module: don't ignore sysfs_create_link() failures

The sysfs_create_link() return code is marked as __must_check, but the module_add_driver() function tries hard to not care, by assigning the return code to a variable. When building with 'make W=1', gcc still warns because this variable is only assigned but not used: drivers/base/module.c: In function 'module_add_driver': drivers/base/module.c:36:6: warning: variable 'no_warn' set but not used [-Wunused-but-set-variable] Rework the code to properly unwind and return the error code to the caller. My reading of the original code was that it tries to not fail when the links already exist, so keep ignoring -EEXIST errors. Fixes: e17e0f5 ("Driver core: show drivers in /sys/module/") See-also: 4a7fb63 ("add __must_check to device management code") Signed-off-by: Arnd Bergmann <[email protected]> Reviewed-by: Luis Chamberlain <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
alexelder · Apr 11, 2024 · 85d2b0a · 85d2b0a
1 parent 0bb322b
commit 85d2b0a
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Showing 3 changed files with 45 additions and 15 deletions.
diff --git a/drivers/base/base.h b/drivers/base/base.h
@@ -192,11 +192,14 @@ extern struct kset *devices_kset;
 void devices_kset_move_last(struct device *dev);
 
 #if defined(CONFIG_MODULES) && defined(CONFIG_SYSFS)
-void module_add_driver(struct module *mod, struct device_driver *drv);
+int module_add_driver(struct module *mod, struct device_driver *drv);
 void module_remove_driver(struct device_driver *drv);
 #else
-static inline void module_add_driver(struct module *mod,
-				     struct device_driver *drv) { }
+static inline int module_add_driver(struct module *mod,
+				    struct device_driver *drv)
+{
+	return 0;
+}
 static inline void module_remove_driver(struct device_driver *drv) { }
 #endif
 

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
@@ -674,7 +674,12 @@ int bus_add_driver(struct device_driver *drv)
 		if (error)
 			goto out_del_list;
 	}
-	module_add_driver(drv->owner, drv);
+	error = module_add_driver(drv->owner, drv);
+	if (error) {
+		printk(KERN_ERR "%s: failed to create module links for %s\n",
+			__func__, drv->name);
+		goto out_detach;
+	}
 
 	error = driver_create_file(drv, &driver_attr_uevent);
 	if (error) {
@@ -699,6 +704,8 @@ int bus_add_driver(struct device_driver *drv)
 
 	return 0;
 
+out_detach:
+	driver_detach(drv);
 out_del_list:
 	klist_del(&priv->knode_bus);
 out_unregister:

diff --git a/drivers/base/module.c b/drivers/base/module.c
@@ -30,14 +30,14 @@ static void module_create_drivers_dir(struct module_kobject *mk)
 	mutex_unlock(&drivers_dir_mutex);
 }
 
-void module_add_driver(struct module *mod, struct device_driver *drv)
+int module_add_driver(struct module *mod, struct device_driver *drv)
 {
 	char *driver_name;
-	int no_warn;
 	struct module_kobject *mk = NULL;
+	int ret;
 
 	if (!drv)
-		return;
+		return 0;
 
 	if (mod)
 		mk = &mod->mkobj;
@@ -56,17 +56,37 @@ void module_add_driver(struct module *mod, struct device_driver *drv)
 	}
 
 	if (!mk)
-		return;
+		return 0;
+
+	ret = sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
+	if (ret)
+		return ret;
 
-	/* Don't check return codes; these calls are idempotent */
-	no_warn = sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
 	driver_name = make_driver_name(drv);
-	if (driver_name) {
-		module_create_drivers_dir(mk);
-		no_warn = sysfs_create_link(mk->drivers_dir, &drv->p->kobj,
-					    driver_name);
-		kfree(driver_name);
+	if (!driver_name) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	module_create_drivers_dir(mk);
+	if (!mk->drivers_dir) {
+		ret = -EINVAL;
+		goto out;
 	}
+
+	ret = sysfs_create_link(mk->drivers_dir, &drv->p->kobj, driver_name);
+	if (ret)
+		goto out;
+
+	kfree(driver_name);
+
+	return 0;
+out:
+	sysfs_remove_link(&drv->p->kobj, "module");
+	sysfs_remove_link(mk->drivers_dir, driver_name);
+	kfree(driver_name);
+
+	return ret;
 }
 
 void module_remove_driver(struct device_driver *drv)