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From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
	mingo@kernel.org, jiangshanlai@gmail.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@kernel.org>
Subject: [PATCH tip/core/rcu 10/10] rcutorture: Add reader-side tests of polling grace-period API
Date: Wed,  6 Jan 2021 08:55:31 -0800	[thread overview]
Message-ID: <20210106165531.20697-10-paulmck@kernel.org> (raw)
In-Reply-To: <20210106165511.GA20555@paulmck-ThinkPad-P72>

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit adds reader-side testing of the polling grace-period API.
This testing verifies that a cookie obtained in an SRCU read-side critical
section does not get a true return from poll_state_synchronize_srcu()
within that same critical section.

Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
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 78ba95d..96d55f0 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1429,6 +1429,7 @@ rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
  */
 static bool rcu_torture_one_read(struct torture_random_state *trsp)
 {
+	unsigned long cookie;
 	int i;
 	unsigned long started;
 	unsigned long completed;
@@ -1444,6 +1445,8 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp)
 	WARN_ON_ONCE(!rcu_is_watching());
 	newstate = rcutorture_extend_mask(readstate, trsp);
 	rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
+	if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
+		cookie = cur_ops->get_gp_state();
 	started = cur_ops->get_gp_seq();
 	ts = rcu_trace_clock_local();
 	p = rcu_dereference_check(rcu_torture_current,
@@ -1480,6 +1483,13 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp)
 	}
 	__this_cpu_inc(rcu_torture_batch[completed]);
 	preempt_enable();
+	if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
+		WARN_ONCE(cur_ops->poll_gp_state(cookie),
+			  "%s: Cookie check 3 failed %s(%d) %lu->%lu\n",
+			  __func__,
+			  rcu_torture_writer_state_getname(),
+			  rcu_torture_writer_state,
+			  cookie, cur_ops->get_gp_state());
 	rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
 	WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
 	// This next splat is expected behavior if leakpointer, especially
-- 
2.9.5


      parent reply	other threads:[~2021-01-06 16:57 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-06 16:55 [PATCH tip/core/rcu 0/10] SRCU updates for v5.12 Paul E. McKenney
2021-01-06 16:55 ` [PATCH tip/core/rcu 01/10] srcu: Make Tiny SRCU use multi-bit grace-period counter paulmck
2021-01-06 16:55 ` [PATCH tip/core/rcu 02/10] srcu: Provide internal interface to start a Tiny SRCU grace period paulmck
2021-01-06 16:55 ` [PATCH tip/core/rcu 03/10] srcu: Provide internal interface to start a Tree " paulmck
2021-01-06 16:55 ` [PATCH tip/core/rcu 04/10] srcu: Provide polling interfaces for Tiny SRCU grace periods paulmck
2021-01-06 16:55 ` [PATCH tip/core/rcu 05/10] srcu: Provide polling interfaces for Tree " paulmck
2021-01-06 16:55 ` [PATCH tip/core/rcu 06/10] srcu: Document " paulmck
2021-01-06 16:55 ` [PATCH tip/core/rcu 07/10] srcu: Add comment explaining cookie overflow/wrap paulmck
2021-01-06 16:55 ` [PATCH tip/core/rcu 08/10] rcutorture: Prepare for ->start_gp_poll and ->poll_gp_state paulmck
2021-01-06 16:55 ` [PATCH tip/core/rcu 09/10] rcutorture: Add writer-side tests of polling grace-period API paulmck
2021-01-06 16:55 ` paulmck [this message]

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