[linux-block.git] / kernel / scftorture.c

// SPDX-License-Identifier: GPL-2.0+
//
// Torture test for smp_call_function() and friends.
//
// Copyright (C) Facebook, 2020.
//
// Author: Paul E. McKenney <paulmck@kernel.org>

#define pr_fmt(fmt) fmt

#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kthread.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/notifier.h>
#include <linux/percpu.h>
#include <linux/rcupdate.h>
#include <linux/rcupdate_trace.h>
#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/stat.h>
#include <linux/srcu.h>
#include <linux/slab.h>
#include <linux/torture.h>
#include <linux/types.h>

#define SCFTORT_STRING "scftorture"
#define SCFTORT_FLAG SCFTORT_STRING ": "

#define SCFTORTOUT(s, x...) \
	pr_alert(SCFTORT_FLAG s, ## x)

#define VERBOSE_SCFTORTOUT(s, x...) \
	do { if (verbose) pr_alert(SCFTORT_FLAG s, ## x); } while (0)

#define VERBOSE_SCFTORTOUT_ERRSTRING(s, x...) \
	do { if (verbose) pr_alert(SCFTORT_FLAG "!!! " s, ## x); } while (0)

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@kernel.org>");

// Wait until there are multiple CPUs before starting test.
torture_param(int, holdoff, IS_BUILTIN(CONFIG_SCF_TORTURE_TEST) ? 10 : 0,
	      "Holdoff time before test start (s)");
torture_param(int, longwait, 0, "Include ridiculously long waits? (seconds)");
torture_param(int, nthreads, -1, "# threads, defaults to -1 for all CPUs.");
torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable");
torture_param(int, shutdown_secs, 0, "Shutdown time (ms), <= zero to disable.");
torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s.");
torture_param(int, stutter_cpus, 5, "Number of jiffies to change CPUs under test, 0=disable");
torture_param(bool, use_cpus_read_lock, 0, "Use cpus_read_lock() to exclude CPU hotplug.");
torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations.");
torture_param(int, weight_single_wait, -1, "Testing weight for single-CPU operations.");
torture_param(int, weight_many, -1, "Testing weight for multi-CPU no-wait operations.");
torture_param(int, weight_many_wait, -1, "Testing weight for multi-CPU operations.");
torture_param(int, weight_all, -1, "Testing weight for all-CPU no-wait operations.");
torture_param(int, weight_all_wait, -1, "Testing weight for all-CPU operations.");

char *torture_type = "";

#ifdef MODULE
# define SCFTORT_SHUTDOWN 0
#else
# define SCFTORT_SHUTDOWN 1
#endif

torture_param(bool, shutdown, SCFTORT_SHUTDOWN, "Shutdown at end of torture test.");

struct scf_statistics {
	struct task_struct *task;
	int cpu;
	long long n_single;
	long long n_single_ofl;
	long long n_single_wait;
	long long n_single_wait_ofl;
	long long n_many;
	long long n_many_wait;
	long long n_all;
	long long n_all_wait;
};

static struct scf_statistics *scf_stats_p;
static struct task_struct *scf_torture_stats_task;
static DEFINE_PER_CPU(long long, scf_invoked_count);

// Data for random primitive selection
#define SCF_PRIM_SINGLE		0
#define SCF_PRIM_MANY		1
#define SCF_PRIM_ALL		2
#define SCF_NPRIMS		(2 * 3) // Need wait and no-wait versions of each.

static char *scf_prim_name[] = {
	"smp_call_function_single",
	"smp_call_function_many",
	"smp_call_function",
};

struct scf_selector {
	unsigned long scfs_weight;
	int scfs_prim;
	bool scfs_wait;
};
static struct scf_selector scf_sel_array[SCF_NPRIMS];
static int scf_sel_array_len;
static unsigned long scf_sel_totweight;

// Communicate between caller and handler.
struct scf_check {
	bool scfc_in;
	bool scfc_out;
	int scfc_cpu; // -1 for not _single().
	bool scfc_wait;
};

// Use to wait for all threads to start.
static atomic_t n_started;
static atomic_t n_errs;
static atomic_t n_mb_in_errs;
static atomic_t n_mb_out_errs;
static atomic_t n_alloc_errs;
static bool scfdone;
static char *bangstr = "";

static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand);

// Print torture statistics.  Caller must ensure serialization.
static void scf_torture_stats_print(void)
{
	int cpu;
	int i;
	long long invoked_count = 0;
	bool isdone = READ_ONCE(scfdone);
	struct scf_statistics scfs = {};

	for_each_possible_cpu(cpu)
		invoked_count += data_race(per_cpu(scf_invoked_count, cpu));
	for (i = 0; i < nthreads; i++) {
		scfs.n_single += scf_stats_p[i].n_single;
		scfs.n_single_ofl += scf_stats_p[i].n_single_ofl;
		scfs.n_single_wait += scf_stats_p[i].n_single_wait;
		scfs.n_single_wait_ofl += scf_stats_p[i].n_single_wait_ofl;
		scfs.n_many += scf_stats_p[i].n_many;
		scfs.n_many_wait += scf_stats_p[i].n_many_wait;
		scfs.n_all += scf_stats_p[i].n_all;
		scfs.n_all_wait += scf_stats_p[i].n_all_wait;
	}
	if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) ||
	    atomic_read(&n_mb_out_errs) || atomic_read(&n_alloc_errs))
		bangstr = "!!! ";
	pr_alert("%s %sscf_invoked_count %s: %lld single: %lld/%lld single_ofl: %lld/%lld many: %lld/%lld all: %lld/%lld ",
		 SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count,
		 scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl,
		 scfs.n_many, scfs.n_many_wait, scfs.n_all, scfs.n_all_wait);
	torture_onoff_stats();
	pr_cont("ste: %d stnmie: %d stnmoe: %d staf: %d\n", atomic_read(&n_errs),
		atomic_read(&n_mb_in_errs), atomic_read(&n_mb_out_errs),
		atomic_read(&n_alloc_errs));
}

