In order to avoid false positive circular locking lockdep splat
when runnng the ww_mutex torture test, we need to make sure that
the ww_mutexes have the same lock class as the acquire_ctx. This
means the ww_mutexes must have the same lockdep key as the
acquire_ctx. Unfortunately the current DEFINE_WW_MUTEX() macro fails
to do that. As a result, we add an init method for the ww_mutex test
to do explicit ww_mutex_init()'s of the ww_mutexes to avoid the false
positive warning.
Suggested-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Waiman Long <long...@redhat.com>
---
kernel/locking/locktorture.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 0ab94e1f1276..3c27f43ab3e8 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -357,10 +357,20 @@ static struct lock_torture_ops mutex_lock_ops = {
};
#include <linux/ww_mutex.h>
+/*
+ * The torture ww_mutexes should belong to the same lock class as
+ * torture_ww_class to avoid lockdep problem. The ww_mutex_init()
+ * function is called for initialization to ensure that.
+ */
static DEFINE_WD_CLASS(torture_ww_class);
-static DEFINE_WW_MUTEX(torture_ww_mutex_0, &torture_ww_class);
-static DEFINE_WW_MUTEX(torture_ww_mutex_1, &torture_ww_class);
-static DEFINE_WW_MUTEX(torture_ww_mutex_2, &torture_ww_class);
+static struct ww_mutex torture_ww_mutex_0, torture_ww_mutex_1,
torture_ww_mutex_2;
+
+static void torture_ww_mutex_init(void)
+{
+ ww_mutex_init(&torture_ww_mutex_0, &torture_ww_class);
+ ww_mutex_init(&torture_ww_mutex_1, &torture_ww_class);
+ ww_mutex_init(&torture_ww_mutex_2, &torture_ww_class);
+}
static int torture_ww_mutex_lock(void)
__acquires(torture_ww_mutex_0)
@@ -418,6 +428,7 @@ __releases(torture_ww_mutex_2)
}
static struct lock_torture_ops ww_mutex_lock_ops = {
+ .init = torture_ww_mutex_init,
.writelock = torture_ww_mutex_lock,
.write_delay = torture_mutex_delay,
.task_boost = torture_boost_dummy,
--
2.18.1
