Commit e72ee5e1 authored by Waiman Long's avatar Waiman Long Committed by Paul E. McKenney
Browse files

rcu-tasks: Use delayed_work to delay rcu_tasks_verify_self_tests() 



Commit 2585014188d5 ("rcu-tasks: Be more patient for RCU Tasks
boot-time testing") fixes false positive rcu_tasks verification check
failure by repeating the test once every second until timeout using
schedule_timeout_uninterruptible().

Since rcu_tasks_verify_selft_tests() is called from do_initcalls()
as a late_initcall, this has the undesirable side effect of delaying
other late_initcall's queued after it by a second or more.  Fix this by
instead using delayed_work to repeat the verification check.

Fixes: 2585014188d5 ("rcu-tasks: Be more patient for RCU Tasks boot-time testing")
Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 1cf1144e

kernel/rcu/tasks.h

+32 −5
Original line number Diff line number Diff line
@@ -1832,6 +1832,11 @@ static void rcu_tasks_initiate_self_tests(void) 
#endif

}



/*

 * Return:  0 - test passed

 *	    1 - test failed, but have not timed out yet

 *	   -1 - test failed and timed out

 */

static int rcu_tasks_verify_self_tests(void)

{

	int ret = 0;
@@ -1847,16 +1852,38 @@ static int rcu_tasks_verify_self_tests(void) 
				ret = -1;

				break;

			}

			schedule_timeout_uninterruptible(1);

			ret = 1;

			break;

		}

	}



	if (ret)

		WARN_ON(1);

	WARN_ON(ret < 0);



	return ret;

}

late_initcall(rcu_tasks_verify_self_tests);



/*

 * Repeat the rcu_tasks_verify_self_tests() call once every second until the

 * test passes or has timed out.

 */

static struct delayed_work rcu_tasks_verify_work;

static void rcu_tasks_verify_work_fn(struct work_struct *work __maybe_unused)

{

	int ret = rcu_tasks_verify_self_tests();



	if (ret <= 0)

		return;



	/* Test fails but not timed out yet, reschedule another check */

	schedule_delayed_work(&rcu_tasks_verify_work, HZ);

}



static int rcu_tasks_verify_schedule_work(void)

{

	INIT_DELAYED_WORK(&rcu_tasks_verify_work, rcu_tasks_verify_work_fn);

	rcu_tasks_verify_work_fn(NULL);

	return 0;

}

late_initcall(rcu_tasks_verify_schedule_work);

#else /* #ifdef CONFIG_PROVE_RCU */

static void rcu_tasks_initiate_self_tests(void) { }

#endif /* #else #ifdef CONFIG_PROVE_RCU */