IB/mlx5: Fix clean_mr() to work in the expected order

commit b9332dad987018745a0c0bb718d12dacfa760489 upstream.

Any dma map underlying the MR should only be freed once the MR is fenced
at the hardware.

As of the above we first destroy the MKEY and just after that can safely
call to dma_unmap_single().

Link: https://lore.kernel.org/r/20190723065733.4899-6-leon@kernel.org
Cc: <stable@vger.kernel.org> # 4.3
Fixes: 8a187ee5 ("IB/mlx5: Support the new memory registration API")
Signed-off-by: NYishai Hadas <yishaih@mellanox.com>
Reviewed-by: NArtemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: NLeon Romanovsky <leonro@mellanox.com>
Reviewed-by: NJason Gunthorpe <jgg@mellanox.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/infiniband/hw/mlx5/mr.c

@@ -1620,10 +1620,10 @@ static void clean_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr)
 		mr->sig = NULL;
 	}
 
-	mlx5_free_priv_descs(mr);
-
-	if (!allocated_from_cache)
+	if (!allocated_from_cache) {
 		destroy_mkey(dev, mr);
+		mlx5_free_priv_descs(mr);
+	}
 }
 
 static void dereg_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr)