/sys/modules/*/holders

/sys/module/usbcore/
  |-- drivers
  |   |-- usb:hub -> ../../../subsystem/usb/drivers/hub
  |   |-- usb:usb -> ../../../subsystem/usb/drivers/usb
  |   `-- usb:usbfs -> ../../../subsystem/usb/drivers/usbfs
  |-- holders
  |   |-- ehci_hcd -> ../../../module/ehci_hcd
  |   |-- uhci_hcd -> ../../../module/uhci_hcd
  |   |-- usb_storage -> ../../../module/usb_storage
  |   `-- usbhid -> ../../../module/usbhid
  |-- initstate

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/module.h

@@ -264,6 +264,7 @@ struct module
 	struct module_attribute *modinfo_attrs;
 	const char *version;
 	const char *srcversion;
+	struct kobject *holders_dir;
 
 	/* Exported symbols */
 	const struct kernel_symbol *syms;

kernel/module.c

@@ -537,6 +537,8 @@ static int already_uses(struct module *a, struct module *b)
 static int use_module(struct module *a, struct module *b)
 {
 	struct module_use *use;
+	int no_warn;
+
 	if (b == NULL || already_uses(a, b)) return 1;
 
 	if (!strong_try_module_get(b))
@@ -552,6 +554,7 @@ static int use_module(struct module *a, struct module *b)
 
 	use->module_which_uses = a;
 	list_add(&use->list, &b->modules_which_use_me);
+	no_warn = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name);
 	return 1;
 }
 
@@ -569,6 +572,7 @@ static void module_unload_free(struct module *mod)
 				module_put(i);
 				list_del(&use->list);
 				kfree(use);
+				sysfs_remove_link(i->holders_dir, mod->name);
 				/* There can be at most one match. */
 				break;
 			}
@@ -1106,9 +1110,7 @@ static void module_remove_modinfo_attrs(struct module *mod)
 	kfree(mod->modinfo_attrs);
 }
 
-static int mod_sysfs_setup(struct module *mod,
-			   struct kernel_param *kparam,
-			   unsigned int num_params)
+static int mod_sysfs_init(struct module *mod)
 {
 	int err;
 
@@ -1125,15 +1127,30 @@ static int mod_sysfs_setup(struct module *mod,
 	kobj_set_kset_s(&mod->mkobj, module_subsys);
 	mod->mkobj.mod = mod;
 
-	/* delay uevent until full sysfs population */
 	kobject_init(&mod->mkobj.kobj);
+
+out:
+	return err;
+}
+
+static int mod_sysfs_setup(struct module *mod,
+			   struct kernel_param *kparam,
+			   unsigned int num_params)
+{
+	int err;
+
+	/* delay uevent until full sysfs population */
 	err = kobject_add(&mod->mkobj.kobj);
 	if (err)
 		goto out;
 
+	mod->holders_dir = kobject_add_dir(&mod->mkobj.kobj, "holders");
+	if (!mod->holders_dir)
+		goto out_unreg;
+
 	err = module_param_sysfs_setup(mod, kparam, num_params);
 	if (err)
-		goto out_unreg_drivers;
+		goto out_unreg_holders;
 
 	err = module_add_modinfo_attrs(mod);
 	if (err)
@@ -1144,7 +1161,9 @@ static int mod_sysfs_setup(struct module *mod,
 
 out_unreg_param:
 	module_param_sysfs_remove(mod);
-out_unreg_drivers:
+out_unreg_holders:
+	kobject_unregister(mod->holders_dir);
+out_unreg:
 	kobject_del(&mod->mkobj.kobj);
 	kobject_put(&mod->mkobj.kobj);
 out:
@@ -1157,6 +1176,8 @@ static void mod_kobject_remove(struct module *mod)
 	module_param_sysfs_remove(mod);
 	if (mod->mkobj.drivers_dir)
 		kobject_unregister(mod->mkobj.drivers_dir);
+	if (mod->holders_dir)
+		kobject_unregister(mod->holders_dir);
 
 	kobject_unregister(&mod->mkobj.kobj);
 }
@@ -1761,6 +1782,10 @@ static struct module *load_module(void __user *umod,
 	/* Now we've moved module, initialize linked lists, etc. */
 	module_unload_init(mod);
 
+	/* Initialize kobject, so we can reference it. */
+	if (mod_sysfs_init(mod) != 0)
+		goto cleanup;
+
 	/* Set up license info based on the info section */
 	set_license(mod, get_modinfo(sechdrs, infoindex, "license"));
 

kernel/params.c

@@ -30,6 +30,8 @@
 #define DEBUGP(fmt, a...)
 #endif
 
+static struct kobj_type module_ktype;
+
 static inline char dash2underscore(char c)
 {
 	if (c == '-')
@@ -671,6 +673,19 @@ static struct sysfs_ops module_sysfs_ops = {
 	.store = module_attr_store,
 };
 
+static int uevent_filter(struct kset *kset, struct kobject *kobj)
+{
+	struct kobj_type *ktype = get_ktype(kobj);
+
+	if (ktype == &module_ktype)
+		return 1;
+	return 0;
+}
+
+static struct kset_uevent_ops module_uevent_ops = {
+	.filter = uevent_filter,
+};
+
 #else
 static struct sysfs_ops module_sysfs_ops = {
 	.show = NULL,
@@ -682,7 +697,7 @@ static struct kobj_type module_ktype = {
 	.sysfs_ops =	&module_sysfs_ops,
 };
 
-decl_subsys(module, &module_ktype, NULL);
+decl_subsys(module, &module_ktype, &module_uevent_ops);
 
 /*
  * param_sysfs_init - wrapper for built-in params support