IB/mad: Check and handle potential DMA mapping errors

Running with DMA_API_DEBUG enabled and not checking for DMA mapping
errors triggers a kernel stack trace with "DMA-API: device driver
failed to check map error" message.  Add these checks to the MAD
module, both to be be more robust and also eliminate these
false-positive stack traces.
Signed-off-by: Yan Burman <yanb@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/core/mad.c

@@ -1022,12 +1022,21 @@ int ib_send_mad(struct ib_mad_send_wr_private *mad_send_wr)
 					mad_send_wr->send_buf.mad,
 					sge[0].length,
 					DMA_TO_DEVICE);
+	if (unlikely(ib_dma_mapping_error(mad_agent->device, sge[0].addr)))
+		return -ENOMEM;
+
 	mad_send_wr->header_mapping = sge[0].addr;
 
 	sge[1].addr = ib_dma_map_single(mad_agent->device,
 					ib_get_payload(mad_send_wr),
 					sge[1].length,
 					DMA_TO_DEVICE);
+	if (unlikely(ib_dma_mapping_error(mad_agent->device, sge[1].addr))) {
+		ib_dma_unmap_single(mad_agent->device,
+				    mad_send_wr->header_mapping,
+				    sge[0].length, DMA_TO_DEVICE);
+		return -ENOMEM;
+	}
 	mad_send_wr->payload_mapping = sge[1].addr;
 
 	spin_lock_irqsave(&qp_info->send_queue.lock, flags);
@@ -2590,6 +2599,11 @@ static int ib_mad_post_receive_mads(struct ib_mad_qp_info *qp_info,
 						 sizeof *mad_priv -
 						   sizeof mad_priv->header,
 						 DMA_FROM_DEVICE);
+		if (unlikely(ib_dma_mapping_error(qp_info->port_priv->device,
+						  sg_list.addr))) {
+			ret = -ENOMEM;
+			break;
+		}
 		mad_priv->header.mapping = sg_list.addr;
 		recv_wr.wr_id = (unsigned long)&mad_priv->header.mad_list;
 		mad_priv->header.mad_list.mad_queue = recv_queue;