From: Paul E. McKenney <paulmck@kernel.org>
Date: Mon, 31 Aug 2020 04:48:23 +0000 (-0700)
Subject: locktorture: Track time of last ->writeunlock()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3480d6774f07341e3e1cf3114f58bef98ea58ae0;p=linux.git

locktorture: Track time of last ->writeunlock()

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.

Acked-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 62d215b2e39f6..316531de2a81c 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");