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linux-next/kernel/rcu/rcutorture.c
Paul E. McKenney 55b2dcf587 rcu: Allow rcutorture to starve grace-period kthread 
This commit provides an rcutorture.stall_gp_kthread module parameter
to allow rcutorture to starve the grace-period kthread.  This allows
testing the code that detects such starvation.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-05-07 10:15:28 -07:00

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// SPDX-License-Identifier: GPL-2.0+
/*
* Read-Copy Update module-based torture test facility
*
* Copyright (C) IBM Corporation, 2005, 2006
*
* Authors: Paul E. McKenney <paulmck@linux.ibm.com>
* Josh Triplett <josh@joshtriplett.org>
*
* See also: Documentation/RCU/torture.txt
*/
#define pr_fmt(fmt) fmt
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/rcupdate.h>
#include <linux/interrupt.h>
#include <linux/sched/signal.h>
#include <uapi/linux/sched/types.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/stat.h>
#include <linux/srcu.h>
#include <linux/slab.h>
#include <linux/trace_clock.h>
#include <asm/byteorder.h>
#include <linux/torture.h>
#include <linux/vmalloc.h>
#include <linux/sched/debug.h>
#include <linux/sched/sysctl.h>
#include <linux/oom.h>
#include <linux/tick.h>
#include "rcu.h"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
#ifndef data_race
#define data_race(expr) \
({ \
expr; \
})
#endif
#ifndef ASSERT_EXCLUSIVE_WRITER
#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0)
#endif
#ifndef ASSERT_EXCLUSIVE_ACCESS
#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0)
#endif
/* Bits for ->extendables field, extendables param, and related definitions. */
#define RCUTORTURE_RDR_SHIFT 8 /* Put SRCU index in upper bits. */
#define RCUTORTURE_RDR_MASK ((1 << RCUTORTURE_RDR_SHIFT) - 1)
#define RCUTORTURE_RDR_BH 0x01 /* Extend readers by disabling bh. */
#define RCUTORTURE_RDR_IRQ 0x02 /* ... disabling interrupts. */
#define RCUTORTURE_RDR_PREEMPT 0x04 /* ... disabling preemption. */
#define RCUTORTURE_RDR_RBH 0x08 /* ... rcu_read_lock_bh(). */
#define RCUTORTURE_RDR_SCHED 0x10 /* ... rcu_read_lock_sched(). */
#define RCUTORTURE_RDR_RCU 0x20 /* ... entering another RCU reader. */
#define RCUTORTURE_RDR_NBITS 6 /* Number of bits defined above. */
#define RCUTORTURE_MAX_EXTEND \
(RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
#define RCUTORTURE_RDR_MAX_LOOPS 0x7 /* Maximum reader extensions. */
/* Must be power of two minus one. */
#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
"Extend readers by disabling bh (1), irqs (2), or preempt (4)");
torture_param(int, fqs_duration, 0,
"Duration of fqs bursts (us), 0 to disable");
torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
torture_param(int, fwd_progress_holdoff, 60,
"Time between forward-progress tests (s)");
torture_param(bool, fwd_progress_need_resched, 1,
"Hide cond_resched() behind need_resched()");
torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
torture_param(bool, gp_normal, false,
"Use normal (non-expedited) GP wait primitives");
torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
torture_param(int, n_barrier_cbs, 0,
"# of callbacks/kthreads for barrier testing");
torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
torture_param(int, nreaders, -1, "Number of RCU reader threads");
torture_param(int, object_debug, 0,
"Enable debug-object double call_rcu() testing");
torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
torture_param(int, onoff_interval, 0,
"Time between CPU hotplugs (jiffies), 0=disable");
torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
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, stall_cpu_block, 0, "Sleep while stalling.");
torture_param(int, stall_gp_kthread, 0,
"Grace-period kthread stall duration (s).");
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");
torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
torture_param(int, test_boost_duration, 4,
"Duration of each boost test, seconds.");
torture_param(int, test_boost_interval, 7,
"Interval between boost tests, seconds.");
torture_param(bool, test_no_idle_hz, true,
"Test support for tickless idle CPUs");
torture_param(int, verbose, 1,
"Enable verbose debugging printk()s");
static char *torture_type = "rcu";
module_param(torture_type, charp, 0444);
MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
static int nrealreaders;
static struct task_struct *writer_task;
static struct task_struct **fakewriter_tasks;
static struct task_struct **reader_tasks;
static struct task_struct *stats_task;
static struct task_struct *fqs_task;
static struct task_struct *boost_tasks[NR_CPUS];
static struct task_struct *stall_task;
static struct task_struct *fwd_prog_task;
static struct task_struct **barrier_cbs_tasks;
static struct task_struct *barrier_task;
#define RCU_TORTURE_PIPE_LEN 10
struct rcu_torture {
struct rcu_head rtort_rcu;
int rtort_pipe_count;
struct list_head rtort_free;
int rtort_mbtest;
};
static LIST_HEAD(rcu_torture_freelist);
static struct rcu_torture __rcu *rcu_torture_current;
static unsigned long rcu_torture_current_version;
static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
static DEFINE_SPINLOCK(rcu_torture_lock);
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
static atomic_t n_rcu_torture_alloc;
static atomic_t n_rcu_torture_alloc_fail;
static atomic_t n_rcu_torture_free;
static atomic_t n_rcu_torture_mberror;
static atomic_t n_rcu_torture_error;
static long n_rcu_torture_barrier_error;
static long n_rcu_torture_boost_ktrerror;
static long n_rcu_torture_boost_rterror;
static long n_rcu_torture_boost_failure;
static long n_rcu_torture_boosts;
static atomic_long_t n_rcu_torture_timers;
static long n_barrier_attempts;
static long n_barrier_successes; /* did rcu_barrier test succeed? */
static struct list_head rcu_torture_removed;
static unsigned long shutdown_jiffies;
static int rcu_torture_writer_state;
#define RTWS_FIXED_DELAY 0
#define RTWS_DELAY 1
#define RTWS_REPLACE 2
#define RTWS_DEF_FREE 3
#define RTWS_EXP_SYNC 4
#define RTWS_COND_GET 5
#define RTWS_COND_SYNC 6
#define RTWS_SYNC 7
#define RTWS_STUTTER 8
#define RTWS_STOPPING 9
static const char * const rcu_torture_writer_state_names[] = {
"RTWS_FIXED_DELAY",
"RTWS_DELAY",
"RTWS_REPLACE",
"RTWS_DEF_FREE",
"RTWS_EXP_SYNC",
"RTWS_COND_GET",
"RTWS_COND_SYNC",
"RTWS_SYNC",
"RTWS_STUTTER",
"RTWS_STOPPING",
};
/* Record reader segment types and duration for first failing read. */
struct rt_read_seg {
int rt_readstate;
unsigned long rt_delay_jiffies;
unsigned long rt_delay_ms;
unsigned long rt_delay_us;
bool rt_preempted;
};
static int err_segs_recorded;
static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
static int rt_read_nsegs;
static const char *rcu_torture_writer_state_getname(void)
{
unsigned int i = READ_ONCE(rcu_torture_writer_state);
if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
return "???";
return rcu_torture_writer_state_names[i];
}
#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
#define rcu_can_boost() 1
#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
#define rcu_can_boost() 0
#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
#ifdef CONFIG_RCU_TRACE
static u64 notrace rcu_trace_clock_local(void)
{
u64 ts = trace_clock_local();
(void)do_div(ts, NSEC_PER_USEC);
return ts;
}
#else /* #ifdef CONFIG_RCU_TRACE */
static u64 notrace rcu_trace_clock_local(void)
{
return 0ULL;
}
#endif /* #else #ifdef CONFIG_RCU_TRACE */
/*
* Stop aggressive CPU-hog tests a bit before the end of the test in order
* to avoid interfering with test shutdown.
*/
static bool shutdown_time_arrived(void)
{
return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
}
static unsigned long boost_starttime; /* jiffies of next boost test start. */
static DEFINE_MUTEX(boost_mutex); /* protect setting boost_starttime */
/* and boost task create/destroy. */
static atomic_t barrier_cbs_count; /* Barrier callbacks registered. */
static bool barrier_phase; /* Test phase. */
static atomic_t barrier_cbs_invoked; /* Barrier callbacks invoked. */
static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
static bool rcu_fwd_cb_nodelay; /* Short rcu_torture_delay() delays. */
/*
* Allocate an element from the rcu_tortures pool.
*/
static struct rcu_torture *
rcu_torture_alloc(void)
{
struct list_head *p;
spin_lock_bh(&rcu_torture_lock);
if (list_empty(&rcu_torture_freelist)) {
atomic_inc(&n_rcu_torture_alloc_fail);
spin_unlock_bh(&rcu_torture_lock);
return NULL;
}
atomic_inc(&n_rcu_torture_alloc);
p = rcu_torture_freelist.next;
list_del_init(p);
spin_unlock_bh(&rcu_torture_lock);
return container_of(p, struct rcu_torture, rtort_free);
}
/*
* Free an element to the rcu_tortures pool.
*/
static void
rcu_torture_free(struct rcu_torture *p)
{
atomic_inc(&n_rcu_torture_free);
spin_lock_bh(&rcu_torture_lock);
list_add_tail(&p->rtort_free, &rcu_torture_freelist);
spin_unlock_bh(&rcu_torture_lock);
}
/*
* Operations vector for selecting different types of tests.
