1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Read-Copy Update module-based torture test facility
   4 *
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   5 * Copyright (C) IBM Corporation, 2005, 2006
   6 *
   7 * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
   8 *	  Josh Triplett <josh@joshtriplett.org>
   9 *
  10 * See also:  Documentation/RCU/torture.rst
  11 */
  12
  13#define pr_fmt(fmt) fmt
  14
  15#include <linux/types.h>
  16#include <linux/kernel.h>
  17#include <linux/init.h>
  18#include <linux/module.h>
  19#include <linux/kthread.h>
  20#include <linux/err.h>
  21#include <linux/spinlock.h>
  22#include <linux/smp.h>
  23#include <linux/rcupdate_wait.h>
  24#include <linux/interrupt.h>
  25#include <linux/sched/signal.h>
  26#include <uapi/linux/sched/types.h>
  27#include <linux/atomic.h>
  28#include <linux/bitops.h>
  29#include <linux/completion.h>
  30#include <linux/moduleparam.h>
  31#include <linux/percpu.h>
  32#include <linux/notifier.h>
  33#include <linux/reboot.h>
  34#include <linux/freezer.h>
  35#include <linux/cpu.h>
  36#include <linux/delay.h>
  37#include <linux/stat.h>
  38#include <linux/srcu.h>
  39#include <linux/slab.h>
  40#include <linux/trace_clock.h>
  41#include <asm/byteorder.h>
  42#include <linux/torture.h>
  43#include <linux/vmalloc.h>
  44#include <linux/sched/debug.h>
  45#include <linux/sched/sysctl.h>
  46#include <linux/oom.h>
  47#include <linux/tick.h>
  48#include <linux/rcupdate_trace.h>
  49
  50#include "rcu.h"
  51
  52MODULE_LICENSE("GPL");
  53MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  54
  55/* Bits for ->extendables field, extendables param, and related definitions. */
  56#define RCUTORTURE_RDR_SHIFT	 8	/* Put SRCU index in upper bits. */
  57#define RCUTORTURE_RDR_MASK	 ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  58#define RCUTORTURE_RDR_BH	 0x01	/* Extend readers by disabling bh. */
  59#define RCUTORTURE_RDR_IRQ	 0x02	/*  ... disabling interrupts. */
  60#define RCUTORTURE_RDR_PREEMPT	 0x04	/*  ... disabling preemption. */
  61#define RCUTORTURE_RDR_RBH	 0x08	/*  ... rcu_read_lock_bh(). */
  62#define RCUTORTURE_RDR_SCHED	 0x10	/*  ... rcu_read_lock_sched(). */
  63#define RCUTORTURE_RDR_RCU	 0x20	/*  ... entering another RCU reader. */
  64#define RCUTORTURE_RDR_NBITS	 6	/* Number of bits defined above. */
  65#define RCUTORTURE_MAX_EXTEND	 \
  66	(RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  67	 RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  68#define RCUTORTURE_RDR_MAX_LOOPS 0x7	/* Maximum reader extensions. */
  69					/* Must be power of two minus one. */
  70#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  71
  72torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  73	      "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
 
 
 
 
 
  74torture_param(int, fqs_duration, 0,
  75	      "Duration of fqs bursts (us), 0 to disable");
  76torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  77torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  78torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  79torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  80torture_param(int, fwd_progress_holdoff, 60,
  81	      "Time between forward-progress tests (s)");
  82torture_param(bool, fwd_progress_need_resched, 1,
  83	      "Hide cond_resched() behind need_resched()");
  84torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  85torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  86torture_param(bool, gp_normal, false,
  87	     "Use normal (non-expedited) GP wait primitives");
  88torture_param(bool, gp_poll, false, "Use polling GP wait primitives");
  89torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  90torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  91torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
  92torture_param(int, n_barrier_cbs, 0,
  93	     "# of callbacks/kthreads for barrier testing");
  94torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  95torture_param(int, nreaders, -1, "Number of RCU reader threads");
  96torture_param(int, object_debug, 0,
  97	     "Enable debug-object double call_rcu() testing");
  98torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  99torture_param(int, onoff_interval, 0,
 100	     "Time between CPU hotplugs (jiffies), 0=disable");
 101torture_param(int, nocbs_nthreads, 0, "Number of NOCB toggle threads, 0 to disable");
 102torture_param(int, nocbs_toggle, 1000, "Time between toggling nocb state (ms)");
 103torture_param(int, read_exit_delay, 13,
 104	      "Delay between read-then-exit episodes (s)");
 105torture_param(int, read_exit_burst, 16,
 106	      "# of read-then-exit bursts per episode, zero to disable");
 107torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
 108torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 109torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 110torture_param(int, stall_cpu_holdoff, 10,
 111	     "Time to wait before starting stall (s).");
 112torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 113torture_param(int, stall_cpu_block, 0, "Sleep while stalling.");
 114torture_param(int, stall_gp_kthread, 0,
 115	      "Grace-period kthread stall duration (s).");
 116torture_param(int, stat_interval, 60,
 117	     "Number of seconds between stats printk()s");
 118torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 119torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 120torture_param(int, test_boost_duration, 4,
 121	     "Duration of each boost test, seconds.");
 122torture_param(int, test_boost_interval, 7,
 123	     "Interval between boost tests, seconds.");
 124torture_param(bool, test_no_idle_hz, true,
 125	     "Test support for tickless idle CPUs");
 126torture_param(int, verbose, 1,
 127	     "Enable verbose debugging printk()s");
 128
 129static char *torture_type = "rcu";
 130module_param(torture_type, charp, 0444);
 131MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 132
 133static int nrealnocbers;
 134static int nrealreaders;
 
 135static struct task_struct *writer_task;
 136static struct task_struct **fakewriter_tasks;
 137static struct task_struct **reader_tasks;
 138static struct task_struct **nocb_tasks;
 139static struct task_struct *stats_task;
 
 140static struct task_struct *fqs_task;
 141static struct task_struct *boost_tasks[NR_CPUS];
 142static struct task_struct *stall_task;
 143static struct task_struct *fwd_prog_task;
 144static struct task_struct **barrier_cbs_tasks;
 145static struct task_struct *barrier_task;
 146static struct task_struct *read_exit_task;
 147
 148#define RCU_TORTURE_PIPE_LEN 10
 149
 150// Mailbox-like structure to check RCU global memory ordering.
 151struct rcu_torture_reader_check {
 152	unsigned long rtc_myloops;
 153	int rtc_chkrdr;
 154	unsigned long rtc_chkloops;
 155	int rtc_ready;
 156	struct rcu_torture_reader_check *rtc_assigner;
 157} ____cacheline_internodealigned_in_smp;
 158
 159// Update-side data structure used to check RCU readers.
 160struct rcu_torture {
 161	struct rcu_head rtort_rcu;
 162	int rtort_pipe_count;
 163	struct list_head rtort_free;
 164	int rtort_mbtest;
 165	struct rcu_torture_reader_check *rtort_chkp;
 166};
 167
 168static LIST_HEAD(rcu_torture_freelist);
 169static struct rcu_torture __rcu *rcu_torture_current;
 170static unsigned long rcu_torture_current_version;
 171static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 172static DEFINE_SPINLOCK(rcu_torture_lock);
 173static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 174static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 175static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 176static struct rcu_torture_reader_check *rcu_torture_reader_mbchk;
 177static atomic_t n_rcu_torture_alloc;
 178static atomic_t n_rcu_torture_alloc_fail;
 179static atomic_t n_rcu_torture_free;
 180static atomic_t n_rcu_torture_mberror;
 181static atomic_t n_rcu_torture_mbchk_fail;
 182static atomic_t n_rcu_torture_mbchk_tries;
 183static atomic_t n_rcu_torture_error;
 184static long n_rcu_torture_barrier_error;
 185static long n_rcu_torture_boost_ktrerror;
 186static long n_rcu_torture_boost_rterror;
 187static long n_rcu_torture_boost_failure;
 188static long n_rcu_torture_boosts;
 189static atomic_long_t n_rcu_torture_timers;
 190static long n_barrier_attempts;
 191static long n_barrier_successes; /* did rcu_barrier test succeed? */
 192static unsigned long n_read_exits;
 193static struct list_head rcu_torture_removed;
 194static unsigned long shutdown_jiffies;
 195static unsigned long start_gp_seq;
 196static atomic_long_t n_nocb_offload;
 197static atomic_long_t n_nocb_deoffload;
 198
 199static int rcu_torture_writer_state;
 200#define RTWS_FIXED_DELAY	0
 201#define RTWS_DELAY		1
 202#define RTWS_REPLACE		2
 203#define RTWS_DEF_FREE		3
 204#define RTWS_EXP_SYNC		4
 205#define RTWS_COND_GET		5
 206#define RTWS_COND_SYNC		6
 207#define RTWS_POLL_GET		7
 208#define RTWS_POLL_WAIT		8
 209#define RTWS_SYNC		9
 210#define RTWS_STUTTER		10
 211#define RTWS_STOPPING		11
 212static const char * const rcu_torture_writer_state_names[] = {
 213	"RTWS_FIXED_DELAY",
 214	"RTWS_DELAY",
 215	"RTWS_REPLACE",
 216	"RTWS_DEF_FREE",
 217	"RTWS_EXP_SYNC",
 218	"RTWS_COND_GET",
 219	"RTWS_COND_SYNC",
 220	"RTWS_POLL_GET",
 221	"RTWS_POLL_WAIT",
 222	"RTWS_SYNC",
 223	"RTWS_STUTTER",
 224	"RTWS_STOPPING",
 225};
 226
 227/* Record reader segment types and duration for first failing read. */
 228struct rt_read_seg {
 229	int rt_readstate;
 230	unsigned long rt_delay_jiffies;
 231	unsigned long rt_delay_ms;
 232	unsigned long rt_delay_us;
 233	bool rt_preempted;
 234};
 235static int err_segs_recorded;
 236static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 237static int rt_read_nsegs;
 238
 239static const char *rcu_torture_writer_state_getname(void)
 240{
 241	unsigned int i = READ_ONCE(rcu_torture_writer_state);
 242
 243	if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 244		return "???";
 245	return rcu_torture_writer_state_names[i];
 246}
 247
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 248#ifdef CONFIG_RCU_TRACE
 249static u64 notrace rcu_trace_clock_local(void)
 250{
 251	u64 ts = trace_clock_local();
 252
 253	(void)do_div(ts, NSEC_PER_USEC);
 254	return ts;
 255}
 256#else /* #ifdef CONFIG_RCU_TRACE */
 257static u64 notrace rcu_trace_clock_local(void)
 258{
 259	return 0ULL;
 260}
 261#endif /* #else #ifdef CONFIG_RCU_TRACE */
 262
 263/*
 264 * Stop aggressive CPU-hog tests a bit before the end of the test in order
 265 * to avoid interfering with test shutdown.
 266 */
 267static bool shutdown_time_arrived(void)
 268{
 269	return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
 270}
 271
 272static unsigned long boost_starttime;	/* jiffies of next boost test start. */
 273static DEFINE_MUTEX(boost_mutex);	/* protect setting boost_starttime */
 274					/*  and boost task create/destroy. */
 275static atomic_t barrier_cbs_count;	/* Barrier callbacks registered. */
 276static bool barrier_phase;		/* Test phase. */
 277static atomic_t barrier_cbs_invoked;	/* Barrier callbacks invoked. */
 278static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 279static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 280
 281static bool rcu_fwd_cb_nodelay;		/* Short rcu_torture_delay() delays. */
 282
 283/*
 284 * Allocate an element from the rcu_tortures pool.
 285 */
 286static struct rcu_torture *
 287rcu_torture_alloc(void)
 288{
 289	struct list_head *p;
 290
 291	spin_lock_bh(&rcu_torture_lock);
 292	if (list_empty(&rcu_torture_freelist)) {
 293		atomic_inc(&n_rcu_torture_alloc_fail);
 294		spin_unlock_bh(&rcu_torture_lock);
 295		return NULL;
 296	}
 297	atomic_inc(&n_rcu_torture_alloc);
 298	p = rcu_torture_freelist.next;
 299	list_del_init(p);
 300	spin_unlock_bh(&rcu_torture_lock);
 301	return container_of(p, struct rcu_torture, rtort_free);
 302}
 303
 304/*
 305 * Free an element to the rcu_tortures pool.
 306 */
 307static void
 308rcu_torture_free(struct rcu_torture *p)
 309{
 310	atomic_inc(&n_rcu_torture_free);
 311	spin_lock_bh(&rcu_torture_lock);
 312	list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 313	spin_unlock_bh(&rcu_torture_lock);
 314}
 315
 316/*
 317 * Operations vector for selecting different types of tests.
 318 */
 319
 320struct rcu_torture_ops {
 321	int ttype;
 322	void (*init)(void);
 323	void (*cleanup)(void);
 324	int (*readlock)(void);
 325	void (*read_delay)(struct torture_random_state *rrsp,
 326			   struct rt_read_seg *rtrsp);
 327	void (*readunlock)(int idx);
 328	int (*readlock_held)(void);
 329	unsigned long (*get_gp_seq)(void);
 330	unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 331	void (*deferred_free)(struct rcu_torture *p);
 332	void (*sync)(void);
 333	void (*exp_sync)(void);
 334	unsigned long (*get_gp_state)(void);
 335	unsigned long (*start_gp_poll)(void);
 336	bool (*poll_gp_state)(unsigned long oldstate);
 337	void (*cond_sync)(unsigned long oldstate);
 338	call_rcu_func_t call;
 339	void (*cb_barrier)(void);
 340	void (*fqs)(void);
 341	void (*stats)(void);
 342	void (*gp_kthread_dbg)(void);
 343	bool (*check_boost_failed)(unsigned long gp_state, int *cpup);
 344	int (*stall_dur)(void);
 345	int irq_capable;
 346	int can_boost;
 347	int extendables;
 348	int slow_gps;
 349	const char *name;
 350};
 351
 352static struct rcu_torture_ops *cur_ops;
 353
 354/*
 355 * Definitions for rcu torture testing.
 356 */
 357
 358static int torture_readlock_not_held(void)
 359{
 360	return rcu_read_lock_bh_held() || rcu_read_lock_sched_held();
 361}
 362
 363static int rcu_torture_read_lock(void) __acquires(RCU)
 364{
 365	rcu_read_lock();
 366	return 0;
 367}
 368
 369static void
 370rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 371{
 372	unsigned long started;
 373	unsigned long completed;
 374	const unsigned long shortdelay_us = 200;
 375	unsigned long longdelay_ms = 300;
 376	unsigned long long ts;
 377
 378	/* We want a short delay sometimes to make a reader delay the grace
 379	 * period, and we want a long delay occasionally to trigger
 380	 * force_quiescent_state. */
 381
 382	if (!READ_ONCE(rcu_fwd_cb_nodelay) &&
 383	    !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 384		started = cur_ops->get_gp_seq();
 385		ts = rcu_trace_clock_local();
 386		if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 387			longdelay_ms = 5; /* Avoid triggering BH limits. */
 388		mdelay(longdelay_ms);
 389		rtrsp->rt_delay_ms = longdelay_ms;
 390		completed = cur_ops->get_gp_seq();
 391		do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 392					  started, completed);
 393	}
 394	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 395		udelay(shortdelay_us);
 396		rtrsp->rt_delay_us = shortdelay_us;
 397	}
 398	if (!preempt_count() &&
 399	    !(torture_random(rrsp) % (nrealreaders * 500))) {
 400		torture_preempt_schedule();  /* QS only if preemptible. */
 401		rtrsp->rt_preempted = true;
 402	}
 403}
 404
 405static void rcu_torture_read_unlock(int idx) __releases(RCU)
 406{
 407	rcu_read_unlock();
 408}
 409
 410/*
 411 * Update callback in the pipe.  This should be invoked after a grace period.
 412 */
 413static bool
 414rcu_torture_pipe_update_one(struct rcu_torture *rp)
 415{
 416	int i;
 417	struct rcu_torture_reader_check *rtrcp = READ_ONCE(rp->rtort_chkp);
 418
 419	if (rtrcp) {
 420		WRITE_ONCE(rp->rtort_chkp, NULL);
 421		smp_store_release(&rtrcp->rtc_ready, 1); // Pair with smp_load_acquire().
 422	}
 423	i = READ_ONCE(rp->rtort_pipe_count);
 424	if (i > RCU_TORTURE_PIPE_LEN)
 425		i = RCU_TORTURE_PIPE_LEN;
 426	atomic_inc(&rcu_torture_wcount[i]);
 427	WRITE_ONCE(rp->rtort_pipe_count, i + 1);
 428	if (rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 429		rp->rtort_mbtest = 0;
 430		return true;
 431	}
 432	return false;
 433}
 434
 435/*
 436 * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 437 * primitives.
 438 */
 439static void
 440rcu_torture_pipe_update(struct rcu_torture *old_rp)
 441{
 442	struct rcu_torture *rp;
 443	struct rcu_torture *rp1;
 444
 445	if (old_rp)
 446		list_add(&old_rp->rtort_free, &rcu_torture_removed);
 447	list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 448		if (rcu_torture_pipe_update_one(rp)) {
 449			list_del(&rp->rtort_free);
 450			rcu_torture_free(rp);
 451		}
 452	}
 453}
 454
 455static void
 456rcu_torture_cb(struct rcu_head *p)
 457{
 458	struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 459
 460	if (torture_must_stop_irq()) {
 461		/* Test is ending, just drop callbacks on the floor. */
 462		/* The next initialization will pick up the pieces. */
 463		return;
 464	}
 465	if (rcu_torture_pipe_update_one(rp))
 466		rcu_torture_free(rp);
 467	else
 468		cur_ops->deferred_free(rp);
 469}
 470
 471static unsigned long rcu_no_completed(void)
 472{
 473	return 0;
 474}
 475
 476static void rcu_torture_deferred_free(struct rcu_torture *p)
 477{
 478	call_rcu(&p->rtort_rcu, rcu_torture_cb);
 479}
 480
 481static void rcu_sync_torture_init(void)
 482{
 483	INIT_LIST_HEAD(&rcu_torture_removed);
 484}
 485
 486static struct rcu_torture_ops rcu_ops = {
 487	.ttype			= RCU_FLAVOR,
 488	.init			= rcu_sync_torture_init,
 489	.readlock		= rcu_torture_read_lock,
 490	.read_delay		= rcu_read_delay,
 491	.readunlock		= rcu_torture_read_unlock,
 492	.readlock_held		= torture_readlock_not_held,
 493	.get_gp_seq		= rcu_get_gp_seq,
 494	.gp_diff		= rcu_seq_diff,
 495	.deferred_free		= rcu_torture_deferred_free,
 496	.sync			= synchronize_rcu,
 497	.exp_sync		= synchronize_rcu_expedited,
 498	.get_gp_state		= get_state_synchronize_rcu,
 499	.start_gp_poll		= start_poll_synchronize_rcu,
 500	.poll_gp_state		= poll_state_synchronize_rcu,
 501	.cond_sync		= cond_synchronize_rcu,
 502	.call			= call_rcu,
 503	.cb_barrier		= rcu_barrier,
 504	.fqs			= rcu_force_quiescent_state,
 505	.stats			= NULL,
 506	.gp_kthread_dbg		= show_rcu_gp_kthreads,
 507	.check_boost_failed	= rcu_check_boost_fail,
 508	.stall_dur		= rcu_jiffies_till_stall_check,
 509	.irq_capable		= 1,
 510	.can_boost		= IS_ENABLED(CONFIG_RCU_BOOST),
 511	.extendables		= RCUTORTURE_MAX_EXTEND,
 512	.name			= "rcu"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 513};
 514
 515/*
 516 * Don't even think about trying any of these in real life!!!
 517 * The names includes "busted", and they really means it!
 518 * The only purpose of these functions is to provide a buggy RCU
 519 * implementation to make sure that rcutorture correctly emits
 520 * buggy-RCU error messages.
 521 */
 522static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 523{
 524	/* This is a deliberate bug for testing purposes only! */
 525	rcu_torture_cb(&p->rtort_rcu);
 526}
 527
 528static void synchronize_rcu_busted(void)
 529{
 530	/* This is a deliberate bug for testing purposes only! */
 531}
 532
 533static void
 534call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 535{
 536	/* This is a deliberate bug for testing purposes only! */
 537	func(head);
 538}
 539
 540static struct rcu_torture_ops rcu_busted_ops = {
 541	.ttype		= INVALID_RCU_FLAVOR,
 542	.init		= rcu_sync_torture_init,
 543	.readlock	= rcu_torture_read_lock,
 544	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
 545	.readunlock	= rcu_torture_read_unlock,
 546	.readlock_held	= torture_readlock_not_held,
 547	.get_gp_seq	= rcu_no_completed,
 548	.deferred_free	= rcu_busted_torture_deferred_free,
 549	.sync		= synchronize_rcu_busted,
 550	.exp_sync	= synchronize_rcu_busted,
 551	.call		= call_rcu_busted,
 552	.cb_barrier	= NULL,
 553	.fqs		= NULL,
 554	.stats		= NULL,
 555	.irq_capable	= 1,
 556	.name		= "busted"
 557};
 558
 559/*
 560 * Definitions for srcu torture testing.
 561 */
 562
 563DEFINE_STATIC_SRCU(srcu_ctl);
 564static struct srcu_struct srcu_ctld;
 565static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 566
 567static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 568{
 569	return srcu_read_lock(srcu_ctlp);
 570}
 571
 572static void
 573srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 574{
 575	long delay;
 576	const long uspertick = 1000000 / HZ;
 577	const long longdelay = 10;
 578
 579	/* We want there to be long-running readers, but not all the time. */
 580
 581	delay = torture_random(rrsp) %
 582		(nrealreaders * 2 * longdelay * uspertick);
 583	if (!delay && in_task()) {
 584		schedule_timeout_interruptible(longdelay);
 585		rtrsp->rt_delay_jiffies = longdelay;
 586	} else {
 587		rcu_read_delay(rrsp, rtrsp);
 588	}
 589}
 590
 591static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 592{
 593	srcu_read_unlock(srcu_ctlp, idx);
 594}
 595
 596static int torture_srcu_read_lock_held(void)
 597{
 598	return srcu_read_lock_held(srcu_ctlp);
 599}
 600
 601static unsigned long srcu_torture_completed(void)
 602{
 603	return srcu_batches_completed(srcu_ctlp);
 604}
 605
 606static void srcu_torture_deferred_free(struct rcu_torture *rp)
 607{
 608	call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 609}
 610
 611static void srcu_torture_synchronize(void)
 612{
 613	synchronize_srcu(srcu_ctlp);
 614}
 615
 616static unsigned long srcu_torture_get_gp_state(void)
 617{
 618	return get_state_synchronize_srcu(srcu_ctlp);
 619}
 620
 621static unsigned long srcu_torture_start_gp_poll(void)
 622{
 623	return start_poll_synchronize_srcu(srcu_ctlp);
 624}
 625
 626static bool srcu_torture_poll_gp_state(unsigned long oldstate)
 627{
 628	return poll_state_synchronize_srcu(srcu_ctlp, oldstate);
 629}
 630
 631static void srcu_torture_call(struct rcu_head *head,
 632			      rcu_callback_t func)
 633{
 634	call_srcu(srcu_ctlp, head, func);
 635}
 636
 637static void srcu_torture_barrier(void)
 638{
 639	srcu_barrier(srcu_ctlp);
 640}
 641
 642static void srcu_torture_stats(void)
 643{
 644	srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 
 
