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rcutorture: Require entire stutter period be post-boot

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Currently, the rcu_torture_writer() function checks that all required
grace periods elapse during a stutter interval, which is a multi-second
time period during which the test load is removed.  However, this check
is suppressed during early boot (that is, before init is spawned) in
order to avoid false positives that otherwise occur due to heavy load
on the single boot CPU.

Unfortunately, this approach is insufficient.  It is possible that the
stutter interval might end just as init is spawned, so that early boot
conditions prevailed during almost the entire stutter interval.

This commit therefore takes a snapshot of boot-complete state just
before the stutter interval, thus suppressing the check for failure to
complete grace periods unless the entire stutter interval took place
after early boot.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2020-11-16 16:01:50 -08:00
parent e76506f0e8
commit 12a910e3cd
1 changed files with 3 additions and 1 deletions
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4
kernel/rcu/rcutorture.c
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@ -1070,6 +1070,7 @@ rcu_torture_fqs(void *arg)
static int
rcu_torture_writer(void *arg)
{
bool boot_ended;
bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
unsigned long cookie;
int expediting = 0;
@ -1239,12 +1240,13 @@ rcu_torture_writer(void *arg)
!rcu_gp_is_normal();
}
rcu_torture_writer_state = RTWS_STUTTER;
boot_ended = rcu_inkernel_boot_has_ended();
stutter_waited = stutter_wait("rcu_torture_writer");
if (stutter_waited &&
!READ_ONCE(rcu_fwd_cb_nodelay) &&
!cur_ops->slow_gps &&
!torture_must_stop() &&
rcu_inkernel_boot_has_ended())
boot_ended)
for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
if (list_empty(&rcu_tortures[i].rtort_free) &&
rcu_access_pointer(rcu_torture_current) !=