TOMOYO: Use mutex_lock_interruptible.

Some of TOMOYO's functions may sleep after mutex_lock(). If OOM-killer selected
a process which is waiting at mutex_lock(), the to-be-killed process can't be
killed. Thus, replace mutex_lock() with mutex_lock_interruptible() so that the
to-be-killed process can immediately return from TOMOYO's functions.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

security/tomoyo/gc.c

@@ -151,7 +151,8 @@ static void tomoyo_del_name(const struct tomoyo_name_entry *ptr)
 
 static void tomoyo_collect_entry(void)
 {
-	mutex_lock(&tomoyo_policy_lock);
+	if (mutex_lock_interruptible(&tomoyo_policy_lock))
+		return;
 	{
 		struct tomoyo_globally_readable_file_entry *ptr;
 		list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list,
@@ -275,8 +276,6 @@ static void tomoyo_collect_entry(void)
 				break;
 		}
 	}
-	mutex_unlock(&tomoyo_policy_lock);
-	mutex_lock(&tomoyo_name_list_lock);
 	{
 		int i;
 		for (i = 0; i < TOMOYO_MAX_HASH; i++) {
@@ -294,7 +293,7 @@ static void tomoyo_collect_entry(void)
 			}
 		}
 	}
-	mutex_unlock(&tomoyo_name_list_lock);
+	mutex_unlock(&tomoyo_policy_lock);
 }
 
 static void tomoyo_kfree_entry(void)