From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
rostedt@goodmis.org, "Paul E. McKenney" <paulmck@kernel.org>,
Brian Foster <bfoster@redhat.com>,
Dave Chinner <david@fromorbit.com>,
Al Viro <viro@zeniv.linux.org.uk>, Ian Kent <raven@themaw.net>
Subject: [PATCH rcu 07/12] rcutorture: Verify that polled GP API sees synchronous grace periods
Date: Mon, 20 Jun 2022 15:51:23 -0700 [thread overview]
Message-ID: <20220620225128.3842050-7-paulmck@kernel.org> (raw)
In-Reply-To: <20220620224943.GA3841634@paulmck-ThinkPad-P17-Gen-1>
This commit causes rcu_torture_writer() to use WARN_ON_ONCE() to check
that the cookie returned by the current RCU flavor's ->get_gp_state()
function (get_state_synchronize_rcu() for vanilla RCU) causes that
flavor's ->poll_gp_state function (poll_state_synchronize_rcu() for
vanilla RCU) to unconditionally return true.
Note that a pair calls to synchronous grace-period-wait functions are
used. This is necessary to account for partially overlapping normal and
expedited grace periods aligning in just the wrong way with polled API
invocations, which can cause those polled API invocations to ignore one or
the other of those partially overlapping grace periods. It is unlikely
that this sort of ignored grace period will be a problem in production,
but rcutorture can make it happen quite within a few tens of seconds.
This commit is in preparation for polled expedited grace periods.
[ paulmck: Apply feedback from Frederic Weisbecker. ]
Link: https://lore.kernel.org/all/20220121142454.1994916-1-bfoster@redhat.com/
Link: https://docs.google.com/document/d/1RNKWW9jQyfjxw2E8dsXVTdvZYh0HnYeSHDKog9jhdN8/edit?usp=sharing
Cc: Brian Foster <bfoster@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/rcutorture.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 4ceec9f4169c7..d2edc763bb92a 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1269,7 +1269,12 @@ rcu_torture_writer(void *arg)
break;
case RTWS_EXP_SYNC:
rcu_torture_writer_state = RTWS_EXP_SYNC;
+ if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
+ cookie = cur_ops->get_gp_state();
cur_ops->exp_sync();
+ cur_ops->exp_sync();
+ if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
+ WARN_ON_ONCE(!cur_ops->poll_gp_state(cookie));
rcu_torture_pipe_update(old_rp);
break;
case RTWS_COND_GET:
@@ -1291,7 +1296,12 @@ rcu_torture_writer(void *arg)
break;
case RTWS_SYNC:
rcu_torture_writer_state = RTWS_SYNC;
+ if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
+ cookie = cur_ops->get_gp_state();
cur_ops->sync();
+ cur_ops->sync();
+ if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
+ WARN_ON_ONCE(!cur_ops->poll_gp_state(cookie));
rcu_torture_pipe_update(old_rp);
break;
default:
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2022-06-20 22:52 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-20 22:49 [PATCH rcu 0/12] Polled grace-period updates for v5.20 Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 01/12] rcu: Make normal polling GP be more precise about sequence numbers Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 02/12] rcu: Provide a get_completed_synchronize_rcu() function Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 03/12] rcutorture: Validate get_completed_synchronize_rcu() Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 04/12] rcu: Switch polled grace-period APIs to ->gp_seq_polled Paul E. McKenney
2022-07-21 0:53 ` Boqun Feng
2022-07-21 1:04 ` Paul E. McKenney
2022-07-21 1:51 ` Boqun Feng
2022-07-21 4:47 ` Paul E. McKenney
2022-07-21 5:49 ` Boqun Feng
2022-07-22 1:03 ` Paul E. McKenney
2022-07-21 1:56 ` Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 05/12] rcu: Make polled grace-period API account for expedited grace periods Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 06/12] rcu: Make Tiny RCU grace periods visible to polled APIs Paul E. McKenney
2022-06-20 22:51 ` Paul E. McKenney [this message]
2022-06-20 22:51 ` [PATCH rcu 08/12] rcu: Add polled expedited grace-period primitives Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 09/12] rcutorture: Test " Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 10/12] rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 11/12] rcu: Diagnose extended sync_rcu_do_polled_gp() loops Paul E. McKenney
2022-06-20 22:51 ` [PATCH rcu 12/12] rcu: Add irqs-disabled indicator to expedited RCU CPU stall warnings Paul E. McKenney
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