 
 
 
 
 
 
 
 
 
 
 645}
 646
 647static void srcu_torture_synchronize_expedited(void)
 648{
 649	synchronize_srcu_expedited(srcu_ctlp);
 650}
 651
 652static struct rcu_torture_ops srcu_ops = {
 653	.ttype		= SRCU_FLAVOR,
 654	.init		= rcu_sync_torture_init,
 655	.readlock	= srcu_torture_read_lock,
 656	.read_delay	= srcu_read_delay,
 657	.readunlock	= srcu_torture_read_unlock,
 658	.readlock_held	= torture_srcu_read_lock_held,
 659	.get_gp_seq	= srcu_torture_completed,
 660	.deferred_free	= srcu_torture_deferred_free,
 661	.sync		= srcu_torture_synchronize,
 662	.exp_sync	= srcu_torture_synchronize_expedited,
 663	.get_gp_state	= srcu_torture_get_gp_state,
 664	.start_gp_poll	= srcu_torture_start_gp_poll,
 665	.poll_gp_state	= srcu_torture_poll_gp_state,
 666	.call		= srcu_torture_call,
 667	.cb_barrier	= srcu_torture_barrier,
 668	.stats		= srcu_torture_stats,
 669	.irq_capable	= 1,
 670	.name		= "srcu"
 671};
 672
 673static void srcu_torture_init(void)
 674{
 675	rcu_sync_torture_init();
 676	WARN_ON(init_srcu_struct(&srcu_ctld));
 677	srcu_ctlp = &srcu_ctld;
 678}
 679
 680static void srcu_torture_cleanup(void)
 681{
 682	cleanup_srcu_struct(&srcu_ctld);
 683	srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 684}
 685
 686/* As above, but dynamically allocated. */
 687static struct rcu_torture_ops srcud_ops = {
 688	.ttype		= SRCU_FLAVOR,
 689	.init		= srcu_torture_init,
 690	.cleanup	= srcu_torture_cleanup,
 691	.readlock	= srcu_torture_read_lock,
 692	.read_delay	= srcu_read_delay,
 693	.readunlock	= srcu_torture_read_unlock,
 694	.readlock_held	= torture_srcu_read_lock_held,
 695	.get_gp_seq	= srcu_torture_completed,
 696	.deferred_free	= srcu_torture_deferred_free,
 697	.sync		= srcu_torture_synchronize,
 698	.exp_sync	= srcu_torture_synchronize_expedited,
 699	.call		= srcu_torture_call,
 700	.cb_barrier	= srcu_torture_barrier,
 701	.stats		= srcu_torture_stats,
 702	.irq_capable	= 1,
 703	.name		= "srcud"
 704};
 705
 706/* As above, but broken due to inappropriate reader extension. */
 707static struct rcu_torture_ops busted_srcud_ops = {
 708	.ttype		= SRCU_FLAVOR,
 709	.init		= srcu_torture_init,
 710	.cleanup	= srcu_torture_cleanup,
 711	.readlock	= srcu_torture_read_lock,
 712	.read_delay	= rcu_read_delay,
 713	.readunlock	= srcu_torture_read_unlock,
 714	.readlock_held	= torture_srcu_read_lock_held,
 715	.get_gp_seq	= srcu_torture_completed,
 716	.deferred_free	= srcu_torture_deferred_free,
 717	.sync		= srcu_torture_synchronize,
 718	.exp_sync	= srcu_torture_synchronize_expedited,
 719	.call		= srcu_torture_call,
 720	.cb_barrier	= srcu_torture_barrier,
 721	.stats		= srcu_torture_stats,
 722	.irq_capable	= 1,
 723	.extendables	= RCUTORTURE_MAX_EXTEND,
 724	.name		= "busted_srcud"
 725};
 726
 727/*
 728 * Definitions for RCU-tasks torture testing.
 729 */
 730
 731static int tasks_torture_read_lock(void)
 732{
 
 733	return 0;
 734}
 735
 736static void tasks_torture_read_unlock(int idx)
 737{
 738}
 739
 740static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 741{
 742	call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 743}
 744
 745static void synchronize_rcu_mult_test(void)
 746{
 747	synchronize_rcu_mult(call_rcu_tasks, call_rcu);
 748}
 749
 750static struct rcu_torture_ops tasks_ops = {
 751	.ttype		= RCU_TASKS_FLAVOR,
 752	.init		= rcu_sync_torture_init,
 753	.readlock	= tasks_torture_read_lock,
 754	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
 755	.readunlock	= tasks_torture_read_unlock,
 756	.get_gp_seq	= rcu_no_completed,
 757	.deferred_free	= rcu_tasks_torture_deferred_free,
 758	.sync		= synchronize_rcu_tasks,
 759	.exp_sync	= synchronize_rcu_mult_test,
 760	.call		= call_rcu_tasks,
 761	.cb_barrier	= rcu_barrier_tasks,
 762	.gp_kthread_dbg	= show_rcu_tasks_classic_gp_kthread,
 763	.fqs		= NULL,
 
 
 764	.stats		= NULL,
 765	.irq_capable	= 1,
 766	.slow_gps	= 1,
 767	.name		= "tasks"
 768};
 769
 