*/
struct rcu_torture_ops {
int ttype;
void (*init)(void);
void (*cleanup)(void);
int (*readlock)(void);
void (*read_delay)(struct torture_random_state *rrsp,
struct rt_read_seg *rtrsp);
void (*readunlock)(int idx);
unsigned long (*get_gp_seq)(void);
unsigned long (*gp_diff)(unsigned long new, unsigned long old);
void (*deferred_free)(struct rcu_torture *p);
void (*sync)(void);
void (*exp_sync)(void);
unsigned long (*get_state)(void);
void (*cond_sync)(unsigned long oldstate);
call_rcu_func_t call;
void (*cb_barrier)(void);
void (*fqs)(void);
void (*stats)(void);
int (*stall_dur)(void);
int irq_capable;
int can_boost;
int extendables;
int slow_gps;
const char *name;
};
static struct rcu_torture_ops *cur_ops;
/*
* Definitions for rcu torture testing.
*/
static int rcu_torture_read_lock(void) __acquires(RCU)
{
rcu_read_lock();
return 0;
}
static void
rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
{
unsigned long started;
unsigned long completed;
const unsigned long shortdelay_us = 200;
unsigned long longdelay_ms = 300;
unsigned long long ts;
/* We want a short delay sometimes to make a reader delay the grace
* period, and we want a long delay occasionally to trigger
* force_quiescent_state. */
if (!READ_ONCE(rcu_fwd_cb_nodelay) &&
!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
started = cur_ops->get_gp_seq();
ts = rcu_trace_clock_local();
if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
longdelay_ms = 5; /* Avoid triggering BH limits. */
mdelay(longdelay_ms);
rtrsp->rt_delay_ms = longdelay_ms;
completed = cur_ops->get_gp_seq();
do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
started, completed);
}
if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
udelay(shortdelay_us);
rtrsp->rt_delay_us = shortdelay_us;
}
if (!preempt_count() &&
!(torture_random(rrsp) % (nrealreaders * 500))) {
torture_preempt_schedule(); /* QS only if preemptible. */
rtrsp->rt_preempted = true;
}
}
static void rcu_torture_read_unlock(int idx) __releases(RCU)
{
rcu_read_unlock();
}
/*
* Update callback in the pipe. This should be invoked after a grace period.
*/
static bool
rcu_torture_pipe_update_one(struct rcu_torture *rp)
{
int i;
i = READ_ONCE(rp->rtort_pipe_count);
if (i > RCU_TORTURE_PIPE_LEN)
i = RCU_TORTURE_PIPE_LEN;
atomic_inc(&rcu_torture_wcount[i]);
WRITE_ONCE(rp->rtort_pipe_count, i + 1);
if (rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
rp->rtort_mbtest = 0;
return true;
}
return false;
}
/*
* Update all callbacks in the pipe. Suitable for synchronous grace-period
* primitives.
*/
static void
rcu_torture_pipe_update(struct rcu_torture *old_rp)
{
struct rcu_torture *rp;
struct rcu_torture *rp1;
if (old_rp)
list_add(&old_rp->rtort_free, &rcu_torture_removed);
list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
if (rcu_torture_pipe_update_one(rp)) {
list_del(&rp->rtort_free);
rcu_torture_free(rp);
}
}
}
static void
rcu_torture_cb(struct rcu_head *p)
{
struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
if (torture_must_stop_irq()) {
/* Test is ending, just drop callbacks on the floor. */
/* The next initialization will pick up the pieces. */
return;
}
if (rcu_torture_pipe_update_one(rp))
rcu_torture_free(rp);
else
cur_ops->deferred_free(rp);
}
static unsigned long rcu_no_completed(void)
{
return 0;
}
static void rcu_torture_deferred_free(struct rcu_torture *p)
{
call_rcu(&p->rtort_rcu, rcu_torture_cb);
}
static void rcu_sync_torture_init(void)
{
INIT_LIST_HEAD(&rcu_torture_removed);
}
static struct rcu_torture_ops rcu_ops = {
.ttype = RCU_FLAVOR,
.init = rcu_sync_torture_init,
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay,
.readunlock = rcu_torture_read_unlock,
.get_gp_seq = rcu_get_gp_seq,
.gp_diff = rcu_seq_diff,
.deferred_free = rcu_torture_deferred_free,
.sync = synchronize_rcu,
.exp_sync = synchronize_rcu_expedited,
.get_state = get_state_synchronize_rcu,
.cond_sync = cond_synchronize_rcu,
.call = call_rcu,
.cb_barrier = rcu_barrier,
.fqs = rcu_force_quiescent_state,
.stats = NULL,
.stall_dur = rcu_jiffies_till_stall_check,
.irq_capable = 1,
.can_boost = rcu_can_boost(),
.extendables = RCUTORTURE_MAX_EXTEND,
.name = "rcu"
};
/*
* Don't even think about trying any of these in real life!!!
* The names includes "busted", and they really means it!
* The only purpose of these functions is to provide a buggy RCU
* implementation to make sure that rcutorture correctly emits
* buggy-RCU error messages.
*/
static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
{
/* This is a deliberate bug for testing purposes only! */
rcu_torture_cb(&p->rtort_rcu);
}
static void synchronize_rcu_busted(void)
{
/* This is a deliberate bug for testing purposes only! */
}
static void
call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
{
/* This is a deliberate bug for testing purposes only! */
func(head);
}
static struct rcu_torture_ops rcu_busted_ops = {
.ttype = INVALID_RCU_FLAVOR,
.init = rcu_sync_torture_init,
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_torture_read_unlock,
.get_gp_seq = rcu_no_completed,
.deferred_free = rcu_busted_torture_deferred_free,
.sync = synchronize_rcu_busted,
.exp_sync = synchronize_rcu_busted,
.call = call_rcu_busted,
.cb_barrier = NULL,
.fqs = NULL,
.stats = NULL,
.irq_capable = 1,
.name = "busted"
};
/*
* Definitions for srcu torture testing.
*/
DEFINE_STATIC_SRCU(srcu_ctl);
static struct srcu_struct srcu_ctld;
static struct srcu_struct *srcu_ctlp = &srcu_ctl;
static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
{
return srcu_read_lock(srcu_ctlp);
}
static void
srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
{
long delay;
const long uspertick = 1000000 / HZ;
const long longdelay = 10;
/* We want there to be long-running readers, but not all the time. */
delay = torture_random(rrsp) %
(nrealreaders * 2 * longdelay * uspertick);
if (!delay && in_task()) {
schedule_timeout_interruptible(longdelay);
rtrsp->rt_delay_jiffies = longdelay;
} else {
rcu_read_delay(rrsp, rtrsp);
}
}
static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
{
srcu_read_unlock(srcu_ctlp, idx);
}
static unsigned long srcu_torture_completed(void)
{
return srcu_batches_completed(srcu_ctlp);
}
static void srcu_torture_deferred_free(struct rcu_torture *rp)
{
call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
}
static void srcu_torture_synchronize(void)
{
synchronize_srcu(srcu_ctlp);
}
static void srcu_torture_call(struct rcu_head *head,
rcu_callback_t func)
{
call_srcu(srcu_ctlp, head, func);
}
static void srcu_torture_barrier(void)
{
srcu_barrier(srcu_ctlp);
}
static void srcu_torture_stats(void)
{
srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
}
static void srcu_torture_synchronize_expedited(void)
{
synchronize_srcu_expedited(srcu_ctlp);
}
static struct rcu_torture_ops srcu_ops = {
.ttype = SRCU_FLAVOR,
.init = rcu_sync_torture_init,
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
.get_gp_seq = srcu_torture_completed,
.deferred_free = srcu_torture_deferred_free,
.sync = srcu_torture_synchronize,
.exp_sync = srcu_torture_synchronize_expedited,
.call = srcu_torture_call,
.cb_barrier = srcu_torture_barrier,
.stats = srcu_torture_stats,
.irq_capable = 1,
.name = "srcu"
};
static void srcu_torture_init(void)
{
rcu_sync_torture_init();
WARN_ON(init_srcu_struct(&srcu_ctld));
srcu_ctlp = &srcu_ctld;
}
static void srcu_torture_cleanup(void)
{
cleanup_srcu_struct(&srcu_ctld);
srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
}
/* As above, but dynamically allocated. */
static struct rcu_torture_ops srcud_ops = {
.ttype = SRCU_FLAVOR,
.init = srcu_torture_init,
.cleanup = srcu_torture_cleanup,
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
.get_gp_seq = srcu_torture_completed,
.deferred_free = srcu_torture_deferred_free,
.sync = srcu_torture_synchronize,
.exp_sync = srcu_torture_synchronize_expedited,
.call = srcu_torture_call,
.cb_barrier = srcu_torture_barrier,
.stats = srcu_torture_stats,
.irq_capable = 1,
.name = "srcud"
};
/* As above, but broken due to inappropriate reader extension. */
static struct rcu_torture_ops busted_srcud_ops = {
.ttype = SRCU_FLAVOR,
.init = srcu_torture_init,
.cleanup = srcu_torture_cleanup,
.readlock = srcu_torture_read_lock,
.read_delay = rcu_read_delay,
.readunlock = srcu_torture_read_unlock,
.get_gp_seq = srcu_torture_completed,
.deferred_free = srcu_torture_deferred_free,
.sync = srcu_torture_synchronize,
.exp_sync = srcu_torture_synchronize_expedited,
.call = srcu_torture_call,
.cb_barrier = srcu_torture_barrier,
.stats = srcu_torture_stats,
.irq_capable = 1,
.extendables = RCUTORTURE_MAX_EXTEND,
.name = "busted_srcud"
};
/*
* Definitions for RCU-tasks torture testing.
