kernel/rcu/rcutorture.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
rcu_torture_writer_state_getname
rcu_trace_clock_local
rcu_trace_clock_local
shutdown_time_arrived
rcu_torture_alloc
rcu_torture_free
rcu_torture_read_lock
rcu_read_delay
rcu_torture_read_unlock
rcu_torture_pipe_update_one
rcu_torture_pipe_update
rcu_torture_cb
rcu_no_completed
rcu_torture_deferred_free
rcu_sync_torture_init
rcu_busted_torture_deferred_free
synchronize_rcu_busted
call_rcu_busted
srcu_torture_read_lock
srcu_read_delay
srcu_torture_read_unlock
srcu_torture_completed
srcu_torture_deferred_free
srcu_torture_synchronize
srcu_torture_call
srcu_torture_barrier
srcu_torture_stats
srcu_torture_synchronize_expedited
srcu_torture_init
srcu_torture_cleanup
tasks_torture_read_lock
tasks_torture_read_unlock
rcu_tasks_torture_deferred_free
synchronize_rcu_trivial
rcu_torture_read_lock_trivial
rcu_torture_read_unlock_trivial
rcutorture_seq_diff
torturing_tasks
rcu_torture_boost_cb
rcu_torture_disable_rt_throttle
rcu_torture_enable_rt_throttle
rcu_torture_boost_failed
rcu_torture_boost
rcu_torture_fqs
rcu_torture_writer
rcu_torture_fakewriter
rcu_torture_timer_cb
rcutorture_one_extend
rcutorture_extend_mask_max
rcutorture_extend_mask
rcutorture_loop_extend
rcu_torture_one_read
rcu_torture_timer
rcu_torture_reader
rcu_torture_stats_print
rcu_torture_stats
rcu_torture_print_module_parms
rcutorture_booster_cleanup
rcutorture_booster_init
rcu_torture_stall
rcu_torture_stall_init
rcu_torture_fwd_prog_cb
rcu_torture_fwd_cb_hist
rcu_torture_fwd_cb_cr
rcu_torture_fwd_prog_cond_resched
rcu_torture_fwd_prog_cbfree
rcu_torture_fwd_prog_nr
rcu_torture_fwd_prog_cr
rcutorture_oom_notify
rcu_torture_fwd_prog
rcu_torture_fwd_prog_init
rcu_torture_barrier_cbf
rcu_torture_barrier_cbs
rcu_torture_barrier
rcu_torture_barrier_init
rcu_torture_barrier_cleanup
rcu_torture_can_boost
rcu_torture_cleanup
rcu_torture_leak_cb
rcu_torture_err_cb
rcu_test_debug_objects
rcutorture_sync
rcu_torture_init
   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.txt
  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.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 
  48 #include "rcu.h"
  49 
  50 MODULE_LICENSE("GPL");
  51 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  52 
  53 
  54 /* Bits for ->extendables field, extendables param, and related definitions. */
  55 #define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
  56 #define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  57 #define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  58 #define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  59 #define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  60 #define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  61 #define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  62 #define RCUTORTURE_RDR_RCU       0x20   /*  ... entering another RCU reader. */
  63 #define RCUTORTURE_RDR_NBITS     6      /* Number of bits defined above. */
  64 #define RCUTORTURE_MAX_EXTEND    \
  65         (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  66          RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  67 #define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  68                                         /* Must be power of two minus one. */
  69 #define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  70 
  71 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  72               "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  73 torture_param(int, fqs_duration, 0,
  74               "Duration of fqs bursts (us), 0 to disable");
  75 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  76 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  77 torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  78 torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  79 torture_param(int, fwd_progress_holdoff, 60,
  80               "Time between forward-progress tests (s)");
  81 torture_param(bool, fwd_progress_need_resched, 1,
  82               "Hide cond_resched() behind need_resched()");
  83 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  84 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  85 torture_param(bool, gp_normal, false,
  86              "Use normal (non-expedited) GP wait primitives");
  87 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  88 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  89 torture_param(int, n_barrier_cbs, 0,
  90              "# of callbacks/kthreads for barrier testing");
  91 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  92 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  93 torture_param(int, object_debug, 0,
  94              "Enable debug-object double call_rcu() testing");
  95 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  96 torture_param(int, onoff_interval, 0,
  97              "Time between CPU hotplugs (jiffies), 0=disable");
  98 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  99 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 100 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 101 torture_param(int, stall_cpu_holdoff, 10,
 102              "Time to wait before starting stall (s).");
 103 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 104 torture_param(int, stat_interval, 60,
 105              "Number of seconds between stats printk()s");
 106 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 107 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 108 torture_param(int, test_boost_duration, 4,
 109              "Duration of each boost test, seconds.");
 110 torture_param(int, test_boost_interval, 7,
 111              "Interval between boost tests, seconds.");
 112 torture_param(bool, test_no_idle_hz, true,
 113              "Test support for tickless idle CPUs");
 114 torture_param(int, verbose, 1,
 115              "Enable verbose debugging printk()s");
 116 
 117 static char *torture_type = "rcu";
 118 module_param(torture_type, charp, 0444);
 119 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 120 
 121 static int nrealreaders;
 122 static struct task_struct *writer_task;
 123 static struct task_struct **fakewriter_tasks;
 124 static struct task_struct **reader_tasks;
 125 static struct task_struct *stats_task;
 126 static struct task_struct *fqs_task;
 127 static struct task_struct *boost_tasks[NR_CPUS];
 128 static struct task_struct *stall_task;
 129 static struct task_struct *fwd_prog_task;
 130 static struct task_struct **barrier_cbs_tasks;
 131 static struct task_struct *barrier_task;
 132 
 133 #define RCU_TORTURE_PIPE_LEN 10
 134 
 135 struct rcu_torture {
 136         struct rcu_head rtort_rcu;
 137         int rtort_pipe_count;
 138         struct list_head rtort_free;
 139         int rtort_mbtest;
 140 };
 141 
 142 static LIST_HEAD(rcu_torture_freelist);
 143 static struct rcu_torture __rcu *rcu_torture_current;
 144 static unsigned long rcu_torture_current_version;
 145 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 146 static DEFINE_SPINLOCK(rcu_torture_lock);
 147 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 148 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 149 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 150 static atomic_t n_rcu_torture_alloc;
 151 static atomic_t n_rcu_torture_alloc_fail;
 152 static atomic_t n_rcu_torture_free;
 153 static atomic_t n_rcu_torture_mberror;
 154 static atomic_t n_rcu_torture_error;
 155 static long n_rcu_torture_barrier_error;
 156 static long n_rcu_torture_boost_ktrerror;
 157 static long n_rcu_torture_boost_rterror;
 158 static long n_rcu_torture_boost_failure;
 159 static long n_rcu_torture_boosts;
 160 static atomic_long_t n_rcu_torture_timers;
 161 static long n_barrier_attempts;
 162 static long n_barrier_successes; /* did rcu_barrier test succeed? */
 163 static struct list_head rcu_torture_removed;
 164 static unsigned long shutdown_jiffies;
 165 
 166 static int rcu_torture_writer_state;
 167 #define RTWS_FIXED_DELAY        0
 168 #define RTWS_DELAY              1
 169 #define RTWS_REPLACE            2
 170 #define RTWS_DEF_FREE           3
 171 #define RTWS_EXP_SYNC           4
 172 #define RTWS_COND_GET           5
 173 #define RTWS_COND_SYNC          6
 174 #define RTWS_SYNC               7
 175 #define RTWS_STUTTER            8
 176 #define RTWS_STOPPING           9
 177 static const char * const rcu_torture_writer_state_names[] = {
 178         "RTWS_FIXED_DELAY",
 179         "RTWS_DELAY",
 180         "RTWS_REPLACE",
 181         "RTWS_DEF_FREE",
 182         "RTWS_EXP_SYNC",
 183         "RTWS_COND_GET",
 184         "RTWS_COND_SYNC",
 185         "RTWS_SYNC",
 186         "RTWS_STUTTER",
 187         "RTWS_STOPPING",
 188 };
 189 
 190 /* Record reader segment types and duration for first failing read. */
 191 struct rt_read_seg {
 192         int rt_readstate;
 193         unsigned long rt_delay_jiffies;
 194         unsigned long rt_delay_ms;
 195         unsigned long rt_delay_us;
 196         bool rt_preempted;
 197 };
 198 static int err_segs_recorded;
 199 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 200 static int rt_read_nsegs;
 201 
 202 static const char *rcu_torture_writer_state_getname(void)
 203 {
 204         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 205 
 206         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 207                 return "???";
 208         return rcu_torture_writer_state_names[i];
 209 }
 210 
 211 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 212 #define rcu_can_boost() 1
 213 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 214 #define rcu_can_boost() 0
 215 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 216 
 217 #ifdef CONFIG_RCU_TRACE
 218 static u64 notrace rcu_trace_clock_local(void)
 219 {
 220         u64 ts = trace_clock_local();
 221 
 222         (void)do_div(ts, NSEC_PER_USEC);
 223         return ts;
 224 }
 225 #else /* #ifdef CONFIG_RCU_TRACE */
 226 static u64 notrace rcu_trace_clock_local(void)
 227 {
 228         return 0ULL;
 229 }
 230 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 231 
 232 /*
 233  * Stop aggressive CPU-hog tests a bit before the end of the test in order
 234  * to avoid interfering with test shutdown.