// Periodically prints torture statistics, if periodic statistics printing
// was specified via the stat_interval module parameter.
static int
scf_torture_stats(void *arg)
{
	VERBOSE_TOROUT_STRING("scf_torture_stats task started");
	do {
		schedule_timeout_interruptible(stat_interval * HZ);
		scf_torture_stats_print();
		torture_shutdown_absorb("scf_torture_stats");
	} while (!torture_must_stop());
	torture_kthread_stopping("scf_torture_stats");
	return 0;
}

// Add a primitive to the scf_sel_array[].
static void scf_sel_add(unsigned long weight, int prim, bool wait)
{
	struct scf_selector *scfsp = &scf_sel_array[scf_sel_array_len];

	// If no weight, if array would overflow, if computing three-place
	// percentages would overflow, or if the scf_prim_name[] array would
	// overflow, don't bother.  In the last three two cases, complain.
	if (!weight ||
	    WARN_ON_ONCE(scf_sel_array_len >= ARRAY_SIZE(scf_sel_array)) ||
	    WARN_ON_ONCE(0 - 100000 * weight <= 100000 * scf_sel_totweight) ||
	    WARN_ON_ONCE(prim >= ARRAY_SIZE(scf_prim_name)))
		return;
	scf_sel_totweight += weight;
	scfsp->scfs_weight = scf_sel_totweight;
	scfsp->scfs_prim = prim;
	scfsp->scfs_wait = wait;
	scf_sel_array_len++;
}

// Dump out weighting percentages for scf_prim_name[] array.
static void scf_sel_dump(void)
{
	int i;
	unsigned long oldw = 0;
	struct scf_selector *scfsp;
	unsigned long w;

	for (i = 0; i < scf_sel_array_len; i++) {
		scfsp = &scf_sel_array[i];
		w = (scfsp->scfs_weight - oldw) * 100000 / scf_sel_totweight;
		pr_info("%s: %3lu.%03lu %s(%s)\n", __func__, w / 1000, w % 1000,
			scf_prim_name[scfsp->scfs_prim],
			scfsp->scfs_wait ? "wait" : "nowait");
		oldw = scfsp->scfs_weight;
	}
}

// Randomly pick a primitive and wait/nowait, based on weightings.
static struct scf_selector *scf_sel_rand(struct torture_random_state *trsp)
{
	int i;
	unsigned long w = torture_random(trsp) % (scf_sel_totweight + 1);

	for (i = 0; i < scf_sel_array_len; i++)
		if (scf_sel_array[i].scfs_weight >= w)
			return &scf_sel_array[i];
	WARN_ON_ONCE(1);
	return &scf_sel_array[0];
}

// Update statistics and occasionally burn up mass quantities of CPU time,
// if told to do so via scftorture.longwait.  Otherwise, occasionally burn
// a little bit.
static void scf_handler(void *scfc_in)
{
	int i;
	int j;
	unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand));
	struct scf_check *scfcp = scfc_in;

	if (likely(scfcp)) {
		WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers.
		if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))
			atomic_inc(&n_mb_in_errs);
	}
	this_cpu_inc(scf_invoked_count);
	if (longwait <= 0) {
		if (!(r & 0xffc0))
			udelay(r & 0x3f);
		goto out;
	}
	if (r & 0xfff)
		goto out;
	r = (r >> 12);
	if (longwait <= 0) {
		udelay((r & 0xff) + 1);
		goto out;
	}
	r = r % longwait + 1;
	for (i = 0; i < r; i++) {
		for (j = 0; j < 1000; j++) {
			udelay(1000);
			cpu_relax();
		}
	}
out:
	if (unlikely(!scfcp))
		return;
	if (scfcp->scfc_wait)
		WRITE_ONCE(scfcp->scfc_out, true);
	else
		kfree(scfcp);
}

// As above, but check for correct CPU.
static void scf_handler_1(void *scfc_in)
{
	struct scf_check *scfcp = scfc_in;

	if (likely(scfcp) && WARN_ONCE(smp_processor_id() != scfcp->scfc_cpu, "%s: Wanted CPU %d got CPU %d\n", __func__, scfcp->scfc_cpu, smp_processor_id())) {
		atomic_inc(&n_errs);
	}
	scf_handler(scfcp);
}

// Randomly do an smp_call_function*() invocation.
static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_random_state *trsp)
{
	uintptr_t cpu;
	int ret = 0;
	struct scf_check *scfcp = NULL;
	struct scf_selector *scfsp = scf_sel_rand(trsp);