*/
static int tasks_torture_read_lock(void)
{
return 0;
}
static void tasks_torture_read_unlock(int idx)
{
}
static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
{
call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
}
static struct rcu_torture_ops tasks_ops = {
.ttype = RCU_TASKS_FLAVOR,
.init = rcu_sync_torture_init,
.readlock = tasks_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = tasks_torture_read_unlock,
.get_gp_seq = rcu_no_completed,
.deferred_free = rcu_tasks_torture_deferred_free,
.sync = synchronize_rcu_tasks,
.exp_sync = synchronize_rcu_tasks,
.call = call_rcu_tasks,
.cb_barrier = rcu_barrier_tasks,
.fqs = NULL,
.stats = NULL,
.irq_capable = 1,
.slow_gps = 1,
.name = "tasks"
};
/*
* Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
* This implementation does not necessarily work well with CPU hotplug.
*/
static void synchronize_rcu_trivial(void)
{
int cpu;
for_each_online_cpu(cpu) {
rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
WARN_ON_ONCE(raw_smp_processor_id() != cpu);
}
}
static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
{
preempt_disable();
return 0;
}
static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
{
preempt_enable();
}
static struct rcu_torture_ops trivial_ops = {
.ttype = RCU_TRIVIAL_FLAVOR,
.init = rcu_sync_torture_init,
.readlock = rcu_torture_read_lock_trivial,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_torture_read_unlock_trivial,
.get_gp_seq = rcu_no_completed,
.sync = synchronize_rcu_trivial,
.exp_sync = synchronize_rcu_trivial,
.fqs = NULL,
.stats = NULL,
.irq_capable = 1,
.name = "trivial"
};
static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
{
if (!cur_ops->gp_diff)
return new - old;
return cur_ops->gp_diff(new, old);
}
static bool __maybe_unused torturing_tasks(void)
{
return cur_ops == &tasks_ops;
}
/*
* RCU torture priority-boost testing. Runs one real-time thread per
* CPU for moderate bursts, repeatedly registering RCU callbacks and
* spinning waiting for them to be invoked. If a given callback takes
* too long to be invoked, we assume that priority inversion has occurred.
*/
struct rcu_boost_inflight {
struct rcu_head rcu;
int inflight;
};
static void rcu_torture_boost_cb(struct rcu_head *head)
{
struct rcu_boost_inflight *rbip =
container_of(head, struct rcu_boost_inflight, rcu);
/* Ensure RCU-core accesses precede clearing ->inflight */
smp_store_release(&rbip->inflight, 0);
}
static int old_rt_runtime = -1;
static void rcu_torture_disable_rt_throttle(void)
{
/*
* Disable RT throttling so that rcutorture's boost threads don't get
* throttled. Only possible if rcutorture is built-in otherwise the
* user should manually do this by setting the sched_rt_period_us and
* sched_rt_runtime sysctls.
*/
if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
return;
old_rt_runtime = sysctl_sched_rt_runtime;
sysctl_sched_rt_runtime = -1;
}
static void rcu_torture_enable_rt_throttle(void)
{
if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
return;
sysctl_sched_rt_runtime = old_rt_runtime;
old_rt_runtime = -1;
}
static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
{
if (end - start > test_boost_duration * HZ - HZ / 2) {
VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
n_rcu_torture_boost_failure++;
return true; /* failed */
}
return false; /* passed */
}
static int rcu_torture_boost(void *arg)
{
unsigned long call_rcu_time;
unsigned long endtime;
unsigned long oldstarttime;
struct rcu_boost_inflight rbi = { .inflight = 0 };
struct sched_param sp;
VERBOSE_TOROUT_STRING("rcu_torture_boost started");
/* Set real-time priority. */
sp.sched_priority = 1;
if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
n_rcu_torture_boost_rterror++;
}
init_rcu_head_on_stack(&rbi.rcu);
/* Each pass through the following loop does one boost-test cycle. */
do {
/* Track if the test failed already in this test interval? */
bool failed = false;
/* Increment n_rcu_torture_boosts once per boost-test */
while (!kthread_should_stop()) {
if (mutex_trylock(&boost_mutex)) {
n_rcu_torture_boosts++;
mutex_unlock(&boost_mutex);
break;
}
schedule_timeout_uninterruptible(1);
}
if (kthread_should_stop())
goto checkwait;
/* Wait for the next test interval. */
oldstarttime = boost_starttime;
while (ULONG_CMP_LT(jiffies, oldstarttime)) {
schedule_timeout_interruptible(oldstarttime - jiffies);
stutter_wait("rcu_torture_boost");
if (torture_must_stop())
goto checkwait;
}
/* Do one boost-test interval. */
endtime = oldstarttime + test_boost_duration * HZ;
call_rcu_time = jiffies;
while (ULONG_CMP_LT(jiffies, endtime)) {
/* If we don't have a callback in flight, post one. */
if (!smp_load_acquire(&rbi.inflight)) {
/* RCU core before ->inflight = 1. */
smp_store_release(&rbi.inflight, 1);
call_rcu(&rbi.rcu, rcu_torture_boost_cb);
/* Check if the boost test failed */
failed = failed ||
rcu_torture_boost_failed(call_rcu_time,
jiffies);
call_rcu_time = jiffies;
}
stutter_wait("rcu_torture_boost");
if (torture_must_stop())
goto checkwait;
}
/*
* If boost never happened, then inflight will always be 1, in
* this case the boost check would never happen in the above
* loop so do another one here.
*/
if (!failed && smp_load_acquire(&rbi.inflight))
rcu_torture_boost_failed(call_rcu_time, jiffies);
/*
* Set the start time of the next test interval.
* Yes, this is vulnerable to long delays, but such
* delays simply cause a false negative for the next
* interval. Besides, we are running at RT priority,
* so delays should be relatively rare.
*/
while (oldstarttime == boost_starttime &&
!kthread_should_stop()) {
if (mutex_trylock(&boost_mutex)) {
boost_starttime = jiffies +
test_boost_interval * HZ;
mutex_unlock(&boost_mutex);
break;
}
schedule_timeout_uninterruptible(1);
}
/* Go do the stutter. */
checkwait: stutter_wait("rcu_torture_boost");
} while (!torture_must_stop());
/* Clean up and exit. */
while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
torture_shutdown_absorb("rcu_torture_boost");
schedule_timeout_uninterruptible(1);
}
destroy_rcu_head_on_stack(&rbi.rcu);
torture_kthread_stopping("rcu_torture_boost");
return 0;
}
/*
* RCU torture force-quiescent-state kthread. Repeatedly induces
* bursts of calls to force_quiescent_state(), increasing the probability
* of occurrence of some important types of race conditions.
*/
static int
rcu_torture_fqs(void *arg)
{
unsigned long fqs_resume_time;
int fqs_burst_remaining;
VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
do {
fqs_resume_time = jiffies + fqs_stutter * HZ;
while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
!kthread_should_stop()) {
schedule_timeout_interruptible(1);
}
fqs_burst_remaining = fqs_duration;
while (fqs_burst_remaining > 0 &&
!kthread_should_stop()) {
cur_ops->fqs();
udelay(fqs_holdoff);
fqs_burst_remaining -= fqs_holdoff;
}
stutter_wait("rcu_torture_fqs");
} while (!torture_must_stop());
torture_kthread_stopping("rcu_torture_fqs");
return 0;
}
/*
* RCU torture writer kthread. Repeatedly substitutes a new structure
* for that pointed to by rcu_torture_current, freeing the old structure
* after a series of grace periods (the "pipeline").
*/
static int
rcu_torture_writer(void *arg)
{
bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
int expediting = 0;
unsigned long gp_snap;
bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
bool gp_sync1 = gp_sync;
int i;
struct rcu_torture *rp;
struct rcu_torture *old_rp;
static DEFINE_TORTURE_RANDOM(rand);
int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
RTWS_COND_GET, RTWS_SYNC };
int nsynctypes = 0;
VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
if (!can_expedite)
pr_alert("%s" TORTURE_FLAG
" GP expediting controlled from boot/sysfs for %s.\n",
torture_type, cur_ops->name);
/* Initialize synctype[] array. If none set, take default. */
if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
synctype[nsynctypes++] = RTWS_COND_GET;
pr_info("%s: Testing conditional GPs.\n", __func__);
} else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
pr_alert("%s: gp_cond without primitives.\n", __func__);
}
if (gp_exp1 && cur_ops->exp_sync) {
synctype[nsynctypes++] = RTWS_EXP_SYNC;
pr_info("%s: Testing expedited GPs.\n", __func__);
} else if (gp_exp && !cur_ops->exp_sync) {
pr_alert("%s: gp_exp without primitives.\n", __func__);
}
if (gp_normal1 && cur_ops->deferred_free) {
synctype[nsynctypes++] = RTWS_DEF_FREE;
pr_info("%s: Testing asynchronous GPs.\n", __func__);
} else if (gp_normal && !cur_ops->deferred_free) {
pr_alert("%s: gp_normal without primitives.\n", __func__);
}
if (gp_sync1 && cur_ops->sync) {
synctype[nsynctypes++] = RTWS_SYNC;
pr_info("%s: Testing normal GPs.\n", __func__);
} else if (gp_sync && !cur_ops->sync) {
pr_alert("%s: gp_sync without primitives.\n", __func__);
}
if (WARN_ONCE(nsynctypes == 0,
"rcu_torture_writer: No update-side primitives.\n")) {
/*
* No updates primitives, so don't try updating.