 235  */
 236 static bool shutdown_time_arrived(void)
 237 {
 238         return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
 239 }
 240 
 241 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 242 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 243                                         /*  and boost task create/destroy. */
 244 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 245 static bool barrier_phase;              /* Test phase. */
 246 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 247 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 248 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 249 
 250 static bool rcu_fwd_cb_nodelay;         /* Short rcu_torture_delay() delays. */
 251 
 252 /*
 253  * Allocate an element from the rcu_tortures pool.
 254  */
 255 static struct rcu_torture *
 256 rcu_torture_alloc(void)
 257 {
 258         struct list_head *p;
 259 
 260         spin_lock_bh(&rcu_torture_lock);
 261         if (list_empty(&rcu_torture_freelist)) {
 262                 atomic_inc(&n_rcu_torture_alloc_fail);
 263                 spin_unlock_bh(&rcu_torture_lock);
 264                 return NULL;
 265         }
 266         atomic_inc(&n_rcu_torture_alloc);
 267         p = rcu_torture_freelist.next;
 268         list_del_init(p);
 269         spin_unlock_bh(&rcu_torture_lock);
 270         return container_of(p, struct rcu_torture, rtort_free);
 271 }
 272 
 273 /*
 274  * Free an element to the rcu_tortures pool.
 275  */
 276 static void
 277 rcu_torture_free(struct rcu_torture *p)
 278 {
 279         atomic_inc(&n_rcu_torture_free);
 280         spin_lock_bh(&rcu_torture_lock);
 281         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 282         spin_unlock_bh(&rcu_torture_lock);
 283 }
 284 
 285 /*
 286  * Operations vector for selecting different types of tests.
 287  */
 288 
 289 struct rcu_torture_ops {
 290         int ttype;
 291         void (*init)(void);
 292         void (*cleanup)(void);
 293         int (*readlock)(void);
 294         void (*read_delay)(struct torture_random_state *rrsp,
 295                            struct rt_read_seg *rtrsp);
 296         void (*readunlock)(int idx);
 297         unsigned long (*get_gp_seq)(void);
 298         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 299         void (*deferred_free)(struct rcu_torture *p);
 300         void (*sync)(void);
 301         void (*exp_sync)(void);
 302         unsigned long (*get_state)(void);
 303         void (*cond_sync)(unsigned long oldstate);
 304         call_rcu_func_t call;
 305         void (*cb_barrier)(void);
 306         void (*fqs)(void);
 307         void (*stats)(void);
 308         int (*stall_dur)(void);
 309         int irq_capable;
 310         int can_boost;
 311         int extendables;
 312         int slow_gps;
 313         const char *name;
 314 };
 315 
 316 static struct rcu_torture_ops *cur_ops;
 317 
 318 /*
 319  * Definitions for rcu torture testing.
 320  */
 321 
 322 static int rcu_torture_read_lock(void) __acquires(RCU)
 323 {
 324         rcu_read_lock();
 325         return 0;
 326 }
 327 
 328 static void
 329 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 330 {
 331         unsigned long started;
 332         unsigned long completed;
 333         const unsigned long shortdelay_us = 200;
 334         unsigned long longdelay_ms = 300;
 335         unsigned long long ts;
 336 
 337         /* We want a short delay sometimes to make a reader delay the grace
 338          * period, and we want a long delay occasionally to trigger
 339          * force_quiescent_state. */
 340 
 341         if (!rcu_fwd_cb_nodelay &&
 342             !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 343                 started = cur_ops->get_gp_seq();
 344                 ts = rcu_trace_clock_local();
 345                 if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 346                         longdelay_ms = 5; /* Avoid triggering BH limits. */
 347                 mdelay(longdelay_ms);
 348                 rtrsp->rt_delay_ms = longdelay_ms;
 349                 completed = cur_ops->get_gp_seq();
 350                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 351                                           started, completed);
 352         }
 353         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 354                 udelay(shortdelay_us);
 355                 rtrsp->rt_delay_us = shortdelay_us;
 356         }
 357         if (!preempt_count() &&
 358             !(torture_random(rrsp) % (nrealreaders * 500))) {
 359                 torture_preempt_schedule();  /* QS only if preemptible. */
 360                 rtrsp->rt_preempted = true;
 361         }
 362 }
 363 
 364 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 365 {
 366         rcu_read_unlock();
 367 }
 368 
 369 /*
 370  * Update callback in the pipe.  This should be invoked after a grace period.
 371  */
 372 static bool
 373 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 374 {
 375         int i;
 376 
 377         i = rp->rtort_pipe_count;
 378         if (i > RCU_TORTURE_PIPE_LEN)
 379                 i = RCU_TORTURE_PIPE_LEN;
 380         atomic_inc(&rcu_torture_wcount[i]);
 381         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 382                 rp->rtort_mbtest = 0;
 383                 return true;
 384         }
 385         return false;
 386 }
 387 
 388 /*
 389  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 390  * primitives.
 391  */
 392 static void
 393 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 394 {
 395         struct rcu_torture *rp;
 396         struct rcu_torture *rp1;
 397 
 398         if (old_rp)
 399                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 400         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 401                 if (rcu_torture_pipe_update_one(rp)) {
 402                         list_del(&rp->rtort_free);
 403                         rcu_torture_free(rp);
 404                 }
 405         }
 406 }
 407 
 408 static void
 409 rcu_torture_cb(struct rcu_head *p)
 410 {
 411         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 412 
 413         if (torture_must_stop_irq()) {
 414                 /* Test is ending, just drop callbacks on the floor. */
 415                 /* The next initialization will pick up the pieces. */
 416                 return;
 417         }
 418         if (rcu_torture_pipe_update_one(rp))
 419                 rcu_torture_free(rp);
 420         else
 421                 cur_ops->deferred_free(rp);
 422 }
 423 
 424 static unsigned long rcu_no_completed(void)
 425 {
 426         return 0;
 427 }
 428 
 429 static void rcu_torture_deferred_free(struct rcu_torture *p)
 430 {
 431         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 432 }
 433 
 434 static void rcu_sync_torture_init(void)
 435 {
 436         INIT_LIST_HEAD(&rcu_torture_removed);
 437 }
 438 
 439 static struct rcu_torture_ops rcu_ops = {
 440         .ttype          = RCU_FLAVOR,
 441         .init           = rcu_sync_torture_init,
 442         .readlock       = rcu_torture_read_lock,
 443         .read_delay     = rcu_read_delay,
 444         .readunlock     = rcu_torture_read_unlock,
 445         .get_gp_seq     = rcu_get_gp_seq,
 446         .gp_diff        = rcu_seq_diff,
 447         .deferred_free  = rcu_torture_deferred_free,
 448         .sync           = synchronize_rcu,
 449         .exp_sync       = synchronize_rcu_expedited,
 450         .get_state      = get_state_synchronize_rcu,
 451         .cond_sync      = cond_synchronize_rcu,
 452         .call           = call_rcu,
 453         .cb_barrier     = rcu_barrier,
 454         .fqs            = rcu_force_quiescent_state,
 455         .stats          = NULL,
 456         .stall_dur      = rcu_jiffies_till_stall_check,
 457         .irq_capable    = 1,
 458         .can_boost      = rcu_can_boost(),
 459         .extendables    = RCUTORTURE_MAX_EXTEND,
 460         .name           = "rcu"
 461 };
 462 
 463 /*
 464  * Don't even think about trying any of these in real life!!!
