IB/mad: Enable loopback of DR SMP responses from userspace

The local loopback of an outgoing DR SMP response is limited to those
that originate at the driver specific SMA implementation during the
driver specific process_mad() function. This patch enables a
returning DR SMP originating in userspace (or elsewhere) to be
delivered to the local managment stack. In this specific case the
driver process_mad() function does not consume or process the MAD, so
a reponse mad has not be created and the original MAD must manually be
copied to the MAD buffer that is to be handed off to the local agent.

Signed-off-by: Steve Welch <[e-mail]>
Acked-by: Hal Rosenstock <[e-mail]>
Signed-off-by: Roland Dreier <[e-mail]>

drivers/infiniband/core/mad.c

···
 	}
 
 	/* Check to post send on QP or process locally */
-	if (smi_check_local_smp(smp, device) == IB_SMI_DISCARD)
+	if (smi_check_local_smp(smp, device) == IB_SMI_DISCARD &&
+	    smi_check_local_returning_smp(smp, device) == IB_SMI_DISCARD)
 		goto out;
 
 	local = kmalloc(sizeof *local, GFP_ATOMIC);
···
 		port_priv = ib_get_mad_port(mad_agent_priv->agent.device,
 					    mad_agent_priv->agent.port_num);
 		if (port_priv) {
-			mad_priv->mad.mad.mad_hdr.tid =
-				((struct ib_mad *)smp)->mad_hdr.tid;
+			memcpy(&mad_priv->mad.mad, smp, sizeof(struct ib_mad));
 			recv_mad_agent = find_mad_agent(port_priv,
 						        &mad_priv->mad.mad);
 		}

drivers/infiniband/core/smi.h

···
 					      u8 node_type, int port_num);
 
 /*
- * Return 1 if the SMP should be handled by the local SMA/SM via process_mad
+ * Return IB_SMI_HANDLE if the SMP should be handled by the local SMA/SM
+ * via process_mad
  */
 static inline enum smi_action smi_check_local_smp(struct ib_smp *smp,
 						  struct ib_device *device)
···
 		(smp->hop_ptr == smp->hop_cnt + 1)) ?
 		IB_SMI_HANDLE : IB_SMI_DISCARD);
 }
+
+/*
+ * Return IB_SMI_HANDLE if the SMP should be handled by the local SMA/SM
+ * via process_mad
+ */
+static inline enum smi_action smi_check_local_returning_smp(struct ib_smp *smp,
+						   struct ib_device *device)
+{
+	/* C14-13:3 -- We're at the end of the DR segment of path */
+	/* C14-13:4 -- Hop Pointer == 0 -> give to SM */
+	return ((device->process_mad &&
+		ib_get_smp_direction(smp) &&
+		!smp->hop_ptr) ? IB_SMI_HANDLE : IB_SMI_DISCARD);
+}
+
 #endif	/* __SMI_H_ */