* The resulting test won't be testing much, hence the
* above WARN_ONCE().
*/
rcu_torture_writer_state = RTWS_STOPPING;
torture_kthread_stopping("rcu_torture_writer");
}
do {
rcu_torture_writer_state = RTWS_FIXED_DELAY;
schedule_timeout_uninterruptible(1);
rp = rcu_torture_alloc();
if (rp == NULL)
continue;
rp->rtort_pipe_count = 0;
rcu_torture_writer_state = RTWS_DELAY;
udelay(torture_random(&rand) & 0x3ff);
rcu_torture_writer_state = RTWS_REPLACE;
old_rp = rcu_dereference_check(rcu_torture_current,
current == writer_task);
rp->rtort_mbtest = 1;
rcu_assign_pointer(rcu_torture_current, rp);
smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
if (old_rp) {
i = old_rp->rtort_pipe_count;
if (i > RCU_TORTURE_PIPE_LEN)
i = RCU_TORTURE_PIPE_LEN;
atomic_inc(&rcu_torture_wcount[i]);
WRITE_ONCE(old_rp->rtort_pipe_count,
old_rp->rtort_pipe_count + 1);
switch (synctype[torture_random(&rand) % nsynctypes]) {
case RTWS_DEF_FREE:
rcu_torture_writer_state = RTWS_DEF_FREE;
cur_ops->deferred_free(old_rp);
break;
case RTWS_EXP_SYNC:
rcu_torture_writer_state = RTWS_EXP_SYNC;
cur_ops->exp_sync();
rcu_torture_pipe_update(old_rp);
break;
case RTWS_COND_GET:
rcu_torture_writer_state = RTWS_COND_GET;
gp_snap = cur_ops->get_state();
i = torture_random(&rand) % 16;
if (i != 0)
schedule_timeout_interruptible(i);
udelay(torture_random(&rand) % 1000);
rcu_torture_writer_state = RTWS_COND_SYNC;
cur_ops->cond_sync(gp_snap);
rcu_torture_pipe_update(old_rp);
break;
case RTWS_SYNC:
rcu_torture_writer_state = RTWS_SYNC;
cur_ops->sync();
rcu_torture_pipe_update(old_rp);
break;
default:
WARN_ON_ONCE(1);
break;
}
}
WRITE_ONCE(rcu_torture_current_version,
rcu_torture_current_version + 1);
/* Cycle through nesting levels of rcu_expedite_gp() calls. */
if (can_expedite &&
!(torture_random(&rand) & 0xff & (!!expediting - 1))) {
WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
if (expediting >= 0)
rcu_expedite_gp();
else
rcu_unexpedite_gp();
if (++expediting > 3)
expediting = -expediting;
} else if (!can_expedite) { /* Disabled during boot, recheck. */
can_expedite = !rcu_gp_is_expedited() &&
!rcu_gp_is_normal();
}
rcu_torture_writer_state = RTWS_STUTTER;
if (stutter_wait("rcu_torture_writer") &&
!READ_ONCE(rcu_fwd_cb_nodelay) &&
!cur_ops->slow_gps &&
!torture_must_stop() &&
rcu_inkernel_boot_has_ended())
for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
if (list_empty(&rcu_tortures[i].rtort_free) &&
rcu_access_pointer(rcu_torture_current) !=
&rcu_tortures[i]) {
rcu_ftrace_dump(DUMP_ALL);
WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
}
} while (!torture_must_stop());
/* Reset expediting back to unexpedited. */
if (expediting > 0)
expediting = -expediting;
while (can_expedite && expediting++ < 0)
rcu_unexpedite_gp();
WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
if (!can_expedite)
pr_alert("%s" TORTURE_FLAG
" Dynamic grace-period expediting was disabled.\n",
torture_type);
rcu_torture_writer_state = RTWS_STOPPING;
torture_kthread_stopping("rcu_torture_writer");
return 0;
}
/*
* RCU torture fake writer kthread. Repeatedly calls sync, with a random
* delay between calls.
*/
static int
rcu_torture_fakewriter(void *arg)
{
DEFINE_TORTURE_RANDOM(rand);
VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
set_user_nice(current, MAX_NICE);
do {
schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
udelay(torture_random(&rand) & 0x3ff);
if (cur_ops->cb_barrier != NULL &&
torture_random(&rand) % (nfakewriters * 8) == 0) {
cur_ops->cb_barrier();
} else if (gp_normal == gp_exp) {
if (cur_ops->sync && torture_random(&rand) & 0x80)
cur_ops->sync();
else if (cur_ops->exp_sync)
cur_ops->exp_sync();
} else if (gp_normal && cur_ops->sync) {
cur_ops->sync();
} else if (cur_ops->exp_sync) {
cur_ops->exp_sync();
}
stutter_wait("rcu_torture_fakewriter");
} while (!torture_must_stop());
torture_kthread_stopping("rcu_torture_fakewriter");
return 0;
}
static void rcu_torture_timer_cb(struct rcu_head *rhp)
{
kfree(rhp);
}
/*
* Do one extension of an RCU read-side critical section using the
* current reader state in readstate (set to zero for initial entry
* to extended critical section), set the new state as specified by
* newstate (set to zero for final exit from extended critical section),
* and random-number-generator state in trsp. If this is neither the
* beginning or end of the critical section and if there was actually a
* change, do a ->read_delay().
*/
static void rcutorture_one_extend(int *readstate, int newstate,
struct torture_random_state *trsp,
struct rt_read_seg *rtrsp)
{
int idxnew = -1;
int idxold = *readstate;
int statesnew = ~*readstate & newstate;
int statesold = *readstate & ~newstate;
WARN_ON_ONCE(idxold < 0);
WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
rtrsp->rt_readstate = newstate;
/* First, put new protection in place to avoid critical-section gap. */
if (statesnew & RCUTORTURE_RDR_BH)
local_bh_disable();
if (statesnew & RCUTORTURE_RDR_IRQ)
local_irq_disable();
if (statesnew & RCUTORTURE_RDR_PREEMPT)
preempt_disable();
if (statesnew & RCUTORTURE_RDR_RBH)
rcu_read_lock_bh();
if (statesnew & RCUTORTURE_RDR_SCHED)
rcu_read_lock_sched();
if (statesnew & RCUTORTURE_RDR_RCU)
idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
/* Next, remove old protection, irq first due to bh conflict. */
if (statesold & RCUTORTURE_RDR_IRQ)
local_irq_enable();
if (statesold & RCUTORTURE_RDR_BH)
local_bh_enable();
if (statesold & RCUTORTURE_RDR_PREEMPT)
preempt_enable();
if (statesold & RCUTORTURE_RDR_RBH)
rcu_read_unlock_bh();
if (statesold & RCUTORTURE_RDR_SCHED)
rcu_read_unlock_sched();
if (statesold & RCUTORTURE_RDR_RCU)
cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
/* Delay if neither beginning nor end and there was a change. */
if ((statesnew || statesold) && *readstate && newstate)
cur_ops->read_delay(trsp, rtrsp);
/* Update the reader state. */
if (idxnew == -1)
idxnew = idxold & ~RCUTORTURE_RDR_MASK;
WARN_ON_ONCE(idxnew < 0);
WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
*readstate = idxnew | newstate;
WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
}
/* Return the biggest extendables mask given current RCU and boot parameters. */
static int rcutorture_extend_mask_max(void)
{
int mask;
WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
mask = mask | RCUTORTURE_RDR_RCU;
return mask;
}
/* Return a random protection state mask, but with at least one bit set. */
static int
rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
{
int mask = rcutorture_extend_mask_max();
unsigned long randmask1 = torture_random(trsp) >> 8;
unsigned long randmask2 = randmask1 >> 3;
WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
/* Mostly only one bit (need preemption!), sometimes lots of bits. */
if (!(randmask1 & 0x7))
mask = mask & randmask2;
else
mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
/* Can't enable bh w/irq disabled. */
if ((mask & RCUTORTURE_RDR_IRQ) &&
((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
(!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
return mask ?: RCUTORTURE_RDR_RCU;
}
/*
* Do a randomly selected number of extensions of an existing RCU read-side
* critical section.
*/
static struct rt_read_seg *
rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
struct rt_read_seg *rtrsp)
{
int i;
int j;
int mask = rcutorture_extend_mask_max();
WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
if (!((mask - 1) & mask))
return rtrsp; /* Current RCU reader not extendable. */
/* Bias towards larger numbers of loops. */
i = (torture_random(trsp) >> 3);
i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
for (j = 0; j < i; j++) {
mask = rcutorture_extend_mask(*readstate, trsp);
rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
}
return &rtrsp[j];
}
/*
* Do one read-side critical section, returning false if there was
* no data to read. Can be invoked both from process context and
* from a timer handler.