 465  * The names includes "busted", and they really means it!
 466  * The only purpose of these functions is to provide a buggy RCU
 467  * implementation to make sure that rcutorture correctly emits
 468  * buggy-RCU error messages.
 469  */
 470 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 471 {
 472         /* This is a deliberate bug for testing purposes only! */
 473         rcu_torture_cb(&p->rtort_rcu);
 474 }
 475 
 476 static void synchronize_rcu_busted(void)
 477 {
 478         /* This is a deliberate bug for testing purposes only! */
 479 }
 480 
 481 static void
 482 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 483 {
 484         /* This is a deliberate bug for testing purposes only! */
 485         func(head);
 486 }
 487 
 488 static struct rcu_torture_ops rcu_busted_ops = {
 489         .ttype          = INVALID_RCU_FLAVOR,
 490         .init           = rcu_sync_torture_init,
 491         .readlock       = rcu_torture_read_lock,
 492         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 493         .readunlock     = rcu_torture_read_unlock,
 494         .get_gp_seq     = rcu_no_completed,
 495         .deferred_free  = rcu_busted_torture_deferred_free,
 496         .sync           = synchronize_rcu_busted,
 497         .exp_sync       = synchronize_rcu_busted,
 498         .call           = call_rcu_busted,
 499         .cb_barrier     = NULL,
 500         .fqs            = NULL,
 501         .stats          = NULL,
 502         .irq_capable    = 1,
 503         .name           = "busted"
 504 };
 505 
 506 /*
 507  * Definitions for srcu torture testing.
 508  */
 509 
 510 DEFINE_STATIC_SRCU(srcu_ctl);
 511 static struct srcu_struct srcu_ctld;
 512 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 513 
 514 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 515 {
 516         return srcu_read_lock(srcu_ctlp);
 517 }
 518 
 519 static void
 520 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 521 {
 522         long delay;
 523         const long uspertick = 1000000 / HZ;
 524         const long longdelay = 10;
 525 
 526         /* We want there to be long-running readers, but not all the time. */
 527 
 528         delay = torture_random(rrsp) %
 529                 (nrealreaders * 2 * longdelay * uspertick);
 530         if (!delay && in_task()) {
 531                 schedule_timeout_interruptible(longdelay);
 532                 rtrsp->rt_delay_jiffies = longdelay;
 533         } else {
 534                 rcu_read_delay(rrsp, rtrsp);
 535         }
 536 }
 537 
 538 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 539 {
 540         srcu_read_unlock(srcu_ctlp, idx);
 541 }
 542 
 543 static unsigned long srcu_torture_completed(void)
 544 {
 545         return srcu_batches_completed(srcu_ctlp);
 546 }
 547 
 548 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 549 {
 550         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 551 }
 552 
 553 static void srcu_torture_synchronize(void)
 554 {
 555         synchronize_srcu(srcu_ctlp);
 556 }
 557 
 558 static void srcu_torture_call(struct rcu_head *head,
 559                               rcu_callback_t func)
 560 {
 561         call_srcu(srcu_ctlp, head, func);
 562 }
 563 
 564 static void srcu_torture_barrier(void)
 565 {
 566         srcu_barrier(srcu_ctlp);
 567 }
 568 
 569 static void srcu_torture_stats(void)
 570 {
 571         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 572 }
 573 
 574 static void srcu_torture_synchronize_expedited(void)
 575 {
 576         synchronize_srcu_expedited(srcu_ctlp);
 577 }
 578 
 579 static struct rcu_torture_ops srcu_ops = {
 580         .ttype          = SRCU_FLAVOR,
 581         .init           = rcu_sync_torture_init,
 582         .readlock       = srcu_torture_read_lock,
 583         .read_delay     = srcu_read_delay,
 584         .readunlock     = srcu_torture_read_unlock,
 585         .get_gp_seq     = srcu_torture_completed,
 586         .deferred_free  = srcu_torture_deferred_free,
 587         .sync           = srcu_torture_synchronize,
 588         .exp_sync       = srcu_torture_synchronize_expedited,
 589         .call           = srcu_torture_call,
 590         .cb_barrier     = srcu_torture_barrier,
 591         .stats          = srcu_torture_stats,
 592         .irq_capable    = 1,
 593         .name           = "srcu"
 594 };
 595 
 596 static void srcu_torture_init(void)
 597 {
 598         rcu_sync_torture_init();
 599         WARN_ON(init_srcu_struct(&srcu_ctld));
 600         srcu_ctlp = &srcu_ctld;
 601 }
 602 
 603 static void srcu_torture_cleanup(void)
 604 {
 605         cleanup_srcu_struct(&srcu_ctld);
 606         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 607 }
 608 
 609 /* As above, but dynamically allocated. */
 610 static struct rcu_torture_ops srcud_ops = {
 611         .ttype          = SRCU_FLAVOR,
 612         .init           = srcu_torture_init,
 613         .cleanup        = srcu_torture_cleanup,
 614         .readlock       = srcu_torture_read_lock,
 615         .read_delay     = srcu_read_delay,
 616         .readunlock     = srcu_torture_read_unlock,
 617         .get_gp_seq     = srcu_torture_completed,
 618         .deferred_free  = srcu_torture_deferred_free,
 619         .sync           = srcu_torture_synchronize,
 620         .exp_sync       = srcu_torture_synchronize_expedited,
 621         .call           = srcu_torture_call,
 622         .cb_barrier     = srcu_torture_barrier,
 623         .stats          = srcu_torture_stats,
 624         .irq_capable    = 1,
 625         .name           = "srcud"
 626 };
 627 
 628 /* As above, but broken due to inappropriate reader extension. */
 629 static struct rcu_torture_ops busted_srcud_ops = {
 630         .ttype          = SRCU_FLAVOR,
 631         .init           = srcu_torture_init,
 632         .cleanup        = srcu_torture_cleanup,
 633         .readlock       = srcu_torture_read_lock,
 634         .read_delay     = rcu_read_delay,
 635         .readunlock     = srcu_torture_read_unlock,
 636         .get_gp_seq     = srcu_torture_completed,
 637         .deferred_free  = srcu_torture_deferred_free,
 638         .sync           = srcu_torture_synchronize,
 639         .exp_sync       = srcu_torture_synchronize_expedited,
 640         .call           = srcu_torture_call,
 641         .cb_barrier     = srcu_torture_barrier,
 642         .stats          = srcu_torture_stats,
 643         .irq_capable    = 1,
 644         .extendables    = RCUTORTURE_MAX_EXTEND,
 645         .name           = "busted_srcud"
 646 };
 647 
 648 /*
 649  * Definitions for RCU-tasks torture testing.
 650  */
 651 
 652 static int tasks_torture_read_lock(void)
 653 {
 654         return 0;
 655 }
 656 
 657 static void tasks_torture_read_unlock(int idx)
 658 {
 659 }
 660 
 661 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 662 {
 663         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 664 }
 665 
 666 static struct rcu_torture_ops tasks_ops = {
 667         .ttype          = RCU_TASKS_FLAVOR,
 668         .init           = rcu_sync_torture_init,
 669         .readlock       = tasks_torture_read_lock,
 670         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 671         .readunlock     = tasks_torture_read_unlock,
 672         .get_gp_seq     = rcu_no_completed,
 673         .deferred_free  = rcu_tasks_torture_deferred_free,
 674         .sync           = synchronize_rcu_tasks,
 675         .exp_sync       = synchronize_rcu_tasks,
 676         .call           = call_rcu_tasks,
 677         .cb_barrier     = rcu_barrier_tasks,
 678         .fqs            = NULL,
 679         .stats          = NULL,
 680         .irq_capable    = 1,
 681         .slow_gps       = 1,
 682         .name           = "tasks"
 683 };
 684 
 685 /*
 686  * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 687  * This implementation does not necessarily work well with CPU hotplug.
