The following commit has been merged into the core/rcu branch of tip:
Commit-ID: fda5ba9ed254727ac5761b81455d8e93c78eba4a
Gitweb: https://git.kernel.org/tip/fda5ba9ed254727ac5761b81455d8e93c78eba4a
Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
AuthorDate: Wed, 02 Sep 2020 21:08:41 -07:00
Committer: Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Fri, 06 Nov 2020 17:13:49 -08:00
torture: Make torture_stutter() use hrtimer
The torture_stutter() function uses schedule_timeout_interruptible()
to time the stutter duration, but this can miss race conditions due to
its being time-synchronized with everything else that is based on the
timer wheels. This commit therefore converts torture_stutter() to use
the high-resolution timers via schedule_hrtimeout(), and also to fuzz
the stutter interval. While in the area, this commit also limits the
spin-loop portion of the stutter_wait() function's wait loop to two
jiffies, down from about one second.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/torture.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/kernel/torture.c b/kernel/torture.c
index be09377..56ff02b 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -641,20 +641,27 @@ EXPORT_SYMBOL_GPL(stutter_wait);
*/
static int torture_stutter(void *arg)
{
+ ktime_t delay;
+ DEFINE_TORTURE_RANDOM(rand);
int wtime;
VERBOSE_TOROUT_STRING("torture_stutter task started");
do {
if (!torture_must_stop() && stutter > 1) {
wtime = stutter;
- if (stutter > HZ + 1) {
+ if (stutter > 2) {
WRITE_ONCE(stutter_pause_test, 1);
- wtime = stutter - HZ - 1;
- schedule_timeout_interruptible(wtime);
- wtime = HZ + 1;
+ wtime = stutter - 3;
+ delay = ktime_divns(NSEC_PER_SEC * wtime, HZ);
+ delay += (torture_random(&rand) >> 3) % NSEC_PER_MSEC;
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_hrtimeout(&delay, HRTIMER_MODE_REL);
+ wtime = 2;
}
WRITE_ONCE(stutter_pause_test, 2);
- schedule_timeout_interruptible(wtime);
+ delay = ktime_divns(NSEC_PER_SEC * wtime, HZ);
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_hrtimeout(&delay, HRTIMER_MODE_REL);
}
WRITE_ONCE(stutter_pause_test, 0);
if (!torture_must_stop())
|