[FIX] kernel crash when removing modules

remove modules, when running US instrumentation

diff --git a/us_manager/us_manager.c b/us_manager/us_manager.c
index 77fd4ee..f8b60d2 100644 (file)
--- a/us_manager/us_manager.c
+++ b/us_manager/us_manager.c
@@ -33,6 +33,9 @@
 
 struct proc_filter *pf;
 
+static DEFINE_MUTEX(mutex_inst);
+static int flag_inst = 0;
+
 void (*ptr_pack_task_event_info)(struct task_struct *task,
                                 int probe_id,
                                 int record_type,
@@ -102,7 +105,7 @@ int usm_unregister_probe(struct dentry *dentry, unsigned long offset)
 }
 EXPORT_SYMBOL_GPL(usm_unregister_probe);
 
-int usm_stop(void)
+static void do_usm_stop(void)
 {
        int iRet = 0, found = 0;
        struct task_struct *task = NULL;
@@ -140,12 +143,9 @@ int usm_stop(void)
 */
 
        sspt_proc_free_all();
-
-       return iRet;
 }
-EXPORT_SYMBOL_GPL(usm_stop);
 
-int usm_start(void)
+static int do_usm_start(void)
 {
        int ret, i;
        struct task_struct *task = NULL, *ts;
@@ -179,6 +179,40 @@ int usm_start(void)
 */
        return 0;
 }
+
+int usm_stop(void)
+{
+       down(&mutex_inst);
+       if (flag_inst == 0)
+               goto unlock;
+
+       do_usm_stop();
+
+       flag_inst = 0;
+unlock:
+       up(&mutex_inst);
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(usm_stop);
+
+int usm_start(void)
+{
+       int ret;
+
+       down(&mutex_inst);
+       if (flag_inst)
+               goto unlock;
+
+       ret = do_usm_start();
+       if (ret == 0)
+               flag_inst = 1;
+
+unlock:
+       up(&mutex_inst);
+
+       return ret;
+}
 EXPORT_SYMBOL_GPL(usm_start);
 
 static int __init init_us_manager(void)
@@ -196,6 +230,11 @@ static int __init init_us_manager(void)
 
 static void __exit exit_us_manager(void)
 {
+       down(&mutex_inst);
+       if (flag_inst)
+               do_usm_stop();
+       up(&mutex_inst);
+
        uninit_msg();
        uninit_helper();
 }