 688  */
 689 
 690 static void synchronize_rcu_trivial(void)
 691 {
 692         int cpu;
 693 
 694         for_each_online_cpu(cpu) {
 695                 rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
 696                 WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 697         }
 698 }
 699 
 700 static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
 701 {
 702         preempt_disable();
 703         return 0;
 704 }
 705 
 706 static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
 707 {
 708         preempt_enable();
 709 }
 710 
 711 static struct rcu_torture_ops trivial_ops = {
 712         .ttype          = RCU_TRIVIAL_FLAVOR,
 713         .init           = rcu_sync_torture_init,
 714         .readlock       = rcu_torture_read_lock_trivial,
 715         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 716         .readunlock     = rcu_torture_read_unlock_trivial,
 717         .get_gp_seq     = rcu_no_completed,
 718         .sync           = synchronize_rcu_trivial,
 719         .exp_sync       = synchronize_rcu_trivial,
 720         .fqs            = NULL,
 721         .stats          = NULL,
 722         .irq_capable    = 1,
 723         .name           = "trivial"
 724 };
 725 
 726 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 727 {
 728         if (!cur_ops->gp_diff)
 729                 return new - old;
 730         return cur_ops->gp_diff(new, old);
 731 }
 732 
 733 static bool __maybe_unused torturing_tasks(void)
 734 {
 735         return cur_ops == &tasks_ops;
 736 }
 737 
 738 /*
 739  * RCU torture priority-boost testing.  Runs one real-time thread per
 740  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 741  * spinning waiting for them to be invoked.  If a given callback takes
 742  * too long to be invoked, we assume that priority inversion has occurred.
 743  */
 744 
 745 struct rcu_boost_inflight {
 746         struct rcu_head rcu;
 747         int inflight;
 748 };
 749 
 750 static void rcu_torture_boost_cb(struct rcu_head *head)
 751 {
 752         struct rcu_boost_inflight *rbip =
 753                 container_of(head, struct rcu_boost_inflight, rcu);
 754 
 755         /* Ensure RCU-core accesses precede clearing ->inflight */
 756         smp_store_release(&rbip->inflight, 0);
 757 }
 758 
 759 static int old_rt_runtime = -1;
 760 
 761 static void rcu_torture_disable_rt_throttle(void)
 762 {
 763         /*
 764          * Disable RT throttling so that rcutorture's boost threads don't get
 765          * throttled. Only possible if rcutorture is built-in otherwise the
 766          * user should manually do this by setting the sched_rt_period_us and
 767          * sched_rt_runtime sysctls.
 768          */
 769         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 770                 return;
 771 
 772         old_rt_runtime = sysctl_sched_rt_runtime;
 773         sysctl_sched_rt_runtime = -1;
 774 }
 775 
 776 static void rcu_torture_enable_rt_throttle(void)
 777 {
 778         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 779                 return;
 780 
 781         sysctl_sched_rt_runtime = old_rt_runtime;
 782         old_rt_runtime = -1;
 783 }
 784 
 785 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 786 {
 787         if (end - start > test_boost_duration * HZ - HZ / 2) {
 788                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 789                 n_rcu_torture_boost_failure++;
 790 
 791                 return true; /* failed */
 792         }
 793 
 794         return false; /* passed */
 795 }
 796 
 797 static int rcu_torture_boost(void *arg)
 798 {
 799         unsigned long call_rcu_time;
 800         unsigned long endtime;
 801         unsigned long oldstarttime;
 802         struct rcu_boost_inflight rbi = { .inflight = 0 };
 803         struct sched_param sp;
 804 
 805         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 806 
 807         /* Set real-time priority. */
 808         sp.sched_priority = 1;
 809         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 810                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 811                 n_rcu_torture_boost_rterror++;
 812         }
 813 
 814         init_rcu_head_on_stack(&rbi.rcu);
 815         /* Each pass through the following loop does one boost-test cycle. */
 816         do {
 817                 /* Track if the test failed already in this test interval? */
 818                 bool failed = false;
 819 
 820                 /* Increment n_rcu_torture_boosts once per boost-test */
 821                 while (!kthread_should_stop()) {
 822                         if (mutex_trylock(&boost_mutex)) {
 823                                 n_rcu_torture_boosts++;
 824                                 mutex_unlock(&boost_mutex);
 825                                 break;
 826                         }
 827                         schedule_timeout_uninterruptible(1);
 828                 }
 829                 if (kthread_should_stop())
 830                         goto checkwait;
 831 
 832                 /* Wait for the next test interval. */
 833                 oldstarttime = boost_starttime;
 834                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 835                         schedule_timeout_interruptible(oldstarttime - jiffies);
 836                         stutter_wait("rcu_torture_boost");
 837                         if (torture_must_stop())
 838                                 goto checkwait;
 839                 }
 840 
 841                 /* Do one boost-test interval. */
 842                 endtime = oldstarttime + test_boost_duration * HZ;
 843                 call_rcu_time = jiffies;
 844                 while (ULONG_CMP_LT(jiffies, endtime)) {
 845                         /* If we don't have a callback in flight, post one. */
 846                         if (!smp_load_acquire(&rbi.inflight)) {
 847                                 /* RCU core before ->inflight = 1. */
 848                                 smp_store_release(&rbi.inflight, 1);
 849                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 850                                 /* Check if the boost test failed */
 851                                 failed = failed ||
 852                                          rcu_torture_boost_failed(call_rcu_time,
 853                                                                  jiffies);
 854                                 call_rcu_time = jiffies;
 855                         }
 856                         stutter_wait("rcu_torture_boost");
 857                         if (torture_must_stop())
 858                                 goto checkwait;
 859                 }
 860 
 861                 /*
 862                  * If boost never happened, then inflight will always be 1, in
 863                  * this case the boost check would never happen in the above
 864                  * loop so do another one here.
 865                  */
 866                 if (!failed && smp_load_acquire(&rbi.inflight))
 867                         rcu_torture_boost_failed(call_rcu_time, jiffies);
 868 
 869                 /*
 870                  * Set the start time of the next test interval.
 871                  * Yes, this is vulnerable to long delays, but such
 872                  * delays simply cause a false negative for the next
 873                  * interval.  Besides, we are running at RT priority,
 874                  * so delays should be relatively rare.
 875                  */
 876                 while (oldstarttime == boost_starttime &&
 877                        !kthread_should_stop()) {
 878                         if (mutex_trylock(&boost_mutex)) {
 879                                 boost_starttime = jiffies +
 880                                                   test_boost_interval * HZ;
 881                                 mutex_unlock(&boost_mutex);
 882                                 break;
 883                         }
 884                         schedule_timeout_uninterruptible(1);
 885                 }
 886 
 887                 /* Go do the stutter. */
 888 checkwait:      stutter_wait("rcu_torture_boost");
 889         } while (!torture_must_stop());
 890 
 891         /* Clean up and exit. */
 892         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 893                 torture_shutdown_absorb("rcu_torture_boost");
 894                 schedule_timeout_uninterruptible(1);
 895         }
 896         destroy_rcu_head_on_stack(&rbi.rcu);
 897         torture_kthread_stopping("rcu_torture_boost");
 898         return 0;
 899 }
 900 
 901 /*
 902  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 903  * bursts of calls to force_quiescent_state(), increasing the probability
 904  * of occurrence of some important types of race conditions.
 905  */
 906 static int
 907 rcu_torture_fqs(void *arg)
 908 {
 909         unsigned long fqs_resume_time;
 910         int fqs_burst_remaining;
 911 
 912         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 913         do {
 914                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 915                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 916                        !kthread_should_stop()) {
 917                         schedule_timeout_interruptible(1);
 918                 }
 919                 fqs_burst_remaining = fqs_duration;
 920                 while (fqs_burst_remaining > 0 &&
 921                        !kthread_should_stop()) {
 922                         cur_ops->fqs();
 923                         udelay(fqs_holdoff);
 924                         fqs_burst_remaining -= fqs_holdoff;
 925                 }
 926                 stutter_wait("rcu_torture_fqs");
 927         } while (!torture_must_stop());
 928         torture_kthread_stopping("rcu_torture_fqs");
 929         return 0;
 930 }
 931 
 932 /*
 933  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 934  * for that pointed to by rcu_torture_current, freeing the old structure
 935  * after a series of grace periods (the "pipeline").
