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Subject[PATCH 2/2] module: avoid exporting module_mutex
Date
Avoid exporting internal locks to modules, export two
functions lock_modules()/unlock_modules() for them instead.

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 | 16 ++++++++++++++--
4 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index aada26f..c184759 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);
+ lock_modules();
fbcon = find_module(name);
- mutex_unlock(&module_mutex);
+ unlock_modules();

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 e0b12f7..1165d5d 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 */
--
1.7.7.6


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