drm_fb_helper_modinit() calls find_module() which only needs rcu_read_lock_sched().
The rest seems still have to hold module_mutex to prevent module insertion/deletion. Instead of exporting module_mutex for them, export two functions lock_modules()/unlock_modules() and hide module_mutex.
Cc: Eric Dumazet eric.dumazet@gmail.com Cc: "Paul E. McKenney" paulmck@linux.vnet.ibm.com Cc: Rusty Russell rusty@rustcorp.com.au Signed-off-by: Cong Wang xiyou.wangcong@gmail.com --- drivers/gpu/drm/drm_fb_helper.c | 4 ++-- include/linux/module.h | 3 ++- kernel/kprobes.c | 4 ++-- kernel/module.c | 24 ++++++++++++++++++------ 4 files changed, 24 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index aada26f..a3aee0e 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -1451,9 +1451,9 @@ static int __init drm_fb_helper_modinit(void) const char *name = "fbcon"; struct module *fbcon;
- mutex_lock(&module_mutex); + rcu_read_lock_sched(); fbcon = find_module(name); - mutex_unlock(&module_mutex); + rcu_read_unlock_sched();
if (!fbcon) request_module_nowait(name); diff --git a/include/linux/module.h b/include/linux/module.h index 4598bf0..5cf6428 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -374,7 +374,8 @@ struct module #define MODULE_ARCH_INIT {} #endif
-extern struct mutex module_mutex; +extern void lock_modules(void); +extern void unlock_modules(void);
/* FIXME: It'd be nice to isolate modules during init, too, so they aren't used before they (may) fail. But presently too much code diff --git a/kernel/kprobes.c b/kernel/kprobes.c index c62b854..0670fb1 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -562,7 +562,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) LIST_HEAD(free_list);
/* Lock modules while optimizing kprobes */ - mutex_lock(&module_mutex); + lock_modules(); mutex_lock(&kprobe_mutex);
/* @@ -587,7 +587,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) do_free_cleaned_kprobes(&free_list);
mutex_unlock(&kprobe_mutex); - mutex_unlock(&module_mutex); + unlock_modules();
/* Step 5: Kick optimizer again if needed */ if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) diff --git a/kernel/module.c b/kernel/module.c index 2e7a5c5..b60f882 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -95,8 +95,20 @@ * 2) module_use links, * 3) module_addr_min/module_addr_max. * (delete uses stop_machine/add uses RCU list operations). */ -DEFINE_MUTEX(module_mutex); -EXPORT_SYMBOL_GPL(module_mutex); +static DEFINE_MUTEX(module_mutex); + +void lock_modules(void) +{ + mutex_lock(&module_mutex); +} +EXPORT_SYMBOL(lock_modules); + +void unlock_modules(void) +{ + mutex_unlock(&module_mutex); +} +EXPORT_SYMBOL(unlock_modules); + static LIST_HEAD(modules); #ifdef CONFIG_KGDB_KDB struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */ @@ -1715,7 +1727,7 @@ void set_all_modules_text_rw(void) { struct module *mod;
- mutex_lock(&module_mutex); + lock_modules(); list_for_each_entry_rcu(mod, &modules, list) { if ((mod->module_core) && (mod->core_text_size)) { set_page_attributes(mod->module_core, @@ -1728,7 +1740,7 @@ void set_all_modules_text_rw(void) set_memory_rw); } } - mutex_unlock(&module_mutex); + unlock_modules(); }
/* Iterate through all modules and set each module's text as RO */ @@ -1736,7 +1748,7 @@ void set_all_modules_text_ro(void) { struct module *mod;
- mutex_lock(&module_mutex); + lock_modules(); list_for_each_entry_rcu(mod, &modules, list) { if ((mod->module_core) && (mod->core_text_size)) { set_page_attributes(mod->module_core, @@ -1749,7 +1761,7 @@ void set_all_modules_text_ro(void) set_memory_ro); } } - mutex_unlock(&module_mutex); + unlock_modules(); } #else static inline void set_section_ro_nx(void *base, unsigned long text_size, unsigned long ro_size, unsigned long total_size) { }