	if (use_cpus_read_lock)
		cpus_read_lock();
	else
		preempt_disable();
	if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) {
		scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC);
		if (WARN_ON_ONCE(!scfcp)) {
			atomic_inc(&n_alloc_errs);
		} else {
			scfcp->scfc_cpu = -1;
			scfcp->scfc_wait = scfsp->scfs_wait;
			scfcp->scfc_out = false;
		}
	}
	switch (scfsp->scfs_prim) {
	case SCF_PRIM_SINGLE:
		cpu = torture_random(trsp) % nr_cpu_ids;
		if (scfsp->scfs_wait)
			scfp->n_single_wait++;
		else
			scfp->n_single++;
		if (scfcp) {
			scfcp->scfc_cpu = cpu;
			barrier(); // Prevent race-reduction compiler optimizations.
			scfcp->scfc_in = true;
		}
		ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait);
		if (ret) {
			if (scfsp->scfs_wait)
				scfp->n_single_wait_ofl++;
			else
				scfp->n_single_ofl++;
			kfree(scfcp);
			scfcp = NULL;
		}
		break;
	case SCF_PRIM_MANY:
		if (scfsp->scfs_wait)
			scfp->n_many_wait++;
		else
			scfp->n_many++;
		if (scfcp) {
			barrier(); // Prevent race-reduction compiler optimizations.
			scfcp->scfc_in = true;
		}
		smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait);
		break;
	case SCF_PRIM_ALL:
		if (scfsp->scfs_wait)
			scfp->n_all_wait++;
		else
			scfp->n_all++;
		if (scfcp) {
			barrier(); // Prevent race-reduction compiler optimizations.
			scfcp->scfc_in = true;
		}
		smp_call_function(scf_handler, scfcp, scfsp->scfs_wait);
		break;
	default:
		WARN_ON_ONCE(1);
		if (scfcp)
			scfcp->scfc_out = true;
	}
	if (scfcp && scfsp->scfs_wait) {
		if (WARN_ON_ONCE(!scfcp->scfc_out))
			atomic_inc(&n_mb_out_errs); // Leak rather than trash!
		else
			kfree(scfcp);
		barrier(); // Prevent race-reduction compiler optimizations.
	}
	if (use_cpus_read_lock)
		cpus_read_unlock();
	else
		preempt_enable();
	if (!(torture_random(trsp) & 0xfff))
		schedule_timeout_uninterruptible(1);
}

// SCF test kthread.  Repeatedly does calls to members of the
// smp_call_function() family of functions.
static int scftorture_invoker(void *arg)
{
	DEFINE_TORTURE_RANDOM(rand);
	struct scf_statistics *scfp = (struct scf_statistics *)arg;

	VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu);
	set_cpus_allowed_ptr(current, cpumask_of(scfp->cpu % nr_cpu_ids));
	set_user_nice(current, MAX_NICE);
	if (holdoff)
		schedule_timeout_interruptible(holdoff * HZ);

	VERBOSE_SCFTORTOUT("scftorture_invoker %d: Waiting for all SCF torturers from cpu %d", scfp->cpu, smp_processor_id());

	// Make sure that the CPU is affinitized appropriately during testing.
	WARN_ON_ONCE(smp_processor_id() != scfp->cpu);

	if (!atomic_dec_return(&n_started))
		while (atomic_read_acquire(&n_started)) {
			if (torture_must_stop()) {
				VERBOSE_SCFTORTOUT("scftorture_invoker %d ended before starting", scfp->cpu);
				goto end;
			}
			schedule_timeout_uninterruptible(1);
		}

	VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu);

	do {
		scftorture_invoke_one(scfp, &rand);
	} while (!torture_must_stop());

	VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu);
end:
	torture_kthread_stopping("scftorture_invoker");
	return 0;
}

static void
scftorture_print_module_parms(const char *tag)
{
	pr_alert(SCFTORT_FLAG
		 "--- %s:  verbose=%d holdoff=%d longwait=%d nthreads=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d stutter_cpus=%d use_cpus_read_lock=%d, weight_single=%d, weight_single_wait=%d, weight_many=%d, weight_many_wait=%d, weight_all=%d, weight_all_wait=%d\n", tag,
		 verbose, holdoff, longwait, nthreads, onoff_holdoff, onoff_interval, shutdown, stat_interval, stutter_cpus, use_cpus_read_lock, weight_single, weight_single_wait, weight_many, weight_many_wait, weight_all, weight_all_wait);
}

static void scf_cleanup_handler(void *unused)
{
}

static void scf_torture_cleanup(void)
{
	int i;

	if (torture_cleanup_begin())
		return;

	WRITE_ONCE(scfdone, true);
	if (nthreads)
		for (i = 0; i < nthreads; i++)
			torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task);
	else
		goto end;
	smp_call_function(scf_cleanup_handler, NULL, 0);
	torture_stop_kthread(scf_torture_stats, scf_torture_stats_task);
	scf_torture_stats_print();  // -After- the stats thread is stopped!
	kfree(scf_stats_p);  // -After- the last stats print has completed!
	scf_stats_p = NULL;

	if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs))
		scftorture_print_module_parms("End of test: FAILURE");
	else if (torture_onoff_failures())
		scftorture_print_module_parms("End of test: LOCK_HOTPLUG");
	else
		scftorture_print_module_parms("End of test: SUCCESS");

end:
	torture_cleanup_end();
}

static int __init scf_torture_init(void)
{
	long i;
	int firsterr = 0;
	unsigned long weight_single1 = weight_single;
	unsigned long weight_single_wait1 = weight_single_wait;
	unsigned long weight_many1 = weight_many;
	unsigned long weight_many_wait1 = weight_many_wait;
	unsigned long weight_all1 = weight_all;
	unsigned long weight_all_wait1 = weight_all_wait;

	if (!torture_init_begin(SCFTORT_STRING, verbose))
		return -EBUSY;

	scftorture_print_module_parms("Start of test");

