IB/mad: initialize mad_agent_priv before putting on lists

There is a potential race in ib_register_mad_agent() where the struct
ib_mad_agent_private is not fully initialized before it is added to
the list of agents per IB port. This means the ib_mad_agent_private
could be seen before the refcount, spin locks, and linked lists are
initialized.  The fix is to initialize the structure earlier.
Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/mad.c

@@ -301,6 +301,16 @@ struct ib_mad_agent *ib_register_mad_agent(struct ib_device *device,
 	mad_agent_priv->agent.context = context;
 	mad_agent_priv->agent.qp = port_priv->qp_info[qpn].qp;
 	mad_agent_priv->agent.port_num = port_num;
+	spin_lock_init(&mad_agent_priv->lock);
+	INIT_LIST_HEAD(&mad_agent_priv->send_list);
+	INIT_LIST_HEAD(&mad_agent_priv->wait_list);
+	INIT_LIST_HEAD(&mad_agent_priv->done_list);
+	INIT_LIST_HEAD(&mad_agent_priv->rmpp_list);
+	INIT_DELAYED_WORK(&mad_agent_priv->timed_work, timeout_sends);
+	INIT_LIST_HEAD(&mad_agent_priv->local_list);
+	INIT_WORK(&mad_agent_priv->local_work, local_completions);
+	atomic_set(&mad_agent_priv->refcount, 1);
+	init_completion(&mad_agent_priv->comp);
 
 	spin_lock_irqsave(&port_priv->reg_lock, flags);
 	mad_agent_priv->agent.hi_tid = ++ib_mad_client_id;
@@ -350,17 +360,6 @@ struct ib_mad_agent *ib_register_mad_agent(struct ib_device *device,
 	list_add_tail(&mad_agent_priv->agent_list, &port_priv->agent_list);
 	spin_unlock_irqrestore(&port_priv->reg_lock, flags);
 
-	spin_lock_init(&mad_agent_priv->lock);
-	INIT_LIST_HEAD(&mad_agent_priv->send_list);
-	INIT_LIST_HEAD(&mad_agent_priv->wait_list);
-	INIT_LIST_HEAD(&mad_agent_priv->done_list);
-	INIT_LIST_HEAD(&mad_agent_priv->rmpp_list);
-	INIT_DELAYED_WORK(&mad_agent_priv->timed_work, timeout_sends);
-	INIT_LIST_HEAD(&mad_agent_priv->local_list);
-	INIT_WORK(&mad_agent_priv->local_work, local_completions);
-	atomic_set(&mad_agent_priv->refcount, 1);
-	init_completion(&mad_agent_priv->comp);
-
 	return &mad_agent_priv->agent;
 
 error4: