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Commit e546f485 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Paul E. McKenney
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rcutorture: add random preemption 



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: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 84483ea4

kernel/rcutorture.c

+6 −0
Original line number Diff line number Diff line
@@ -303,6 +303,10 @@ 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)
@@ -536,6 +540,8 @@ 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)