	if (weight_single == -1 && weight_single_wait == -1 &&
	    weight_many == -1 && weight_many_wait == -1 &&
	    weight_all == -1 && weight_all_wait == -1) {
		weight_single1 = 2 * nr_cpu_ids;
		weight_single_wait1 = 2 * nr_cpu_ids;
		weight_many1 = 2;
		weight_many_wait1 = 2;
		weight_all1 = 1;
		weight_all_wait1 = 1;
	} else {
		if (weight_single == -1)
			weight_single1 = 0;
		if (weight_single_wait == -1)
			weight_single_wait1 = 0;
		if (weight_many == -1)
			weight_many1 = 0;
		if (weight_many_wait == -1)
			weight_many_wait1 = 0;
		if (weight_all == -1)
			weight_all1 = 0;
		if (weight_all_wait == -1)
			weight_all_wait1 = 0;
	}
	if (weight_single1 == 0 && weight_single_wait1 == 0 &&
	    weight_many1 == 0 && weight_many_wait1 == 0 &&
	    weight_all1 == 0 && weight_all_wait1 == 0) {
		VERBOSE_SCFTORTOUT_ERRSTRING("all zero weights makes no sense");
		firsterr = -EINVAL;
		goto unwind;
	}
	scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false);
	scf_sel_add(weight_single_wait1, SCF_PRIM_SINGLE, true);
	scf_sel_add(weight_many1, SCF_PRIM_MANY, false);
	scf_sel_add(weight_many_wait1, SCF_PRIM_MANY, true);
	scf_sel_add(weight_all1, SCF_PRIM_ALL, false);
	scf_sel_add(weight_all_wait1, SCF_PRIM_ALL, true);
	scf_sel_dump();

	if (onoff_interval > 0) {
		firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval, NULL);
		if (firsterr)
			goto unwind;
	}
	if (shutdown_secs > 0) {
		firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup);
		if (firsterr)
			goto unwind;
	}

	// Worker tasks invoking smp_call_function().
	if (nthreads < 0)
		nthreads = num_online_cpus();
	scf_stats_p = kcalloc(nthreads, sizeof(scf_stats_p[0]), GFP_KERNEL);
	if (!scf_stats_p) {
		VERBOSE_SCFTORTOUT_ERRSTRING("out of memory");
		firsterr = -ENOMEM;
		goto unwind;
	}

	VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads\n", nthreads);

	atomic_set(&n_started, nthreads);
	for (i = 0; i < nthreads; i++) {
		scf_stats_p[i].cpu = i;
		firsterr = torture_create_kthread(scftorture_invoker, (void *)&scf_stats_p[i],
						  scf_stats_p[i].task);
		if (firsterr)
			goto unwind;
	}
	if (stat_interval > 0) {
		firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task);
		if (firsterr)
			goto unwind;
	}

	torture_init_end();
	return 0;