*/
static bool rcu_torture_one_read(struct torture_random_state *trsp)
{
int i;
unsigned long started;
unsigned long completed;
int newstate;
struct rcu_torture *p;
int pipe_count;
int readstate = 0;
struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
struct rt_read_seg *rtrsp = &rtseg[0];
struct rt_read_seg *rtrsp1;
unsigned long long ts;
newstate = rcutorture_extend_mask(readstate, trsp);
rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
started = cur_ops->get_gp_seq();
ts = rcu_trace_clock_local();
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
srcu_read_lock_held(srcu_ctlp) ||
torturing_tasks());
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
return false;
}
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
preempt_disable();
pipe_count = READ_ONCE(p->rtort_pipe_count);
if (pipe_count > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
completed = cur_ops->get_gp_seq();
if (pipe_count > 1) {
do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
ts, started, completed);
rcu_ftrace_dump(DUMP_ALL);
}
__this_cpu_inc(rcu_torture_count[pipe_count]);
completed = rcutorture_seq_diff(completed, started);
if (completed > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
completed = RCU_TORTURE_PIPE_LEN;
}
__this_cpu_inc(rcu_torture_batch[completed]);
preempt_enable();
rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
/* If error or close call, record the sequence of reader protections. */
if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
i = 0;
for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
err_segs[i++] = *rtrsp1;
rt_read_nsegs = i;
}
return true;
}
static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
/*
* RCU torture reader from timer handler. Dereferences rcu_torture_current,
* incrementing the corresponding element of the pipeline array. The
* counter in the element should never be greater than 1, otherwise, the
* RCU implementation is broken.
*/
static void rcu_torture_timer(struct timer_list *unused)
{
atomic_long_inc(&n_rcu_torture_timers);
(void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
/* Test call_rcu() invocation from interrupt handler. */
if (cur_ops->call) {
struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
if (rhp)
cur_ops->call(rhp, rcu_torture_timer_cb);
}
}
/*
* RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
* incrementing the corresponding element of the pipeline array. The
* counter in the element should never be greater than 1, otherwise, the
* RCU implementation is broken.
*/
static int
rcu_torture_reader(void *arg)
{
unsigned long lastsleep = jiffies;
long myid = (long)arg;
int mynumonline = myid;
DEFINE_TORTURE_RANDOM(rand);
struct timer_list t;
VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
set_user_nice(current, MAX_NICE);
if (irqreader && cur_ops->irq_capable)
timer_setup_on_stack(&t, rcu_torture_timer, 0);
tick_dep_set_task(current, TICK_DEP_BIT_RCU);
do {
if (irqreader && cur_ops->irq_capable) {
if (!timer_pending(&t))
mod_timer(&t, jiffies + 1);
}
if (!rcu_torture_one_read(&rand) && !torture_must_stop())
schedule_timeout_interruptible(HZ);
if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
schedule_timeout_interruptible(1);
lastsleep = jiffies + 10;
}
while (num_online_cpus() < mynumonline && !torture_must_stop())
schedule_timeout_interruptible(HZ / 5);
stutter_wait("rcu_torture_reader");
} while (!torture_must_stop());
if (irqreader && cur_ops->irq_capable) {
del_timer_sync(&t);
destroy_timer_on_stack(&t);
}
tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
torture_kthread_stopping("rcu_torture_reader");
return 0;
}
/*
* Print torture statistics. Caller must ensure that there is only
* one call to this function at a given time!!! This is normally
* accomplished by relying on the module system to only have one copy
* of the module loaded, and then by giving the rcu_torture_stats
* kthread full control (or the init/cleanup functions when rcu_torture_stats
* thread is not running).
*/
static void
rcu_torture_stats_print(void)
{
int cpu;
int i;
long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
struct rcu_torture *rtcp;
static unsigned long rtcv_snap = ULONG_MAX;
static bool splatted;
struct task_struct *wtp;
for_each_possible_cpu(cpu) {
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]);
batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]);
}
}
for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
if (pipesummary[i] != 0)
break;
}
pr_alert("%s%s ", torture_type, TORTURE_FLAG);
rtcp = rcu_access_pointer(rcu_torture_current);
pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
rtcp,
rtcp && !rcu_stall_is_suppressed_at_boot() ? "ver" : "VER",
rcu_torture_current_version,
list_empty(&rcu_torture_freelist),
atomic_read(&n_rcu_torture_alloc),
atomic_read(&n_rcu_torture_alloc_fail),
atomic_read(&n_rcu_torture_free));
pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
atomic_read(&n_rcu_torture_mberror),
n_rcu_torture_barrier_error,
n_rcu_torture_boost_ktrerror,
n_rcu_torture_boost_rterror);
pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
n_rcu_torture_boost_failure,
n_rcu_torture_boosts,
atomic_long_read(&n_rcu_torture_timers));
torture_onoff_stats();
pr_cont("barrier: %ld/%ld:%ld\n",
data_race(n_barrier_successes),
data_race(n_barrier_attempts),
data_race(n_rcu_torture_barrier_error));
pr_alert("%s%s ", torture_type, TORTURE_FLAG);
if (atomic_read(&n_rcu_torture_mberror) ||
n_rcu_torture_barrier_error || n_rcu_torture_boost_ktrerror ||
n_rcu_torture_boost_rterror || n_rcu_torture_boost_failure ||
i > 1) {
pr_cont("%s", "!!! ");
atomic_inc(&n_rcu_torture_error);
WARN_ON_ONCE(atomic_read(&n_rcu_torture_mberror));
WARN_ON_ONCE(n_rcu_torture_barrier_error); // rcu_barrier()
WARN_ON_ONCE(n_rcu_torture_boost_ktrerror); // no boost kthread
WARN_ON_ONCE(n_rcu_torture_boost_rterror); // can't set RT prio
WARN_ON_ONCE(n_rcu_torture_boost_failure); // RCU boost failed
WARN_ON_ONCE(i > 1); // Too-short grace period
}
pr_cont("Reader Pipe: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
pr_cont(" %ld", pipesummary[i]);
pr_cont("\n");
pr_alert("%s%s ", torture_type, TORTURE_FLAG);
pr_cont("Reader Batch: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
pr_cont(" %ld", batchsummary[i]);
pr_cont("\n");
pr_alert("%s%s ", torture_type, TORTURE_FLAG);
pr_cont("Free-Block Circulation: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
}
pr_cont("\n");
if (cur_ops->stats)
cur_ops->stats();
if (rtcv_snap == rcu_torture_current_version &&
rcu_access_pointer(rcu_torture_current) &&
!rcu_stall_is_suppressed()) {
int __maybe_unused flags = 0;
unsigned long __maybe_unused gp_seq = 0;
rcutorture_get_gp_data(cur_ops->ttype,
&flags, &gp_seq);
srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
&flags, &gp_seq);
wtp = READ_ONCE(writer_task);
pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
rcu_torture_writer_state_getname(),
rcu_torture_writer_state, gp_seq, flags,
wtp == NULL ? ~0UL : wtp->state,
wtp == NULL ? -1 : (int)task_cpu(wtp));
if (!splatted && wtp) {
sched_show_task(wtp);
splatted = true;
}
show_rcu_gp_kthreads();
rcu_ftrace_dump(DUMP_ALL);
}
rtcv_snap = rcu_torture_current_version;
}
/*
* Periodically prints torture statistics, if periodic statistics printing
* was specified via the stat_interval module parameter.
*/
static int
rcu_torture_stats(void *arg)
{
VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
do {
schedule_timeout_interruptible(stat_interval * HZ);
rcu_torture_stats_print();
torture_shutdown_absorb("rcu_torture_stats");
} while (!torture_must_stop());
torture_kthread_stopping("rcu_torture_stats");
return 0;
}
static void
rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
{
pr_alert("%s" TORTURE_FLAG
"--- %s: nreaders=%d nfakewriters=%d "
"stat_interval=%d verbose=%d test_no_idle_hz=%d "
"shuffle_interval=%d stutter=%d irqreader=%d "
"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_irqsoff=%d "
"stall_cpu_block=%d "
"n_barrier_cbs=%d "
"onoff_interval=%d onoff_holdoff=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
stat_interval, verbose, test_no_idle_hz, shuffle_interval,
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_irqsoff,
stall_cpu_block,
n_barrier_cbs,
onoff_interval, onoff_holdoff);
}
static int rcutorture_booster_cleanup(unsigned int cpu)
{
struct task_struct *t;
if (boost_tasks[cpu] == NULL)
return 0;
mutex_lock(&boost_mutex);
t = boost_tasks[cpu];
boost_tasks[cpu] = NULL;
rcu_torture_enable_rt_throttle();
mutex_unlock(&boost_mutex);
/* This must be outside of the mutex, otherwise deadlock! */
torture_stop_kthread(rcu_torture_boost, t);
return 0;
}
static int rcutorture_booster_init(unsigned int cpu)
{
int retval;
if (boost_tasks[cpu] != NULL)
return 0; /* Already created, nothing more to do. */
/* Don't allow time recalculation while creating a new task. */
mutex_lock(&boost_mutex);
rcu_torture_disable_rt_throttle();
VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
cpu_to_node(cpu),
"rcu_torture_boost");
if (IS_ERR(boost_tasks[cpu])) {
retval = PTR_ERR(boost_tasks[cpu]);
VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
n_rcu_torture_boost_ktrerror++;
boost_tasks[cpu] = NULL;
mutex_unlock(&boost_mutex);
return retval;
}
kthread_bind(boost_tasks[cpu], cpu);
wake_up_process(boost_tasks[cpu]);
mutex_unlock(&boost_mutex);
return 0;
}
/*
* CPU-stall kthread. It waits as specified by stall_cpu_holdoff, then
* induces a CPU stall for the time specified by stall_cpu.
