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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@kernel.org>
This commit is contained in:
Paul E. McKenney 2020-09-02 21:08:41 -07:00
parent 19012b786e
commit fda5ba9ed2
1 changed files with 12 additions and 5 deletions
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17
kernel/torture.c
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@ -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())