of: Disabling OF functions that use sysfs if CONFIG_SYSFS disabled

This patch is to the fix the recent runtime bug in kernel reported by
<fengguang.wu@intel.com>. The bug was exposed by commit b951f9dc,
"Enabling OF selftest to run without machine's devicetree" and is
exposed when CONFIG_OF_SELFTEST is enabled and CONFIG_SYSFS is
disabled.

Mail Subject: [OF test] BUG: unable to handle kernel NULL pointer
dereference at 00000038

Tested on x86 and arm architecture
Signed-off-by: Gaurav Minocha <gaurav.minocha.os@gmail.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

drivers/of/base.c

@@ -138,6 +138,9 @@ int __of_add_property_sysfs(struct device_node *np, struct property *pp)
 	/* Important: Don't leak passwords */
 	bool secure = strncmp(pp->name, "security-", 9) == 0;
 
+	if (!IS_ENABLED(CONFIG_SYSFS))
+		return 0;
+
 	if (!of_kset || !of_node_is_attached(np))
 		return 0;
 
@@ -158,6 +161,9 @@ int __of_attach_node_sysfs(struct device_node *np)
 	struct property *pp;
 	int rc;
 
+	if (!IS_ENABLED(CONFIG_SYSFS))
+		return 0;
+
 	if (!of_kset)
 		return 0;
 
@@ -1713,6 +1719,9 @@ int __of_remove_property(struct device_node *np, struct property *prop)
 
 void __of_remove_property_sysfs(struct device_node *np, struct property *prop)
 {
+	if (!IS_ENABLED(CONFIG_SYSFS))
+		return;
+
 	/* at early boot, bail here and defer setup to of_init() */
 	if (of_kset && of_node_is_attached(np))
 		sysfs_remove_bin_file(&np->kobj, &prop->attr);
@@ -1777,6 +1786,9 @@ int __of_update_property(struct device_node *np, struct property *newprop,
 void __of_update_property_sysfs(struct device_node *np, struct property *newprop,
 		struct property *oldprop)
 {
+	if (!IS_ENABLED(CONFIG_SYSFS))
+		return;
+
 	/* At early boot, bail out and defer setup to of_init() */
 	if (!of_kset)
 		return;

drivers/of/dynamic.c

@@ -45,6 +45,9 @@ void __of_detach_node_sysfs(struct device_node *np)
 {
 	struct property *pp;
 
+	if (!IS_ENABLED(CONFIG_SYSFS))
+		return;
+
 	BUG_ON(!of_node_is_initialized(np));
 	if (!of_kset)
 		return;