scsi: libsas: Remove an empty branch in sas_check_parent_topology()

There is an empty "all good" branch in sas_check_parent_topology(). We can
reverse the test statement and remove the empty branch.

Moreover, factor out a helper sas_check_edge_expander_topo() to make the
code more readable.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230421093744.1583609-3-yanaijie@huawei.comReviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libsas/sas_expander.c

@@ -1240,6 +1240,37 @@ static int sas_check_eeds(struct domain_device *child,
 	return res;
 }
 
+static int sas_check_edge_expander_topo(struct domain_device *child,
+					struct ex_phy *parent_phy)
+{
+	struct expander_device *child_ex = &child->ex_dev;
+	struct expander_device *parent_ex = &child->parent->ex_dev;
+	struct ex_phy *child_phy;
+
+	child_phy = &child_ex->ex_phy[parent_phy->attached_phy_id];
+
+	if (child->dev_type == SAS_FANOUT_EXPANDER_DEVICE) {
+		if (parent_phy->routing_attr != SUBTRACTIVE_ROUTING ||
+		    child_phy->routing_attr != TABLE_ROUTING)
+			goto error;
+	} else if (parent_phy->routing_attr == SUBTRACTIVE_ROUTING) {
+		if (child_phy->routing_attr == SUBTRACTIVE_ROUTING)
+			return sas_check_eeds(child, parent_phy, child_phy);
+		else if (child_phy->routing_attr != TABLE_ROUTING)
+			goto error;
+	} else if (parent_phy->routing_attr == TABLE_ROUTING) {
+		if (child_phy->routing_attr != SUBTRACTIVE_ROUTING &&
+		    (child_phy->routing_attr != TABLE_ROUTING ||
+		     !child_ex->t2t_supp || !parent_ex->t2t_supp))
+			goto error;
+	}
+
+	return 0;
+error:
+	sas_print_parent_topology_bug(child, parent_phy, child_phy);
+	return -ENODEV;
+}
+
 /* Here we spill over 80 columns.  It is intentional.
  */
 static int sas_check_parent_topology(struct domain_device *child)
@@ -1272,29 +1303,8 @@ static int sas_check_parent_topology(struct domain_device *child)
 
 		switch (child->parent->dev_type) {
 		case SAS_EDGE_EXPANDER_DEVICE:
-			if (child->dev_type == SAS_FANOUT_EXPANDER_DEVICE) {
-				if (parent_phy->routing_attr != SUBTRACTIVE_ROUTING ||
-				    child_phy->routing_attr != TABLE_ROUTING) {
-					sas_print_parent_topology_bug(child, parent_phy, child_phy);
-					res = -ENODEV;
-				}
-			} else if (parent_phy->routing_attr == SUBTRACTIVE_ROUTING) {
-				if (child_phy->routing_attr == SUBTRACTIVE_ROUTING) {
-					res = sas_check_eeds(child, parent_phy, child_phy);
-				} else if (child_phy->routing_attr != TABLE_ROUTING) {
-					sas_print_parent_topology_bug(child, parent_phy, child_phy);
-					res = -ENODEV;
-				}
-			} else if (parent_phy->routing_attr == TABLE_ROUTING) {
-				if (child_phy->routing_attr == SUBTRACTIVE_ROUTING ||
-				    (child_phy->routing_attr == TABLE_ROUTING &&
-				     child_ex->t2t_supp && parent_ex->t2t_supp)) {
-					/* All good */;
-				} else {
-					sas_print_parent_topology_bug(child, parent_phy, child_phy);
-					res = -ENODEV;
-				}
-			}
+			if (sas_check_edge_expander_topo(child, parent_phy))
+				res = -ENODEV;
 			break;
 		case SAS_FANOUT_EXPANDER_DEVICE:
 			if (parent_phy->routing_attr != TABLE_ROUTING ||