From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Currently, if rcu_torture_writer() sees fewer than ten grace periods
having elapsed during a call to stutter_wait() that actually waited,
the rtort_pipe_count warning is emitted. This has worked well for
a long time. Except that the rcutorture TREE07 scenario now does a
short-term 14-second RCU CPU stall, which can most definitely case
false-positive rtort_pipe_count warnings.
This commit therefore changes rcu_torture_writer() to compute the
full expected holdoff and stall duration, and to refuse to report any
rtort_pipe_count warnings until after all stalls have completed.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
---
kernel/rcu/rcutorture.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 7567ca8e743c..45d6b4c3d199 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1368,9 +1368,13 @@ rcu_torture_writer(void *arg)
struct rcu_torture *rp;
struct rcu_torture *old_rp;
static DEFINE_TORTURE_RANDOM(rand);
+ unsigned long stallsdone = jiffies;
bool stutter_waited;
unsigned long ulo[NUM_ACTIVE_RCU_POLL_OLDSTATE];
+ // If a new stall test is added, this must be adjusted.
+ if (stall_cpu_holdoff + stall_gp_kthread + stall_cpu)
+ stallsdone += (stall_cpu_holdoff + stall_gp_kthread + stall_cpu + 60) * HZ;
VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
if (!can_expedite)
pr_alert("%s" TORTURE_FLAG
@@ -1576,11 +1580,11 @@ rcu_torture_writer(void *arg)
!atomic_read(&rcu_fwd_cb_nodelay) &&
!cur_ops->slow_gps &&
!torture_must_stop() &&
- boot_ended)
+ boot_ended &&
+ time_after(jiffies, stallsdone))
for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
if (list_empty(&rcu_tortures[i].rtort_free) &&
- rcu_access_pointer(rcu_torture_current) !=
- &rcu_tortures[i]) {
+ rcu_access_pointer(rcu_torture_current) != &rcu_tortures[i]) {
tracing_off();
show_rcu_gp_kthreads();
WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
@@ -2441,7 +2445,8 @@ static struct notifier_block rcu_torture_stall_block = {
/*
* CPU-stall kthread. It waits as specified by stall_cpu_holdoff, then
- * induces a CPU stall for the time specified by stall_cpu.
+ * induces a CPU stall for the time specified by stall_cpu. If a new
+ * stall test is added, stallsdone in rcu_torture_writer() must be adjusted.
*/
static int rcu_torture_stall(void *args)
{
--
2.43.0
