Commit 2b1516e5 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcutorture: Add interrupt-disable capability to stall-warning tests 



When rcutorture sees the rcutorture.stall_cpu kernel boot parameter,
it loops with preemption disabled, which does in fact normally
generate an RCU CPU stall warning message.  However, there are test
scenarios that need the stalling CPU to have interrupts disabled.
This commit therefore adds an rcutorture.stall_cpu_irqsoff kernel
boot parameter that causes the stalling CPU to disable interrupts.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 8a5776a5

Documentation/admin-guide/kernel-parameters.txt

+3 −0
Original line number Diff line number Diff line
@@ -3539,6 +3539,9 @@ 
	rcutorture.stall_cpu_holdoff= [KNL]

			Time to wait (s) after boot before inducing stall.



	rcutorture.stall_cpu_irqsoff= [KNL]

			Disable interrupts while stalling if set.



	rcutorture.stat_interval= [KNL]

			Time (s) between statistics printk()s.

kernel/rcu/rcutorture.c

+13 −5
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable."); 
torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");

torture_param(int, stall_cpu_holdoff, 10,

	     "Time to wait before starting stall (s).");

torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");

torture_param(int, stat_interval, 60,

	     "Number of seconds between stats printk()s");

torture_param(int, stutter, 5, "Number of seconds to run/halt test");
@@ -1357,7 +1358,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag) 
		 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "

		 "test_boost=%d/%d test_boost_interval=%d "

		 "test_boost_duration=%d shutdown_secs=%d "

		 "stall_cpu=%d stall_cpu_holdoff=%d "

		 "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "

		 "n_barrier_cbs=%d "

		 "onoff_interval=%d onoff_holdoff=%d\n",

		 torture_type, tag, nrealreaders, nfakewriters,
@@ -1365,7 +1366,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag) 
		 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,

		 test_boost, cur_ops->can_boost,

		 test_boost_interval, test_boost_duration, shutdown_secs,

		 stall_cpu, stall_cpu_holdoff,

		 stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,

		 n_barrier_cbs,

		 onoff_interval, onoff_holdoff);

}
@@ -1430,11 +1431,18 @@ static int rcu_torture_stall(void *args) 
	if (!kthread_should_stop()) {

		stop_at = get_seconds() + stall_cpu;

		/* RCU CPU stall is expected behavior in following code. */

		pr_alert("rcu_torture_stall start.\n");

		rcu_read_lock();

		if (stall_cpu_irqsoff)

			local_irq_disable();

		else

			preempt_disable();

		pr_alert("rcu_torture_stall start on CPU %d.\n",

			 smp_processor_id());

		while (ULONG_CMP_LT(get_seconds(), stop_at))

			continue;  /* Induce RCU CPU stall warning. */

		if (stall_cpu_irqsoff)

			local_irq_enable();

		else

			preempt_enable();

		rcu_read_unlock();

		pr_alert("rcu_torture_stall end.\n");

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