*/
static int rcu_torture_stall(void *args)
{
int idx;
unsigned long stop_at;
VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
if (stall_cpu_holdoff > 0) {
VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
}
if (!kthread_should_stop() && stall_gp_kthread > 0) {
VERBOSE_TOROUT_STRING("rcu_torture_stall begin GP stall");
rcu_gp_set_torture_wait(stall_gp_kthread * HZ);
for (idx = 0; idx < stall_gp_kthread + 2; idx++) {
if (kthread_should_stop())
break;
schedule_timeout_uninterruptible(HZ);
}
}
if (!kthread_should_stop() && stall_cpu > 0) {
VERBOSE_TOROUT_STRING("rcu_torture_stall begin CPU stall");
stop_at = ktime_get_seconds() + stall_cpu;
/* RCU CPU stall is expected behavior in following code. */
idx = cur_ops->readlock();
if (stall_cpu_irqsoff)
local_irq_disable();
else if (!stall_cpu_block)
preempt_disable();
pr_alert("rcu_torture_stall start on CPU %d.\n",
raw_smp_processor_id());
while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
stop_at))
if (stall_cpu_block)
schedule_timeout_uninterruptible(HZ);
if (stall_cpu_irqsoff)
local_irq_enable();
else if (!stall_cpu_block)
preempt_enable();
cur_ops->readunlock(idx);
}
pr_alert("rcu_torture_stall end.\n");
torture_shutdown_absorb("rcu_torture_stall");
while (!kthread_should_stop())
schedule_timeout_interruptible(10 * HZ);
return 0;
}
/* Spawn CPU-stall kthread, if stall_cpu specified. */
static int __init rcu_torture_stall_init(void)
{
if (stall_cpu <= 0 && stall_gp_kthread <= 0)
return 0;
return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
}
/* State structure for forward-progress self-propagating RCU callback. */
struct fwd_cb_state {
struct rcu_head rh;
int stop;
};
/*
* Forward-progress self-propagating RCU callback function. Because
* callbacks run from softirq, this function is an implicit RCU read-side
* critical section.
*/
static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
{
struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
if (READ_ONCE(fcsp->stop)) {
WRITE_ONCE(fcsp->stop, 2);
return;
}
cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
}
/* State for continuous-flood RCU callbacks. */
struct rcu_fwd_cb {
struct rcu_head rh;
struct rcu_fwd_cb *rfc_next;
struct rcu_fwd *rfc_rfp;
int rfc_gps;
};
#define MAX_FWD_CB_JIFFIES (8 * HZ) /* Maximum CB test duration. */
#define MIN_FWD_CB_LAUNDERS 3 /* This many CB invocations to count. */
#define MIN_FWD_CBS_LAUNDERED 100 /* Number of counted CBs. */
#define FWD_CBS_HIST_DIV 10 /* Histogram buckets/second. */
#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
struct rcu_launder_hist {
long n_launders;
unsigned long launder_gp_seq;
};
struct rcu_fwd {
spinlock_t rcu_fwd_lock;
struct rcu_fwd_cb *rcu_fwd_cb_head;
struct rcu_fwd_cb **rcu_fwd_cb_tail;
long n_launders_cb;
unsigned long rcu_fwd_startat;
struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
unsigned long rcu_launder_gp_seq_start;
};
struct rcu_fwd *rcu_fwds;
bool rcu_fwd_emergency_stop;
static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
{
unsigned long gps;
unsigned long gps_old;
int i;
int j;
for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
if (rfp->n_launders_hist[i].n_launders > 0)
break;
pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
__func__, jiffies - rfp->rcu_fwd_startat);
gps_old = rfp->rcu_launder_gp_seq_start;
for (j = 0; j <= i; j++) {
gps = rfp->n_launders_hist[j].launder_gp_seq;
pr_cont(" %ds/%d: %ld:%ld",
j + 1, FWD_CBS_HIST_DIV,
rfp->n_launders_hist[j].n_launders,
rcutorture_seq_diff(gps, gps_old));
gps_old = gps;
}
pr_cont("\n");
}
/* Callback function for continuous-flood RCU callbacks. */
static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
{
unsigned long flags;
int i;
struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
struct rcu_fwd_cb **rfcpp;
struct rcu_fwd *rfp = rfcp->rfc_rfp;
rfcp->rfc_next = NULL;
rfcp->rfc_gps++;
spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
rfcpp = rfp->rcu_fwd_cb_tail;
rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
WRITE_ONCE(*rfcpp, rfcp);
WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
if (i >= ARRAY_SIZE(rfp->n_launders_hist))
i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
rfp->n_launders_hist[i].n_launders++;
rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
}
// Give the scheduler a chance, even on nohz_full CPUs.
static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
{
if (IS_ENABLED(CONFIG_PREEMPTION) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
// Real call_rcu() floods hit userspace, so emulate that.
if (need_resched() || (iter & 0xfff))
schedule();
return;
}
// No userspace emulation: CB invocation throttles call_rcu()
cond_resched();
}
/*
* Free all callbacks on the rcu_fwd_cb_head list, either because the
* test is over or because we hit an OOM event.
*/
static unsigned long rcu_torture_fwd_prog_cbfree(struct rcu_fwd *rfp)
{
unsigned long flags;
unsigned long freed = 0;
struct rcu_fwd_cb *rfcp;
for (;;) {
spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
rfcp = rfp->rcu_fwd_cb_head;
if (!rfcp) {
spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
break;
}
rfp->rcu_fwd_cb_head = rfcp->rfc_next;
if (!rfp->rcu_fwd_cb_head)
rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
kfree(rfcp);
freed++;
rcu_torture_fwd_prog_cond_resched(freed);
if (tick_nohz_full_enabled()) {
local_irq_save(flags);
rcu_momentary_dyntick_idle();
local_irq_restore(flags);
}
}
return freed;
}
/* Carry out need_resched()/cond_resched() forward-progress testing. */
static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
int *tested, int *tested_tries)
{
unsigned long cver;
unsigned long dur;
struct fwd_cb_state fcs;
unsigned long gps;
int idx;
int sd;
int sd4;
bool selfpropcb = false;
unsigned long stopat;
static DEFINE_TORTURE_RANDOM(trs);
if (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
init_rcu_head_on_stack(&fcs.rh);
selfpropcb = true;
}
/* Tight loop containing cond_resched(). */
WRITE_ONCE(rcu_fwd_cb_nodelay, true);
cur_ops->sync(); /* Later readers see above write. */
if (selfpropcb) {
WRITE_ONCE(fcs.stop, 0);
cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
}
cver = READ_ONCE(rcu_torture_current_version);
gps = cur_ops->get_gp_seq();
sd = cur_ops->stall_dur() + 1;
sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
dur = sd4 + torture_random(&trs) % (sd - sd4);
WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
stopat = rfp->rcu_fwd_startat + dur;
while (time_before(jiffies, stopat) &&
!shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
idx = cur_ops->readlock();
udelay(10);
cur_ops->readunlock(idx);
if (!fwd_progress_need_resched || need_resched())
cond_resched();
}
(*tested_tries)++;
if (!time_before(jiffies, stopat) &&
!shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
(*tested)++;
cver = READ_ONCE(rcu_torture_current_version) - cver;
gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
WARN_ON(!cver && gps < 2);
pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
}
if (selfpropcb) {
WRITE_ONCE(fcs.stop, 1);
cur_ops->sync(); /* Wait for running CB to complete. */
cur_ops->cb_barrier(); /* Wait for queued callbacks. */
}
if (selfpropcb) {
WARN_ON(READ_ONCE(fcs.stop) != 2);
destroy_rcu_head_on_stack(&fcs.rh);
}
schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
WRITE_ONCE(rcu_fwd_cb_nodelay, false);
}
/* Carry out call_rcu() forward-progress testing. */
static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
{
unsigned long cver;
unsigned long flags;
unsigned long gps;
int i;
long n_launders;
long n_launders_cb_snap;
long n_launders_sa;
long n_max_cbs;
long n_max_gps;
struct rcu_fwd_cb *rfcp;
struct rcu_fwd_cb *rfcpn;
unsigned long stopat;
unsigned long stoppedat;
if (READ_ONCE(rcu_fwd_emergency_stop))
return; /* Get out of the way quickly, no GP wait! */
if (!cur_ops->call)
return; /* Can't do call_rcu() fwd prog without ->call. */
/* Loop continuously posting RCU callbacks. */
WRITE_ONCE(rcu_fwd_cb_nodelay, true);
cur_ops->sync(); /* Later readers see above write. */
WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
n_launders = 0;
rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
n_launders_sa = 0;
n_max_cbs = 0;
n_max_gps = 0;
for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
rfp->n_launders_hist[i].n_launders = 0;
cver = READ_ONCE(rcu_torture_current_version);
gps = cur_ops->get_gp_seq();
rfp->rcu_launder_gp_seq_start = gps;
tick_dep_set_task(current, TICK_DEP_BIT_RCU);
while (time_before(jiffies, stopat) &&
!shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
rfcpn = NULL;
if (rfcp)
rfcpn = READ_ONCE(rfcp->rfc_next);
if (rfcpn) {
if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
break;
rfp->rcu_fwd_cb_head = rfcpn;
n_launders++;
n_launders_sa++;
} else {
rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
if (WARN_ON_ONCE(!rfcp)) {
schedule_timeout_interruptible(1);
continue;
}
n_max_cbs++;
n_launders_sa = 0;
rfcp->rfc_gps = 0;
rfcp->rfc_rfp = rfp;
}
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()) {
local_irq_save(flags);
rcu_momentary_dyntick_idle();
local_irq_restore(flags);
}
}
stoppedat = jiffies;
n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
cver = READ_ONCE(rcu_torture_current_version) - cver;
gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
(void)rcu_torture_fwd_prog_cbfree(rfp);
if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
!shutdown_time_arrived()) {
WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
__func__,
stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
n_launders + n_max_cbs - n_launders_cb_snap,
n_launders, n_launders_sa,
n_max_gps, n_max_cbs, cver, gps);
rcu_torture_fwd_cb_hist(rfp);
}
schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
WRITE_ONCE(rcu_fwd_cb_nodelay, false);
}
/*
* OOM notifier, but this only prints diagnostic information for the
* current forward-progress test.