 936  */
 937 static int
 938 rcu_torture_writer(void *arg)
 939 {
 940         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 941         int expediting = 0;
 942         unsigned long gp_snap;
 943         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 944         bool gp_sync1 = gp_sync;
 945         int i;
 946         struct rcu_torture *rp;
 947         struct rcu_torture *old_rp;
 948         static DEFINE_TORTURE_RANDOM(rand);
 949         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 950                            RTWS_COND_GET, RTWS_SYNC };
 951         int nsynctypes = 0;
 952 
 953         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 954         if (!can_expedite)
 955                 pr_alert("%s" TORTURE_FLAG
 956                          " GP expediting controlled from boot/sysfs for %s.\n",
 957                          torture_type, cur_ops->name);
 958 
 959         /* Initialize synctype[] array.  If none set, take default. */
 960         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 961                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 962         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 963                 synctype[nsynctypes++] = RTWS_COND_GET;
 964                 pr_info("%s: Testing conditional GPs.\n", __func__);
 965         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 966                 pr_alert("%s: gp_cond without primitives.\n", __func__);
 967         }
 968         if (gp_exp1 && cur_ops->exp_sync) {
 969                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 970                 pr_info("%s: Testing expedited GPs.\n", __func__);
 971         } else if (gp_exp && !cur_ops->exp_sync) {
 972                 pr_alert("%s: gp_exp without primitives.\n", __func__);
 973         }
 974         if (gp_normal1 && cur_ops->deferred_free) {
 975                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 976                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
 977         } else if (gp_normal && !cur_ops->deferred_free) {
 978                 pr_alert("%s: gp_normal without primitives.\n", __func__);
 979         }
 980         if (gp_sync1 && cur_ops->sync) {
 981                 synctype[nsynctypes++] = RTWS_SYNC;
 982                 pr_info("%s: Testing normal GPs.\n", __func__);
 983         } else if (gp_sync && !cur_ops->sync) {
 984                 pr_alert("%s: gp_sync without primitives.\n", __func__);
 985         }
 986         if (WARN_ONCE(nsynctypes == 0,
 987                       "rcu_torture_writer: No update-side primitives.\n")) {
 988                 /*
 989                  * No updates primitives, so don't try updating.
 990                  * The resulting test won't be testing much, hence the
 991                  * above WARN_ONCE().
 992                  */
 993                 rcu_torture_writer_state = RTWS_STOPPING;
 994                 torture_kthread_stopping("rcu_torture_writer");
 995         }
 996 
 997         do {
 998                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 999                 schedule_timeout_uninterruptible(1);
1000                 rp = rcu_torture_alloc();
1001                 if (rp == NULL)
1002                         continue;
1003                 rp->rtort_pipe_count = 0;
1004                 rcu_torture_writer_state = RTWS_DELAY;
1005                 udelay(torture_random(&rand) & 0x3ff);
1006                 rcu_torture_writer_state = RTWS_REPLACE;
1007                 old_rp = rcu_dereference_check(rcu_torture_current,
1008                                                current == writer_task);
1009                 rp->rtort_mbtest = 1;
1010                 rcu_assign_pointer(rcu_torture_current, rp);
1011                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1012                 if (old_rp) {
1013                         i = old_rp->rtort_pipe_count;
1014                         if (i > RCU_TORTURE_PIPE_LEN)
1015                                 i = RCU_TORTURE_PIPE_LEN;
1016                         atomic_inc(&rcu_torture_wcount[i]);
1017                         old_rp->rtort_pipe_count++;
1018                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1019                         case RTWS_DEF_FREE:
1020                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1021                                 cur_ops->deferred_free(old_rp);
1022                                 break;
1023                         case RTWS_EXP_SYNC:
1024                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1025                                 cur_ops->exp_sync();
1026                                 rcu_torture_pipe_update(old_rp);
1027                                 break;
1028                         case RTWS_COND_GET:
1029                                 rcu_torture_writer_state = RTWS_COND_GET;
1030                                 gp_snap = cur_ops->get_state();
1031                                 i = torture_random(&rand) % 16;
1032                                 if (i != 0)
1033                                         schedule_timeout_interruptible(i);
1034                                 udelay(torture_random(&rand) % 1000);
1035                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1036                                 cur_ops->cond_sync(gp_snap);
1037                                 rcu_torture_pipe_update(old_rp);
1038                                 break;
1039                         case RTWS_SYNC:
1040                                 rcu_torture_writer_state = RTWS_SYNC;
1041                                 cur_ops->sync();
1042                                 rcu_torture_pipe_update(old_rp);
1043                                 break;
1044                         default:
1045                                 WARN_ON_ONCE(1);
1046                                 break;
1047                         }
1048                 }
1049                 WRITE_ONCE(rcu_torture_current_version,
1050                            rcu_torture_current_version + 1);
1051                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1052                 if (can_expedite &&
1053                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1054                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1055                         if (expediting >= 0)
1056                                 rcu_expedite_gp();
1057                         else
1058                                 rcu_unexpedite_gp();
1059                         if (++expediting > 3)
1060                                 expediting = -expediting;
1061                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1062                         can_expedite = !rcu_gp_is_expedited() &&
1063                                        !rcu_gp_is_normal();
1064                 }
1065                 rcu_torture_writer_state = RTWS_STUTTER;
1066                 if (stutter_wait("rcu_torture_writer") &&
1067                     !READ_ONCE(rcu_fwd_cb_nodelay) &&
1068                     !cur_ops->slow_gps &&
1069                     !torture_must_stop())
1070                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1071                                 if (list_empty(&rcu_tortures[i].rtort_free) &&
1072                                     rcu_access_pointer(rcu_torture_current) !=
1073                                     &rcu_tortures[i]) {
1074                                         rcu_ftrace_dump(DUMP_ALL);
1075                                         WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
1076                                 }
1077         } while (!torture_must_stop());
1078         /* Reset expediting back to unexpedited. */
1079         if (expediting > 0)
1080                 expediting = -expediting;
1081         while (can_expedite && expediting++ < 0)
1082                 rcu_unexpedite_gp();
1083         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1084         if (!can_expedite)
1085                 pr_alert("%s" TORTURE_FLAG
1086                          " Dynamic grace-period expediting was disabled.\n",
1087                          torture_type);
1088         rcu_torture_writer_state = RTWS_STOPPING;
1089         torture_kthread_stopping("rcu_torture_writer");
1090         return 0;
1091 }
1092 
1093 /*
1094  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1095  * delay between calls.
1096  */
1097 static int
1098 rcu_torture_fakewriter(void *arg)
1099 {
1100         DEFINE_TORTURE_RANDOM(rand);
1101 
1102         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1103         set_user_nice(current, MAX_NICE);
1104 
1105         do {
1106                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1107                 udelay(torture_random(&rand) & 0x3ff);
1108                 if (cur_ops->cb_barrier != NULL &&
1109                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1110                         cur_ops->cb_barrier();
1111                 } else if (gp_normal == gp_exp) {
1112                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1113                                 cur_ops->sync();
1114                         else if (cur_ops->exp_sync)
1115                                 cur_ops->exp_sync();
1116                 } else if (gp_normal && cur_ops->sync) {
1117                         cur_ops->sync();
1118                 } else if (cur_ops->exp_sync) {
1119                         cur_ops->exp_sync();
1120                 }
1121                 stutter_wait("rcu_torture_fakewriter");
1122         } while (!torture_must_stop());
1123 
1124         torture_kthread_stopping("rcu_torture_fakewriter");
1125         return 0;
1126 }
1127 
1128 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1129 {
1130         kfree(rhp);
1131 }
1132 
1133 /*
1134  * Do one extension of an RCU read-side critical section using the
1135  * current reader state in readstate (set to zero for initial entry
1136  * to extended critical section), set the new state as specified by
1137  * newstate (set to zero for final exit from extended critical section),
1138  * and random-number-generator state in trsp.  If this is neither the
1139  * beginning or end of the critical section and if there was actually a
1140  * change, do a ->read_delay().
