(*ifm), flags);
+       if (!nlh)
+               goto out;
+
+       ifm = nlmsg_data(nlh);
+       memset(ifm, 0, sizeof(*ifm));
+
+       ret = nla_put_string(skb, IFLA_IFNAME, name);
+       if (ret)
+               goto out;
+
+       nlmsg_end(skb, nlh);
+
+ out:
+       if (ret < 0) {
+               kfree_skb(skb);
+               skb = ERR_PTR(ret);
+       }
+
+       return skb;
+}
+
+static int rtnl_do(struct sk_buff *skb)
 {
        int ret = -ENOMEM;
        struct socket *rtnl = NULL;
-       struct sk_buff *skb = NULL;
+       struct sk_buff *rskb = NULL;
        struct nlmsghdr *nlh;
        struct msghdr msg;
        struct kvec kvec;
 
-       skb = new_link_msg(fn, data, name);
-       if (IS_ERR(skb)) {
-               ckpt_debug("failed to create new link message: %li\n",
-                          PTR_ERR(skb));
-               return ERR_PTR(PTR_ERR(skb));
-       }
-
        memset(&msg, 0, sizeof(msg));
        kvec.iov_len = skb->len;
        kvec.iov_base = skb->head;
@@ -510,25 +537,56 @@ static struct net_device *rtnl_newlink(new_link_fn fn, 
void *data, char *name)
                goto out;
        }
 
-       /* Free the send skb to make room for the receive skb */
-       kfree_skb(skb);
-
-       nlh = rtnl_get_response(rtnl, &skb);
+       nlh = rtnl_get_response(rtnl, &rskb);
        if (IS_ERR(nlh)) {
                ret = PTR_ERR(nlh);
                ckpt_debug("RTNETLINK said: %i\n", ret);
        }
  out:
        rtnl_close(rtnl);
+       kfree_skb(rskb);
  out_noclose:
-       kfree_skb(skb);
+       return ret;
+}
 
+static struct net_device *rtnl_newlink(new_link_fn fn, void *data, char *name)
+{
+       struct sk_buff *skb;
+       int ret;
+
+       skb = new_link_msg(fn, data, name);
+       if (IS_ERR(skb)) {
+               ckpt_debug("failed to create new link message: %li\n",
+                          PTR_ERR(skb));
+               return ERR_PTR(PTR_ERR(skb));
+       }
+
+       ret = rtnl_do(skb);
+       kfree_skb(skb);
        if (ret < 0)
                return ERR_PTR(ret);
        else
                return dev_get_by_name(current->nsproxy->net_ns, name);
 }
 
+static int rtnl_dellink(char *name)
+{
+       struct sk_buff *skb;
+       int ret;
+
+       skb = del_link_msg(name);
+       if (IS_ERR(skb)) {
+               ckpt_debug("failed to create del link message: %li\n",
+                          PTR_ERR(skb));
+               return PTR_ERR(skb);
+       }
+
+       ret = rtnl_do(skb);
+       kfree_skb(skb);
+
+       return ret;
+}
+
 static int netdev_noop(void *data)
 {
        return 0;
-- 
1.6.3.3

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