Commit fd2a749d authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Boqun Feng
Browse files

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: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
parent 67050837

kernel/rcu/rcutorture.c

+9 −4
Original line number Diff line number Diff line
@@ -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)

{