From: Lai Jiangshan <laijs@cn.fujitsu.com>
Add random preemption to help we to torture the preemptable rcu.
srcu_read_delay() also calls rcu_read_delay() for shorter delays.
Added comment to preempt_schedule() call indicating that no quiescent
states happen if preemption is disabled.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutorture.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 6535ac8..430cb7f 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -304,6 +304,10 @@ static void rcu_read_delay(struct rcu_random_state *rrsp)
mdelay(longdelay_ms);
if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
udelay(shortdelay_us);
+#ifdef CONFIG_PREEMPT
+ if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
+ preempt_schedule(); /* No QS if preempt_disable() in effect */
+#endif
}
static void rcu_torture_read_unlock(int idx) __releases(RCU)
@@ -537,6 +541,8 @@ static void srcu_read_delay(struct rcu_random_state *rrsp)
delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
if (!delay)
schedule_timeout_interruptible(longdelay);
+ else
+ rcu_read_delay(rrsp);
}
static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
--
1.7.0.6
--