*/
static int rcutorture_oom_notify(struct notifier_block *self,
unsigned long notused, void *nfreed)
{
struct rcu_fwd *rfp = rcu_fwds;
WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
__func__);
rcu_torture_fwd_cb_hist(rfp);
rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rfp->rcu_fwd_startat)) / 2);
WRITE_ONCE(rcu_fwd_emergency_stop, true);
smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
pr_info("%s: Freed %lu RCU callbacks.\n",
__func__, rcu_torture_fwd_prog_cbfree(rfp));
rcu_barrier();
pr_info("%s: Freed %lu RCU callbacks.\n",
__func__, rcu_torture_fwd_prog_cbfree(rfp));
rcu_barrier();
pr_info("%s: Freed %lu RCU callbacks.\n",
__func__, rcu_torture_fwd_prog_cbfree(rfp));
smp_mb(); /* Frees before return to avoid redoing OOM. */
(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
pr_info("%s returning after OOM processing.\n", __func__);
return NOTIFY_OK;
}
static struct notifier_block rcutorture_oom_nb = {
.notifier_call = rcutorture_oom_notify
};
/* Carry out grace-period forward-progress testing. */
static int rcu_torture_fwd_prog(void *args)
{
struct rcu_fwd *rfp = args;
int tested = 0;
int tested_tries = 0;
VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
rcu_bind_current_to_nocb();
if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
set_user_nice(current, MAX_NICE);
do {
schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
WRITE_ONCE(rcu_fwd_emergency_stop, false);
register_oom_notifier(&rcutorture_oom_nb);
if (!IS_ENABLED(CONFIG_TINY_RCU) ||
rcu_inkernel_boot_has_ended())
rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
if (rcu_inkernel_boot_has_ended())
rcu_torture_fwd_prog_cr(rfp);
unregister_oom_notifier(&rcutorture_oom_nb);
/* Avoid slow periods, better to test when busy. */
stutter_wait("rcu_torture_fwd_prog");
} while (!torture_must_stop());
/* Short runs might not contain a valid forward-progress attempt. */
WARN_ON(!tested && tested_tries >= 5);
pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
torture_kthread_stopping("rcu_torture_fwd_prog");
return 0;
}
/* If forward-progress checking is requested and feasible, spawn the thread. */
static int __init rcu_torture_fwd_prog_init(void)
{
struct rcu_fwd *rfp;
if (!fwd_progress)
return 0; /* Not requested, so don't do it. */
if (!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");
return 0;
}
if (stall_cpu > 0) {
VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
return -EINVAL; /* In module, can fail back to user. */
WARN_ON(1); /* Make sure rcutorture notices conflict. */
return 0;
}
if (fwd_progress_holdoff <= 0)
fwd_progress_holdoff = 1;
if (fwd_progress_div <= 0)
fwd_progress_div = 4;
rfp = kzalloc(sizeof(*rfp), GFP_KERNEL);
if (!rfp)
return -ENOMEM;
spin_lock_init(&rfp->rcu_fwd_lock);
rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);
}
/* Callback function for RCU barrier testing. */
static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
{
atomic_inc(&barrier_cbs_invoked);
}
/* IPI handler to get callback posted on desired CPU, if online. */
static void rcu_torture_barrier1cb(void *rcu_void)
{
struct rcu_head *rhp = rcu_void;
cur_ops->call(rhp, rcu_torture_barrier_cbf);
}
/* kthread function to register callbacks used to test RCU barriers. */
static int rcu_torture_barrier_cbs(void *arg)
{
long myid = (long)arg;
bool lastphase = 0;
bool newphase;
struct rcu_head rcu;
init_rcu_head_on_stack(&rcu);
VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
set_user_nice(current, MAX_NICE);
do {
wait_event(barrier_cbs_wq[myid],
(newphase =
smp_load_acquire(&barrier_phase)) != lastphase ||
torture_must_stop());
lastphase = newphase;
if (torture_must_stop())
break;
/*
* The above smp_load_acquire() ensures barrier_phase load
* is ordered before the following ->call().
*/
if (smp_call_function_single(myid, rcu_torture_barrier1cb,
&rcu, 1)) {
// IPI failed, so use direct call from current CPU.
cur_ops->call(&rcu, rcu_torture_barrier_cbf);
}
if (atomic_dec_and_test(&barrier_cbs_count))
wake_up(&barrier_wq);
} while (!torture_must_stop());
if (cur_ops->cb_barrier != NULL)
cur_ops->cb_barrier();
destroy_rcu_head_on_stack(&rcu);
torture_kthread_stopping("rcu_torture_barrier_cbs");
return 0;
}
/* kthread function to drive and coordinate RCU barrier testing. */
static int rcu_torture_barrier(void *arg)
{
int i;
VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
do {
atomic_set(&barrier_cbs_invoked, 0);
atomic_set(&barrier_cbs_count, n_barrier_cbs);
/* Ensure barrier_phase ordered after prior assignments. */
smp_store_release(&barrier_phase, !barrier_phase);
for (i = 0; i < n_barrier_cbs; i++)
wake_up(&barrier_cbs_wq[i]);
wait_event(barrier_wq,
atomic_read(&barrier_cbs_count) == 0 ||
torture_must_stop());
if (torture_must_stop())
break;
n_barrier_attempts++;
cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
n_rcu_torture_barrier_error++;
pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
atomic_read(&barrier_cbs_invoked),
n_barrier_cbs);
WARN_ON(1);
// Wait manually for the remaining callbacks
i = 0;
do {
if (WARN_ON(i++ > HZ))
i = INT_MIN;
schedule_timeout_interruptible(1);
cur_ops->cb_barrier();
} while (atomic_read(&barrier_cbs_invoked) !=
n_barrier_cbs &&
!torture_must_stop());
smp_mb(); // Can't trust ordering if broken.
if (!torture_must_stop())
pr_err("Recovered: barrier_cbs_invoked = %d\n",
atomic_read(&barrier_cbs_invoked));
} else {
n_barrier_successes++;
}
schedule_timeout_interruptible(HZ / 10);
} while (!torture_must_stop());
torture_kthread_stopping("rcu_torture_barrier");
return 0;
}
/* Initialize RCU barrier testing. */
static int rcu_torture_barrier_init(void)
{
int i;
int ret;
if (n_barrier_cbs <= 0)
return 0;
if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
pr_alert("%s" TORTURE_FLAG
" Call or barrier ops missing for %s,\n",
torture_type, cur_ops->name);
pr_alert("%s" TORTURE_FLAG
" RCU barrier testing omitted from run.\n",
torture_type);
return 0;
}
atomic_set(&barrier_cbs_count, 0);
atomic_set(&barrier_cbs_invoked, 0);
barrier_cbs_tasks =
kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
GFP_KERNEL);
barrier_cbs_wq =
kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
return -ENOMEM;
for (i = 0; i < n_barrier_cbs; i++) {
init_waitqueue_head(&barrier_cbs_wq[i]);
ret = torture_create_kthread(rcu_torture_barrier_cbs,
(void *)(long)i,
barrier_cbs_tasks[i]);
if (ret)
return ret;
}
return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
}
/* Clean up after RCU barrier testing. */
static void rcu_torture_barrier_cleanup(void)
{
int i;
torture_stop_kthread(rcu_torture_barrier, barrier_task);
if (barrier_cbs_tasks != NULL) {
for (i = 0; i < n_barrier_cbs; i++)
torture_stop_kthread(rcu_torture_barrier_cbs,
barrier_cbs_tasks[i]);
kfree(barrier_cbs_tasks);
barrier_cbs_tasks = NULL;
}
if (barrier_cbs_wq != NULL) {
kfree(barrier_cbs_wq);
barrier_cbs_wq = NULL;
}
}
static bool rcu_torture_can_boost(void)
{
static int boost_warn_once;
int prio;
if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
return false;
prio = rcu_get_gp_kthreads_prio();
if (!prio)
return false;
if (prio < 2) {
if (boost_warn_once == 1)
return false;
pr_alert("%s: WARN: RCU kthread priority too low to test boosting. Skipping RCU boost test. Try passing rcutree.kthread_prio > 1 on the kernel command line.\n", KBUILD_MODNAME);
boost_warn_once = 1;
return false;
}
return true;
}
static enum cpuhp_state rcutor_hp;
static void
rcu_torture_cleanup(void)
{
int firsttime;
int flags = 0;
unsigned long gp_seq = 0;
int i;
if (torture_cleanup_begin()) {
if (cur_ops->cb_barrier != NULL)
cur_ops->cb_barrier();
return;
}
if (!cur_ops) {
torture_cleanup_end();
return;
}
show_rcu_gp_kthreads();
rcu_torture_barrier_cleanup();
torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
torture_stop_kthread(rcu_torture_stall, stall_task);
torture_stop_kthread(rcu_torture_writer, writer_task);
if (reader_tasks) {
for (i = 0; i < nrealreaders; i++)
torture_stop_kthread(rcu_torture_reader,
reader_tasks[i]);
kfree(reader_tasks);
}
rcu_torture_current = NULL;
if (fakewriter_tasks) {
for (i = 0; i < nfakewriters; i++) {
torture_stop_kthread(rcu_torture_fakewriter,
fakewriter_tasks[i]);
}
kfree(fakewriter_tasks);
fakewriter_tasks = NULL;
}
rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
pr_alert("%s: End-test grace-period state: g%lu f%#x\n",
cur_ops->name, gp_seq, flags);
torture_stop_kthread(rcu_torture_stats, stats_task);
torture_stop_kthread(rcu_torture_fqs, fqs_task);
if (rcu_torture_can_boost())
cpuhp_remove_state(rcutor_hp);
/*
* Wait for all RCU callbacks to fire, then do torture-type-specific
* cleanup operations.