 
 770/*
 771 * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 772 * This implementation does not necessarily work well with CPU hotplug.
 773 */
 774
 775static void synchronize_rcu_trivial(void)
 776{
 777	int cpu;
 778
 779	for_each_online_cpu(cpu) {
 780		rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
 781		WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 782	}
 783}
 784
 785static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
 786{
 787	preempt_disable();
 788	return 0;
 789}
 790
 791static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
 792{
 793	preempt_enable();
 794}
 795
 796static struct rcu_torture_ops trivial_ops = {
 797	.ttype		= RCU_TRIVIAL_FLAVOR,
 798	.init		= rcu_sync_torture_init,
 799	.readlock	= rcu_torture_read_lock_trivial,
 800	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
 801	.readunlock	= rcu_torture_read_unlock_trivial,
 802	.readlock_held	= torture_readlock_not_held,
 803	.get_gp_seq	= rcu_no_completed,
 804	.sync		= synchronize_rcu_trivial,
 805	.exp_sync	= synchronize_rcu_trivial,
 806	.fqs		= NULL,
 807	.stats		= NULL,
 808	.irq_capable	= 1,
 809	.name		= "trivial"
 810};
 811
 812/*
 813 * Definitions for rude RCU-tasks torture testing.
 814 */
 815
 816static void rcu_tasks_rude_torture_deferred_free(struct rcu_torture *p)
 817{
 818	call_rcu_tasks_rude(&p->rtort_rcu, rcu_torture_cb);
 819}
 820
 821static struct rcu_torture_ops tasks_rude_ops = {
 822	.ttype		= RCU_TASKS_RUDE_FLAVOR,
 823	.init		= rcu_sync_torture_init,
 824	.readlock	= rcu_torture_read_lock_trivial,
 825	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
 826	.readunlock	= rcu_torture_read_unlock_trivial,
 827	.get_gp_seq	= rcu_no_completed,
 828	.deferred_free	= rcu_tasks_rude_torture_deferred_free,
 829	.sync		= synchronize_rcu_tasks_rude,
 830	.exp_sync	= synchronize_rcu_tasks_rude,
 831	.call		= call_rcu_tasks_rude,
 832	.cb_barrier	= rcu_barrier_tasks_rude,
 833	.gp_kthread_dbg	= show_rcu_tasks_rude_gp_kthread,
 834	.fqs		= NULL,
 835	.stats		= NULL,
 836	.irq_capable	= 1,
 837	.name		= "tasks-rude"
 838};
 839
 840/*
 841 * Definitions for tracing RCU-tasks torture testing.
 842 */
 843
 844static int tasks_tracing_torture_read_lock(void)
 845{
 846	rcu_read_lock_trace();
 847	return 0;
 848}
 849
 850static void tasks_tracing_torture_read_unlock(int idx)
 851{
 852	rcu_read_unlock_trace();
 853}
 854
 855static void rcu_tasks_tracing_torture_deferred_free(struct rcu_torture *p)
 856{
 857	call_rcu_tasks_trace(&p->rtort_rcu, rcu_torture_cb);
 858}
 859
 860static struct rcu_torture_ops tasks_tracing_ops = {
 861	.ttype		= RCU_TASKS_TRACING_FLAVOR,
 862	.init		= rcu_sync_torture_init,
 863	.readlock	= tasks_tracing_torture_read_lock,
 864	.read_delay	= srcu_read_delay,  /* just reuse srcu's version. */
 865	.readunlock	= tasks_tracing_torture_read_unlock,
 866	.readlock_held	= rcu_read_lock_trace_held,
 867	.get_gp_seq	= rcu_no_completed,
 868	.deferred_free	= rcu_tasks_tracing_torture_deferred_free,
 869	.sync		= synchronize_rcu_tasks_trace,
 870	.exp_sync	= synchronize_rcu_tasks_trace,
 871	.call		= call_rcu_tasks_trace,
 872	.cb_barrier	= rcu_barrier_tasks_trace,
 873	.gp_kthread_dbg	= show_rcu_tasks_trace_gp_kthread,
 874	.fqs		= NULL,
 875	.stats		= NULL,
 876	.irq_capable	= 1,
 877	.slow_gps	= 1,
 878	.name		= "tasks-tracing"
 879};
 880
 881static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 882{
 883	if (!cur_ops->gp_diff)
 884		return new - old;
 885	return cur_ops->gp_diff(new, old);
 886}
 887
 
 
 888/*
 889 * RCU torture priority-boost testing.  Runs one real-time thread per
 890 * CPU for moderate bursts, repeatedly starting grace periods and waiting
 891 * for them to complete.  If a given grace period takes too long, we assume
 892 * that priority inversion has occurred.
 893 */
 894
 895static int old_rt_runtime = -1;
 896
 897static void rcu_torture_disable_rt_throttle(void)
 898{
 899	/*
 900	 * Disable RT throttling so that rcutorture's boost threads don't get
 901	 * throttled. Only possible if rcutorture is built-in otherwise the
 902	 * user should manually do this by setting the sched_rt_period_us and
 903	 * sched_rt_runtime sysctls.
 904	 */
 905	if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 906		return;
 907
 908	old_rt_runtime = sysctl_sched_rt_runtime;
 909	sysctl_sched_rt_runtime = -1;
 910}
 911
 912static void rcu_torture_enable_rt_throttle(void)
 913{
 914	if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 915		return;
 916
 917	sysctl_sched_rt_runtime = old_rt_runtime;
 918	old_rt_runtime = -1;
 919}
 920
 921static bool rcu_torture_boost_failed(unsigned long gp_state, unsigned long *start)
 922{
 923	int cpu;
 924	static int dbg_done;
 925	unsigned long end = jiffies;
 926	bool gp_done;
 927	unsigned long j;
 928	static unsigned long last_persist;
 929	unsigned long lp;
 930	unsigned long mininterval = test_boost_duration * HZ - HZ / 2;
 931
 932	if (end - *start > mininterval) {
 933		// Recheck after checking time to avoid false positives.
 934		smp_mb(); // Time check before grace-period check.
 935		if (cur_ops->poll_gp_state(gp_state))
 936			return false; // passed, though perhaps just barely
 937		if (cur_ops->check_boost_failed && !cur_ops->check_boost_failed(gp_state, &cpu)) {
 938			// At most one persisted message per boost test.
 939			j = jiffies;
 940			lp = READ_ONCE(last_persist);
 941			if (time_after(j, lp + mininterval) && cmpxchg(&last_persist, lp, j) == lp)
 942				pr_info("Boost inversion persisted: No QS from CPU %d\n", cpu);
 943			return false; // passed on a technicality
 944		}
 945		VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 946		n_rcu_torture_boost_failure++;
 947		if (!xchg(&dbg_done, 1) && cur_ops->gp_kthread_dbg) {
 948			pr_info("Boost inversion thread ->rt_priority %u gp_state %lu jiffies %lu\n",
 949				current->rt_priority, gp_state, end - *start);
 950			cur_ops->gp_kthread_dbg();
 951			// Recheck after print to flag grace period ending during splat.
 952			gp_done = cur_ops->poll_gp_state(gp_state);
 953			pr_info("Boost inversion: GP %lu %s.\n", gp_state,
 954				gp_done ? "ended already" : "still pending");
 955
 956		}
 957
 958		return true; // failed
 959	} else if (cur_ops->check_boost_failed && !cur_ops->check_boost_failed(gp_state, NULL)) {
 960		*start = jiffies;
 961	}
 962
 963	return false; // passed
 
 964}
 965
 966static int rcu_torture_boost(void *arg)
 967{
 
 968	unsigned long endtime;
 969	unsigned long gp_state;
 970	unsigned long gp_state_time;
 971	unsigned long oldstarttime;
 
 
 972
 973	VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 974
 975	/* Set real-time priority. */
 976	sched_set_fifo_low(current);
 
 
 
 
 977
 
 978	/* Each pass through the following loop does one boost-test cycle. */
 979	do {
 980		bool failed = false; // Test failed already in this test interval
 981		bool gp_initiated = false;
 982
 983		if (kthread_should_stop())
 984			goto checkwait;
 985
 986		/* Wait for the next test interval. */
 987		oldstarttime = boost_starttime;
 988		while (time_before(jiffies, oldstarttime)) {
 989			schedule_timeout_interruptible(oldstarttime - jiffies);
 990			if (stutter_wait("rcu_torture_boost"))
 991				sched_set_fifo_low(current);
 992			if (torture_must_stop())
 993				goto checkwait;
 994		}
 995
 996		// Do one boost-test interval.
 997		endtime = oldstarttime + test_boost_duration * HZ;
 998		while (time_before(jiffies, endtime)) {
 999			// Has current GP gone too long?
1000			if (gp_initiated && !failed && !cur_ops->poll_gp_state(gp_state))
1001				failed = rcu_torture_boost_failed(gp_state, &gp_state_time);
1002			// If we don't have a grace period in flight, start one.
1003			if (!gp_initiated || cur_ops->poll_gp_state(gp_state)) {
1004				gp_state = cur_ops->start_gp_poll();
1005				gp_initiated = true;
1006				gp_state_time = jiffies;
1007			}
1008			if (stutter_wait("rcu_torture_boost")) {
1009				sched_set_fifo_low(current);
1010				// If the grace period already ended,
1011				// we don't know when that happened, so
1012				// start over.
1013				if (cur_ops->poll_gp_state(gp_state))
1014					gp_initiated = false;
1015			}
 
1016			if (torture_must_stop())
1017				goto checkwait;
1018		}
1019
1020		// In case the grace period extended beyond the end of the loop.
1021		if (gp_initiated && !failed && !cur_ops->poll_gp_state(gp_state))
1022			rcu_torture_boost_failed(gp_state, &gp_state_time);
1023
1024		/*
1025		 * Set the start time of the next test interval.
1026		 * Yes, this is vulnerable to long delays, but such
1027		 * delays simply cause a false negative for the next
1028		 * interval.  Besides, we are running at RT priority,
1029		 * so delays should be relatively rare.
1030		 */
1031		while (oldstarttime == boost_starttime && !kthread_should_stop()) {
 
1032			if (mutex_trylock(&boost_mutex)) {
1033				if (oldstarttime == boost_starttime) {
1034					boost_starttime = jiffies + test_boost_interval * HZ;
1035					n_rcu_torture_boosts++;
1036				}
1037				mutex_unlock(&boost_mutex);
1038				break;
1039			}
1040			schedule_timeout_uninterruptible(1);
1041		}
1042
1043		/* Go do the stutter. */
1044checkwait:	if (stutter_wait("rcu_torture_boost"))
1045			sched_set_fifo_low(current);
1046	} while (!torture_must_stop());
1047
1048	/* Clean up and exit. */
1049	while (!kthread_should_stop()) {
1050		torture_shutdown_absorb("rcu_torture_boost");
1051		schedule_timeout_uninterruptible(1);
1052	}
 
1053	torture_kthread_stopping("rcu_torture_boost");
1054	return 0;
1055}
1056
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1057/*
1058 * RCU torture force-quiescent-state kthread.  Repeatedly induces
1059 * bursts of calls to force_quiescent_state(), increasing the probability
1060 * of occurrence of some important types of race conditions.
1061 */
1062static int
1063rcu_torture_fqs(void *arg)
1064{
1065	unsigned long fqs_resume_time;
1066	int fqs_burst_remaining;
1067	int oldnice = task_nice(current);
1068
1069	VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
1070	do {
1071		fqs_resume_time = jiffies + fqs_stutter * HZ;
1072		while (time_before(jiffies, fqs_resume_time) &&
1073		       !kthread_should_stop()) {
1074			schedule_timeout_interruptible(1);
1075		}
1076		fqs_burst_remaining = fqs_duration;
1077		while (fqs_burst_remaining > 0 &&
1078		       !kthread_should_stop()) {
1079			cur_ops->fqs();
1080			udelay(fqs_holdoff);
1081			fqs_burst_remaining -= fqs_holdoff;
1082		}
1083		if (stutter_wait("rcu_torture_fqs"))
1084			sched_set_normal(current, oldnice);
1085	} while (!torture_must_stop());
1086	torture_kthread_stopping("rcu_torture_fqs");
1087	return 0;
1088}
1089
1090// Used by writers to randomly choose from the available grace-period
1091// primitives.  The only purpose of the initialization is to size the array.
1092static int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC, RTWS_COND_GET, RTWS_POLL_GET, RTWS_SYNC };
1093static int nsynctypes;
1094
1095/*
1096 * Determine which grace-period primitives are available.
1097 */
1098static void rcu_torture_write_types(void)
1099{
1100	bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
1101	bool gp_poll1 = gp_poll, gp_sync1 = gp_sync;
1102
1103	/* Initialize synctype[] array.  If none set, take default. */
1104	if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_poll1 && !gp_sync1)
1105		gp_cond1 = gp_exp1 = gp_normal1 = gp_poll1 = gp_sync1 = true;
1106	if (gp_cond1 && cur_ops->get_gp_state && cur_ops->cond_sync) {
1107		synctype[nsynctypes++] = RTWS_COND_GET;
1108		pr_info("%s: Testing conditional GPs.\n", __func__);
1109	} else if (gp_cond && (!cur_ops->get_gp_state || !cur_ops->cond_sync)) {
1110		pr_alert("%s: gp_cond without primitives.\n", __func__);
1111	}
1112	if (gp_exp1 && cur_ops->exp_sync) {
1113		synctype[nsynctypes++] = RTWS_EXP_SYNC;
1114		pr_info("%s: Testing expedited GPs.\n", __func__);
1115	} else if (gp_exp && !cur_ops->exp_sync) {
1116		pr_alert("%s: gp_exp without primitives.\n", __func__);
1117	}
1118	if (gp_normal1 && cur_ops->deferred_free) {
1119		synctype[nsynctypes++] = RTWS_DEF_FREE;
1120		pr_info("%s: Testing asynchronous GPs.\n", __func__);
1121	} else if (gp_normal && !cur_ops->deferred_free) {
1122		pr_alert("%s: gp_normal without primitives.\n", __func__);
1123	}
1124	if (gp_poll1 && cur_ops->start_gp_poll && cur_ops->poll_gp_state) {
1125		synctype[nsynctypes++] = RTWS_POLL_GET;
1126		pr_info("%s: Testing polling GPs.\n", __func__);
1127	} else if (gp_poll && (!cur_ops->start_gp_poll || !cur_ops->poll_gp_state)) {
1128		pr_alert("%s: gp_poll without primitives.\n", __func__);
1129	}
1130	if (gp_sync1 && cur_ops->sync) {
1131		synctype[nsynctypes++] = RTWS_SYNC;
1132		pr_info("%s: Testing normal GPs.\n", __func__);
1133	} else if (gp_sync && !cur_ops->sync) {
1134		pr_alert("%s: gp_sync without primitives.\n", __func__);
1135	}
1136}
1137
1138/*
1139 * RCU torture writer kthread.  Repeatedly substitutes a new structure
1140 * for that pointed to by rcu_torture_current, freeing the old structure
1141 * after a series of grace periods (the "pipeline").
1142 */
1143static int
1144rcu_torture_writer(void *arg)
1145{
1146	bool boot_ended;
1147	bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
1148	unsigned long cookie;
1149	int expediting = 0;
1150	unsigned long gp_snap;
 
 
1151	int i;
1152	int idx;
1153	int oldnice = task_nice(current);
1154	struct rcu_torture *rp;
1155	struct rcu_torture *old_rp;
1156	static DEFINE_TORTURE_RANDOM(rand);
1157	bool stutter_waited;
 
 
1158
1159	VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
1160	if (!can_expedite)
1161		pr_alert("%s" TORTURE_FLAG
1162			 " GP expediting controlled from boot/sysfs for %s.\n",
1163			 torture_type, cur_ops->name);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1164	if (WARN_ONCE(nsynctypes == 0,
1165		      "rcu_torture_writer: No update-side primitives.\n")) {
1166		/*
1167		 * No updates primitives, so don't try updating.
1168		 * The resulting test won't be testing much, hence the
1169		 * above WARN_ONCE().
1170		 */
1171		rcu_torture_writer_state = RTWS_STOPPING;
1172		torture_kthread_stopping("rcu_torture_writer");
1173	}
1174
1175	do {
1176		rcu_torture_writer_state = RTWS_FIXED_DELAY;
1177		torture_hrtimeout_us(500, 1000, &rand);
1178		rp = rcu_torture_alloc();
1179		if (rp == NULL)
1180			continue;
1181		rp->rtort_pipe_count = 0;
1182		rcu_torture_writer_state = RTWS_DELAY;
1183		udelay(torture_random(&rand) & 0x3ff);
1184		rcu_torture_writer_state = RTWS_REPLACE;
1185		old_rp = rcu_dereference_check(rcu_torture_current,
1186					       current == writer_task);
1187		rp->rtort_mbtest = 1;
1188		rcu_assign_pointer(rcu_torture_current, rp);
1189		smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1190		if (old_rp) {
1191			i = old_rp->rtort_pipe_count;
1192			if (i > RCU_TORTURE_PIPE_LEN)
1193				i = RCU_TORTURE_PIPE_LEN;
1194			atomic_inc(&rcu_torture_wcount[i]);
1195			WRITE_ONCE(old_rp->rtort_pipe_count,
1196				   old_rp->rtort_pipe_count + 1);
1197			if (cur_ops->get_gp_state && cur_ops->poll_gp_state) {
1198				idx = cur_ops->readlock();
1199				cookie = cur_ops->get_gp_state();
1200				WARN_ONCE(rcu_torture_writer_state != RTWS_DEF_FREE &&
1201					  cur_ops->poll_gp_state(cookie),
1202					  "%s: Cookie check 1 failed %s(%d) %lu->%lu\n",
1203					  __func__,
1204					  rcu_torture_writer_state_getname(),
1205					  rcu_torture_writer_state,
1206					  cookie, cur_ops->get_gp_state());
1207				cur_ops->readunlock(idx);
1208			}
1209			switch (synctype[torture_random(&rand) % nsynctypes]) {
1210			case RTWS_DEF_FREE:
1211				rcu_torture_writer_state = RTWS_DEF_FREE;
1212				cur_ops->deferred_free(old_rp);
1213				break;
1214			case RTWS_EXP_SYNC:
1215				rcu_torture_writer_state = RTWS_EXP_SYNC;
1216				cur_ops->exp_sync();
1217				rcu_torture_pipe_update(old_rp);
1218				break;
1219			case RTWS_COND_GET:
1220				rcu_torture_writer_state = RTWS_COND_GET;
1221				gp_snap = cur_ops->get_gp_state();
1222				torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
 
