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Commit 7c590fcc authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcutorture: Maintain self-propagating CB only during forward-progress test 



The current forward-progress testing maintains a self-propagating
callback during the full test.  This could result in false negatives
for stutter-end checking, where it might appear that RCU was clearing
out old callbacks only because it was being continually motivated by
the self-propagating callback.  This commit therefore shuts down the
self-propagating callback at the end of each forward-progress test
interval.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 474e59b4

kernel/rcu/rcutorture.c

+10 −5
Original line number Diff line number Diff line
@@ -1706,7 +1706,7 @@ static int rcu_torture_fwd_prog(void *args) 
{

	unsigned long cver;

	unsigned long dur;

	struct fwd_cb_state fcs = { .stop = 0 };

	struct fwd_cb_state fcs;

	unsigned long gps;

	int idx;

	int sd;
@@ -1722,11 +1722,14 @@ static int rcu_torture_fwd_prog(void *args) 
		set_user_nice(current, MAX_NICE);

	if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {

		init_rcu_head_on_stack(&fcs.rh);

		cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);

		selfpropcb = true;

	}

	do {

		schedule_timeout_interruptible(fwd_progress_holdoff * HZ);

		if  (selfpropcb) {

			WRITE_ONCE(fcs.stop, 0);

			cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);

		}

		cver = READ_ONCE(rcu_torture_current_version);

		gps = cur_ops->get_gp_seq();

		sd = cur_ops->stall_dur() + 1;
@@ -1748,13 +1751,15 @@ static int rcu_torture_fwd_prog(void *args) 
			WARN_ON(!cver && gps < 2);

			pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);

		}

		if (selfpropcb) {

			WRITE_ONCE(fcs.stop, 1);

			cur_ops->sync(); /* Wait for running CB to complete. */

			cur_ops->cb_barrier(); /* Wait for queued callbacks. */

		}

		/* Avoid slow periods, better to test when busy. */

		stutter_wait("rcu_torture_fwd_prog");

	} while (!torture_must_stop());

	if (selfpropcb) {

		WRITE_ONCE(fcs.stop, 1);

		cur_ops->sync(); /* Wait for running callback to complete. */

		cur_ops->cb_barrier(); /* Wait for queued callbacks. */

		WARN_ON(READ_ONCE(fcs.stop) != 2);

		destroy_rcu_head_on_stack(&fcs.rh);

	}