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 {
-		ret = iommu_take_ownership(tbl);
-		if (!ret)
-			container->tbl = tbl;
+		goto unlock_exit;
 	}
 
+	ret = iommu_take_ownership(tbl);
+	if (!ret)
+		container->tbl = tbl;
+
+unlock_exit:
 	mutex_unlock(&container->lock);
 
 	return ret;
@@ -487,19 +492,22 @@ 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 {
-		if (container->enabled) {
-			pr_warn("tce_vfio: detaching group #%u from enabled container, forcing disable\n",
-					iommu_group_id(tbl->it_group));
-			tce_iommu_disable(container);
-		}
+		goto unlock_exit;
+	}
 
-		/* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
-				iommu_group_id(iommu_group), iommu_group); */
-		container->tbl = NULL;
-		tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
-		iommu_release_ownership(tbl);
+	if (container->enabled) {
+		pr_warn("tce_vfio: detaching group #%u from enabled container, forcing disable\n",
+				iommu_group_id(tbl->it_group));
+		tce_iommu_disable(container);
 	}
+
+	/* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
+	   iommu_group_id(iommu_group), iommu_group); */
+	container->tbl = NULL;
+	tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
+	iommu_release_ownership(tbl);
+
+unlock_exit:
 	mutex_unlock(&container->lock);
 }