Commit 7c1b3e0c authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Frederic Weisbecker
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rcutorture: Add test of RCU CPU stall notifiers 



This commit registers an RCU CPU stall notifier when testing RCU CPU
stalls.  The notifier logs a message similar to the following:

	rcu_torture_stall_nf: v=1, duration=21001.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
parent 5b404fda

kernel/rcu/rcutorture.c

+21 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <linux/spinlock.h>

#include <linux/smp.h>

#include <linux/rcupdate_wait.h>

#include <linux/rcu_notifier.h>

#include <linux/interrupt.h>

#include <linux/sched/signal.h>

#include <uapi/linux/sched/types.h>
@@ -2428,6 +2429,16 @@ static int rcutorture_booster_init(unsigned int cpu) 
	return 0;

}



static int rcu_torture_stall_nf(struct notifier_block *nb, unsigned long v, void *ptr)

{

	pr_info("%s: v=%lu, duration=%lu.\n", __func__, v, (unsigned long)ptr);

	return NOTIFY_OK;

}



static struct notifier_block rcu_torture_stall_block = {

	.notifier_call = rcu_torture_stall_nf,

};



/*

 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then

 * induces a CPU stall for the time specified by stall_cpu.
@@ -2435,9 +2446,14 @@ static int rcutorture_booster_init(unsigned int cpu) 
static int rcu_torture_stall(void *args)

{

	int idx;

	int ret;

	unsigned long stop_at;



	VERBOSE_TOROUT_STRING("rcu_torture_stall task started");

	ret = rcu_stall_chain_notifier_register(&rcu_torture_stall_block);

	if (ret)

		pr_info("%s: rcu_stall_chain_notifier_register() returned %d, %sexpected.\n",

			__func__, ret, !IS_ENABLED(CONFIG_RCU_STALL_COMMON) ? "un" : "");

	if (stall_cpu_holdoff > 0) {

		VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");

		schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
@@ -2481,6 +2497,11 @@ static int rcu_torture_stall(void *args) 
		cur_ops->readunlock(idx);

	}

	pr_alert("%s end.\n", __func__);

	if (!ret) {

		ret = rcu_stall_chain_notifier_unregister(&rcu_torture_stall_block);

		if (ret)

			pr_info("%s: rcu_stall_chain_notifier_unregister() returned %d.\n", __func__, ret);

	}

	torture_shutdown_absorb("rcu_torture_stall");

	while (!kthread_should_stop())

		schedule_timeout_interruptible(10 * HZ);