 
 
1223				rcu_torture_writer_state = RTWS_COND_SYNC;
1224				cur_ops->cond_sync(gp_snap);
1225				rcu_torture_pipe_update(old_rp);
1226				break;
1227			case RTWS_POLL_GET:
1228				rcu_torture_writer_state = RTWS_POLL_GET;
1229				gp_snap = cur_ops->start_gp_poll();
1230				rcu_torture_writer_state = RTWS_POLL_WAIT;
1231				while (!cur_ops->poll_gp_state(gp_snap))
1232					torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1233								  &rand);
1234				rcu_torture_pipe_update(old_rp);
1235				break;
1236			case RTWS_SYNC:
1237				rcu_torture_writer_state = RTWS_SYNC;
1238				cur_ops->sync();
1239				rcu_torture_pipe_update(old_rp);
1240				break;
1241			default:
1242				WARN_ON_ONCE(1);
1243				break;
1244			}
1245		}
1246		WRITE_ONCE(rcu_torture_current_version,
1247			   rcu_torture_current_version + 1);
1248		/* Cycle through nesting levels of rcu_expedite_gp() calls. */
1249		if (can_expedite &&
1250		    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1251			WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1252			if (expediting >= 0)
1253				rcu_expedite_gp();
1254			else
1255				rcu_unexpedite_gp();
1256			if (++expediting > 3)
1257				expediting = -expediting;
1258		} else if (!can_expedite) { /* Disabled during boot, recheck. */
1259			can_expedite = !rcu_gp_is_expedited() &&
1260				       !rcu_gp_is_normal();
1261		}
1262		rcu_torture_writer_state = RTWS_STUTTER;
1263		boot_ended = rcu_inkernel_boot_has_ended();
1264		stutter_waited = stutter_wait("rcu_torture_writer");
1265		if (stutter_waited &&
1266		    !READ_ONCE(rcu_fwd_cb_nodelay) &&
1267		    !cur_ops->slow_gps &&
1268		    !torture_must_stop() &&
1269		    boot_ended)
1270			for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1271				if (list_empty(&rcu_tortures[i].rtort_free) &&
1272				    rcu_access_pointer(rcu_torture_current) !=
1273				    &rcu_tortures[i]) {
1274					rcu_ftrace_dump(DUMP_ALL);
1275					WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
1276				}
1277		if (stutter_waited)
1278			sched_set_normal(current, oldnice);
1279	} while (!torture_must_stop());
1280	rcu_torture_current = NULL;  // Let stats task know that we are done.
1281	/* Reset expediting back to unexpedited. */
1282	if (expediting > 0)
1283		expediting = -expediting;
1284	while (can_expedite && expediting++ < 0)
1285		rcu_unexpedite_gp();
1286	WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1287	if (!can_expedite)
1288		pr_alert("%s" TORTURE_FLAG
1289			 " Dynamic grace-period expediting was disabled.\n",
1290			 torture_type);
1291	rcu_torture_writer_state = RTWS_STOPPING;
1292	torture_kthread_stopping("rcu_torture_writer");
1293	return 0;
1294}
1295
1296/*
1297 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1298 * delay between calls.
1299 */
1300static int
1301rcu_torture_fakewriter(void *arg)
1302{
1303	unsigned long gp_snap;
1304	DEFINE_TORTURE_RANDOM(rand);
1305
1306	VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1307	set_user_nice(current, MAX_NICE);
1308
1309	do {
1310		torture_hrtimeout_jiffies(torture_random(&rand) % 10, &rand);
 
1311		if (cur_ops->cb_barrier != NULL &&
1312		    torture_random(&rand) % (nfakewriters * 8) == 0) {
1313			cur_ops->cb_barrier();
1314		} else {
1315			switch (synctype[torture_random(&rand) % nsynctypes]) {
1316			case RTWS_DEF_FREE:
1317				break;
1318			case RTWS_EXP_SYNC:
1319				cur_ops->exp_sync();
1320				break;
1321			case RTWS_COND_GET:
1322				gp_snap = cur_ops->get_gp_state();
1323				torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1324				cur_ops->cond_sync(gp_snap);
1325				break;
1326			case RTWS_POLL_GET:
1327				gp_snap = cur_ops->start_gp_poll();
1328				while (!cur_ops->poll_gp_state(gp_snap)) {
1329					torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1330								  &rand);
1331				}
1332				break;
1333			case RTWS_SYNC:
1334				cur_ops->sync();
1335				break;
1336			default:
1337				WARN_ON_ONCE(1);
1338				break;
1339			}
 
1340		}
1341		stutter_wait("rcu_torture_fakewriter");
1342	} while (!torture_must_stop());
1343
1344	torture_kthread_stopping("rcu_torture_fakewriter");
1345	return 0;
1346}
1347
1348static void rcu_torture_timer_cb(struct rcu_head *rhp)
1349{
1350	kfree(rhp);
1351}
1352
1353// Set up and carry out testing of RCU's global memory ordering
1354static void rcu_torture_reader_do_mbchk(long myid, struct rcu_torture *rtp,
1355					struct torture_random_state *trsp)
1356{
1357	unsigned long loops;
1358	int noc = torture_num_online_cpus();
1359	int rdrchked;
1360	int rdrchker;
1361	struct rcu_torture_reader_check *rtrcp; // Me.
1362	struct rcu_torture_reader_check *rtrcp_assigner; // Assigned us to do checking.
1363	struct rcu_torture_reader_check *rtrcp_chked; // Reader being checked.
1364	struct rcu_torture_reader_check *rtrcp_chker; // Reader doing checking when not me.
1365
1366	if (myid < 0)
1367		return; // Don't try this from timer handlers.
1368
1369	// Increment my counter.
1370	rtrcp = &rcu_torture_reader_mbchk[myid];
1371	WRITE_ONCE(rtrcp->rtc_myloops, rtrcp->rtc_myloops + 1);
1372
1373	// Attempt to assign someone else some checking work.
1374	rdrchked = torture_random(trsp) % nrealreaders;
1375	rtrcp_chked = &rcu_torture_reader_mbchk[rdrchked];
1376	rdrchker = torture_random(trsp) % nrealreaders;
1377	rtrcp_chker = &rcu_torture_reader_mbchk[rdrchker];
1378	if (rdrchked != myid && rdrchked != rdrchker && noc >= rdrchked && noc >= rdrchker &&
1379	    smp_load_acquire(&rtrcp->rtc_chkrdr) < 0 && // Pairs with smp_store_release below.
1380	    !READ_ONCE(rtp->rtort_chkp) &&
1381	    !smp_load_acquire(&rtrcp_chker->rtc_assigner)) { // Pairs with smp_store_release below.
1382		rtrcp->rtc_chkloops = READ_ONCE(rtrcp_chked->rtc_myloops);
1383		WARN_ON_ONCE(rtrcp->rtc_chkrdr >= 0);
1384		rtrcp->rtc_chkrdr = rdrchked;
1385		WARN_ON_ONCE(rtrcp->rtc_ready); // This gets set after the grace period ends.
1386		if (cmpxchg_relaxed(&rtrcp_chker->rtc_assigner, NULL, rtrcp) ||
1387		    cmpxchg_relaxed(&rtp->rtort_chkp, NULL, rtrcp))
1388			(void)cmpxchg_relaxed(&rtrcp_chker->rtc_assigner, rtrcp, NULL); // Back out.
1389	}
1390
1391	// If assigned some completed work, do it!
1392	rtrcp_assigner = READ_ONCE(rtrcp->rtc_assigner);
1393	if (!rtrcp_assigner || !smp_load_acquire(&rtrcp_assigner->rtc_ready))
1394		return; // No work or work not yet ready.
1395	rdrchked = rtrcp_assigner->rtc_chkrdr;
1396	if (WARN_ON_ONCE(rdrchked < 0))
1397		return;
1398	rtrcp_chked = &rcu_torture_reader_mbchk[rdrchked];
1399	loops = READ_ONCE(rtrcp_chked->rtc_myloops);
1400	atomic_inc(&n_rcu_torture_mbchk_tries);
1401	if (ULONG_CMP_LT(loops, rtrcp_assigner->rtc_chkloops))
1402		atomic_inc(&n_rcu_torture_mbchk_fail);
1403	rtrcp_assigner->rtc_chkloops = loops + ULONG_MAX / 2;
1404	rtrcp_assigner->rtc_ready = 0;
1405	smp_store_release(&rtrcp->rtc_assigner, NULL); // Someone else can assign us work.
1406	smp_store_release(&rtrcp_assigner->rtc_chkrdr, -1); // Assigner can again assign.
1407}
1408
1409/*
1410 * Do one extension of an RCU read-side critical section using the
1411 * current reader state in readstate (set to zero for initial entry
1412 * to extended critical section), set the new state as specified by
1413 * newstate (set to zero for final exit from extended critical section),
1414 * and random-number-generator state in trsp.  If this is neither the
1415 * beginning or end of the critical section and if there was actually a
1416 * change, do a ->read_delay().
1417 */
1418static void rcutorture_one_extend(int *readstate, int newstate,
1419				  struct torture_random_state *trsp,
1420				  struct rt_read_seg *rtrsp)
1421{
1422	unsigned long flags;
1423	int idxnew = -1;
1424	int idxold = *readstate;
1425	int statesnew = ~*readstate & newstate;
1426	int statesold = *readstate & ~newstate;
1427
1428	WARN_ON_ONCE(idxold < 0);
1429	WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1430	rtrsp->rt_readstate = newstate;
1431
1432	/* First, put new protection in place to avoid critical-section gap. */
1433	if (statesnew & RCUTORTURE_RDR_BH)
1434		local_bh_disable();
1435	if (statesnew & RCUTORTURE_RDR_IRQ)
1436		local_irq_disable();
1437	if (statesnew & RCUTORTURE_RDR_PREEMPT)
1438		preempt_disable();
1439	if (statesnew & RCUTORTURE_RDR_RBH)
1440		rcu_read_lock_bh();
1441	if (statesnew & RCUTORTURE_RDR_SCHED)
1442		rcu_read_lock_sched();
1443	if (statesnew & RCUTORTURE_RDR_RCU)
1444		idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1445
1446	/* Next, remove old protection, irq first due to bh conflict. */
1447	if (statesold & RCUTORTURE_RDR_IRQ)
1448		local_irq_enable();
1449	if (statesold & RCUTORTURE_RDR_BH)
1450		local_bh_enable();
1451	if (statesold & RCUTORTURE_RDR_PREEMPT)
1452		preempt_enable();
1453	if (statesold & RCUTORTURE_RDR_RBH)
1454		rcu_read_unlock_bh();
1455	if (statesold & RCUTORTURE_RDR_SCHED)
1456		rcu_read_unlock_sched();
1457	if (statesold & RCUTORTURE_RDR_RCU) {
1458		bool lockit = !statesnew && !(torture_random(trsp) & 0xffff);
1459
1460		if (lockit)
1461			raw_spin_lock_irqsave(&current->pi_lock, flags);
1462		cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1463		if (lockit)
1464			raw_spin_unlock_irqrestore(&current->pi_lock, flags);
1465	}
1466
1467	/* Delay if neither beginning nor end and there was a change. */
1468	if ((statesnew || statesold) && *readstate && newstate)
1469		cur_ops->read_delay(trsp, rtrsp);
1470
1471	/* Update the reader state. */
1472	if (idxnew == -1)
1473		idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1474	WARN_ON_ONCE(idxnew < 0);
1475	WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1476	*readstate = idxnew | newstate;
1477	WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1478	WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1479}
1480
1481/* Return the biggest extendables mask given current RCU and boot parameters. */
1482static int rcutorture_extend_mask_max(void)
1483{
1484	int mask;
1485
1486	WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1487	mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1488	mask = mask | RCUTORTURE_RDR_RCU;
1489	return mask;
1490}
1491
1492/* Return a random protection state mask, but with at least one bit set. */
1493static int
1494rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1495{
1496	int mask = rcutorture_extend_mask_max();
1497	unsigned long randmask1 = torture_random(trsp) >> 8;
1498	unsigned long randmask2 = randmask1 >> 3;
1499
1500	WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1501	/* Mostly only one bit (need preemption!), sometimes lots of bits. */
1502	if (!(randmask1 & 0x7))
1503		mask = mask & randmask2;
1504	else
1505		mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1506	/* Can't enable bh w/irq disabled. */
1507	if ((mask & RCUTORTURE_RDR_IRQ) &&
1508	    ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1509	     (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1510		mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1511	return mask ?: RCUTORTURE_RDR_RCU;
1512}
1513
1514/*
1515 * Do a randomly selected number of extensions of an existing RCU read-side
1516 * critical section.
1517 */
1518static struct rt_read_seg *
1519rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1520		       struct rt_read_seg *rtrsp)
1521{
1522	int i;
1523	int j;
1524	int mask = rcutorture_extend_mask_max();
1525
1526	WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1527	if (!((mask - 1) & mask))
1528		return rtrsp;  /* Current RCU reader not extendable. */
1529	/* Bias towards larger numbers of loops. */
1530	i = (torture_random(trsp) >> 3);
1531	i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1532	for (j = 0; j < i; j++) {
1533		mask = rcutorture_extend_mask(*readstate, trsp);
1534		rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1535	}
1536	return &rtrsp[j];
1537}
1538
1539/*
1540 * Do one read-side critical section, returning false if there was
1541 * no data to read.  Can be invoked both from process context and
1542 * from a timer handler.
 