1141  */
1142 static void rcutorture_one_extend(int *readstate, int newstate,
1143                                   struct torture_random_state *trsp,
1144                                   struct rt_read_seg *rtrsp)
1145 {
1146         int idxnew = -1;
1147         int idxold = *readstate;
1148         int statesnew = ~*readstate & newstate;
1149         int statesold = *readstate & ~newstate;
1150 
1151         WARN_ON_ONCE(idxold < 0);
1152         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1153         rtrsp->rt_readstate = newstate;
1154 
1155         /* First, put new protection in place to avoid critical-section gap. */
1156         if (statesnew & RCUTORTURE_RDR_BH)
1157                 local_bh_disable();
1158         if (statesnew & RCUTORTURE_RDR_IRQ)
1159                 local_irq_disable();
1160         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1161                 preempt_disable();
1162         if (statesnew & RCUTORTURE_RDR_RBH)
1163                 rcu_read_lock_bh();
1164         if (statesnew & RCUTORTURE_RDR_SCHED)
1165                 rcu_read_lock_sched();
1166         if (statesnew & RCUTORTURE_RDR_RCU)
1167                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1168 
1169         /* Next, remove old protection, irq first due to bh conflict. */
1170         if (statesold & RCUTORTURE_RDR_IRQ)
1171                 local_irq_enable();
1172         if (statesold & RCUTORTURE_RDR_BH)
1173                 local_bh_enable();
1174         if (statesold & RCUTORTURE_RDR_PREEMPT)
1175                 preempt_enable();
1176         if (statesold & RCUTORTURE_RDR_RBH)
1177                 rcu_read_unlock_bh();
1178         if (statesold & RCUTORTURE_RDR_SCHED)
1179                 rcu_read_unlock_sched();
1180         if (statesold & RCUTORTURE_RDR_RCU)
1181                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1182 
1183         /* Delay if neither beginning nor end and there was a change. */
1184         if ((statesnew || statesold) && *readstate && newstate)
1185                 cur_ops->read_delay(trsp, rtrsp);
1186 
1187         /* Update the reader state. */
1188         if (idxnew == -1)
1189                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1190         WARN_ON_ONCE(idxnew < 0);
1191         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1192         *readstate = idxnew | newstate;
1193         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1194         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1195 }
1196 
1197 /* Return the biggest extendables mask given current RCU and boot parameters. */
1198 static int rcutorture_extend_mask_max(void)
1199 {
1200         int mask;
1201 
1202         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1203         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1204         mask = mask | RCUTORTURE_RDR_RCU;
1205         return mask;
1206 }
1207 
1208 /* Return a random protection state mask, but with at least one bit set. */
1209 static int
1210 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1211 {
1212         int mask = rcutorture_extend_mask_max();
1213         unsigned long randmask1 = torture_random(trsp) >> 8;
1214         unsigned long randmask2 = randmask1 >> 3;
1215 
1216         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1217         /* Mostly only one bit (need preemption!), sometimes lots of bits. */
1218         if (!(randmask1 & 0x7))
1219                 mask = mask & randmask2;
1220         else
1221                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1222         /* Can't enable bh w/irq disabled. */
1223         if ((mask & RCUTORTURE_RDR_IRQ) &&
1224             ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1225              (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1226                 mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1227         return mask ?: RCUTORTURE_RDR_RCU;
1228 }
1229 
1230 /*
1231  * Do a randomly selected number of extensions of an existing RCU read-side
1232  * critical section.
1233  */
1234 static struct rt_read_seg *
1235 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1236                        struct rt_read_seg *rtrsp)
1237 {
1238         int i;
1239         int j;
1240         int mask = rcutorture_extend_mask_max();
1241 
1242         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1243         if (!((mask - 1) & mask))
1244                 return rtrsp;  /* Current RCU reader not extendable. */
1245         /* Bias towards larger numbers of loops. */
1246         i = (torture_random(trsp) >> 3);
1247         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1248         for (j = 0; j < i; j++) {
1249                 mask = rcutorture_extend_mask(*readstate, trsp);
1250                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1251         }
1252         return &rtrsp[j];
1253 }
1254 
1255 /*
1256  * Do one read-side critical section, returning false if there was
1257  * no data to read.  Can be invoked both from process context and
1258  * from a timer handler.
1259  */
1260 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1261 {
1262         int i;
1263         unsigned long started;
1264         unsigned long completed;
1265         int newstate;
1266         struct rcu_torture *p;
1267         int pipe_count;
1268         int readstate = 0;
1269         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1270         struct rt_read_seg *rtrsp = &rtseg[0];
1271         struct rt_read_seg *rtrsp1;
1272         unsigned long long ts;
1273 
1274         newstate = rcutorture_extend_mask(readstate, trsp);
1275         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1276         started = cur_ops->get_gp_seq();
1277         ts = rcu_trace_clock_local();
1278         p = rcu_dereference_check(rcu_torture_current,
1279                                   rcu_read_lock_bh_held() ||
1280                                   rcu_read_lock_sched_held() ||
1281                                   srcu_read_lock_held(srcu_ctlp) ||
1282                                   torturing_tasks());
1283         if (p == NULL) {
1284                 /* Wait for rcu_torture_writer to get underway */
1285                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1286                 return false;
1287         }
1288         if (p->rtort_mbtest == 0)
1289                 atomic_inc(&n_rcu_torture_mberror);
1290         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1291         preempt_disable();
1292         pipe_count = p->rtort_pipe_count;
1293         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1294                 /* Should not happen, but... */
1295                 pipe_count = RCU_TORTURE_PIPE_LEN;
1296         }
1297         completed = cur_ops->get_gp_seq();
1298         if (pipe_count > 1) {
1299                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1300                                           ts, started, completed);
1301                 rcu_ftrace_dump(DUMP_ALL);
1302         }
1303         __this_cpu_inc(rcu_torture_count[pipe_count]);
1304         completed = rcutorture_seq_diff(completed, started);
1305         if (completed > RCU_TORTURE_PIPE_LEN) {
1306                 /* Should not happen, but... */
1307                 completed = RCU_TORTURE_PIPE_LEN;
1308         }
1309         __this_cpu_inc(rcu_torture_batch[completed]);
1310         preempt_enable();
1311         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1312         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1313 
1314         /* If error or close call, record the sequence of reader protections. */
1315         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1316                 i = 0;
1317                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1318                         err_segs[i++] = *rtrsp1;
1319                 rt_read_nsegs = i;
1320         }
1321 
1322         return true;
1323 }
1324 
1325 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1326 
1327 /*
1328  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1329  * incrementing the corresponding element of the pipeline array.  The
1330  * counter in the element should never be greater than 1, otherwise, the
1331  * RCU implementation is broken.
1332  */
1333 static void rcu_torture_timer(struct timer_list *unused)
1334 {
1335         atomic_long_inc(&n_rcu_torture_timers);
1336         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1337 
1338         /* Test call_rcu() invocation from interrupt handler. */
1339         if (cur_ops->call) {
1340                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1341 
1342                 if (rhp)
1343                         cur_ops->call(rhp, rcu_torture_timer_cb);
1344         }
1345 }
1346 
1347 /*
1348  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1349  * incrementing the corresponding element of the pipeline array.  The
1350  * counter in the element should never be greater than 1, otherwise, the
1351  * RCU implementation is broken.
1352  */
1353 static int
1354 rcu_torture_reader(void *arg)
1355 {
1356         unsigned long lastsleep = jiffies;
1357         long myid = (long)arg;
1358         int mynumonline = myid;
1359         DEFINE_TORTURE_RANDOM(rand);
1360         struct timer_list t;
1361 
1362         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1363         set_user_nice(current, MAX_NICE);
1364         if (irqreader && cur_ops->irq_capable)
1365                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1366 
1367         do {
1368                 if (irqreader && cur_ops->irq_capable) {
1369                         if (!timer_pending(&t))
1370                                 mod_timer(&t, jiffies + 1);
1371                 }
1372                 if (!rcu_torture_one_read(&rand))
1373                         schedule_timeout_interruptible(HZ);
1374                 if (time_after(jiffies, lastsleep)) {
1375                         schedule_timeout_interruptible(1);
1376                         lastsleep = jiffies + 10;
1377                 }
1378                 while (num_online_cpus() < mynumonline && !torture_must_stop())
1379                         schedule_timeout_interruptible(HZ / 5);
1380                 stutter_wait("rcu_torture_reader");
1381         } while (!torture_must_stop());
1382         if (irqreader && cur_ops->irq_capable) {
1383                 del_timer_sync(&t);
1384                 destroy_timer_on_stack(&t);
1385         }
1386         torture_kthread_stopping("rcu_torture_reader");
1387         return 0;
1388 }
1389 
1390 /*
1391  * Print torture statistics.  Caller must ensure that there is only
1392  * one call to this function at a given time!!!  This is normally
1393  * accomplished by relying on the module system to only have one copy
1394  * of the module loaded, and then by giving the rcu_torture_stats
1395  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1396  * thread is not running).
