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rcutorture: Suppress rtort_pipe_count warnings until after stalls 

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@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit is contained in:
Paul E. McKenney 2024-01-03 10:59:25 -08:00 committed by Boqun Feng
parent 67050837ec
commit fd2a749d3f
1 changed files with 9 additions and 4 deletions
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13
kernel/rcu/rcutorture.c
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@ -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)
{