From bbc9462f0cb0c8917a4908e856731708f0cee910 Mon Sep 17 00:00:00 2001 From: Shyam Saini Date: Thu, 27 Feb 2025 10:49:27 -0800 Subject: [PATCH 1/4] kernel: param: rename locate_module_kobject The locate_module_kobject() function looks up an existing module_kobject for a given module name. If it cannot find the corresponding module_kobject, it creates one for the given name. This commit renames 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 Link: https://lore.kernel.org/r/20250227184930.34163-2-shyamsaini@linux.microsoft.com Signed-off-by: Petr Pavlu --- kernel/params.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/params.c b/kernel/params.c index 2509f216c9f3..a2441ce059ae 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -760,7 +760,7 @@ 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; @@ -802,7 +802,7 @@ 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; @@ -873,7 +873,7 @@ 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 1c7777feb0e2f5925908c489513656ebb443a699 Mon Sep 17 00:00:00 2001 From: Shyam Saini Date: Thu, 27 Feb 2025 10:49:28 -0800 Subject: [PATCH 2/4] kernel: refactor lookup_or_create_module_kobject() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In the unlikely event of the allocation failing, it is better to let the machine boot with a not fully populated sysfs than to kill it with this BUG_ON(). All callers are already prepared for lookup_or_create_module_kobject() returning NULL. This is also preparation for calling this function from non __init code, where using BUG_ON for allocation failure handling is not acceptable. Since we are here, also start using IS_ENABLED instead of #ifdef construct. Suggested-by: Thomas Weißschuh Suggested-by: Rasmus Villemoes Signed-off-by: Shyam Saini Link: https://lore.kernel.org/r/20250227184930.34163-3-shyamsaini@linux.microsoft.com Signed-off-by: Petr Pavlu --- kernel/params.c | 41 +++++++++++++++++++---------------------- 1 file changed, 19 insertions(+), 22 deletions(-) diff --git a/kernel/params.c b/kernel/params.c index a2441ce059ae..787662663e34 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -767,31 +767,28 @@ static struct module_kobject * __init lookup_or_create_module_kobject(const char 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; - } + if (kobj) + return to_module_kobject(kobj); - /* So that we hold reference in both cases. */ - kobject_get(&mk->kobj); + mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL); + if (!mk) + return NULL; + + mk->mod = THIS_MODULE; + mk->kobj.kset = module_kset; + err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL, "%s", name); + if (IS_ENABLED(CONFIG_MODULES) && !err) + err = sysfs_create_file(&mk->kobj, &module_uevent.attr); + 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; } From 7c76c813cfc42a7376378a0c4b7250db2eebab81 Mon Sep 17 00:00:00 2001 From: Shyam Saini Date: Thu, 27 Feb 2025 10:49:29 -0800 Subject: [PATCH 3/4] kernel: globalize lookup_or_create_module_kobject() lookup_or_create_module_kobject() is marked as static and __init, to make it global drop static keyword. Since this function can be called from non-init code, use __modinit instead of __init, __modinit marker will make it __init if CONFIG_MODULES is not defined. Suggested-by: Rasmus Villemoes Signed-off-by: Shyam Saini Link: https://lore.kernel.org/r/20250227184930.34163-4-shyamsaini@linux.microsoft.com Signed-off-by: Petr Pavlu --- include/linux/module.h | 2 ++ kernel/params.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/module.h b/include/linux/module.h index d94b196d5a34..b3329110d668 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -162,6 +162,8 @@ extern void cleanup_module(void); #define __INITRODATA_OR_MODULE __INITRODATA #endif /*CONFIG_MODULES*/ +struct module_kobject *lookup_or_create_module_kobject(const char *name); + /* Generic info of form tag = "info" */ #define MODULE_INFO(tag, info) __MODULE_INFO(tag, tag, info) diff --git a/kernel/params.c b/kernel/params.c index 787662663e34..e668fc90b83e 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -760,7 +760,7 @@ 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 __modinit * lookup_or_create_module_kobject(const char *name) { struct module_kobject *mk; struct kobject *kobj; From f95bbfe18512c5c018720468959edac056a17196 Mon Sep 17 00:00:00 2001 From: Shyam Saini Date: Thu, 27 Feb 2025 10:49:30 -0800 Subject: [PATCH 4/4] drivers: base: handle module_kobject creation module_add_driver() relies on module_kset list for /sys/module//drivers directory creation. Since, commit 96a1a2412acba ("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") Cc: stable@vger.kernel.org # requires all other patches from the series Suggested-by: Rasmus Villemoes Signed-off-by: Shyam Saini Acked-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20250227184930.34163-5-shyamsaini@linux.microsoft.com Signed-off-by: Petr Pavlu --- 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 5bc71bea883a..218aaa096455 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); } }