1543 */
1544static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
1545{
1546	unsigned long cookie;
1547	int i;
1548	unsigned long started;
1549	unsigned long completed;
1550	int newstate;
 
1551	struct rcu_torture *p;
1552	int pipe_count;
1553	int readstate = 0;
1554	struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1555	struct rt_read_seg *rtrsp = &rtseg[0];
1556	struct rt_read_seg *rtrsp1;
1557	unsigned long long ts;
1558
1559	WARN_ON_ONCE(!rcu_is_watching());
1560	newstate = rcutorture_extend_mask(readstate, trsp);
1561	rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1562	if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
1563		cookie = cur_ops->get_gp_state();
1564	started = cur_ops->get_gp_seq();
1565	ts = rcu_trace_clock_local();
1566	p = rcu_dereference_check(rcu_torture_current,
1567				  !cur_ops->readlock_held || cur_ops->readlock_held());
 
 
 
1568	if (p == NULL) {
1569		/* Wait for rcu_torture_writer to get underway */
1570		rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1571		return false;
1572	}
1573	if (p->rtort_mbtest == 0)
1574		atomic_inc(&n_rcu_torture_mberror);
1575	rcu_torture_reader_do_mbchk(myid, p, trsp);
1576	rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
 
 
1577	preempt_disable();
1578	pipe_count = READ_ONCE(p->rtort_pipe_count);
1579	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1580		/* Should not happen, but... */
1581		pipe_count = RCU_TORTURE_PIPE_LEN;
1582	}
1583	completed = cur_ops->get_gp_seq();
1584	if (pipe_count > 1) {
1585		do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1586					  ts, started, completed);
1587		rcu_ftrace_dump(DUMP_ALL);
1588	}
1589	__this_cpu_inc(rcu_torture_count[pipe_count]);
1590	completed = rcutorture_seq_diff(completed, started);
 
 
1591	if (completed > RCU_TORTURE_PIPE_LEN) {
1592		/* Should not happen, but... */
1593		completed = RCU_TORTURE_PIPE_LEN;
1594	}
1595	__this_cpu_inc(rcu_torture_batch[completed]);
1596	preempt_enable();
1597	if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
1598		WARN_ONCE(cur_ops->poll_gp_state(cookie),
1599			  "%s: Cookie check 2 failed %s(%d) %lu->%lu\n",
1600			  __func__,
1601			  rcu_torture_writer_state_getname(),
1602			  rcu_torture_writer_state,
1603			  cookie, cur_ops->get_gp_state());
1604	rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1605	WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1606	// This next splat is expected behavior if leakpointer, especially
1607	// for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.
1608	WARN_ON_ONCE(leakpointer && READ_ONCE(p->rtort_pipe_count) > 1);
1609
1610	/* If error or close call, record the sequence of reader protections. */
1611	if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1612		i = 0;
1613		for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1614			err_segs[i++] = *rtrsp1;
1615		rt_read_nsegs = i;
1616	}
1617
1618	return true;
1619}
1620
1621static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1622
1623/*
1624 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1625 * incrementing the corresponding element of the pipeline array.  The
1626 * counter in the element should never be greater than 1, otherwise, the
1627 * RCU implementation is broken.
1628 */
1629static void rcu_torture_timer(struct timer_list *unused)
1630{
1631	atomic_long_inc(&n_rcu_torture_timers);
1632	(void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand), -1);
1633
1634	/* Test call_rcu() invocation from interrupt handler. */
1635	if (cur_ops->call) {
1636		struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1637
1638		if (rhp)
1639			cur_ops->call(rhp, rcu_torture_timer_cb);
1640	}
1641}
1642
1643/*
1644 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1645 * incrementing the corresponding element of the pipeline array.  The
1646 * counter in the element should never be greater than 1, otherwise, the
1647 * RCU implementation is broken.
1648 */
1649static int
1650rcu_torture_reader(void *arg)
1651{
1652	unsigned long lastsleep = jiffies;
1653	long myid = (long)arg;
1654	int mynumonline = myid;
1655	DEFINE_TORTURE_RANDOM(rand);
 
 
1656	struct timer_list t;
 
1657
1658	VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1659	set_user_nice(current, MAX_NICE);
1660	if (irqreader && cur_ops->irq_capable)
1661		timer_setup_on_stack(&t, rcu_torture_timer, 0);
1662	tick_dep_set_task(current, TICK_DEP_BIT_RCU);
1663	do {
1664		if (irqreader && cur_ops->irq_capable) {
1665			if (!timer_pending(&t))
1666				mod_timer(&t, jiffies + 1);
1667		}
1668		if (!rcu_torture_one_read(&rand, myid) && !torture_must_stop())
 
 
 
 
 
 
 
 
 
 
 
 
 
1669			schedule_timeout_interruptible(HZ);
1670		if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
1671			torture_hrtimeout_us(500, 1000, &rand);
1672			lastsleep = jiffies + 10;
1673		}
1674		while (torture_num_online_cpus() < mynumonline && !torture_must_stop())
1675			schedule_timeout_interruptible(HZ / 5);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1676		stutter_wait("rcu_torture_reader");
1677	} while (!torture_must_stop());
1678	if (irqreader && cur_ops->irq_capable) {
1679		del_timer_sync(&t);
1680		destroy_timer_on_stack(&t);
1681	}
1682	tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
1683	torture_kthread_stopping("rcu_torture_reader");
1684	return 0;
1685}
1686
1687/*
1688 * Randomly Toggle CPUs' callback-offload state.  This uses hrtimers to
1689 * increase race probabilities and fuzzes the interval between toggling.
1690 */
1691static int rcu_nocb_toggle(void *arg)
1692{
1693	int cpu;
1694	int maxcpu = -1;
1695	int oldnice = task_nice(current);
1696	long r;
1697	DEFINE_TORTURE_RANDOM(rand);
1698	ktime_t toggle_delay;
1699	unsigned long toggle_fuzz;
1700	ktime_t toggle_interval = ms_to_ktime(nocbs_toggle);
1701
1702	VERBOSE_TOROUT_STRING("rcu_nocb_toggle task started");
1703	while (!rcu_inkernel_boot_has_ended())
1704		schedule_timeout_interruptible(HZ / 10);
1705	for_each_online_cpu(cpu)
1706		maxcpu = cpu;
1707	WARN_ON(maxcpu < 0);
1708	if (toggle_interval > ULONG_MAX)
1709		toggle_fuzz = ULONG_MAX >> 3;
1710	else
1711		toggle_fuzz = toggle_interval >> 3;
1712	if (toggle_fuzz <= 0)
1713		toggle_fuzz = NSEC_PER_USEC;
1714	do {
1715		r = torture_random(&rand);
1716		cpu = (r >> 4) % (maxcpu + 1);
1717		if (r & 0x1) {
1718			rcu_nocb_cpu_offload(cpu);
1719			atomic_long_inc(&n_nocb_offload);
1720		} else {
1721			rcu_nocb_cpu_deoffload(cpu);
1722			atomic_long_inc(&n_nocb_deoffload);
1723		}
1724		toggle_delay = torture_random(&rand) % toggle_fuzz + toggle_interval;
1725		set_current_state(TASK_INTERRUPTIBLE);
1726		schedule_hrtimeout(&toggle_delay, HRTIMER_MODE_REL);
1727		if (stutter_wait("rcu_nocb_toggle"))
1728			sched_set_normal(current, oldnice);
1729	} while (!torture_must_stop());
1730	torture_kthread_stopping("rcu_nocb_toggle");
1731	return 0;
1732}
1733
1734/*
1735 * Print torture statistics.  Caller must ensure that there is only
1736 * one call to this function at a given time!!!  This is normally
1737 * accomplished by relying on the module system to only have one copy
1738 * of the module loaded, and then by giving the rcu_torture_stats
1739 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1740 * thread is not running).
1741 */
1742static void
1743rcu_torture_stats_print(void)
1744{
1745	int cpu;
1746	int i;
1747	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1748	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1749	struct rcu_torture *rtcp;
1750	static unsigned long rtcv_snap = ULONG_MAX;
1751	static bool splatted;
1752	struct task_struct *wtp;
1753
1754	for_each_possible_cpu(cpu) {
1755		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1756			pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]);
1757			batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]);
1758		}
1759	}
1760	for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1761		if (pipesummary[i] != 0)
1762			break;
1763	}
1764
1765	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1766	rtcp = rcu_access_pointer(rcu_torture_current);
1767	pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1768		rtcp,
1769		rtcp && !rcu_stall_is_suppressed_at_boot() ? "ver" : "VER",
1770		rcu_torture_current_version,
1771		list_empty(&rcu_torture_freelist),
1772		atomic_read(&n_rcu_torture_alloc),
1773		atomic_read(&n_rcu_torture_alloc_fail),
1774		atomic_read(&n_rcu_torture_free));
1775	pr_cont("rtmbe: %d rtmbkf: %d/%d rtbe: %ld rtbke: %ld rtbre: %ld ",
1776		atomic_read(&n_rcu_torture_mberror),
1777		atomic_read(&n_rcu_torture_mbchk_fail), atomic_read(&n_rcu_torture_mbchk_tries),
1778		n_rcu_torture_barrier_error,
1779		n_rcu_torture_boost_ktrerror,
1780		n_rcu_torture_boost_rterror);
1781	pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1782		n_rcu_torture_boost_failure,
1783		n_rcu_torture_boosts,
1784		atomic_long_read(&n_rcu_torture_timers));
1785	torture_onoff_stats();
1786	pr_cont("barrier: %ld/%ld:%ld ",
1787		data_race(n_barrier_successes),
1788		data_race(n_barrier_attempts),
1789		data_race(n_rcu_torture_barrier_error));
1790	pr_cont("read-exits: %ld ", data_race(n_read_exits)); // Statistic.
1791	pr_cont("nocb-toggles: %ld:%ld\n",
1792		atomic_long_read(&n_nocb_offload), atomic_long_read(&n_nocb_deoffload));
1793
1794	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1795	if (atomic_read(&n_rcu_torture_mberror) ||
1796	    atomic_read(&n_rcu_torture_mbchk_fail) ||
1797	    n_rcu_torture_barrier_error || n_rcu_torture_boost_ktrerror ||
1798	    n_rcu_torture_boost_rterror || n_rcu_torture_boost_failure ||
 
