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linux-stable/kernel/scftorture.c
Paul E. McKenney 22b6d14992 scftorture: Avoid false-positive warnings in scftorture_invoker() 
If the call to set_cpus_allowed_ptr() in scftorture_invoker()
fails, a later WARN_ONCE() complains.  But with the advent of
570a752b7a ("lib/smp_processor_id: Use is_percpu_thread() instead of
nr_cpus_allowed"), this complaint can be drowned out by complaints from
smp_processor_id().  The rationale for this change is that scftorture's
kthreads are not marked with PF_NO_SETAFFINITY, which means that a system
administrator could change affinity at any time.

However, scftorture is a torture test, and the system administrator might
well have a valid test-the-test reason for changing affinity.  This commit
therefore changes to raw_smp_processor_id() in order to avoid the noise,
and also adds a WARN_ON_ONCE() to the call to set_cpus_allowed_ptr() in
order to directly detect immediate failure.  There is no WARN_ON_ONCE()
within the test loop, allowing human-reflex-based affinity resetting,
if desired.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-07-06 12:37:55 -07:00

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// 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, 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_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_resched;
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_RESCHED 0
#define SCF_PRIM_SINGLE 1
#define SCF_PRIM_MANY 2
#define SCF_PRIM_ALL 3
#define SCF_NPRIMS 7 // Need wait and no-wait versions of each,
// except for SCF_PRIM_RESCHED.
static char *scf_prim_name[] = {
"resched_cpu",
"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);
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_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 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_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_RESCHED:
if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST)) {
cpu = torture_random(trsp) % nr_cpu_ids;
scfp->n_resched++;
resched_cpu(cpu);
}
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_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))
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_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_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_resched1 = weight_resched;
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_resched == -1 && weight_single == -1 && weight_single_wait == -1 &&
weight_many == -1 && weight_many_wait == -1 &&
weight_all == -1 && weight_all_wait == -1) {
weight_resched1 = 2 * nr_cpu_ids;
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_resched == -1)
weight_resched1 = 0;
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;
}
if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST))
scf_sel_add(weight_resched1, SCF_PRIM_RESCHED, false);
else if (weight_resched1)
VERBOSE_SCFTORTOUT_ERRSTRING("built as module, weight_resched ignored");
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;
}
if (stutter > 0) {
firsterr = torture_stutter_init(stutter, stutter);
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);
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