From ac4b3e09e8e08540e963b6dbf05b34657a32168d Mon Sep 17 00:00:00 2001 From: Shyam Saini Date: Mon, 3 Feb 2025 21:22:20 -0800 Subject: [PATCH 1/3] kernel: param: rename locate_module_kobject locate_module_kobject() look up for existing module_kobject For given module name locate_module_kobject() look up for corresponding module_kobject if it exists. If it coudln't find its corresponding module_kobject then it creates one for the given name. Rename locate_module_kobject() to lookup_or_create_module_kobject(), to better describe its operations. This doesn't change anything functionality wise. Suggested-by: Rasmus Villemoes Signed-off-by: Shyam Saini --- kernel/params.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/params.c b/kernel/params.c index 0074d29c9b80ce..4b43baaf7c83f1 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -763,7 +763,7 @@ void destroy_params(const struct kernel_param *params, unsigned num) params[i].ops->free(params[i].arg); } -static struct module_kobject * __init locate_module_kobject(const char *name) +static struct module_kobject * __init lookup_or_create_module_kobject(const char *name) { struct module_kobject *mk; struct kobject *kobj; @@ -805,10 +805,9 @@ static void __init kernel_add_sysfs_param(const char *name, struct module_kobject *mk; int err; - mk = locate_module_kobject(name); + mk = lookup_or_create_module_kobject(name); if (!mk) return; - /* We need to remove old parameters before adding more. */ if (mk->mp) sysfs_remove_group(&mk->kobj, &mk->mp->grp); @@ -876,7 +875,7 @@ static void __init version_sysfs_builtin(void) int err; for (vattr = __start___modver; vattr < __stop___modver; vattr++) { - mk = locate_module_kobject(vattr->module_name); + mk = lookup_or_create_module_kobject(vattr->module_name); if (mk) { err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr); WARN_ON_ONCE(err); From 86320eed2d77d1781900002e08d40a51e47eb00d Mon Sep 17 00:00:00 2001 From: Shyam Saini Date: Mon, 3 Feb 2025 21:22:21 -0800 Subject: [PATCH 2/3] include: move lookup_or_create_module_kobject()/to_module* to module.h Move the following to module.h to allow common usages: - lookup_or_create_module_kobject() - to_module_attr - to_module_kobject This makes lookup_or_create_module_kobject() as inline. Signed-off-by: Shyam Saini --- include/linux/module.h | 39 +++++++++++++++++++++++++++++++++++++++ kernel/params.c | 39 --------------------------------------- 2 files changed, 39 insertions(+), 39 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 12f8a7d4fc1c1e..ba5f5e6c392714 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -894,8 +894,47 @@ static inline void *module_writable_address(struct module *mod, void *loc) #endif /* CONFIG_MODULES */ #ifdef CONFIG_SYSFS +/* sysfs output in /sys/modules/XYZ/parameters/ */ +#define to_module_attr(n) container_of_const(n, struct module_attribute, attr) +#define to_module_kobject(n) container_of(n, struct module_kobject, kobj) extern struct kset *module_kset; extern const struct kobj_type module_ktype; + +static inline struct module_kobject * __init lookup_or_create_module_kobject(const char *name) +{ + struct module_kobject *mk; + struct kobject *kobj; + int err; + + kobj = kset_find_obj(module_kset, name); + if (kobj) { + mk = to_module_kobject(kobj); + } else { + mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL); + BUG_ON(!mk); + + mk->mod = THIS_MODULE; + 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); + pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n", + name, err); + return NULL; + } + + /* So that we hold reference in both cases. */ + kobject_get(&mk->kobj); + } + + return mk; +} + #endif /* CONFIG_SYSFS */ #define symbol_request(x) try_then_request_module(symbol_get(x), "symbol:" #x) diff --git a/kernel/params.c b/kernel/params.c index 4b43baaf7c83f1..3c0798b79f76f3 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -537,10 +537,6 @@ const struct kernel_param_ops param_ops_string = { }; EXPORT_SYMBOL(param_ops_string); -/* sysfs output in /sys/modules/XYZ/parameters/ */ -#define to_module_attr(n) container_of_const(n, struct module_attribute, attr) -#define to_module_kobject(n) container_of(n, struct module_kobject, kobj) - struct param_attribute { struct module_attribute mattr; @@ -763,41 +759,6 @@ void destroy_params(const struct kernel_param *params, unsigned num) params[i].ops->free(params[i].arg); } -static struct module_kobject * __init lookup_or_create_module_kobject(const char *name) -{ - struct module_kobject *mk; - struct kobject *kobj; - int err; - - kobj = kset_find_obj(module_kset, name); - if (kobj) { - mk = to_module_kobject(kobj); - } else { - mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL); - BUG_ON(!mk); - - mk->mod = THIS_MODULE; - 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); - pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n", - name, err); - return NULL; - } - - /* So that we hold reference in both cases. */ - kobject_get(&mk->kobj); - } - - return mk; -} - static void __init kernel_add_sysfs_param(const char *name, const struct kernel_param *kparam, unsigned int name_skip) From 322d5ead80789ae881ff471bc2d3e0371f34ca27 Mon Sep 17 00:00:00 2001 From: Shyam Saini Date: Mon, 3 Feb 2025 21:22:22 -0800 Subject: [PATCH 3/3] drivers: base: handle module_kboject creation module_add_driver() relies on module_kset list for /sys/module//drivers directory creation. Since, commit 96a1a2412acb ("kernel/params.c: defer most of param_sysfs_init() to late_initcall time") drivers which are initialized from subsys_initcall() or any other higher precedence initcall couldn't find the related kobject entry in the module_kset list because module_kset is not fully populated by the time module_add_driver() refers it. As a consequence, module_add_driver() returns early without calling make_driver_name(). Therefore, /sys/module//drivers is never created. Fix this issue by letting module_add_driver() handle module_kobject creation itself. Fixes: 96a1a2412acb ("kernel/params.c: defer most of param_sysfs_init() to late_initcall time") Suggested-by: Rasmus Villemoes Signed-off-by: Shyam Saini --- drivers/base/module.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/drivers/base/module.c b/drivers/base/module.c index 5bc71bea883a06..218aaa0964552f 100644 --- a/drivers/base/module.c +++ b/drivers/base/module.c @@ -42,16 +42,13 @@ int module_add_driver(struct module *mod, const struct device_driver *drv) if (mod) mk = &mod->mkobj; else if (drv->mod_name) { - struct kobject *mkobj; - - /* Lookup built-in module entry in /sys/modules */ - mkobj = kset_find_obj(module_kset, drv->mod_name); - if (mkobj) { - mk = container_of(mkobj, struct module_kobject, kobj); + /* Lookup or create built-in module entry in /sys/modules */ + mk = lookup_or_create_module_kobject(drv->mod_name); + if (mk) { /* remember our module structure */ drv->p->mkobj = mk; - /* kset_find_obj took a reference */ - kobject_put(mkobj); + /* lookup_or_create_module_kobject took a reference */ + kobject_put(&mk->kobj); } }