1397  */
1398 static void
1399 rcu_torture_stats_print(void)
1400 {
1401         int cpu;
1402         int i;
1403         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1404         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1405         static unsigned long rtcv_snap = ULONG_MAX;
1406         static bool splatted;
1407         struct task_struct *wtp;
1408 
1409         for_each_possible_cpu(cpu) {
1410                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1411                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1412                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1413                 }
1414         }
1415         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1416                 if (pipesummary[i] != 0)
1417                         break;
1418         }
1419 
1420         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1421         pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1422                 rcu_torture_current,
1423                 rcu_torture_current ? "ver" : "VER",
1424                 rcu_torture_current_version,
1425                 list_empty(&rcu_torture_freelist),
1426                 atomic_read(&n_rcu_torture_alloc),
1427                 atomic_read(&n_rcu_torture_alloc_fail),
1428                 atomic_read(&n_rcu_torture_free));
1429         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1430                 atomic_read(&n_rcu_torture_mberror),
1431                 n_rcu_torture_barrier_error,
1432                 n_rcu_torture_boost_ktrerror,
1433                 n_rcu_torture_boost_rterror);
1434         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1435                 n_rcu_torture_boost_failure,
1436                 n_rcu_torture_boosts,
1437                 atomic_long_read(&n_rcu_torture_timers));
1438         torture_onoff_stats();
1439         pr_cont("barrier: %ld/%ld:%ld\n",
1440                 n_barrier_successes,
1441                 n_barrier_attempts,
1442                 n_rcu_torture_barrier_error);
1443 
1444         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1445         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1446             n_rcu_torture_barrier_error != 0 ||
1447             n_rcu_torture_boost_ktrerror != 0 ||
1448             n_rcu_torture_boost_rterror != 0 ||
1449             n_rcu_torture_boost_failure != 0 ||
1450             i > 1) {
1451                 pr_cont("%s", "!!! ");
1452                 atomic_inc(&n_rcu_torture_error);
1453                 WARN_ON_ONCE(1);
1454         }
1455         pr_cont("Reader Pipe: ");
1456         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1457                 pr_cont(" %ld", pipesummary[i]);
1458         pr_cont("\n");
1459 
1460         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1461         pr_cont("Reader Batch: ");
1462         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1463                 pr_cont(" %ld", batchsummary[i]);
1464         pr_cont("\n");
1465 
1466         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1467         pr_cont("Free-Block Circulation: ");
1468         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1469                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1470         }
1471         pr_cont("\n");
1472 
1473         if (cur_ops->stats)
1474                 cur_ops->stats();
1475         if (rtcv_snap == rcu_torture_current_version &&
1476             rcu_torture_current != NULL) {
1477                 int __maybe_unused flags = 0;
1478                 unsigned long __maybe_unused gp_seq = 0;
1479 
1480                 rcutorture_get_gp_data(cur_ops->ttype,
1481                                        &flags, &gp_seq);
1482                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1483                                         &flags, &gp_seq);
1484                 wtp = READ_ONCE(writer_task);
1485                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1486                          rcu_torture_writer_state_getname(),
1487                          rcu_torture_writer_state, gp_seq, flags,
1488                          wtp == NULL ? ~0UL : wtp->state,
1489                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1490                 if (!splatted && wtp) {
1491                         sched_show_task(wtp);
1492                         splatted = true;
1493                 }
1494                 show_rcu_gp_kthreads();
1495                 rcu_ftrace_dump(DUMP_ALL);
1496         }
1497         rtcv_snap = rcu_torture_current_version;
1498 }
1499 
1500 /*
1501  * Periodically prints torture statistics, if periodic statistics printing
1502  * was specified via the stat_interval module parameter.
1503  */
1504 static int
1505 rcu_torture_stats(void *arg)
1506 {
1507         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1508         do {
1509                 schedule_timeout_interruptible(stat_interval * HZ);
1510                 rcu_torture_stats_print();
1511                 torture_shutdown_absorb("rcu_torture_stats");
1512         } while (!torture_must_stop());
1513         torture_kthread_stopping("rcu_torture_stats");
1514         return 0;
1515 }
1516 
1517 static void
1518 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1519 {
1520         pr_alert("%s" TORTURE_FLAG
1521                  "--- %s: nreaders=%d nfakewriters=%d "
1522                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1523                  "shuffle_interval=%d stutter=%d irqreader=%d "
1524                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1525                  "test_boost=%d/%d test_boost_interval=%d "
1526                  "test_boost_duration=%d shutdown_secs=%d "
1527                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1528                  "n_barrier_cbs=%d "
1529                  "onoff_interval=%d onoff_holdoff=%d\n",
1530                  torture_type, tag, nrealreaders, nfakewriters,
1531                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1532                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1533                  test_boost, cur_ops->can_boost,
1534                  test_boost_interval, test_boost_duration, shutdown_secs,
1535                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1536                  n_barrier_cbs,
1537                  onoff_interval, onoff_holdoff);
1538 }
1539 
1540 static int rcutorture_booster_cleanup(unsigned int cpu)
1541 {
1542         struct task_struct *t;
1543 
1544         if (boost_tasks[cpu] == NULL)
1545                 return 0;
1546         mutex_lock(&boost_mutex);
1547         t = boost_tasks[cpu];
1548         boost_tasks[cpu] = NULL;
1549         rcu_torture_enable_rt_throttle();
1550         mutex_unlock(&boost_mutex);
1551 
1552         /* This must be outside of the mutex, otherwise deadlock! */
1553         torture_stop_kthread(rcu_torture_boost, t);
1554         return 0;
1555 }
1556 
1557 static int rcutorture_booster_init(unsigned int cpu)
1558 {
1559         int retval;
1560 
1561         if (boost_tasks[cpu] != NULL)
1562                 return 0;  /* Already created, nothing more to do. */
1563 
1564         /* Don't allow time recalculation while creating a new task. */
1565         mutex_lock(&boost_mutex);
1566         rcu_torture_disable_rt_throttle();
1567         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1568         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1569                                                   cpu_to_node(cpu),
1570                                                   "rcu_torture_boost");
1571         if (IS_ERR(boost_tasks[cpu])) {
1572                 retval = PTR_ERR(boost_tasks[cpu]);
1573                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1574                 n_rcu_torture_boost_ktrerror++;
1575                 boost_tasks[cpu] = NULL;
1576                 mutex_unlock(&boost_mutex);
1577                 return retval;
1578         }
1579         kthread_bind(boost_tasks[cpu], cpu);
1580         wake_up_process(boost_tasks[cpu]);
1581         mutex_unlock(&boost_mutex);
1582         return 0;
1583 }
1584 
1585 /*
1586  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1587  * induces a CPU stall for the time specified by stall_cpu.
1588  */
1589 static int rcu_torture_stall(void *args)
1590 {
1591         unsigned long stop_at;
1592 
1593         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1594         if (stall_cpu_holdoff > 0) {
1595                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1596                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1597                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1598         }
1599         if (!kthread_should_stop()) {
1600                 stop_at = ktime_get_seconds() + stall_cpu;
1601                 /* RCU CPU stall is expected behavior in following code. */
1602                 rcu_read_lock();
1603                 if (stall_cpu_irqsoff)
1604                         local_irq_disable();
1605                 else
1606                         preempt_disable();
1607                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1608                          smp_processor_id());
1609                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1610                                     stop_at))
1611                         continue;  /* Induce RCU CPU stall warning. */
1612                 if (stall_cpu_irqsoff)
1613                         local_irq_enable();
1614                 else
1615                         preempt_enable();
1616                 rcu_read_unlock();
1617                 pr_alert("rcu_torture_stall end.\n");
1618         }
1619         torture_shutdown_absorb("rcu_torture_stall");
1620         while (!kthread_should_stop())
1621                 schedule_timeout_interruptible(10 * HZ);
1622         return 0;
1623 }
1624 
1625 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1626 static int __init rcu_torture_stall_init(void)
1627 {
1628         if (stall_cpu <= 0)
1629                 return 0;
1630         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1631 }
1632 
1633 /* State structure for forward-progress self-propagating RCU callback. */
1634 struct fwd_cb_state {
1635         struct rcu_head rh;
1636         int stop;
1637 };
1638 
1639 /*
1640  * Forward-progress self-propagating RCU callback function.  Because
1641  * callbacks run from softirq, this function is an implicit RCU read-side
1642  * critical section.
