powerpc/pseries/mobility: refactor node lookup during DT update

In pseries_devicetree_update(), with each call to ibm,update-nodes the
partition firmware communicates the node to be deleted or updated by
placing its phandle in the work buffer. Each of delete_dt_node(),
update_dt_node(), and add_dt_node() have duplicate lookups using the
phandle value and corresponding refcount management.

Move the lookup and of_node_put() into pseries_devicetree_update(),
and emit a warning on any failed lookups.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201207215200.1785968-29-nathanl@linux.ibm.com

arch/powerpc/platforms/pseries/mobility.c

@@ -61,18 +61,10 @@ static int mobility_rtas_call(int token, char *buf, s32 scope)
 	return rc;
 }
 
-static int delete_dt_node(__be32 phandle)
+static int delete_dt_node(struct device_node *dn)
 {
-	struct device_node *dn;
-
-	dn = of_find_node_by_phandle(be32_to_cpu(phandle));
-	if (!dn)
-		return -ENOENT;
-
 	pr_debug("removing node %pOFfp\n", dn);
-
 	dlpar_detach_node(dn);
-	of_node_put(dn);
 	return 0;
 }
 
@@ -137,10 +129,9 @@ static int update_dt_property(struct device_node *dn, struct property **prop,
 	return 0;
 }
 
-static int update_dt_node(__be32 phandle, s32 scope)
+static int update_dt_node(struct device_node *dn, s32 scope)
 {
 	struct update_props_workarea *upwa;
-	struct device_node *dn;
 	struct property *prop = NULL;
 	int i, rc, rtas_rc;
 	char *prop_data;
@@ -157,14 +148,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
 	if (!rtas_buf)
 		return -ENOMEM;
 
-	dn = of_find_node_by_phandle(be32_to_cpu(phandle));
-	if (!dn) {
-		kfree(rtas_buf);
-		return -ENOENT;
-	}
-
 	upwa = (struct update_props_workarea *)&rtas_buf[0];
-	upwa->phandle = phandle;
+	upwa->phandle = cpu_to_be32(dn->phandle);
 
 	do {
 		rtas_rc = mobility_rtas_call(update_properties_token, rtas_buf,
@@ -224,26 +209,18 @@ static int update_dt_node(__be32 phandle, s32 scope)
 		cond_resched();
 	} while (rtas_rc == 1);
 
-	of_node_put(dn);
 	kfree(rtas_buf);
 	return 0;
 }
 
-static int add_dt_node(__be32 parent_phandle, __be32 drc_index)
+static int add_dt_node(struct device_node *parent_dn, __be32 drc_index)
 {
 	struct device_node *dn;
-	struct device_node *parent_dn;
 	int rc;
 
-	parent_dn = of_find_node_by_phandle(be32_to_cpu(parent_phandle));
-	if (!parent_dn)
-		return -ENOENT;
-
 	dn = dlpar_configure_connector(drc_index, parent_dn);
-	if (!dn) {
-		of_node_put(parent_dn);
+	if (!dn)
 		return -ENOENT;
-	}
 
 	rc = dlpar_attach_node(dn, parent_dn);
 	if (rc)
@@ -251,7 +228,6 @@ static int add_dt_node(__be32 parent_phandle, __be32 drc_index)
 
 	pr_debug("added node %pOFfp\n", dn);
 
-	of_node_put(parent_dn);
 	return rc;
 }
 
@@ -284,22 +260,31 @@ int pseries_devicetree_update(s32 scope)
 			data++;
 
 			for (i = 0; i < node_count; i++) {
+				struct device_node *np;
 				__be32 phandle = *data++;
 				__be32 drc_index;
 
+				np = of_find_node_by_phandle(be32_to_cpu(phandle));
+				if (!np) {
+					pr_warn("Failed lookup: phandle 0x%x for action 0x%x\n",
+						be32_to_cpu(phandle), action);
+					continue;
+				}
+
 				switch (action) {
 				case DELETE_DT_NODE:
-					delete_dt_node(phandle);
+					delete_dt_node(np);
 					break;
 				case UPDATE_DT_NODE:
-					update_dt_node(phandle, scope);
+					update_dt_node(np, scope);
 					break;
 				case ADD_DT_NODE:
 					drc_index = *data++;
-					add_dt_node(phandle, drc_index);
+					add_dt_node(np, drc_index);
 					break;
 				}
 
+				of_node_put(np);
 				cond_resched();
 			}
 		}