unwind:
	torture_init_end();
	scf_torture_cleanup();
	return firsterr;
}

module_init(scf_torture_init);
module_exit(scf_torture_cleanup);
Commit	Line	Data
e9d338a0 PM	1	// SPDX-License-Identifier: GPL-2.0+
	2	//
	3	// Torture test for smp_call_function() and friends.
	4	//
	5	// Copyright (C) Facebook, 2020.
	6	//
	7	// Author: Paul E. McKenney <paulmck@kernel.org>
	8
	9	#define pr_fmt(fmt) fmt
	10
	11	#include <linux/atomic.h>
	12	#include <linux/bitops.h>
	13	#include <linux/completion.h>
	14	#include <linux/cpu.h>
	15	#include <linux/delay.h>
	16	#include <linux/err.h>
	17	#include <linux/init.h>
	18	#include <linux/interrupt.h>
	19	#include <linux/kthread.h>
	20	#include <linux/kernel.h>
	21	#include <linux/mm.h>
	22	#include <linux/module.h>
	23	#include <linux/moduleparam.h>
	24	#include <linux/notifier.h>
	25	#include <linux/percpu.h>
	26	#include <linux/rcupdate.h>
	27	#include <linux/rcupdate_trace.h>
	28	#include <linux/reboot.h>
	29	#include <linux/sched.h>
	30	#include <linux/spinlock.h>
	31	#include <linux/smp.h>
	32	#include <linux/stat.h>
	33	#include <linux/srcu.h>
	34	#include <linux/slab.h>
	35	#include <linux/torture.h>
	36	#include <linux/types.h>
	37
	38	#define SCFTORT_STRING "scftorture"
	39	#define SCFTORT_FLAG SCFTORT_STRING ": "
	40
	41	#define SCFTORTOUT(s, x...) \
	42	pr_alert(SCFTORT_FLAG s, ## x)
	43
	44	#define VERBOSE_SCFTORTOUT(s, x...) \
	45	do { if (verbose) pr_alert(SCFTORT_FLAG s, ## x); } while (0)
	46
	47	#define VERBOSE_SCFTORTOUT_ERRSTRING(s, x...) \
	48	do { if (verbose) pr_alert(SCFTORT_FLAG "!!! " s, ## x); } while (0)
	49
	50	MODULE_LICENSE("GPL");
	51	MODULE_AUTHOR("Paul E. McKenney <paulmck@kernel.org>");
	52
	53	// Wait until there are multiple CPUs before starting test.
	54	torture_param(int, holdoff, IS_BUILTIN(CONFIG_SCF_TORTURE_TEST) ? 10 : 0,
	55	"Holdoff time before test start (s)");
	56	torture_param(int, longwait, 0, "Include ridiculously long waits? (seconds)");
	57	torture_param(int, nthreads, -1, "# threads, defaults to -1 for all CPUs.");
	58	torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
	59	torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable");
	60	torture_param(int, shutdown_secs, 0, "Shutdown time (ms), <= zero to disable.");
	61	torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s.");
	62	torture_param(int, stutter_cpus, 5, "Number of jiffies to change CPUs under test, 0=disable");
	63	torture_param(bool, use_cpus_read_lock, 0, "Use cpus_read_lock() to exclude CPU hotplug.");
	64	torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
65	torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations.");
66	torture_param(int, weight_single_wait, -1, "Testing weight for single-CPU operations.");
5022b8ac PM	67	torture_param(int, weight_many, -1, "Testing weight for multi-CPU no-wait operations.");
5022b8ac PM	68	torture_param(int, weight_many_wait, -1, "Testing weight for multi-CPU operations.");
e9d338a0 PM	69	torture_param(int, weight_all, -1, "Testing weight for all-CPU no-wait operations.");
	70	torture_param(int, weight_all_wait, -1, "Testing weight for all-CPU operations.");
	71
	72	char *torture_type = "";
	73
	74	#ifdef MODULE
	75	# define SCFTORT_SHUTDOWN 0
	76	#else
	77	# define SCFTORT_SHUTDOWN 1
	78	#endif
	79
	80	torture_param(bool, shutdown, SCFTORT_SHUTDOWN, "Shutdown at end of torture test.");
	81
	82	struct scf_statistics {
	83	struct task_struct *task;
	84	int cpu;
	85	long long n_single;
5022b8ac	86	long long n_single_ofl;
e9d338a0	87	long long n_single_wait;
5022b8ac PM	88	long long n_single_wait_ofl;
	89	long long n_many;
	90	long long n_many_wait;
e9d338a0 PM	91	long long n_all;
	92	long long n_all_wait;
	93	};
	94
	95	static struct scf_statistics *scf_stats_p;
	96	static struct task_struct *scf_torture_stats_task;
	97	static DEFINE_PER_CPU(long long, scf_invoked_count);
	98
5022b8ac PM	99	// Data for random primitive selection
	100	#define SCF_PRIM_SINGLE 0
	101	#define SCF_PRIM_MANY 1
	102	#define SCF_PRIM_ALL 2
	103	#define SCF_NPRIMS (2 * 3) // Need wait and no-wait versions of each.
	104
	105	static char *scf_prim_name[] = {
	106	"smp_call_function_single",
	107	"smp_call_function_many",
	108	"smp_call_function",
	109	};
	110
	111	struct scf_selector {
	112	unsigned long scfs_weight;
	113	int scfs_prim;
	114	bool scfs_wait;
	115	};
	116	static struct scf_selector scf_sel_array[SCF_NPRIMS];
	117	static int scf_sel_array_len;
	118	static unsigned long scf_sel_totweight;
	119
b93e21a5 PM	120	// Communicate between caller and handler.
	121	struct scf_check {
	122	bool scfc_in;
	123	bool scfc_out;
	124	int scfc_cpu; // -1 for not _single().
	125	bool scfc_wait;
	126	};
	127
e9d338a0 PM	128	// Use to wait for all threads to start.
	129	static atomic_t n_started;
	130	static atomic_t n_errs;
b93e21a5 PM	131	static atomic_t n_mb_in_errs;
	132	static atomic_t n_mb_out_errs;
	133	static atomic_t n_alloc_errs;
e9d338a0	134	static bool scfdone;
dbf83b65	135	static char *bangstr = "";
e9d338a0	136
9a52a574	137	static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand);
