[PATCH tip/core/rcu 03/28] locktorture: Track time of last ->writeunlock()

[paulmck]

From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>

This commit adds a last_lock_release variable that tracks the time of
the last ->writeunlock() call, which allows easier diagnosing of lock
hangs when using a kernel debugger.

Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/locking/locktorture.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 62d215b..316531d 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -60,6 +60,7 @@ static struct task_struct **reader_tasks;
 
 static bool lock_is_write_held;
 static bool lock_is_read_held;
+static unsigned long last_lock_release;
 
 struct lock_stress_stats {
 	long n_lock_fail;
@@ -632,6 +633,7 @@ static int lock_torture_writer(void *arg)
 		lwsp->n_lock_acquired++;
 		cxt.cur_ops->write_delay(&rand);
 		lock_is_write_held = false;
+		WRITE_ONCE(last_lock_release, jiffies);
 		cxt.cur_ops->writeunlock();
 
 		stutter_wait("lock_torture_writer");
-- 
2.9.5