From cf2fde7b39e9446e2af015215d7fb695781af0c1 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 26 Jun 2015 06:44:38 +0930 Subject: [PATCH] param: fix module param locks when !CONFIG_SYSFS. As Dan Streetman points out, the entire point of locking for is to stop sysfs accesses, so they're elided entirely in the !SYSFS case. Reported-by: Stephen Rothwell Signed-off-by: Rusty Russell --- include/linux/module.h | 2 ++ kernel/module.c | 9 ++++++++- kernel/params.c | 18 ++++++++++++++---- 3 files changed, 24 insertions(+), 5 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 6ba0e87fa804..46efa1c9de60 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -240,7 +240,9 @@ struct module { unsigned int num_syms; /* Kernel parameters. */ +#ifdef CONFIG_SYSFS struct mutex param_lock; +#endif struct kernel_param *kp; unsigned int num_kp; diff --git a/kernel/module.c b/kernel/module.c index 8ec33ce202a6..b4994adf7187 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1820,6 +1820,10 @@ static void mod_sysfs_fini(struct module *mod) mod_kobject_put(mod); } +static void init_param_lock(struct module *mod) +{ + mutex_init(&mod->param_lock); +} #else /* !CONFIG_SYSFS */ static int mod_sysfs_setup(struct module *mod, @@ -1842,6 +1846,9 @@ static void del_usage_links(struct module *mod) { } +static void init_param_lock(struct module *mod) +{ +} #endif /* CONFIG_SYSFS */ static void mod_sysfs_teardown(struct module *mod) @@ -3442,7 +3449,7 @@ static int load_module(struct load_info *info, const char __user *uargs, if (err) goto unlink_mod; - mutex_init(&mod->param_lock); + init_param_lock(mod); /* Now we've got everything in the final locations, we can * find optional sections. */ diff --git a/kernel/params.c b/kernel/params.c index 8890d0b8dffc..faa461c16f12 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -25,12 +25,22 @@ #include #include +#ifdef CONFIG_SYSFS /* Protects all built-in parameters, modules use their own param_lock */ static DEFINE_MUTEX(param_lock); /* Use the module's mutex, or if built-in use the built-in mutex */ #define KPARAM_MUTEX(mod) ((mod) ? &(mod)->param_lock : ¶m_lock) -#define KPARAM_IS_LOCKED(mod) mutex_is_locked(KPARAM_MUTEX(mod)) + +static inline void check_kparam_locked(struct module *mod) +{ + BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod))); +} +#else +static inline void check_kparam_locked(struct module *mod) +{ +} +#endif /* !CONFIG_SYSFS */ /* This just allows us to keep track of which parameters are kmalloced. */ struct kmalloced_param { @@ -459,7 +469,7 @@ static int param_array(struct module *mod, /* nul-terminate and parse */ save = val[len]; ((char *)val)[len] = '\0'; - BUG_ON(!KPARAM_IS_LOCKED(mod)); + check_kparam_locked(mod); ret = set(val, &kp); if (ret != 0) @@ -496,7 +506,7 @@ static int param_array_get(char *buffer, const struct kernel_param *kp) if (i) buffer[off++] = ','; p.arg = arr->elem + arr->elemsize * i; - BUG_ON(!KPARAM_IS_LOCKED(p.mod)); + check_kparam_locked(p.mod); ret = arr->ops->get(buffer + off, &p); if (ret < 0) return ret; @@ -616,6 +626,7 @@ static ssize_t param_attr_store(struct module_attribute *mattr, #define __modinit __init #endif +#ifdef CONFIG_SYSFS void kernel_param_lock(struct module *mod) { mutex_lock(KPARAM_MUTEX(mod)); @@ -626,7 +637,6 @@ void kernel_param_unlock(struct module *mod) mutex_unlock(KPARAM_MUTEX(mod)); } -#ifdef CONFIG_SYSFS EXPORT_SYMBOL(kernel_param_lock); EXPORT_SYMBOL(kernel_param_unlock);