e9d338a0 PM	138
	139	// Print torture statistics. Caller must ensure serialization.
	140	static void scf_torture_stats_print(void)
	141	{
	142	int cpu;
dba3142b	143	int i;
e9d338a0 PM	144	long long invoked_count = 0;
e9d338a0 PM	145	bool isdone = READ_ONCE(scfdone);
dba3142b	146	struct scf_statistics scfs = {};
e9d338a0 PM	147
	148	for_each_possible_cpu(cpu)
	149	invoked_count += data_race(per_cpu(scf_invoked_count, cpu));
dba3142b PM	150	for (i = 0; i < nthreads; i++) {
	151	scfs.n_single += scf_stats_p[i].n_single;
	152	scfs.n_single_ofl += scf_stats_p[i].n_single_ofl;
	153	scfs.n_single_wait += scf_stats_p[i].n_single_wait;
	154	scfs.n_single_wait_ofl += scf_stats_p[i].n_single_wait_ofl;
	155	scfs.n_many += scf_stats_p[i].n_many;
	156	scfs.n_many_wait += scf_stats_p[i].n_many_wait;
	157	scfs.n_all += scf_stats_p[i].n_all;
	158	scfs.n_all_wait += scf_stats_p[i].n_all_wait;
	159	}
dbf83b65 PM	160	if (atomic_read(&n_errs) \|\| atomic_read(&n_mb_in_errs) \|\|
	161	atomic_read(&n_mb_out_errs) \|\| atomic_read(&n_alloc_errs))
	162	bangstr = "!!! ";
	163	pr_alert("%s %sscf_invoked_count %s: %lld single: %lld/%lld single_ofl: %lld/%lld many: %lld/%lld all: %lld/%lld ",
	164	SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count,
dba3142b PM	165	scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl,
dba3142b PM	166	scfs.n_many, scfs.n_many_wait, scfs.n_all, scfs.n_all_wait);
e9d338a0	167	torture_onoff_stats();
dbf83b65 PM	168	pr_cont("ste: %d stnmie: %d stnmoe: %d staf: %d\n", atomic_read(&n_errs),
	169	atomic_read(&n_mb_in_errs), atomic_read(&n_mb_out_errs),
	170	atomic_read(&n_alloc_errs));
e9d338a0 PM	171	}
	172
	173	// Periodically prints torture statistics, if periodic statistics printing
	174	// was specified via the stat_interval module parameter.
	175	static int
	176	scf_torture_stats(void *arg)
	177	{
	178	VERBOSE_TOROUT_STRING("scf_torture_stats task started");
	179	do {
	180	schedule_timeout_interruptible(stat_interval * HZ);
	181	scf_torture_stats_print();
	182	torture_shutdown_absorb("scf_torture_stats");
	183	} while (!torture_must_stop());
	184	torture_kthread_stopping("scf_torture_stats");
	185	return 0;
	186	}
	187
5022b8ac PM	188	// Add a primitive to the scf_sel_array[].
	189	static void scf_sel_add(unsigned long weight, int prim, bool wait)
	190	{
	191	struct scf_selector *scfsp = &scf_sel_array[scf_sel_array_len];
	192
	193	// If no weight, if array would overflow, if computing three-place
	194	// percentages would overflow, or if the scf_prim_name[] array would
	195	// overflow, don't bother. In the last three two cases, complain.
	196	if (!weight \|\|
	197	WARN_ON_ONCE(scf_sel_array_len >= ARRAY_SIZE(scf_sel_array)) \|\|
	198	WARN_ON_ONCE(0 - 100000 * weight <= 100000 * scf_sel_totweight) \|\|
	199	WARN_ON_ONCE(prim >= ARRAY_SIZE(scf_prim_name)))
	200	return;
	201	scf_sel_totweight += weight;
	202	scfsp->scfs_weight = scf_sel_totweight;
	203	scfsp->scfs_prim = prim;
	204	scfsp->scfs_wait = wait;
	205	scf_sel_array_len++;
	206	}
	207
	208	// Dump out weighting percentages for scf_prim_name[] array.
	209	static void scf_sel_dump(void)
	210	{
	211	int i;
	212	unsigned long oldw = 0;
	213	struct scf_selector *scfsp;
	214	unsigned long w;
	215
	216	for (i = 0; i < scf_sel_array_len; i++) {
	217	scfsp = &scf_sel_array[i];
	218	w = (scfsp->scfs_weight - oldw) * 100000 / scf_sel_totweight;
	219	pr_info("%s: %3lu.%03lu %s(%s)\n", __func__, w / 1000, w % 1000,
	220	scf_prim_name[scfsp->scfs_prim],
	221	scfsp->scfs_wait ? "wait" : "nowait");
	222	oldw = scfsp->scfs_weight;
	223	}
	224	}
	225
	226	// Randomly pick a primitive and wait/nowait, based on weightings.
	227	static struct scf_selector scf_sel_rand(struct torture_random_state trsp)
	228	{
	229	int i;
	230	unsigned long w = torture_random(trsp) % (scf_sel_totweight + 1);
	231
	232	for (i = 0; i < scf_sel_array_len; i++)
	233	if (scf_sel_array[i].scfs_weight >= w)
	234	return &scf_sel_array[i];
	235	WARN_ON_ONCE(1);
	236	return &scf_sel_array[0];
	237	}
	238
e9d338a0 PM	239	// Update statistics and occasionally burn up mass quantities of CPU time,
	240	// if told to do so via scftorture.longwait. Otherwise, occasionally burn
	241	// a little bit.
b93e21a5	242	static void scf_handler(void *scfc_in)
e9d338a0 PM	243	{
	244	int i;
	245	int j;
	246	unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand));
b93e21a5	247	struct scf_check *scfcp = scfc_in;
e9d338a0	248
980205ee PM	249	if (likely(scfcp)) {
	250	WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers.
	251	if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))
	252	atomic_inc(&n_mb_in_errs);
	253	}
e9d338a0 PM	254	this_cpu_inc(scf_invoked_count);
	255	if (longwait <= 0) {
	256	if (!(r & 0xffc0))
	257	udelay(r & 0x3f);
b93e21a5	258	goto out;
e9d338a0 PM	259	}
e9d338a0 PM	260	if (r & 0xfff)
b93e21a5	261	goto out;
e9d338a0 PM	262	r = (r >> 12);
	263	if (longwait <= 0) {
	264	udelay((r & 0xff) + 1);
b93e21a5	265	goto out;
e9d338a0 PM	266	}
	267	r = r % longwait + 1;
	268	for (i = 0; i < r; i++) {
