net/mlx4_en: Notify user when TX ring in error state

When hardware gets into error state, must notify user about it.
When QP in error state no traffic will be tx'ed from the attached
tx_ring.

Driver should know how to recover from this unexpected state. I will send later
on the recovery flow, but having the print shouldn't be delayed.
Signed-off-by: NAmir Vadai <amirv@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_tx.c

@@ -362,6 +362,15 @@ static void mlx4_en_process_tx_cq(struct net_device *dev, struct mlx4_en_cq *cq)
 		 */
 		rmb();
 
+		if (unlikely((cqe->owner_sr_opcode & MLX4_CQE_OPCODE_MASK) ==
+			     MLX4_CQE_OPCODE_ERROR)) {
+			struct mlx4_err_cqe *cqe_err = (struct mlx4_err_cqe *)cqe;
+
+			en_err(priv, "CQE error - vendor syndrome: 0x%x syndrome: 0x%x\n",
+			       cqe_err->vendor_err_syndrome,
+			       cqe_err->syndrome);
+		}
+
 		/* Skip over last polled CQE */
 		new_index = be16_to_cpu(cqe->wqe_index) & size_mask;