*/
if (cur_ops->cb_barrier != NULL)
cur_ops->cb_barrier();
if (cur_ops->cleanup != NULL)
cur_ops->cleanup();
rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
if (err_segs_recorded) {
pr_alert("Failure/close-call rcutorture reader segments:\n");
if (rt_read_nsegs == 0)
pr_alert("\t: No segments recorded!!!\n");
firsttime = 1;
for (i = 0; i < rt_read_nsegs; i++) {
pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
if (err_segs[i].rt_delay_jiffies != 0) {
pr_cont("%s%ldjiffies", firsttime ? "" : "+",
err_segs[i].rt_delay_jiffies);
firsttime = 0;
}
if (err_segs[i].rt_delay_ms != 0) {
pr_cont("%s%ldms", firsttime ? "" : "+",
err_segs[i].rt_delay_ms);
firsttime = 0;
}
if (err_segs[i].rt_delay_us != 0) {
pr_cont("%s%ldus", firsttime ? "" : "+",
err_segs[i].rt_delay_us);
firsttime = 0;
}
pr_cont("%s\n",
err_segs[i].rt_preempted ? "preempted" : "");
}
}
if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
else if (torture_onoff_failures())
rcu_torture_print_module_parms(cur_ops,
"End of test: RCU_HOTPLUG");
else
rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
torture_cleanup_end();
}
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
static void rcu_torture_leak_cb(struct rcu_head *rhp)
{
}
static void rcu_torture_err_cb(struct rcu_head *rhp)
{
/*
* This -might- happen due to race conditions, but is unlikely.
* The scenario that leads to this happening is that the
* first of the pair of duplicate callbacks is queued,
* someone else starts a grace period that includes that
* callback, then the second of the pair must wait for the
* next grace period. Unlikely, but can happen. If it
* does happen, the debug-objects subsystem won't have splatted.
*/
pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
}
#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
/*
* Verify that double-free causes debug-objects to complain, but only
* if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y. Otherwise, say that the test
* cannot be carried out.
*/
static void rcu_test_debug_objects(void)
{
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
struct rcu_head rh1;
struct rcu_head rh2;
init_rcu_head_on_stack(&rh1);
init_rcu_head_on_stack(&rh2);
pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
/* Try to queue the rh2 pair of callbacks for the same grace period. */
preempt_disable(); /* Prevent preemption from interrupting test. */
rcu_read_lock(); /* Make it impossible to finish a grace period. */
call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
local_irq_disable(); /* Make it harder to start a new grace period. */
call_rcu(&rh2, rcu_torture_leak_cb);
call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
local_irq_enable();
rcu_read_unlock();
preempt_enable();
/* Wait for them all to get done so we can safely return. */
rcu_barrier();
pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
destroy_rcu_head_on_stack(&rh1);
destroy_rcu_head_on_stack(&rh2);
#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
}
static void rcutorture_sync(void)
{
static unsigned long n;
if (cur_ops->sync && !(++n & 0xfff))
cur_ops->sync();
}
static int __init
rcu_torture_init(void)
{
long i;
int cpu;
int firsterr = 0;
static struct rcu_torture_ops *torture_ops[] = {
&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
&busted_srcud_ops, &tasks_ops, &trivial_ops,
};
if (!torture_init_begin(torture_type, verbose))
return -EBUSY;
/* Process args and tell the world that the torturer is on the job. */
for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
cur_ops = torture_ops[i];
if (strcmp(torture_type, cur_ops->name) == 0)
break;
}
if (i == ARRAY_SIZE(torture_ops)) {
pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
torture_type);
pr_alert("rcu-torture types:");
for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
pr_cont(" %s", torture_ops[i]->name);
pr_cont("\n");
WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
firsterr = -EINVAL;
cur_ops = NULL;
goto unwind;
}
if (cur_ops->fqs == NULL && fqs_duration != 0) {
pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
fqs_duration = 0;
}
if (cur_ops->init)
cur_ops->init();
if (nreaders >= 0) {
nrealreaders = nreaders;
} else {
nrealreaders = num_online_cpus() - 2 - nreaders;
if (nrealreaders <= 0)
nrealreaders = 1;
}
rcu_torture_print_module_parms(cur_ops, "Start of test");
/* Set up the freelist. */
INIT_LIST_HEAD(&rcu_torture_freelist);
for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
rcu_tortures[i].rtort_mbtest = 0;
list_add_tail(&rcu_tortures[i].rtort_free,
&rcu_torture_freelist);
}
/* Initialize the statistics so that each run gets its own numbers. */
rcu_torture_current = NULL;
rcu_torture_current_version = 0;
atomic_set(&n_rcu_torture_alloc, 0);
atomic_set(&n_rcu_torture_alloc_fail, 0);
atomic_set(&n_rcu_torture_free, 0);
atomic_set(&n_rcu_torture_mberror, 0);
atomic_set(&n_rcu_torture_error, 0);
n_rcu_torture_barrier_error = 0;
n_rcu_torture_boost_ktrerror = 0;
n_rcu_torture_boost_rterror = 0;
n_rcu_torture_boost_failure = 0;
n_rcu_torture_boosts = 0;
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
atomic_set(&rcu_torture_wcount[i], 0);
for_each_possible_cpu(cpu) {
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
per_cpu(rcu_torture_count, cpu)[i] = 0;
per_cpu(rcu_torture_batch, cpu)[i] = 0;
}
}
err_segs_recorded = 0;
rt_read_nsegs = 0;
/* Start up the kthreads. */
firsterr = torture_create_kthread(rcu_torture_writer, NULL,
writer_task);
if (firsterr)
goto unwind;
if (nfakewriters > 0) {
fakewriter_tasks = kcalloc(nfakewriters,
sizeof(fakewriter_tasks[0]),
GFP_KERNEL);
if (fakewriter_tasks == NULL) {
VERBOSE_TOROUT_ERRSTRING("out of memory");
firsterr = -ENOMEM;
goto unwind;
}
}
for (i = 0; i < nfakewriters; i++) {
firsterr = torture_create_kthread(rcu_torture_fakewriter,
NULL, fakewriter_tasks[i]);
if (firsterr)
goto unwind;
}
reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
GFP_KERNEL);
if (reader_tasks == NULL) {
VERBOSE_TOROUT_ERRSTRING("out of memory");
firsterr = -ENOMEM;
goto unwind;
}
for (i = 0; i < nrealreaders; i++) {
firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
reader_tasks[i]);
if (firsterr)
goto unwind;
}
if (stat_interval > 0) {
firsterr = torture_create_kthread(rcu_torture_stats, NULL,
stats_task);
if (firsterr)
goto unwind;
}
if (test_no_idle_hz && shuffle_interval > 0) {
firsterr = torture_shuffle_init(shuffle_interval * HZ);
if (firsterr)
goto unwind;
}
if (stutter < 0)
stutter = 0;
if (stutter) {
int t;
t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
firsterr = torture_stutter_init(stutter * HZ, t);
if (firsterr)
goto unwind;
}
if (fqs_duration < 0)
fqs_duration = 0;
if (fqs_duration) {
/* Create the fqs thread */
firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
fqs_task);
if (firsterr)
goto unwind;
}
if (test_boost_interval < 1)
test_boost_interval = 1;
if (test_boost_duration < 2)
test_boost_duration = 2;
if (rcu_torture_can_boost()) {
boost_starttime = jiffies + test_boost_interval * HZ;
firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
rcutorture_booster_init,
rcutorture_booster_cleanup);
if (firsterr < 0)
goto unwind;
rcutor_hp = firsterr;
}
shutdown_jiffies = jiffies + shutdown_secs * HZ;
firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
if (firsterr)
goto unwind;
firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
rcutorture_sync);
if (firsterr)
goto unwind;
firsterr = rcu_torture_stall_init();
if (firsterr)
goto unwind;
firsterr = rcu_torture_fwd_prog_init();
if (firsterr)
goto unwind;
firsterr = rcu_torture_barrier_init();
if (firsterr)
goto unwind;
if (object_debug)
rcu_test_debug_objects();
torture_init_end();
return 0;
unwind:
torture_init_end();
rcu_torture_cleanup();
return firsterr;
}
module_init(rcu_torture_init);
module_exit(rcu_torture_cleanup);
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