[GENETLINK] ctrl: Avoid empty CTRL_ATTR_OPS attribute when dumping

Based on Jamal's patch but compiled and even tested. :-)

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 22 deletions

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 8903ef93db5b..cc874f0fcbdb 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -394,10 +394,7 @@ static struct genl_family genl_ctrl = {
 static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
                           u32 flags, struct sk_buff *skb, u8 cmd)
 {
-        struct nlattr *nla_ops;
-        struct genl_ops *ops;
         void *hdr;
-        int idx = 1;
 
         hdr = genlmsg_put(skb, pid, seq, &genl_ctrl, flags, cmd);
         if (hdr == NULL)
@@ -409,33 +406,39 @@ static int ctrl_fill_info(struct genl_family *family, u32 pid, u32 seq,
         NLA_PUT_U32(skb, CTRL_ATTR_HDRSIZE, family->hdrsize);
         NLA_PUT_U32(skb, CTRL_ATTR_MAXATTR, family->maxattr);
 
-        nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
-        if (nla_ops == NULL)
-                goto nla_put_failure;
-
-        list_for_each_entry(ops, &family->ops_list, ops_list) {
-                struct nlattr *nest;
+        if (!list_empty(&family->ops_list)) {
+                struct nlattr *nla_ops;
+                struct genl_ops *ops;
+                int idx = 1;
 
-                nest = nla_nest_start(skb, idx++);
-                if (nest == NULL)
+                nla_ops = nla_nest_start(skb, CTRL_ATTR_OPS);
+                if (nla_ops == NULL)
                         goto nla_put_failure;
 
-                NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
-                NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
+                list_for_each_entry(ops, &family->ops_list, ops_list) {
+                        struct nlattr *nest;
 
-                if (ops->policy)
-                        NLA_PUT_FLAG(skb, CTRL_ATTR_OP_POLICY);
+                        nest = nla_nest_start(skb, idx++);
+                        if (nest == NULL)
+                                goto nla_put_failure;
 
-                if (ops->doit)
-                        NLA_PUT_FLAG(skb, CTRL_ATTR_OP_DOIT);
+                        NLA_PUT_U32(skb, CTRL_ATTR_OP_ID, ops->cmd);
+                        NLA_PUT_U32(skb, CTRL_ATTR_OP_FLAGS, ops->flags);
 
-                if (ops->dumpit)
-                        NLA_PUT_FLAG(skb, CTRL_ATTR_OP_DUMPIT);
+                        if (ops->policy)
+                                NLA_PUT_FLAG(skb, CTRL_ATTR_OP_POLICY);
 
-                nla_nest_end(skb, nest);
-        }
+                        if (ops->doit)
+                                NLA_PUT_FLAG(skb, CTRL_ATTR_OP_DOIT);
+
+                        if (ops->dumpit)
+                                NLA_PUT_FLAG(skb, CTRL_ATTR_OP_DUMPIT);
 
-        nla_nest_end(skb, nla_ops);
+                        nla_nest_end(skb, nest);
+                }
+
+                nla_nest_end(skb, nla_ops);
+        }
 
         return genlmsg_end(skb, hdr);