vfio: powerpc/spapr: Rework groups attaching

This is to make extended ownership and multiple groups support patches
simpler for review.

This should cause no behavioural change.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
[aw: for the vfio related changes]
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/vfio/vfio_iommu_spapr_tce.c

@@ -460,16 +460,21 @@ static int tce_iommu_attach_group(void *iommu_data,
 				iommu_group_id(container->tbl->it_group),
 				iommu_group_id(iommu_group));
 		ret = -EBUSY;
-	} else if (container->enabled) {
+		goto unlock_exit;
+	}
+
+	if (container->enabled) {
 		pr_err("tce_vfio: attaching group #%u to enabled container\n",
 				iommu_group_id(iommu_group));
 		ret = -EBUSY;
-	} else {
+		goto unlock_exit;
+	}
+
 	ret = iommu_take_ownership(tbl);
 	if (!ret)
 		container->tbl = tbl;
-	}
 
+unlock_exit:
 	mutex_unlock(&container->lock);
 
 	return ret;
@@ -487,7 +492,9 @@ static void tce_iommu_detach_group(void *iommu_data,
 		pr_warn("tce_vfio: detaching group #%u, expected group is #%u\n",
 				iommu_group_id(iommu_group),
 				iommu_group_id(tbl->it_group));
-	} else {
+		goto unlock_exit;
+	}
+
 	if (container->enabled) {
 		pr_warn("tce_vfio: detaching group #%u from enabled container, forcing disable\n",
 				iommu_group_id(tbl->it_group));
@@ -499,7 +506,8 @@ static void tce_iommu_detach_group(void *iommu_data,
 	container->tbl = NULL;
 	tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
 	iommu_release_ownership(tbl);
-	}
+
+unlock_exit:
 	mutex_unlock(&container->lock);
 }