On Tue, 25 Aug 2015 21:43:29 +0200, Christophe Ricard wrote:

 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
 {
+	struct netlink_sock *nlk;
 	struct sk_buff *skb;
 	struct nlmsghdr *rep;
 	struct nlmsgerr *errmsg;
 	size_t payload = sizeof(*errmsg);
+	struct sock *sk;
 
-	/* error messages get the original request appened */
-	if (err)
+	sk = netlink_lookup(sock_net(in_skb->sk),
+			    in_skb->sk->sk_protocol,
+			    NETLINK_CB(in_skb).portid);

The necessity to look up the socket for every ack was what I didn't
like about this. Would it be possible to add a socket parameter to
various code paths that lead to netlink_ack (or a boolean, as David
suggested)? It will probably be needed to add it to
netlink_sock->netlink_rcv, netlink_kernel_cfg->input, etc.

As an alternative, David also suggested to attach the sender socket to
in_skb->sk. Could work, too.

Thanks,

 Jiri

-- 
Jiri Benc