Commit 613b00fb authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcutorture: Add ability to limit callback-flood intensity 



The RCU tasks flavors of RCU now need concurrent callback flooding to
test their ability to switch between single-queue mode and per-CPU queue
mode, but their lack of heavy-duty forward-progress features rules out
the use of rcutorture's current callback-flooding code.  This commit
therefore provides the ability to limit the intensity of the callback
floods using a new ->cbflood_max field in the rcu_operations structure.
When this field is zero, there is no limit, otherwise, each callback-flood
kthread allocates at most ->cbflood_max callbacks.

Cc: Neeraj Upadhyay <neeraj.iitr10@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 82e31003

kernel/rcu/rcutorture.c

+14 −5
Original line number Diff line number Diff line
@@ -348,6 +348,7 @@ struct rcu_torture_ops { 
	void (*gp_kthread_dbg)(void);

	bool (*check_boost_failed)(unsigned long gp_state, int *cpup);

	int (*stall_dur)(void);

	long cbflood_max;

	int irq_capable;

	int can_boost;

	int extendables;
@@ -841,6 +842,7 @@ static struct rcu_torture_ops tasks_rude_ops = { 
	.call		= call_rcu_tasks_rude,

	.cb_barrier	= rcu_barrier_tasks_rude,

	.gp_kthread_dbg	= show_rcu_tasks_rude_gp_kthread,

	.cbflood_max	= 50000,

	.fqs		= NULL,

	.stats		= NULL,

	.irq_capable	= 1,
@@ -881,6 +883,7 @@ static struct rcu_torture_ops tasks_tracing_ops = { 
	.call		= call_rcu_tasks_trace,

	.cb_barrier	= rcu_barrier_tasks_trace,

	.gp_kthread_dbg	= show_rcu_tasks_trace_gp_kthread,

	.cbflood_max	= 50000,

	.fqs		= NULL,

	.stats		= NULL,

	.irq_capable	= 1,
@@ -2387,7 +2390,7 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp) 
			rfp->rcu_fwd_cb_head = rfcpn;

			n_launders++;

			n_launders_sa++;

		} else {

		} else if (!cur_ops->cbflood_max || cur_ops->cbflood_max > n_max_cbs) {

			rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);

			if (WARN_ON_ONCE(!rfcp)) {

				schedule_timeout_interruptible(1);
@@ -2397,7 +2400,10 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp) 
			n_launders_sa = 0;

			rfcp->rfc_gps = 0;

			rfcp->rfc_rfp = rfp;

		} else {

			rfcp = NULL;

		}

		if (rfcp)

			cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);

		rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);

		if (tick_nohz_full_enabled()) {
@@ -2506,8 +2512,10 @@ static int rcu_torture_fwd_prog(void *args) 
		pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id);

		if (rcu_inkernel_boot_has_ended() && torture_num_online_cpus() > rfp->rcu_fwd_id)

			rcu_torture_fwd_prog_cr(rfp);

		if (!IS_ENABLED(CONFIG_TINY_RCU) ||

		    (rcu_inkernel_boot_has_ended() && torture_num_online_cpus() > rfp->rcu_fwd_id))

		if ((cur_ops->stall_dur && cur_ops->stall_dur() > 0) &&

		    (!IS_ENABLED(CONFIG_TINY_RCU) ||

		     (rcu_inkernel_boot_has_ended() &&

		      torture_num_online_cpus() > rfp->rcu_fwd_id)))

			rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);



		/* Avoid slow periods, better to test when busy. */
@@ -2539,7 +2547,8 @@ static int __init rcu_torture_fwd_prog_init(void) 
		fwd_progress = nr_cpu_ids;

	}

	if ((!cur_ops->sync && !cur_ops->call) ||

	    !cur_ops->stall_dur || cur_ops->stall_dur() <= 0 || cur_ops == &rcu_busted_ops) {

	    (!cur_ops->cbflood_max && (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0)) ||

	    cur_ops == &rcu_busted_ops) {

		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");

		fwd_progress = 0;

		return 0;