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[25/25] rcutorture: Limit read-side polling-API testing

Message ID 20220831181210.2695080-25-paulmck@kernel.org (mailing list archive)
State New, archived
Headers show
Series Polled grace-period updates for v6.1 | expand

Commit Message

Paul E. McKenney Aug. 31, 2022, 6:12 p.m. UTC 
RCU's polled grace-period API is reasonably lightweight, but still
contains heavyweight memory barriers.  This commit therefore limits
testing of this API from rcutorture's readers in order to avoid the
false negatives that these heavyweight operations could provoke.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/rcutorture.c | 41 +++++++++++++++++++++++------------------
 1 file changed, 23 insertions(+), 18 deletions(-)
diff mbox series

Patch

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index fe1836aad6466..91103279d7b4f 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1903,6 +1903,7 @@  rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
  */
 static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
 {
+	bool checkpolling = !(torture_random(trsp) & 0xfff);
 	unsigned long cookie;
 	struct rcu_gp_oldstate cookie_full;
 	int i;
@@ -1920,10 +1921,12 @@  static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
 	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();
-	if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full)
-		cur_ops->get_gp_state_full(&cookie_full);
+	if (checkpolling) {
+		if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
+			cookie = cur_ops->get_gp_state();
+		if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full)
+			cur_ops->get_gp_state_full(&cookie_full);
+	}
 	started = cur_ops->get_gp_seq();
 	ts = rcu_trace_clock_local();
 	p = rcu_dereference_check(rcu_torture_current,
@@ -1957,20 +1960,22 @@  static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
 	}
 	__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 2 failed %s(%d) %lu->%lu\n",
-			  __func__,
-			  rcu_torture_writer_state_getname(),
-			  rcu_torture_writer_state,
-			  cookie, cur_ops->get_gp_state());
-	if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full)
-		WARN_ONCE(cur_ops->poll_gp_state_full(&cookie_full),
-			  "%s: Cookie check 6 failed %s(%d) online %*pbl\n",
-			  __func__,
-			  rcu_torture_writer_state_getname(),
-			  rcu_torture_writer_state,
-			  cpumask_pr_args(cpu_online_mask));
+	if (checkpolling) {
+		if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
+			WARN_ONCE(cur_ops->poll_gp_state(cookie),
+				  "%s: Cookie check 2 failed %s(%d) %lu->%lu\n",
+				  __func__,
+				  rcu_torture_writer_state_getname(),
+				  rcu_torture_writer_state,
+				  cookie, cur_ops->get_gp_state());
+		if (cur_ops->get_gp_state_full && cur_ops->poll_gp_state_full)
+			WARN_ONCE(cur_ops->poll_gp_state_full(&cookie_full),
+				  "%s: Cookie check 6 failed %s(%d) online %*pbl\n",
+				  __func__,
+				  rcu_torture_writer_state_getname(),
+				  rcu_torture_writer_state,
+				  cpumask_pr_args(cpu_online_mask));
+	}
 	rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
 	WARN_ON_ONCE(readstate);
 	// This next splat is expected behavior if leakpointer, especially