1799	    i > 1) {
1800		pr_cont("%s", "!!! ");
1801		atomic_inc(&n_rcu_torture_error);
1802		WARN_ON_ONCE(atomic_read(&n_rcu_torture_mberror));
1803		WARN_ON_ONCE(atomic_read(&n_rcu_torture_mbchk_fail));
1804		WARN_ON_ONCE(n_rcu_torture_barrier_error);  // rcu_barrier()
1805		WARN_ON_ONCE(n_rcu_torture_boost_ktrerror); // no boost kthread
1806		WARN_ON_ONCE(n_rcu_torture_boost_rterror); // can't set RT prio
1807		WARN_ON_ONCE(n_rcu_torture_boost_failure); // boost failed (TIMER_SOFTIRQ RT prio?)
1808		WARN_ON_ONCE(i > 1); // Too-short grace period
1809	}
1810	pr_cont("Reader Pipe: ");
1811	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1812		pr_cont(" %ld", pipesummary[i]);
1813	pr_cont("\n");
1814
1815	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1816	pr_cont("Reader Batch: ");
1817	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1818		pr_cont(" %ld", batchsummary[i]);
1819	pr_cont("\n");
1820
1821	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1822	pr_cont("Free-Block Circulation: ");
1823	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1824		pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1825	}
1826	pr_cont("\n");
1827
1828	if (cur_ops->stats)
1829		cur_ops->stats();
1830	if (rtcv_snap == rcu_torture_current_version &&
1831	    rcu_access_pointer(rcu_torture_current) &&
1832	    !rcu_stall_is_suppressed()) {
1833		int __maybe_unused flags = 0;
1834		unsigned long __maybe_unused gp_seq = 0;
1835
1836		rcutorture_get_gp_data(cur_ops->ttype,
1837				       &flags, &gp_seq);
1838		srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1839					&flags, &gp_seq);
1840		wtp = READ_ONCE(writer_task);
1841		pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#x cpu %d\n",
1842			 rcu_torture_writer_state_getname(),
1843			 rcu_torture_writer_state, gp_seq, flags,
1844			 wtp == NULL ? ~0U : wtp->__state,
1845			 wtp == NULL ? -1 : (int)task_cpu(wtp));
1846		if (!splatted && wtp) {
1847			sched_show_task(wtp);
1848			splatted = true;
1849		}
1850		if (cur_ops->gp_kthread_dbg)
1851			cur_ops->gp_kthread_dbg();
1852		rcu_ftrace_dump(DUMP_ALL);
1853	}
1854	rtcv_snap = rcu_torture_current_version;
1855}
1856
1857/*
1858 * Periodically prints torture statistics, if periodic statistics printing
1859 * was specified via the stat_interval module parameter.
1860 */
1861static int
1862rcu_torture_stats(void *arg)
1863{
1864	VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1865	do {
1866		schedule_timeout_interruptible(stat_interval * HZ);
1867		rcu_torture_stats_print();
1868		torture_shutdown_absorb("rcu_torture_stats");
1869	} while (!torture_must_stop());
1870	torture_kthread_stopping("rcu_torture_stats");
1871	return 0;
1872}
1873
1874/* Test mem_dump_obj() and friends.  */
1875static void rcu_torture_mem_dump_obj(void)
1876{
1877	struct rcu_head *rhp;
1878	struct kmem_cache *kcp;
1879	static int z;
1880
1881	kcp = kmem_cache_create("rcuscale", 136, 8, SLAB_STORE_USER, NULL);
1882	rhp = kmem_cache_alloc(kcp, GFP_KERNEL);
1883	pr_alert("mem_dump_obj() slab test: rcu_torture_stats = %px, &rhp = %px, rhp = %px, &z = %px\n", stats_task, &rhp, rhp, &z);
1884	pr_alert("mem_dump_obj(ZERO_SIZE_PTR):");
1885	mem_dump_obj(ZERO_SIZE_PTR);
1886	pr_alert("mem_dump_obj(NULL):");
1887	mem_dump_obj(NULL);
1888	pr_alert("mem_dump_obj(%px):", &rhp);
1889	mem_dump_obj(&rhp);
1890	pr_alert("mem_dump_obj(%px):", rhp);
1891	mem_dump_obj(rhp);
1892	pr_alert("mem_dump_obj(%px):", &rhp->func);
1893	mem_dump_obj(&rhp->func);
1894	pr_alert("mem_dump_obj(%px):", &z);
1895	mem_dump_obj(&z);
1896	kmem_cache_free(kcp, rhp);
1897	kmem_cache_destroy(kcp);
1898	rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
1899	pr_alert("mem_dump_obj() kmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
1900	pr_alert("mem_dump_obj(kmalloc %px):", rhp);
1901	mem_dump_obj(rhp);
1902	pr_alert("mem_dump_obj(kmalloc %px):", &rhp->func);
1903	mem_dump_obj(&rhp->func);
1904	kfree(rhp);
1905	rhp = vmalloc(4096);
1906	pr_alert("mem_dump_obj() vmalloc test: rcu_torture_stats = %px, &rhp = %px, rhp = %px\n", stats_task, &rhp, rhp);
1907	pr_alert("mem_dump_obj(vmalloc %px):", rhp);
1908	mem_dump_obj(rhp);
1909	pr_alert("mem_dump_obj(vmalloc %px):", &rhp->func);
1910	mem_dump_obj(&rhp->func);
1911	vfree(rhp);
1912}
1913
1914static void
1915rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1916{
1917	pr_alert("%s" TORTURE_FLAG
1918		 "--- %s: nreaders=%d nfakewriters=%d "
1919		 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1920		 "shuffle_interval=%d stutter=%d irqreader=%d "
1921		 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1922		 "test_boost=%d/%d test_boost_interval=%d "
1923		 "test_boost_duration=%d shutdown_secs=%d "
1924		 "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1925		 "stall_cpu_block=%d "
1926		 "n_barrier_cbs=%d "
1927		 "onoff_interval=%d onoff_holdoff=%d "
1928		 "read_exit_delay=%d read_exit_burst=%d "
1929		 "nocbs_nthreads=%d nocbs_toggle=%d\n",
1930		 torture_type, tag, nrealreaders, nfakewriters,
1931		 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1932		 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1933		 test_boost, cur_ops->can_boost,
1934		 test_boost_interval, test_boost_duration, shutdown_secs,
1935		 stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1936		 stall_cpu_block,
1937		 n_barrier_cbs,
1938		 onoff_interval, onoff_holdoff,
1939		 read_exit_delay, read_exit_burst,
1940		 nocbs_nthreads, nocbs_toggle);
1941}
1942
1943static int rcutorture_booster_cleanup(unsigned int cpu)
1944{
1945	struct task_struct *t;
1946
1947	if (boost_tasks[cpu] == NULL)
1948		return 0;
1949	mutex_lock(&boost_mutex);
1950	t = boost_tasks[cpu];
1951	boost_tasks[cpu] = NULL;
1952	rcu_torture_enable_rt_throttle();
1953	mutex_unlock(&boost_mutex);
1954
1955	/* This must be outside of the mutex, otherwise deadlock! */
1956	torture_stop_kthread(rcu_torture_boost, t);
1957	return 0;
1958}
1959
1960static int rcutorture_booster_init(unsigned int cpu)
1961{
1962	int retval;
1963
1964	if (boost_tasks[cpu] != NULL)
1965		return 0;  /* Already created, nothing more to do. */
1966
1967	/* Don't allow time recalculation while creating a new task. */
1968	mutex_lock(&boost_mutex);
1969	rcu_torture_disable_rt_throttle();
1970	VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1971	boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1972						  cpu_to_node(cpu),
1973						  "rcu_torture_boost");
1974	if (IS_ERR(boost_tasks[cpu])) {
1975		retval = PTR_ERR(boost_tasks[cpu]);
1976		VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1977		n_rcu_torture_boost_ktrerror++;
1978		boost_tasks[cpu] = NULL;
1979		mutex_unlock(&boost_mutex);
1980		return retval;
1981	}
1982	kthread_bind(boost_tasks[cpu], cpu);
1983	wake_up_process(boost_tasks[cpu]);
1984	mutex_unlock(&boost_mutex);
1985	return 0;
1986}
1987
1988/*
1989 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1990 * induces a CPU stall for the time specified by stall_cpu.
1991 */
1992static int rcu_torture_stall(void *args)
1993{
1994	int idx;
1995	unsigned long stop_at;
1996
1997	VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1998	if (stall_cpu_holdoff > 0) {
1999		VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
2000		schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
2001		VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
2002	}
2003	if (!kthread_should_stop() && stall_gp_kthread > 0) {
2004		VERBOSE_TOROUT_STRING("rcu_torture_stall begin GP stall");
2005		rcu_gp_set_torture_wait(stall_gp_kthread * HZ);
2006		for (idx = 0; idx < stall_gp_kthread + 2; idx++) {
2007			if (kthread_should_stop())
2008				break;
2009			schedule_timeout_uninterruptible(HZ);
2010		}
2011	}
2012	if (!kthread_should_stop() && stall_cpu > 0) {
2013		VERBOSE_TOROUT_STRING("rcu_torture_stall begin CPU stall");
2014		stop_at = ktime_get_seconds() + stall_cpu;
2015		/* RCU CPU stall is expected behavior in following code. */
2016		idx = cur_ops->readlock();
2017		if (stall_cpu_irqsoff)
2018			local_irq_disable();
2019		else if (!stall_cpu_block)
2020			preempt_disable();
2021		pr_alert("%s start on CPU %d.\n",
2022			  __func__, raw_smp_processor_id());
2023		while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
2024				    stop_at))
2025			if (stall_cpu_block)
2026				schedule_timeout_uninterruptible(HZ);
2027		if (stall_cpu_irqsoff)
2028			local_irq_enable();
2029		else if (!stall_cpu_block)
2030			preempt_enable();
2031		cur_ops->readunlock(idx);
2032	}
2033	pr_alert("%s end.\n", __func__);
2034	torture_shutdown_absorb("rcu_torture_stall");
2035	while (!kthread_should_stop())
2036		schedule_timeout_interruptible(10 * HZ);
2037	return 0;
2038}
2039
2040/* Spawn CPU-stall kthread, if stall_cpu specified. */
2041static int __init rcu_torture_stall_init(void)
2042{
2043	if (stall_cpu <= 0 && stall_gp_kthread <= 0)
2044		return 0;
2045	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
2046}
2047
2048/* State structure for forward-progress self-propagating RCU callback. */
2049struct fwd_cb_state {
2050	struct rcu_head rh;
2051	int stop;
2052};
2053
2054/*
2055 * Forward-progress self-propagating RCU callback function.  Because
2056 * callbacks run from softirq, this function is an implicit RCU read-side
2057 * critical section.
2058 */
2059static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
2060{
2061	struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
2062
2063	if (READ_ONCE(fcsp->stop)) {
2064		WRITE_ONCE(fcsp->stop, 2);
2065		return;
2066	}
2067	cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
2068}
2069
2070/* State for continuous-flood RCU callbacks. */
2071struct rcu_fwd_cb {
2072	struct rcu_head rh;
2073	struct rcu_fwd_cb *rfc_next;
2074	struct rcu_fwd *rfc_rfp;
2075	int rfc_gps;
2076};
2077
2078#define MAX_FWD_CB_JIFFIES	(8 * HZ) /* Maximum CB test duration. */
2079#define MIN_FWD_CB_LAUNDERS	3	/* This many CB invocations to count. */
2080#define MIN_FWD_CBS_LAUNDERED	100	/* Number of counted CBs. */
2081#define FWD_CBS_HIST_DIV	10	/* Histogram buckets/second. */
2082#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
2083
2084struct rcu_launder_hist {
2085	long n_launders;
2086	unsigned long launder_gp_seq;
2087};
2088
2089struct rcu_fwd {
2090	spinlock_t rcu_fwd_lock;
2091	struct rcu_fwd_cb *rcu_fwd_cb_head;
2092	struct rcu_fwd_cb **rcu_fwd_cb_tail;
2093	long n_launders_cb;
2094	unsigned long rcu_fwd_startat;
2095	struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
2096	unsigned long rcu_launder_gp_seq_start;
2097};
2098
2099static DEFINE_MUTEX(rcu_fwd_mutex);
2100static struct rcu_fwd *rcu_fwds;
2101static bool rcu_fwd_emergency_stop;
2102
2103static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
2104{
2105	unsigned long gps;
2106	unsigned long gps_old;
2107	int i;
2108	int j;
2109
2110	for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
2111		if (rfp->n_launders_hist[i].n_launders > 0)
2112			break;
2113	pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
2114		 __func__, jiffies - rfp->rcu_fwd_startat);
2115	gps_old = rfp->rcu_launder_gp_seq_start;
2116	for (j = 0; j <= i; j++) {
2117		gps = rfp->n_launders_hist[j].launder_gp_seq;
2118		pr_cont(" %ds/%d: %ld:%ld",
2119			j + 1, FWD_CBS_HIST_DIV,
2120			rfp->n_launders_hist[j].n_launders,
2121			rcutorture_seq_diff(gps, gps_old));
2122		gps_old = gps;
2123	}
2124	pr_cont("\n");
2125}
2126
2127/* Callback function for continuous-flood RCU callbacks. */
2128static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
2129{
2130	unsigned long flags;
2131	int i;
2132	struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
2133	struct rcu_fwd_cb **rfcpp;
2134	struct rcu_fwd *rfp = rfcp->rfc_rfp;
2135
2136	rfcp->rfc_next = NULL;
2137	rfcp->rfc_gps++;
2138	spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
2139	rfcpp = rfp->rcu_fwd_cb_tail;
2140	rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
2141	WRITE_ONCE(*rfcpp, rfcp);
2142	WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
2143	i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
2144	if (i >= ARRAY_SIZE(rfp->n_launders_hist))
2145		i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
2146	rfp->n_launders_hist[i].n_launders++;
2147	rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
2148	spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2149}
2150
2151// Give the scheduler a chance, even on nohz_full CPUs.
2152static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
2153{
2154	if (IS_ENABLED(CONFIG_PREEMPTION) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
2155		// Real call_rcu() floods hit userspace, so emulate that.
2156		if (need_resched() || (iter & 0xfff))
2157			schedule();
2158		return;
2159	}
2160	// No userspace emulation: CB invocation throttles call_rcu()
2161	cond_resched();
2162}
2163
2164/*
2165 * Free all callbacks on the rcu_fwd_cb_head list, either because the
2166 * test is over or because we hit an OOM event.
2167 */
2168static unsigned long rcu_torture_fwd_prog_cbfree(struct rcu_fwd *rfp)
2169{
2170	unsigned long flags;
2171	unsigned long freed = 0;
2172	struct rcu_fwd_cb *rfcp;
2173
2174	for (;;) {
2175		spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
2176		rfcp = rfp->rcu_fwd_cb_head;
2177		if (!rfcp) {
2178			spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2179			break;
2180		}
2181		rfp->rcu_fwd_cb_head = rfcp->rfc_next;
2182		if (!rfp->rcu_fwd_cb_head)
2183			rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
2184		spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2185		kfree(rfcp);
2186		freed++;
2187		rcu_torture_fwd_prog_cond_resched(freed);
2188		if (tick_nohz_full_enabled()) {
2189			local_irq_save(flags);
2190			rcu_momentary_dyntick_idle();
2191			local_irq_restore(flags);
2192		}
2193	}
2194	return freed;
2195}
2196
2197/* Carry out need_resched()/cond_resched() forward-progress testing. */
2198static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
2199				    int *tested, int *tested_tries)
2200{
2201	unsigned long cver;
2202	unsigned long dur;
2203	struct fwd_cb_state fcs;
2204	unsigned long gps;
2205	int idx;
2206	int sd;
2207	int sd4;
2208	bool selfpropcb = false;
2209	unsigned long stopat;
2210	static DEFINE_TORTURE_RANDOM(trs);
2211
2212	if (!cur_ops->sync)
2213		return; // Cannot do need_resched() forward progress testing without ->sync.
2214	if (cur_ops->call && cur_ops->cb_barrier) {
2215		init_rcu_head_on_stack(&fcs.rh);
2216		selfpropcb = true;
2217	}
2218
2219	/* Tight loop containing cond_resched(). */
2220	WRITE_ONCE(rcu_fwd_cb_nodelay, true);
2221	cur_ops->sync(); /* Later readers see above write. */
2222	if  (selfpropcb) {
2223		WRITE_ONCE(fcs.stop, 0);
2224		cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
2225	}
2226	cver = READ_ONCE(rcu_torture_current_version);
2227	gps = cur_ops->get_gp_seq();
2228	sd = cur_ops->stall_dur() + 1;
2229	sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
2230	dur = sd4 + torture_random(&trs) % (sd - sd4);
2231	WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
2232	stopat = rfp->rcu_fwd_startat + dur;
2233	while (time_before(jiffies, stopat) &&
2234	       !shutdown_time_arrived() &&
2235	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2236		idx = cur_ops->readlock();
2237		udelay(10);
2238		cur_ops->readunlock(idx);
2239		if (!fwd_progress_need_resched || need_resched())
2240			cond_resched();
2241	}
2242	(*tested_tries)++;
2243	if (!time_before(jiffies, stopat) &&
2244	    !shutdown_time_arrived() &&
2245	    !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2246		(*tested)++;
2247		cver = READ_ONCE(rcu_torture_current_version) - cver;
2248		gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
2249		WARN_ON(!cver && gps < 2);
2250		pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
2251	}
2252	if (selfpropcb) {
2253		WRITE_ONCE(fcs.stop, 1);
2254		cur_ops->sync(); /* Wait for running CB to complete. */
2255		cur_ops->cb_barrier(); /* Wait for queued callbacks. */
2256	}
2257
2258	if (selfpropcb) {
2259		WARN_ON(READ_ONCE(fcs.stop) != 2);
2260		destroy_rcu_head_on_stack(&fcs.rh);
2261	}
2262	schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
2263	WRITE_ONCE(rcu_fwd_cb_nodelay, false);
2264}
2265
2266/* Carry out call_rcu() forward-progress testing. */
2267static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
2268{
2269	unsigned long cver;
2270	unsigned long flags;
2271	unsigned long gps;
2272	int i;
2273	long n_launders;
2274	long n_launders_cb_snap;
2275	long n_launders_sa;
2276	long n_max_cbs;
2277	long n_max_gps;
2278	struct rcu_fwd_cb *rfcp;
2279	struct rcu_fwd_cb *rfcpn;
2280	unsigned long stopat;
2281	unsigned long stoppedat;
2282
2283	if (READ_ONCE(rcu_fwd_emergency_stop))
2284		return; /* Get out of the way quickly, no GP wait! */
2285	if (!cur_ops->call)
2286		return; /* Can't do call_rcu() fwd prog without ->call. */
2287
2288	/* Loop continuously posting RCU callbacks. */
2289	WRITE_ONCE(rcu_fwd_cb_nodelay, true);
2290	cur_ops->sync(); /* Later readers see above write. */
2291	WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
2292	stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
2293	n_launders = 0;
2294	rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
2295	n_launders_sa = 0;
2296	n_max_cbs = 0;
2297	n_max_gps = 0;
2298	for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
2299		rfp->n_launders_hist[i].n_launders = 0;
2300	cver = READ_ONCE(rcu_torture_current_version);
2301	gps = cur_ops->get_gp_seq();
2302	rfp->rcu_launder_gp_seq_start = gps;
2303	tick_dep_set_task(current, TICK_DEP_BIT_RCU);
2304	while (time_before(jiffies, stopat) &&
2305	       !shutdown_time_arrived() &&
2306	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2307		rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
2308		rfcpn = NULL;
2309		if (rfcp)
2310			rfcpn = READ_ONCE(rfcp->rfc_next);
2311		if (rfcpn) {
2312			if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
2313			    ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
2314				break;
2315			rfp->rcu_fwd_cb_head = rfcpn;
2316			n_launders++;
2317			n_launders_sa++;
2318		} else {
2319			rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
2320			if (WARN_ON_ONCE(!rfcp)) {
2321				schedule_timeout_interruptible(1);
2322				continue;
2323			}
2324			n_max_cbs++;
2325			n_launders_sa = 0;
2326			rfcp->rfc_gps = 0;
2327			rfcp->rfc_rfp = rfp;
2328		}
2329		cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
2330		rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
2331		if (tick_nohz_full_enabled()) {
2332			local_irq_save(flags);
2333			rcu_momentary_dyntick_idle();
2334			local_irq_restore(flags);
2335		}
2336	}
2337	stoppedat = jiffies;
2338	n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
2339	cver = READ_ONCE(rcu_torture_current_version) - cver;
2340	gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
2341	cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
2342	(void)rcu_torture_fwd_prog_cbfree(rfp);
2343
2344	if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
2345	    !shutdown_time_arrived()) {
2346		WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
2347		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",
2348			 __func__,
2349			 stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
2350			 n_launders + n_max_cbs - n_launders_cb_snap,
2351			 n_launders, n_launders_sa,
2352			 n_max_gps, n_max_cbs, cver, gps);
2353		rcu_torture_fwd_cb_hist(rfp);
2354	}
2355	schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
2356	tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
2357	WRITE_ONCE(rcu_fwd_cb_nodelay, false);
2358}
2359
2360
2361/*
2362 * OOM notifier, but this only prints diagnostic information for the
2363 * current forward-progress test.
2364 */
2365static int rcutorture_oom_notify(struct notifier_block *self,
2366				 unsigned long notused, void *nfreed)
2367{
2368	struct rcu_fwd *rfp;
2369
2370	mutex_lock(&rcu_fwd_mutex);
2371	rfp = rcu_fwds;
2372	if (!rfp) {
2373		mutex_unlock(&rcu_fwd_mutex);
2374		return NOTIFY_OK;
2375	}
2376	WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
2377	     __func__);
2378	rcu_torture_fwd_cb_hist(rfp);
2379	rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rfp->rcu_fwd_startat)) / 2);
2380	WRITE_ONCE(rcu_fwd_emergency_stop, true);
2381	smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
2382	pr_info("%s: Freed %lu RCU callbacks.\n",
2383		__func__, rcu_torture_fwd_prog_cbfree(rfp));
2384	rcu_barrier();
2385	pr_info("%s: Freed %lu RCU callbacks.\n",
2386		__func__, rcu_torture_fwd_prog_cbfree(rfp));
2387	rcu_barrier();
2388	pr_info("%s: Freed %lu RCU callbacks.\n",
2389		__func__, rcu_torture_fwd_prog_cbfree(rfp));
2390	smp_mb(); /* Frees before return to avoid redoing OOM. */
2391	(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
2392	pr_info("%s returning after OOM processing.\n", __func__);
2393	mutex_unlock(&rcu_fwd_mutex);
2394	return NOTIFY_OK;
2395}
2396
2397static struct notifier_block rcutorture_oom_nb = {
2398	.notifier_call = rcutorture_oom_notify
2399};
2400
2401/* Carry out grace-period forward-progress testing. */
2402static int rcu_torture_fwd_prog(void *args)
2403{
2404	int oldnice = task_nice(current);
2405	struct rcu_fwd *rfp = args;
2406	int tested = 0;
2407	int tested_tries = 0;
2408
2409	VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
2410	rcu_bind_current_to_nocb();
2411	if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
2412		set_user_nice(current, MAX_NICE);
2413	do {
2414		schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
2415		WRITE_ONCE(rcu_fwd_emergency_stop, false);
2416		if (!IS_ENABLED(CONFIG_TINY_RCU) ||
2417		    rcu_inkernel_boot_has_ended())
2418			rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
2419		if (rcu_inkernel_boot_has_ended())
2420			rcu_torture_fwd_prog_cr(rfp);
2421
2422		/* Avoid slow periods, better to test when busy. */
2423		if (stutter_wait("rcu_torture_fwd_prog"))
2424			sched_set_normal(current, oldnice);
2425	} while (!torture_must_stop());
2426	/* Short runs might not contain a valid forward-progress attempt. */
2427	WARN_ON(!tested && tested_tries >= 5);
2428	pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
2429	torture_kthread_stopping("rcu_torture_fwd_prog");
2430	return 0;
2431}
2432
2433/* If forward-progress checking is requested and feasible, spawn the thread. */
2434static int __init rcu_torture_fwd_prog_init(void)
2435{
2436	struct rcu_fwd *rfp;
2437
2438	if (!fwd_progress)
2439		return 0; /* Not requested, so don't do it. */
2440	if ((!cur_ops->sync && !cur_ops->call) ||
2441	    !cur_ops->stall_dur || cur_ops->stall_dur() <= 0 || cur_ops == &rcu_busted_ops) {
2442		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
2443		return 0;
2444	}
2445	if (stall_cpu > 0) {
2446		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
2447		if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
2448			return -EINVAL; /* In module, can fail back to user. */
2449		WARN_ON(1); /* Make sure rcutorture notices conflict. */
2450		return 0;
2451	}
2452	if (fwd_progress_holdoff <= 0)
2453		fwd_progress_holdoff = 1;
2454	if (fwd_progress_div <= 0)
2455		fwd_progress_div = 4;
2456	rfp = kzalloc(sizeof(*rfp), GFP_KERNEL);
2457	if (!rfp)
2458		return -ENOMEM;
2459	spin_lock_init(&rfp->rcu_fwd_lock);
2460	rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
2461	mutex_lock(&rcu_fwd_mutex);
2462	rcu_fwds = rfp;
2463	mutex_unlock(&rcu_fwd_mutex);
2464	register_oom_notifier(&rcutorture_oom_nb);
2465	return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);
2466}
2467
2468static void rcu_torture_fwd_prog_cleanup(void)
2469{
2470	struct rcu_fwd *rfp;
2471
2472	torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2473	rfp = rcu_fwds;
2474	mutex_lock(&rcu_fwd_mutex);
2475	rcu_fwds = NULL;
2476	mutex_unlock(&rcu_fwd_mutex);
2477	unregister_oom_notifier(&rcutorture_oom_nb);
2478	kfree(rfp);
2479}
2480
2481/* Callback function for RCU barrier testing. */
2482static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
2483{
2484	atomic_inc(&barrier_cbs_invoked);
2485}
2486
2487/* IPI handler to get callback posted on desired CPU, if online. */
2488static void rcu_torture_barrier1cb(void *rcu_void)
2489{
2490	struct rcu_head *rhp = rcu_void;
2491
2492	cur_ops->call(rhp, rcu_torture_barrier_cbf);
2493}
2494
2495/* kthread function to register callbacks used to test RCU barriers. */
2496static int rcu_torture_barrier_cbs(void *arg)
2497{
2498	long myid = (long)arg;
2499	bool lastphase = false;
2500	bool newphase;
2501	struct rcu_head rcu;
2502
2503	init_rcu_head_on_stack(&rcu);
2504	VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
2505	set_user_nice(current, MAX_NICE);
2506	do {
2507		wait_event(barrier_cbs_wq[myid],
2508			   (newphase =
2509			    smp_load_acquire(&barrier_phase)) != lastphase ||
2510			   torture_must_stop());
2511		lastphase = newphase;
2512		if (torture_must_stop())
2513			break;
2514		/*
2515		 * The above smp_load_acquire() ensures barrier_phase load
2516		 * is ordered before the following ->call().
2517		 */
2518		if (smp_call_function_single(myid, rcu_torture_barrier1cb,
2519					     &rcu, 1)) {
2520			// IPI failed, so use direct call from current CPU.
2521			cur_ops->call(&rcu, rcu_torture_barrier_cbf);
2522		}
2523		if (atomic_dec_and_test(&barrier_cbs_count))
2524			wake_up(&barrier_wq);
2525	} while (!torture_must_stop());
2526	if (cur_ops->cb_barrier != NULL)
2527		cur_ops->cb_barrier();
2528	destroy_rcu_head_on_stack(&rcu);
2529	torture_kthread_stopping("rcu_torture_barrier_cbs");
2530	return 0;
2531}
2532
2533/* kthread function to drive and coordinate RCU barrier testing. */
2534static int rcu_torture_barrier(void *arg)
2535{
2536	int i;
2537
2538	VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
2539	do {
2540		atomic_set(&barrier_cbs_invoked, 0);
2541		atomic_set(&barrier_cbs_count, n_barrier_cbs);
2542		/* Ensure barrier_phase ordered after prior assignments. */
2543		smp_store_release(&barrier_phase, !barrier_phase);
2544		for (i = 0; i < n_barrier_cbs; i++)
2545			wake_up(&barrier_cbs_wq[i]);
2546		wait_event(barrier_wq,
2547			   atomic_read(&barrier_cbs_count) == 0 ||
2548			   torture_must_stop());
2549		if (torture_must_stop())
2550			break;
2551		n_barrier_attempts++;
2552		cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
2553		if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
2554			n_rcu_torture_barrier_error++;
2555			pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
2556			       atomic_read(&barrier_cbs_invoked),
2557			       n_barrier_cbs);
2558			WARN_ON(1);
2559			// Wait manually for the remaining callbacks
2560			i = 0;
2561			do {
2562				if (WARN_ON(i++ > HZ))
2563					i = INT_MIN;
2564				schedule_timeout_interruptible(1);
2565				cur_ops->cb_barrier();
2566			} while (atomic_read(&barrier_cbs_invoked) !=
2567				 n_barrier_cbs &&
2568				 !torture_must_stop());
2569			smp_mb(); // Can't trust ordering if broken.
2570			if (!torture_must_stop())
2571				pr_err("Recovered: barrier_cbs_invoked = %d\n",
2572				       atomic_read(&barrier_cbs_invoked));
2573		} else {
2574			n_barrier_successes++;
2575		}
 