	269	for (j = 0; j < 1000; j++) {
	270	udelay(1000);
	271	cpu_relax();
	272	}
	273	}
b93e21a5 PM	274	out:
	275	if (unlikely(!scfcp))
	276	return;
	277	if (scfcp->scfc_wait)
	278	WRITE_ONCE(scfcp->scfc_out, true);
	279	else
	280	kfree(scfcp);
e9d338a0 PM	281	}
e9d338a0 PM	282
5022b8ac	283	// As above, but check for correct CPU.
b93e21a5	284	static void scf_handler_1(void *scfc_in)
5022b8ac	285	{
b93e21a5 PM	286	struct scf_check *scfcp = scfc_in;
	287
	288	if (likely(scfcp) && WARN_ONCE(smp_processor_id() != scfcp->scfc_cpu, "%s: Wanted CPU %d got CPU %d\n", __func__, scfcp->scfc_cpu, smp_processor_id())) {
5022b8ac	289	atomic_inc(&n_errs);
b93e21a5 PM	290	}
b93e21a5 PM	291	scf_handler(scfcp);
5022b8ac PM	292	}
5022b8ac PM	293
e9d338a0	294	// Randomly do an smp_call_function*() invocation.
5022b8ac	295	static void scftorture_invoke_one(struct scf_statistics scfp, struct torture_random_state trsp)
e9d338a0	296	{
5022b8ac	297	uintptr_t cpu;
676e5469	298	int ret = 0;
b93e21a5	299	struct scf_check *scfcp = NULL;
5022b8ac PM	300	struct scf_selector *scfsp = scf_sel_rand(trsp);
5022b8ac PM	301
e9d338a0 PM	302	if (use_cpus_read_lock)
	303	cpus_read_lock();
	304	else
	305	preempt_disable();
34e8c483	306	if (scfsp->scfs_prim == SCF_PRIM_SINGLE \|\| scfsp->scfs_wait) {
b93e21a5	307	scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC);
4df55bdd	308	if (WARN_ON_ONCE(!scfcp)) {
b93e21a5	309	atomic_inc(&n_alloc_errs);
4df55bdd PM	310	} else {
	311	scfcp->scfc_cpu = -1;
	312	scfcp->scfc_wait = scfsp->scfs_wait;
	313	scfcp->scfc_out = false;
	314	}
34e8c483 PM	315	}
	316	switch (scfsp->scfs_prim) {
	317	case SCF_PRIM_SINGLE:
5022b8ac PM	318	cpu = torture_random(trsp) % nr_cpu_ids;
	319	if (scfsp->scfs_wait)
	320	scfp->n_single_wait++;
	321	else
	322	scfp->n_single++;
b93e21a5 PM	323	if (scfcp) {
b93e21a5 PM	324	scfcp->scfc_cpu = cpu;
ee7035d2	325	barrier(); // Prevent race-reduction compiler optimizations.
b93e21a5 PM	326	scfcp->scfc_in = true;
	327	}
	328	ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait);
5022b8ac PM	329	if (ret) {
	330	if (scfsp->scfs_wait)
	331	scfp->n_single_wait_ofl++;
	332	else
	333	scfp->n_single_ofl++;
b93e21a5	334	kfree(scfcp);
676e5469	335	scfcp = NULL;
5022b8ac PM	336	}
	337	break;
	338	case SCF_PRIM_MANY:
	339	if (scfsp->scfs_wait)
	340	scfp->n_many_wait++;
	341	else
	342	scfp->n_many++;
ee7035d2 PM	343	if (scfcp) {
ee7035d2 PM	344	barrier(); // Prevent race-reduction compiler optimizations.
980205ee	345	scfcp->scfc_in = true;
ee7035d2	346	}
980205ee	347	smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait);
5022b8ac PM	348	break;
	349	case SCF_PRIM_ALL:
	350	if (scfsp->scfs_wait)
	351	scfp->n_all_wait++;
	352	else
	353	scfp->n_all++;
ee7035d2 PM	354	if (scfcp) {
ee7035d2 PM	355	barrier(); // Prevent race-reduction compiler optimizations.
34e8c483	356	scfcp->scfc_in = true;
ee7035d2	357	}
34e8c483	358	smp_call_function(scf_handler, scfcp, scfsp->scfs_wait);
5022b8ac	359	break;
de77d4da PM	360	default:
	361	WARN_ON_ONCE(1);
	362	if (scfcp)
	363	scfcp->scfc_out = true;
5022b8ac	364	}
676e5469 PM	365	if (scfcp && scfsp->scfs_wait) {
	366	if (WARN_ON_ONCE(!scfcp->scfc_out))
	367	atomic_inc(&n_mb_out_errs); // Leak rather than trash!
	368	else
	369	kfree(scfcp);
ee7035d2	370	barrier(); // Prevent race-reduction compiler optimizations.
676e5469	371	}
e9d338a0 PM	372	if (use_cpus_read_lock)
	373	cpus_read_unlock();
	374	else
	375	preempt_enable();
	376	if (!(torture_random(trsp) & 0xfff))
	377	schedule_timeout_uninterruptible(1);
	378	}
	379
	380	// SCF test kthread. Repeatedly does calls to members of the
	381	// smp_call_function() family of functions.
	382	static int scftorture_invoker(void *arg)
	383	{
	384	DEFINE_TORTURE_RANDOM(rand);
	385	struct scf_statistics scfp = (struct scf_statistics )arg;
	386
	387	VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu);
	388	set_cpus_allowed_ptr(current, cpumask_of(scfp->cpu % nr_cpu_ids));
	389	set_user_nice(current, MAX_NICE);
	390	if (holdoff)
	391	schedule_timeout_interruptible(holdoff * HZ);
	392
	393	VERBOSE_SCFTORTOUT("scftorture_invoker %d: Waiting for all SCF torturers from cpu %d", scfp->cpu, smp_processor_id());
	394
	395	// Make sure that the CPU is affinitized appropriately during testing.
	396	WARN_ON_ONCE(smp_processor_id() != scfp->cpu);
	397
	398	if (!atomic_dec_return(&n_started))
	399	while (atomic_read_acquire(&n_started)) {
	400	if (torture_must_stop()) {
	401	VERBOSE_SCFTORTOUT("scftorture_invoker %d ended before starting", scfp->cpu);
	402	goto end;
	403	}
	404	schedule_timeout_uninterruptible(1);
	405	}
	406
	407	VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu);
	408
	409	do {
	410	scftorture_invoke_one(scfp, &rand);
	411	} while (!torture_must_stop());
	412
	413	VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu);
	414	end:
	415	torture_kthread_stopping("scftorture_invoker");
	416	return 0;
	417	}
	418
	419	static void
	420	scftorture_print_module_parms(const char *tag)
	421	{
	422	pr_alert(SCFTORT_FLAG
