From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 17/17] rcutorture: Maintain self-propagating CB only during forward-progress test
Date: Wed, 29 Aug 2018 14:47:50 -0700 [thread overview]
Message-ID: <20180829214750.26972-17-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180829214722.GA23411@linux.vnet.ibm.com>
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 <paulmck@linux.vnet.ibm.com>
---
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
prev parent reply other threads:[~2018-08-29 21:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 21:47 [PATCH tip/core/rcu 0/17] Torture-test changes for v4.20/v5.0 Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 01/17] torture: Stop overwriting Make.out file with obsolete version Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 02/17] rcutorture: Force occasional reader waits Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 03/17] rcutorture: Warn on bad torture type for built-in tests Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 04/17] rcuperf: Warn on bad perf " Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 05/17] rcutorture: Remove TREE06 and TREE08 from the default test list Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 06/17] rcutorture: Add forward-progress tests for RCU grace periods Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 07/17] rcutorture: Also use GP sequence to judge forward progress Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 08/17] rcutorture: Avoid no-test complaint if too few forward-progress tries Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 09/17] rcutorture: Vary forward-progress test interval Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 10/17] rcutorture: Add self-propagating callback to forward-progress testing Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 11/17] rcutorture: Increase rcu_read_delay() longdelay_ms Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 12/17] rcutorture: Limit reader duration if irq or bh disabled Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 13/17] rcutorture: Reduce priority of forward-progress testing Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 14/17] rcutorture: Adjust number of reader kthreads per CPU-hotplug operations Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 15/17] rcutorture: Print forward-progress test interval on error Paul E. McKenney
2018-08-29 21:47 ` [PATCH tip/core/rcu 16/17] rcutorture: Check GP completion at stutter end Paul E. McKenney
2018-08-29 21:47 ` Paul E. McKenney [this message]
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