2576		schedule_timeout_interruptible(HZ / 10);
2577	} while (!torture_must_stop());
2578	torture_kthread_stopping("rcu_torture_barrier");
2579	return 0;
2580}
2581
2582/* Initialize RCU barrier testing. */
2583static int rcu_torture_barrier_init(void)
2584{
2585	int i;
2586	int ret;
2587
2588	if (n_barrier_cbs <= 0)
2589		return 0;
2590	if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2591		pr_alert("%s" TORTURE_FLAG
2592			 " Call or barrier ops missing for %s,\n",
2593			 torture_type, cur_ops->name);
2594		pr_alert("%s" TORTURE_FLAG
2595			 " RCU barrier testing omitted from run.\n",
2596			 torture_type);
2597		return 0;
2598	}
2599	atomic_set(&barrier_cbs_count, 0);
2600	atomic_set(&barrier_cbs_invoked, 0);
2601	barrier_cbs_tasks =
2602		kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2603			GFP_KERNEL);
2604	barrier_cbs_wq =
2605		kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
 
2606	if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2607		return -ENOMEM;
2608	for (i = 0; i < n_barrier_cbs; i++) {
2609		init_waitqueue_head(&barrier_cbs_wq[i]);
2610		ret = torture_create_kthread(rcu_torture_barrier_cbs,
2611					     (void *)(long)i,
2612					     barrier_cbs_tasks[i]);
2613		if (ret)
2614			return ret;
2615	}
2616	return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2617}
2618
2619/* Clean up after RCU barrier testing. */
2620static void rcu_torture_barrier_cleanup(void)
2621{
2622	int i;
2623
2624	torture_stop_kthread(rcu_torture_barrier, barrier_task);
2625	if (barrier_cbs_tasks != NULL) {
2626		for (i = 0; i < n_barrier_cbs; i++)
2627			torture_stop_kthread(rcu_torture_barrier_cbs,
2628					     barrier_cbs_tasks[i]);
2629		kfree(barrier_cbs_tasks);
2630		barrier_cbs_tasks = NULL;
2631	}
2632	if (barrier_cbs_wq != NULL) {
2633		kfree(barrier_cbs_wq);
2634		barrier_cbs_wq = NULL;
2635	}
2636}
2637
2638static bool rcu_torture_can_boost(void)
 
2639{
2640	static int boost_warn_once;
2641	int prio;
2642
2643	if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2644		return false;
2645	if (!cur_ops->start_gp_poll || !cur_ops->poll_gp_state)
2646		return false;
2647
2648	prio = rcu_get_gp_kthreads_prio();
2649	if (!prio)
2650		return false;
2651
2652	if (prio < 2) {
2653		if (boost_warn_once == 1)
2654			return false;
2655
2656		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);
2657		boost_warn_once = 1;
2658		return false;
 
 
 
 
 
 
 
2659	}
2660
2661	return true;
2662}
2663
2664static bool read_exit_child_stop;
2665static bool read_exit_child_stopped;
2666static wait_queue_head_t read_exit_wq;
2667
2668// Child kthread which just does an rcutorture reader and exits.
2669static int rcu_torture_read_exit_child(void *trsp_in)
2670{
2671	struct torture_random_state *trsp = trsp_in;
2672
2673	set_user_nice(current, MAX_NICE);
2674	// Minimize time between reading and exiting.
2675	while (!kthread_should_stop())
2676		schedule_timeout_uninterruptible(1);
2677	(void)rcu_torture_one_read(trsp, -1);
2678	return 0;
2679}
2680
2681// Parent kthread which creates and destroys read-exit child kthreads.
2682static int rcu_torture_read_exit(void *unused)
2683{
2684	int count = 0;
2685	bool errexit = false;
2686	int i;
2687	struct task_struct *tsp;
2688	DEFINE_TORTURE_RANDOM(trs);
2689
2690	// Allocate and initialize.
2691	set_user_nice(current, MAX_NICE);
2692	VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of test");
2693
2694	// Each pass through this loop does one read-exit episode.
2695	do {
2696		if (++count > read_exit_burst) {
2697			VERBOSE_TOROUT_STRING("rcu_torture_read_exit: End of episode");
2698			rcu_barrier(); // Wait for task_struct free, avoid OOM.
2699			for (i = 0; i < read_exit_delay; i++) {
2700				schedule_timeout_uninterruptible(HZ);
2701				if (READ_ONCE(read_exit_child_stop))
2702					break;
2703			}
2704			if (!READ_ONCE(read_exit_child_stop))
2705				VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of episode");
2706			count = 0;
2707		}
2708		if (READ_ONCE(read_exit_child_stop))
2709			break;
2710		// Spawn child.
2711		tsp = kthread_run(rcu_torture_read_exit_child,
2712				     &trs, "%s",
2713				     "rcu_torture_read_exit_child");
2714		if (IS_ERR(tsp)) {
2715			VERBOSE_TOROUT_ERRSTRING("out of memory");
2716			errexit = true;
2717			tsp = NULL;
2718			break;
2719		}
2720		cond_resched();
2721		kthread_stop(tsp);
2722		n_read_exits ++;
2723		stutter_wait("rcu_torture_read_exit");
2724	} while (!errexit && !READ_ONCE(read_exit_child_stop));
2725
2726	// Clean up and exit.
2727	smp_store_release(&read_exit_child_stopped, true); // After reaping.
2728	smp_mb(); // Store before wakeup.
2729	wake_up(&read_exit_wq);
2730	while (!torture_must_stop())
2731		schedule_timeout_uninterruptible(1);
2732	torture_kthread_stopping("rcu_torture_read_exit");
2733	return 0;
2734}
2735
2736static int rcu_torture_read_exit_init(void)
2737{
2738	if (read_exit_burst <= 0)
2739		return -EINVAL;
2740	init_waitqueue_head(&read_exit_wq);
2741	read_exit_child_stop = false;
2742	read_exit_child_stopped = false;
2743	return torture_create_kthread(rcu_torture_read_exit, NULL,
2744				      read_exit_task);
2745}
2746
2747static void rcu_torture_read_exit_cleanup(void)
2748{
2749	if (!read_exit_task)
2750		return;
2751	WRITE_ONCE(read_exit_child_stop, true);
2752	smp_mb(); // Above write before wait.
2753	wait_event(read_exit_wq, smp_load_acquire(&read_exit_child_stopped));
2754	torture_stop_kthread(rcutorture_read_exit, read_exit_task);
2755}
2756
2757static enum cpuhp_state rcutor_hp;
 
 
2758
2759static void
2760rcu_torture_cleanup(void)
2761{
2762	int firsttime;
2763	int flags = 0;
2764	unsigned long gp_seq = 0;
2765	int i;
2766
 
