rcutorture: Halt forward-progress checks at end of run

Once removed, an rcu_torture element can be deferred-freed by a chain
of call_rcu() invocations, with each callback invoking another round of
call_rcu() until either a fixed number of call_rcu() invocations have
been chained or until the test ends.  This means that if the test ends,
some of the rcu_torture elements will be "stranded" partway through the
deferred-free process, which results in false-positive warnings from
rcu_torture_writer() due to lack of forward progress should the test
end just at the end of a stutter interval.

This commit therefore suppresses rcu_torture_writer()'s forward-progress
checks when the test ends in order to avoid these false-positive reports..

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index ef6f6dedf4c469c3b2fe1fd0c0aac5e93cdabab3..a3f5488a319a21e72d0f6318c4ad60a1e3708983 100644 (file)
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1014,7 +1014,8 @@ rcu_torture_writer(void *arg)
                rcu_torture_writer_state = RTWS_STUTTER;
                if (stutter_wait("rcu_torture_writer") &&
                    !READ_ONCE(rcu_fwd_cb_nodelay) &&
-                   !cur_ops->slow_gps)
+                   !cur_ops->slow_gps &&
+                   !torture_must_stop())
                        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
                                if (list_empty(&rcu_tortures[i].rtort_free) &&
                                    rcu_access_pointer(rcu_torture_current) !=