module: add /sys/module/<name>/uevent files

Userspace wants to manage module parameters with udev rules.
This currently only works for loaded modules, but not for
built-in ones.

To allow access to the built-in modules we need to
re-trigger all module load events that happened before any
userspace was running. We already do the same thing for all
devices, subsystems(buses) and drivers.

This adds the currently missing /sys/module/<name>/uevent files
to all module entries.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (split & trivial fix)

include/linux/module.h

@@ -75,6 +75,7 @@ struct module_version_attribute {
 extern ssize_t __modver_version_show(struct module_attribute *,
 				     struct module_kobject *, char *);
 
+extern struct module_attribute module_uevent;
 
 /* These are either module local, or the kernel's dummy ones. */
 extern int init_module(void);

kernel/module.c

@@ -975,10 +975,27 @@ static struct module_attribute initstate = {
 	.show = show_initstate,
 };
 
+static ssize_t store_uevent(struct module_attribute *mattr,
+			    struct module_kobject *mk,
+			    const char *buffer, size_t count)
+{
+	enum kobject_action action;
+
+	if (kobject_action_type(buffer, count, &action) == 0)
+		kobject_uevent(&mk->kobj, action);
+	return count;
+}
+
+struct module_attribute module_uevent = {
+	.attr = { .name = "uevent", .mode = 0200 },
+	.store = store_uevent,
+};
+
 static struct module_attribute *modinfo_attrs[] = {
 	&modinfo_version,
 	&modinfo_srcversion,
 	&initstate,
+	&module_uevent,
 #ifdef CONFIG_MODULE_UNLOAD
 	&refcnt,
 #endif

kernel/params.c

@@ -730,6 +730,10 @@ static struct module_kobject * __init locate_module_kobject(const char *name)
 		mk->kobj.kset = module_kset;
 		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
 					   "%s", name);
+#ifdef CONFIG_MODULES
+		if (!err)
+			err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
+#endif
 		if (err) {
 			kobject_put(&mk->kobj);
 			printk(KERN_ERR