2767	if (torture_cleanup_begin()) {
2768		if (cur_ops->cb_barrier != NULL)
2769			cur_ops->cb_barrier();
2770		return;
2771	}
2772	if (!cur_ops) {
2773		torture_cleanup_end();
2774		return;
2775	}
2776
2777	if (cur_ops->gp_kthread_dbg)
2778		cur_ops->gp_kthread_dbg();
2779	rcu_torture_read_exit_cleanup();
2780	rcu_torture_barrier_cleanup();
2781	rcu_torture_fwd_prog_cleanup();
2782	torture_stop_kthread(rcu_torture_stall, stall_task);
2783	torture_stop_kthread(rcu_torture_writer, writer_task);
2784
2785	if (nocb_tasks) {
2786		for (i = 0; i < nrealnocbers; i++)
2787			torture_stop_kthread(rcu_nocb_toggle, nocb_tasks[i]);
2788		kfree(nocb_tasks);
2789		nocb_tasks = NULL;
2790	}
2791
2792	if (reader_tasks) {
2793		for (i = 0; i < nrealreaders; i++)
2794			torture_stop_kthread(rcu_torture_reader,
2795					     reader_tasks[i]);
2796		kfree(reader_tasks);
2797		reader_tasks = NULL;
2798	}
2799	kfree(rcu_torture_reader_mbchk);
2800	rcu_torture_reader_mbchk = NULL;
2801
2802	if (fakewriter_tasks) {
2803		for (i = 0; i < nfakewriters; i++)
2804			torture_stop_kthread(rcu_torture_fakewriter,
2805					     fakewriter_tasks[i]);
 
2806		kfree(fakewriter_tasks);
2807		fakewriter_tasks = NULL;
2808	}
2809
2810	rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2811	srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2812	pr_alert("%s:  End-test grace-period state: g%ld f%#x total-gps=%ld\n",
2813		 cur_ops->name, (long)gp_seq, flags,
2814		 rcutorture_seq_diff(gp_seq, start_gp_seq));
2815	torture_stop_kthread(rcu_torture_stats, stats_task);
2816	torture_stop_kthread(rcu_torture_fqs, fqs_task);
2817	if (rcu_torture_can_boost())
2818		cpuhp_remove_state(rcutor_hp);
 
 
 
 
 
 
2819
2820	/*
2821	 * Wait for all RCU callbacks to fire, then do torture-type-specific
2822	 * cleanup operations.
2823	 */
2824	if (cur_ops->cb_barrier != NULL)
2825		cur_ops->cb_barrier();
2826	if (cur_ops->cleanup != NULL)
2827		cur_ops->cleanup();
2828
2829	rcu_torture_mem_dump_obj();
2830
2831	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2832
2833	if (err_segs_recorded) {
2834		pr_alert("Failure/close-call rcutorture reader segments:\n");
2835		if (rt_read_nsegs == 0)
2836			pr_alert("\t: No segments recorded!!!\n");
2837		firsttime = 1;
2838		for (i = 0; i < rt_read_nsegs; i++) {
2839			pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2840			if (err_segs[i].rt_delay_jiffies != 0) {
2841				pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2842					err_segs[i].rt_delay_jiffies);
2843				firsttime = 0;
2844			}
2845			if (err_segs[i].rt_delay_ms != 0) {
2846				pr_cont("%s%ldms", firsttime ? "" : "+",
2847					err_segs[i].rt_delay_ms);
2848				firsttime = 0;
2849			}
2850			if (err_segs[i].rt_delay_us != 0) {
2851				pr_cont("%s%ldus", firsttime ? "" : "+",
2852					err_segs[i].rt_delay_us);
2853				firsttime = 0;
2854			}
2855			pr_cont("%s\n",
2856				err_segs[i].rt_preempted ? "preempted" : "");
2857
2858		}
2859	}
2860	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2861		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2862	else if (torture_onoff_failures())
2863		rcu_torture_print_module_parms(cur_ops,
2864					       "End of test: RCU_HOTPLUG");
2865	else
2866		rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2867	torture_cleanup_end();
2868}
2869
2870#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2871static void rcu_torture_leak_cb(struct rcu_head *rhp)
2872{
2873}
2874
2875static void rcu_torture_err_cb(struct rcu_head *rhp)
2876{
2877	/*
2878	 * This -might- happen due to race conditions, but is unlikely.
2879	 * The scenario that leads to this happening is that the
2880	 * first of the pair of duplicate callbacks is queued,
2881	 * someone else starts a grace period that includes that
2882	 * callback, then the second of the pair must wait for the
2883	 * next grace period.  Unlikely, but can happen.  If it
2884	 * does happen, the debug-objects subsystem won't have splatted.
2885	 */
2886	pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2887}
2888#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2889
2890/*
2891 * Verify that double-free causes debug-objects to complain, but only
2892 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2893 * cannot be carried out.
2894 */
2895static void rcu_test_debug_objects(void)
2896{
2897#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2898	struct rcu_head rh1;
2899	struct rcu_head rh2;
2900	struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
2901
2902	init_rcu_head_on_stack(&rh1);
2903	init_rcu_head_on_stack(&rh2);
2904	pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2905
2906	/* Try to queue the rh2 pair of callbacks for the same grace period. */
2907	preempt_disable(); /* Prevent preemption from interrupting test. */
2908	rcu_read_lock(); /* Make it impossible to finish a grace period. */
2909	call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2910	local_irq_disable(); /* Make it harder to start a new grace period. */
2911	call_rcu(&rh2, rcu_torture_leak_cb);
2912	call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2913	if (rhp) {
2914		call_rcu(rhp, rcu_torture_leak_cb);
2915		call_rcu(rhp, rcu_torture_err_cb); /* Another duplicate callback. */
2916	}
2917	local_irq_enable();
2918	rcu_read_unlock();
2919	preempt_enable();
2920
2921	/* Wait for them all to get done so we can safely return. */
2922	rcu_barrier();
2923	pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2924	destroy_rcu_head_on_stack(&rh1);
2925	destroy_rcu_head_on_stack(&rh2);
2926#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2927	pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2928#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2929}
2930
2931static void rcutorture_sync(void)
2932{
2933	static unsigned long n;
2934
2935	if (cur_ops->sync && !(++n & 0xfff))
2936		cur_ops->sync();
2937}
2938
2939static int __init
2940rcu_torture_init(void)
2941{
2942	long i;
2943	int cpu;
2944	int firsterr = 0;
2945	int flags = 0;
2946	unsigned long gp_seq = 0;
2947	static struct rcu_torture_ops *torture_ops[] = {
2948		&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2949		&busted_srcud_ops, &tasks_ops, &tasks_rude_ops,
2950		&tasks_tracing_ops, &trivial_ops,
2951	};
2952
2953	if (!torture_init_begin(torture_type, verbose))
2954		return -EBUSY;
2955
2956	/* Process args and tell the world that the torturer is on the job. */
2957	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2958		cur_ops = torture_ops[i];
2959		if (strcmp(torture_type, cur_ops->name) == 0)
2960			break;
2961	}
2962	if (i == ARRAY_SIZE(torture_ops)) {
2963		pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2964			 torture_type);
2965		pr_alert("rcu-torture types:");
2966		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2967			pr_cont(" %s", torture_ops[i]->name);
2968		pr_cont("\n");
2969		firsterr = -EINVAL;
2970		cur_ops = NULL;
2971		goto unwind;
2972	}
2973	if (cur_ops->fqs == NULL && fqs_duration != 0) {
2974		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2975		fqs_duration = 0;
2976	}
2977	if (cur_ops->init)
2978		cur_ops->init();
2979
2980	if (nreaders >= 0) {
2981		nrealreaders = nreaders;
2982	} else {
2983		nrealreaders = num_online_cpus() - 2 - nreaders;
2984		if (nrealreaders <= 0)
2985			nrealreaders = 1;
2986	}
2987	rcu_torture_print_module_parms(cur_ops, "Start of test");
2988	rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2989	srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2990	start_gp_seq = gp_seq;
2991	pr_alert("%s:  Start-test grace-period state: g%ld f%#x\n",
2992		 cur_ops->name, (long)gp_seq, flags);
2993
2994	/* Set up the freelist. */
2995
2996	INIT_LIST_HEAD(&rcu_torture_freelist);
2997	for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2998		rcu_tortures[i].rtort_mbtest = 0;
2999		list_add_tail(&rcu_tortures[i].rtort_free,
3000			      &rcu_torture_freelist);
3001	}
3002
3003	/* Initialize the statistics so that each run gets its own numbers. */
3004
3005	rcu_torture_current = NULL;
3006	rcu_torture_current_version = 0;
3007	atomic_set(&n_rcu_torture_alloc, 0);
3008	atomic_set(&n_rcu_torture_alloc_fail, 0);
3009	atomic_set(&n_rcu_torture_free, 0);
3010	atomic_set(&n_rcu_torture_mberror, 0);
3011	atomic_set(&n_rcu_torture_mbchk_fail, 0);
3012	atomic_set(&n_rcu_torture_mbchk_tries, 0);
3013	atomic_set(&n_rcu_torture_error, 0);
3014	n_rcu_torture_barrier_error = 0;
3015	n_rcu_torture_boost_ktrerror = 0;
3016	n_rcu_torture_boost_rterror = 0;
3017	n_rcu_torture_boost_failure = 0;
3018	n_rcu_torture_boosts = 0;
3019	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
3020		atomic_set(&rcu_torture_wcount[i], 0);
3021	for_each_possible_cpu(cpu) {
3022		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
3023			per_cpu(rcu_torture_count, cpu)[i] = 0;
3024			per_cpu(rcu_torture_batch, cpu)[i] = 0;
3025		}
3026	}
3027	err_segs_recorded = 0;
3028	rt_read_nsegs = 0;
3029
3030	/* Start up the kthreads. */
3031
3032	rcu_torture_write_types();
3033	firsterr = torture_create_kthread(rcu_torture_writer, NULL,
3034					  writer_task);
3035	if (firsterr)
3036		goto unwind;
3037	if (nfakewriters > 0) {
3038		fakewriter_tasks = kcalloc(nfakewriters,
3039					   sizeof(fakewriter_tasks[0]),
3040					   GFP_KERNEL);
3041		if (fakewriter_tasks == NULL) {
3042			VERBOSE_TOROUT_ERRSTRING("out of memory");
3043			firsterr = -ENOMEM;
3044			goto unwind;
3045		}
3046	}
3047	for (i = 0; i < nfakewriters; i++) {
3048		firsterr = torture_create_kthread(rcu_torture_fakewriter,
3049						  NULL, fakewriter_tasks[i]);
3050		if (firsterr)
3051			goto unwind;
3052	}
3053	reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
3054			       GFP_KERNEL);
3055	rcu_torture_reader_mbchk = kcalloc(nrealreaders, sizeof(*rcu_torture_reader_mbchk),
3056					   GFP_KERNEL);
3057	if (!reader_tasks || !rcu_torture_reader_mbchk) {
3058		VERBOSE_TOROUT_ERRSTRING("out of memory");
3059		firsterr = -ENOMEM;
3060		goto unwind;
3061	}
3062	for (i = 0; i < nrealreaders; i++) {
3063		rcu_torture_reader_mbchk[i].rtc_chkrdr = -1;
3064		firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
3065						  reader_tasks[i]);
3066		if (firsterr)
3067			goto unwind;
3068	}
3069	nrealnocbers = nocbs_nthreads;
3070	if (WARN_ON(nrealnocbers < 0))
3071		nrealnocbers = 1;
3072	if (WARN_ON(nocbs_toggle < 0))
3073		nocbs_toggle = HZ;
3074	if (nrealnocbers > 0) {
3075		nocb_tasks = kcalloc(nrealnocbers, sizeof(nocb_tasks[0]), GFP_KERNEL);
3076		if (nocb_tasks == NULL) {
3077			VERBOSE_TOROUT_ERRSTRING("out of memory");
3078			firsterr = -ENOMEM;
3079			goto unwind;
3080		}
3081	} else {
3082		nocb_tasks = NULL;
3083	}
3084	for (i = 0; i < nrealnocbers; i++) {
3085		firsterr = torture_create_kthread(rcu_nocb_toggle, NULL, nocb_tasks[i]);
3086		if (firsterr)
3087			goto unwind;
3088	}
3089	if (stat_interval > 0) {
3090		firsterr = torture_create_kthread(rcu_torture_stats, NULL,
3091						  stats_task);
3092		if (firsterr)
3093			goto unwind;
3094	}
3095	if (test_no_idle_hz && shuffle_interval > 0) {
3096		firsterr = torture_shuffle_init(shuffle_interval * HZ);
3097		if (firsterr)
3098			goto unwind;
3099	}
3100	if (stutter < 0)
3101		stutter = 0;
3102	if (stutter) {
3103		int t;
3104
3105		t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
3106		firsterr = torture_stutter_init(stutter * HZ, t);
3107		if (firsterr)
3108			goto unwind;
3109	}
3110	if (fqs_duration < 0)
3111		fqs_duration = 0;
3112	if (fqs_duration) {
3113		/* Create the fqs thread */
3114		firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
3115						  fqs_task);
3116		if (firsterr)
3117			goto unwind;
3118	}
3119	if (test_boost_interval < 1)
3120		test_boost_interval = 1;
3121	if (test_boost_duration < 2)
3122		test_boost_duration = 2;
3123	if (rcu_torture_can_boost()) {
 
3124
3125		boost_starttime = jiffies + test_boost_interval * HZ;
3126
3127		firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
3128					     rcutorture_booster_init,
3129					     rcutorture_booster_cleanup);
3130		if (firsterr < 0)
3131			goto unwind;
3132		rcutor_hp = firsterr;
3133
3134		// Testing RCU priority boosting requires rcutorture do
3135		// some serious abuse.  Counter this by running ksoftirqd
3136		// at higher priority.
3137		if (IS_BUILTIN(CONFIG_RCU_TORTURE_TEST)) {
3138			for_each_online_cpu(cpu) {
3139				struct sched_param sp;
3140				struct task_struct *t;
3141
3142				t = per_cpu(ksoftirqd, cpu);
3143				WARN_ON_ONCE(!t);
3144				sp.sched_priority = 2;
3145				sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
3146			}
3147		}
3148	}
3149	shutdown_jiffies = jiffies + shutdown_secs * HZ;
3150	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
3151	if (firsterr)
3152		goto unwind;
3153	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
3154				      rcutorture_sync);
3155	if (firsterr)
3156		goto unwind;
3157	firsterr = rcu_torture_stall_init();
3158	if (firsterr)
3159		goto unwind;
3160	firsterr = rcu_torture_fwd_prog_init();
3161	if (firsterr)
3162		goto unwind;
3163	firsterr = rcu_torture_barrier_init();
3164	if (firsterr)
3165		goto unwind;
3166	firsterr = rcu_torture_read_exit_init();
3167	if (firsterr)
3168		goto unwind;
3169	if (object_debug)
3170		rcu_test_debug_objects();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3171	torture_init_end();
3172	return 0;
3173
3174unwind:
3175	torture_init_end();
3176	rcu_torture_cleanup();
3177	if (shutdown_secs) {
3178		WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
3179		kernel_power_off();
3180	}
3181	return firsterr;
3182}
3183
3184module_init(rcu_torture_init);
3185module_exit(rcu_torture_cleanup);