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: Paul E. McKenney <[email protected]> --- kernel/rcu/rcutorture.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index ae10ad531993..a02a2f21386b 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -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); } -- 2.17.1