5022b8ac PM	423	"--- %s: verbose=%d holdoff=%d longwait=%d nthreads=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d stutter_cpus=%d use_cpus_read_lock=%d, weight_single=%d, weight_single_wait=%d, weight_many=%d, weight_many_wait=%d, weight_all=%d, weight_all_wait=%d\n", tag,
5022b8ac PM	424	verbose, holdoff, longwait, nthreads, onoff_holdoff, onoff_interval, shutdown, stat_interval, stutter_cpus, use_cpus_read_lock, weight_single, weight_single_wait, weight_many, weight_many_wait, weight_all, weight_all_wait);
e9d338a0 PM	425	}
	426
	427	static void scf_cleanup_handler(void *unused)
	428	{
	429	}
	430
	431	static void scf_torture_cleanup(void)
	432	{
	433	int i;
	434
	435	if (torture_cleanup_begin())
	436	return;
	437
	438	WRITE_ONCE(scfdone, true);
	439	if (nthreads)
	440	for (i = 0; i < nthreads; i++)
	441	torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task);
	442	else
	443	goto end;
e9d338a0 PM	444	smp_call_function(scf_cleanup_handler, NULL, 0);
	445	torture_stop_kthread(scf_torture_stats, scf_torture_stats_task);
	446	scf_torture_stats_print(); // -After- the stats thread is stopped!
dba3142b PM	447	kfree(scf_stats_p); // -After- the last stats print has completed!
dba3142b PM	448	scf_stats_p = NULL;
e9d338a0	449
dbf83b65	450	if (atomic_read(&n_errs) \|\| atomic_read(&n_mb_in_errs) \|\| atomic_read(&n_mb_out_errs))
e9d338a0 PM	451	scftorture_print_module_parms("End of test: FAILURE");
	452	else if (torture_onoff_failures())
	453	scftorture_print_module_parms("End of test: LOCK_HOTPLUG");
	454	else
	455	scftorture_print_module_parms("End of test: SUCCESS");
	456
	457	end:
	458	torture_cleanup_end();
	459	}
	460
	461	static int __init scf_torture_init(void)
	462	{
	463	long i;
	464	int firsterr = 0;
5022b8ac PM	465	unsigned long weight_single1 = weight_single;
	466	unsigned long weight_single_wait1 = weight_single_wait;
	467	unsigned long weight_many1 = weight_many;
	468	unsigned long weight_many_wait1 = weight_many_wait;
	469	unsigned long weight_all1 = weight_all;
	470	unsigned long weight_all_wait1 = weight_all_wait;
e9d338a0 PM	471
	472	if (!torture_init_begin(SCFTORT_STRING, verbose))
	473	return -EBUSY;
	474
	475	scftorture_print_module_parms("Start of test");
	476
	477	if (weight_single == -1 && weight_single_wait == -1 &&
5022b8ac	478	weight_many == -1 && weight_many_wait == -1 &&
e9d338a0	479	weight_all == -1 && weight_all_wait == -1) {
5022b8ac PM	480	weight_single1 = 2 * nr_cpu_ids;
	481	weight_single_wait1 = 2 * nr_cpu_ids;
	482	weight_many1 = 2;
	483	weight_many_wait1 = 2;
	484	weight_all1 = 1;
	485	weight_all_wait1 = 1;
e9d338a0 PM	486	} else {
e9d338a0 PM	487	if (weight_single == -1)
5022b8ac	488	weight_single1 = 0;
e9d338a0	489	if (weight_single_wait == -1)
5022b8ac PM	490	weight_single_wait1 = 0;
	491	if (weight_many == -1)
	492	weight_many1 = 0;
	493	if (weight_many_wait == -1)
	494	weight_many_wait1 = 0;
e9d338a0	495	if (weight_all == -1)
5022b8ac	496	weight_all1 = 0;
e9d338a0	497	if (weight_all_wait == -1)
5022b8ac	498	weight_all_wait1 = 0;
e9d338a0	499	}
5022b8ac PM	500	if (weight_single1 == 0 && weight_single_wait1 == 0 &&
	501	weight_many1 == 0 && weight_many_wait1 == 0 &&
	502	weight_all1 == 0 && weight_all_wait1 == 0) {
	503	VERBOSE_SCFTORTOUT_ERRSTRING("all zero weights makes no sense");
e9d338a0 PM	504	firsterr = -EINVAL;
	505	goto unwind;
	506	}
5022b8ac PM	507	scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false);
	508	scf_sel_add(weight_single_wait1, SCF_PRIM_SINGLE, true);
	509	scf_sel_add(weight_many1, SCF_PRIM_MANY, false);
	510	scf_sel_add(weight_many_wait1, SCF_PRIM_MANY, true);
	511	scf_sel_add(weight_all1, SCF_PRIM_ALL, false);
	512	scf_sel_add(weight_all_wait1, SCF_PRIM_ALL, true);
	513	scf_sel_dump();
e9d338a0 PM	514
	515	if (onoff_interval > 0) {
	516	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval, NULL);
	517	if (firsterr)
	518	goto unwind;
	519	}
	520	if (shutdown_secs > 0) {
	521	firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup);
	522	if (firsterr)
	523	goto unwind;
	524	}
	525
	526	// Worker tasks invoking smp_call_function().
	527	if (nthreads < 0)
	528	nthreads = num_online_cpus();
	529	scf_stats_p = kcalloc(nthreads, sizeof(scf_stats_p[0]), GFP_KERNEL);
	530	if (!scf_stats_p) {
	531	VERBOSE_SCFTORTOUT_ERRSTRING("out of memory");
	532	firsterr = -ENOMEM;
	533	goto unwind;
	534	}
	535
	536	VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads\n", nthreads);
	537
	538	atomic_set(&n_started, nthreads);
	539	for (i = 0; i < nthreads; i++) {
	540	scf_stats_p[i].cpu = i;
	541	firsterr = torture_create_kthread(scftorture_invoker, (void *)&scf_stats_p[i],
	542	scf_stats_p[i].task);
	543	if (firsterr)
	544	goto unwind;
	545	}
	546	if (stat_interval > 0) {
	547	firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task);
	548	if (firsterr)
	549	goto unwind;
	550	}
	551
	552	torture_init_end();
	553	return 0;
	554
	555	unwind:
	556	torture_init_end();
	557	scf_torture_cleanup();
	558	return firsterr;
	559	}
	560
	561	module_init(scf_torture_init);
	562	module_exit(scf_torture_cleanup);