// 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 VERBOSE_SCFTORTOUT(s, x...) \

do { if (verbose) pr_alert(SCFTORT_FLAG s "\n", ## x); } while (0)

#define SCFTORTOUT_ERRSTRING(s, x...) pr_alert(SCFTORT_FLAG "!!! " s "\n", ## x)

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, 5, "Number of jiffies to run/halt 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_resched, -1, "Testing weight for resched_cpu() operations.");

torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations.");

torture_param(int, weight_single_rpc, -1, "Testing weight for single-CPU RPC 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 {

};

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_RESCHED 0

#define SCF_PRIM_SINGLE 1

#define SCF_PRIM_SINGLE_RPC 2

#define SCF_PRIM_MANY 3

#define SCF_PRIM_ALL 4

#define SCF_NPRIMS 8 // Need wait and no-wait versions of each,

// except for SCF_PRIM_RESCHED and

// SCF_PRIM_SINGLE_RPC.

static char *scf_prim_name[] = {

"resched_cpu",

"smp_call_function_single",

"smp_call_function_single_rpc",

"smp_call_function_many",

"smp_call_function",

};

struct scf_selector {

};

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 {

};

// 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);

extern void resched_cpu(int cpu); // An alternative IPI vector.

// 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_resched += scf_stats_p[i].n_resched;

scfs.n_single += scf_stats_p[i].n_single;

scfs.n_single_ofl += scf_stats_p[i].n_single_ofl;

scfs.n_single_rpc += scf_stats_p[i].n_single_rpc;

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 resched: %lld single: %lld/%lld single_ofl: %lld/%lld single_rpc: %lld single_rpc_ofl: %lld many: %lld/%lld all: %lld/%lld ",

SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count, scfs.n_resched,

scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl,

scfs.n_single_rpc, scfs.n_single_rpc_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);

if (scfcp->scfc_rpc)

complete(&scfcp->scfc_completion);

} 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;

scfcp->scfc_rpc = false;

}

}

switch (scfsp->scfs_prim) {

case SCF_PRIM_RESCHED:

if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST)) {

cpu = torture_random(trsp) % nr_cpu_ids;

scfp->n_resched++;

resched_cpu(cpu);

this_cpu_inc(scf_invoked_count);

}

break;

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_SINGLE_RPC:

if (!scfcp)

break;

cpu = torture_random(trsp) % nr_cpu_ids;

scfp->n_single_rpc++;

scfcp->scfc_cpu = cpu;

scfcp->scfc_wait = true;

init_completion(&scfcp->scfc_completion);

scfcp->scfc_rpc = true;

barrier(); // Prevent race-reduction compiler optimizations.

scfcp->scfc_in = true;

ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, 0);

if (!ret) {

if (use_cpus_read_lock)

cpus_read_unlock();

else

preempt_enable();

wait_for_completion(&scfcp->scfc_completion);

if (use_cpus_read_lock)

cpus_read_lock();

else

preempt_disable();

} else {

scfp->n_single_rpc_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((num_online_cpus() > 1 || scfsp->scfs_prim == SCF_PRIM_SINGLE) &&

!scfcp->scfc_out)) {

pr_warn("%s: Memory-ordering failure, scfs_prim: %d.\n", __func__, scfsp->scfs_prim);

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)

{

int cpu;

int curcpu;

DEFINE_TORTURE_RANDOM(rand);

struct scf_statistics *scfp = (struct scf_statistics *)arg;

bool was_offline = false;

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

cpu = scfp->cpu % nr_cpu_ids;

WARN_ON_ONCE(set_cpus_allowed_ptr(current, cpumask_of(cpu)));

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, raw_smp_processor_id());

// Make sure that the CPU is affinitized appropriately during testing.

curcpu = raw_smp_processor_id();

WARN_ONCE(curcpu != scfp->cpu % nr_cpu_ids,

"%s: Wanted CPU %d, running on %d, nr_cpu_ids = %d\n",

__func__, scfp->cpu, curcpu, nr_cpu_ids);

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 (cpu_is_offline(cpu) && !torture_must_stop()) {

schedule_timeout_interruptible(HZ / 5);

was_offline = true;

}

if (was_offline) {

set_cpus_allowed_ptr(current, cpumask_of(cpu));

was_offline = false;

}

cond_resched();

stutter_wait("scftorture_invoker");

} 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=%d use_cpus_read_lock=%d, weight_resched=%d, weight_single=%d, weight_single_rpc=%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, use_cpus_read_lock, weight_resched, weight_single, weight_single_rpc, 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 && scf_stats_p)

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_resched1 = weight_resched;

unsigned long weight_single1 = weight_single;

unsigned long weight_single_rpc1 = weight_single_rpc;

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_resched <= 0 &&

weight_single <= 0 && weight_single_rpc <= 0 && weight_single_wait <= 0 &&

weight_many <= 0 && weight_many_wait <= 0 &&

weight_all <= 0 && weight_all_wait <= 0) {

weight_resched1 = weight_resched == 0 ? 0 : 2 * nr_cpu_ids;

weight_single1 = weight_single == 0 ? 0 : 2 * nr_cpu_ids;

weight_single_rpc1 = weight_single_rpc == 0 ? 0 : 2 * nr_cpu_ids;

weight_single_wait1 = weight_single_wait == 0 ? 0 : 2 * nr_cpu_ids;

weight_many1 = weight_many == 0 ? 0 : 2;

weight_many_wait1 = weight_many_wait == 0 ? 0 : 2;

weight_all1 = weight_all == 0 ? 0 : 1;

weight_all_wait1 = weight_all_wait == 0 ? 0 : 1;

} else {

if (weight_resched == -1)

weight_resched1 = 0;

if (weight_single == -1)

weight_single1 = 0;

if (weight_single_rpc == -1)

weight_single_rpc1 = 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_resched1 == 0 && weight_single1 == 0 && weight_single_rpc1 == 0 &&

weight_single_wait1 == 0 && weight_many1 == 0 && weight_many_wait1 == 0 &&

weight_all1 == 0 && weight_all_wait1 == 0) {

SCFTORTOUT_ERRSTRING("all zero weights makes no sense");

firsterr = -EINVAL;

goto unwind;

}

if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST))

scf_sel_add(weight_resched1, SCF_PRIM_RESCHED, false);

else if (weight_resched1)

SCFTORTOUT_ERRSTRING("built as module, weight_resched ignored");

scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false);

scf_sel_add(weight_single_rpc1, SCF_PRIM_SINGLE_RPC, true);

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 (torture_init_error(firsterr))

goto unwind;

}

if (shutdown_secs > 0) {

firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup);

if (torture_init_error(firsterr))

goto unwind;

}

if (stutter > 0) {

firsterr = torture_stutter_init(stutter, stutter);

if (torture_init_error(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) {

SCFTORTOUT_ERRSTRING("out of memory");

firsterr = -ENOMEM;

goto unwind;

}

VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads", 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 (torture_init_error(firsterr))

goto unwind;

}

if (stat_interval > 0) {

firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task);

if (torture_init_error(firsterr))

goto unwind;

}

torture_init_end();

return 0;

unwind:

torture_init_end();

scf_torture_cleanup();

if (shutdown_secs) {

WARN_ON(!IS_MODULE(CONFIG_SCF_TORTURE_TEST));

kernel_power_off();

}

return firsterr;

}

module_init(scf_torture_init);

module_exit(scf_torture_cleanup);