On Wed, Dec 11, 2019 at 11:34:00AM +0100, Håkon Bugge wrote: > In rdma_nl_rcv_skb(), the local variable err is assigned the return > value of the supplied callback function, which could be one of > ib_nl_handle_resolve_resp(), ib_nl_handle_set_timeout(), or > ib_nl_handle_ip_res_resp(). These three functions all return skb->len > on success. > > rdma_nl_rcv_skb() is merely a copy of netlink_rcv_skb(). The callback > functions used by the latter have the convention: "Returns 0 on > success or a negative error code". > > In particular, the statement (equal for both functions): > > if (nlh->nlmsg_flags & NLM_F_ACK || err) > > implies that rdma_nl_rcv_skb() always will ack a message, independent > of the NLM_F_ACK being set in nlmsg_flags or not. The more accurate description is that rdma_nl_rcv_skb() always generates NLMSG_ERROR without relation to NLM_F_ACK flag. The NLM_F_ACK flag is requested to get acknowledges for the success. > > The fix could be to change the above statement, but it is better to > keep the two *_rcv_skb() functions equal in this respect and instead > change the callback functions in the rdma subsystem to the correct > convention. AFAIR, RTNETLINK has the same implementation as RDMA netlink. Thanks
