/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>

3 files changed, 48 insertions, 7 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index 90dc2542978c..419d3ef293dd 100644
--- a/include/linux/module.h
+++ b/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;
diff --git a/kernel/module.c b/kernel/module.c
index 9de4209f6a67..8a94e054230c 100644
--- a/kernel/module.c
+++ b/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"));
 
diff --git a/kernel/params.c b/kernel/params.c
index cbaac85942d5..553cf7d6a4be 100644
--- a/kernel/params.c
+++ b/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