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: e17e0f51aeea ("Driver core: show drivers in /sys/module/")
See-also: 4a7fb6363f2d ("add __must_check to device management code")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20240408080616.3911573-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/base.h b/drivers/base/base.h
index 0738ccad08b2e03c31696b9208200909b9de0171..db4f910e8e36e990dd8a0783ed8f13104cdde270 100644 (file)
--- 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
index daee55c9b2d9e1476bf34b13de20b022eb680d03..ffea0728b8b2fba61064c6ab9fbd2e5042022912 100644 (file)
--- 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
index 46ad4d636731ddf8f20b3696b018b99cadcaeb88..a1b55da07127d8734ec7a2c981aadcc03a100677 100644 (file)
--- 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)