[PATCH rcu 07/25] rcutorture: Verify long-running reader prevents full polling from completing

From: Paul E. McKenney
Date: Wed Aug 31 2022 - 14:14:39 EST


This commit adds full-state polling checks to accompany the old-style
polling checks in the rcu_torture_one_read() function. If a polling
cycle within an RCU reader completes, a WARN_ONCE() is triggered.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/rcutorture.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 236bd6b57277f..3d85420108477 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1770,6 +1770,7 @@ rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
{
unsigned long cookie;
+ struct rcu_gp_oldstate cookie_full;
int i;
unsigned long started;
unsigned long completed;
@@ -1787,6 +1788,8 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
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);
started = cur_ops->get_gp_seq();
ts = rcu_trace_clock_local();
p = rcu_dereference_check(rcu_torture_current,
@@ -1827,6 +1830,13 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
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
--
2.31.1.189.g2e36527f23