1643  */
1644 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1645 {
1646         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1647 
1648         if (READ_ONCE(fcsp->stop)) {
1649                 WRITE_ONCE(fcsp->stop, 2);
1650                 return;
1651         }
1652         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1653 }
1654 
1655 /* State for continuous-flood RCU callbacks. */
1656 struct rcu_fwd_cb {
1657         struct rcu_head rh;
1658         struct rcu_fwd_cb *rfc_next;
1659         int rfc_gps;
1660 };
1661 static DEFINE_SPINLOCK(rcu_fwd_lock);
1662 static struct rcu_fwd_cb *rcu_fwd_cb_head;
1663 static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1664 static long n_launders_cb;
1665 static unsigned long rcu_fwd_startat;
1666 static bool rcu_fwd_emergency_stop;
1667 #define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
1668 #define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
1669 #define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
1670 #define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
1671 struct rcu_launder_hist {
1672         long n_launders;
1673         unsigned long launder_gp_seq;
1674 };
1675 #define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
1676 static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
1677 static unsigned long rcu_launder_gp_seq_start;
1678 
1679 static void rcu_torture_fwd_cb_hist(void)
1680 {
1681         unsigned long gps;
1682         unsigned long gps_old;
1683         int i;
1684         int j;
1685 
1686         for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
1687                 if (n_launders_hist[i].n_launders > 0)
1688                         break;
1689         pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1690                  __func__, jiffies - rcu_fwd_startat);
1691         gps_old = rcu_launder_gp_seq_start;
1692         for (j = 0; j <= i; j++) {
1693                 gps = n_launders_hist[j].launder_gp_seq;
1694                 pr_cont(" %ds/%d: %ld:%ld",
1695                         j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
1696                         rcutorture_seq_diff(gps, gps_old));
1697                 gps_old = gps;
1698         }
1699         pr_cont("\n");
1700 }
1701 
1702 /* Callback function for continuous-flood RCU callbacks. */
1703 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1704 {
1705         unsigned long flags;
1706         int i;
1707         struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1708         struct rcu_fwd_cb **rfcpp;
1709 
1710         rfcp->rfc_next = NULL;
1711         rfcp->rfc_gps++;
1712         spin_lock_irqsave(&rcu_fwd_lock, flags);
1713         rfcpp = rcu_fwd_cb_tail;
1714         rcu_fwd_cb_tail = &rfcp->rfc_next;
1715         WRITE_ONCE(*rfcpp, rfcp);
1716         WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
1717         i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1718         if (i >= ARRAY_SIZE(n_launders_hist))
1719                 i = ARRAY_SIZE(n_launders_hist) - 1;
1720         n_launders_hist[i].n_launders++;
1721         n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
1722         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1723 }
1724 
1725 // Give the scheduler a chance, even on nohz_full CPUs.
1726 static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
1727 {
1728         if (IS_ENABLED(CONFIG_PREEMPT) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
1729                 // Real call_rcu() floods hit userspace, so emulate that.
1730                 if (need_resched() || (iter & 0xfff))
1731                         schedule();
1732         } else {
1733                 // No userspace emulation: CB invocation throttles call_rcu()
1734                 cond_resched();
1735         }
1736 }
1737 
1738 /*
1739  * Free all callbacks on the rcu_fwd_cb_head list, either because the
1740  * test is over or because we hit an OOM event.
1741  */
1742 static unsigned long rcu_torture_fwd_prog_cbfree(void)
1743 {
1744         unsigned long flags;
1745         unsigned long freed = 0;
1746         struct rcu_fwd_cb *rfcp;
1747 
1748         for (;;) {
1749                 spin_lock_irqsave(&rcu_fwd_lock, flags);
1750                 rfcp = rcu_fwd_cb_head;
1751                 if (!rfcp) {
1752                         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1753                         break;
1754                 }
1755                 rcu_fwd_cb_head = rfcp->rfc_next;
1756                 if (!rcu_fwd_cb_head)
1757                         rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1758                 spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1759                 kfree(rfcp);
1760                 freed++;
1761                 rcu_torture_fwd_prog_cond_resched(freed);
1762         }
1763         return freed;
1764 }
1765 
1766 /* Carry out need_resched()/cond_resched() forward-progress testing. */
1767 static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
1768 {
1769         unsigned long cver;
1770         unsigned long dur;
1771         struct fwd_cb_state fcs;
1772         unsigned long gps;
1773         int idx;
1774         int sd;
1775         int sd4;
1776         bool selfpropcb = false;
1777         unsigned long stopat;
1778         static DEFINE_TORTURE_RANDOM(trs);
1779 
1780         if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1781                 init_rcu_head_on_stack(&fcs.rh);
1782                 selfpropcb = true;
1783         }
1784 
1785         /* Tight loop containing cond_resched(). */
1786         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1787         cur_ops->sync(); /* Later readers see above write. */
1788         if  (selfpropcb) {
1789                 WRITE_ONCE(fcs.stop, 0);
1790                 cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1791         }
1792         cver = READ_ONCE(rcu_torture_current_version);
1793         gps = cur_ops->get_gp_seq();
1794         sd = cur_ops->stall_dur() + 1;
1795         sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1796         dur = sd4 + torture_random(&trs) % (sd - sd4);
1797         WRITE_ONCE(rcu_fwd_startat, jiffies);
1798         stopat = rcu_fwd_startat + dur;
1799         while (time_before(jiffies, stopat) &&
1800                !shutdown_time_arrived() &&
1801                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1802                 idx = cur_ops->readlock();
1803                 udelay(10);
1804                 cur_ops->readunlock(idx);
1805                 if (!fwd_progress_need_resched || need_resched())
1806                         rcu_torture_fwd_prog_cond_resched(1);
1807         }
1808         (*tested_tries)++;
1809         if (!time_before(jiffies, stopat) &&
1810             !shutdown_time_arrived() &&
1811             !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1812                 (*tested)++;
1813                 cver = READ_ONCE(rcu_torture_current_version) - cver;
1814                 gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1815                 WARN_ON(!cver && gps < 2);
1816                 pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1817         }
1818         if (selfpropcb) {
1819                 WRITE_ONCE(fcs.stop, 1);
1820                 cur_ops->sync(); /* Wait for running CB to complete. */
1821                 cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1822         }
1823 
1824         if (selfpropcb) {
1825                 WARN_ON(READ_ONCE(fcs.stop) != 2);
1826                 destroy_rcu_head_on_stack(&fcs.rh);
1827         }
1828         schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
1829         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1830 }
1831 
1832 /* Carry out call_rcu() forward-progress testing. */
1833 static void rcu_torture_fwd_prog_cr(void)
1834 {
1835         unsigned long cver;
1836         unsigned long gps;
1837         int i;
1838         long n_launders;
1839         long n_launders_cb_snap;
1840         long n_launders_sa;
1841         long n_max_cbs;
1842         long n_max_gps;
1843         struct rcu_fwd_cb *rfcp;
1844         struct rcu_fwd_cb *rfcpn;
1845         unsigned long stopat;
1846         unsigned long stoppedat;
1847 
1848         if (READ_ONCE(rcu_fwd_emergency_stop))
1849                 return; /* Get out of the way quickly, no GP wait! */
1850         if (!cur_ops->call)
1851                 return; /* Can't do call_rcu() fwd prog without ->call. */
1852 
1853         /* Loop continuously posting RCU callbacks. */
1854         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1855         cur_ops->sync(); /* Later readers see above write. */
1856         WRITE_ONCE(rcu_fwd_startat, jiffies);
1857         stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1858         n_launders = 0;
1859         n_launders_cb = 0;
1860         n_launders_sa = 0;
1861         n_max_cbs = 0;
1862         n_max_gps = 0;
1863         for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
1864                 n_launders_hist[i].n_launders = 0;
1865         cver = READ_ONCE(rcu_torture_current_version);
1866         gps = cur_ops->get_gp_seq();
1867         rcu_launder_gp_seq_start = gps;
1868         while (time_before(jiffies, stopat) &&
1869                !shutdown_time_arrived() &&
1870                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1871                 rfcp = READ_ONCE(rcu_fwd_cb_head);
1872                 rfcpn = NULL;
1873                 if (rfcp)
1874                         rfcpn = READ_ONCE(rfcp->rfc_next);
1875                 if (rfcpn) {
1876                         if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
1877                             ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
1878                                 break;
1879                         rcu_fwd_cb_head = rfcpn;
1880                         n_launders++;
1881                         n_launders_sa++;
1882                 } else {
1883                         rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
1884                         if (WARN_ON_ONCE(!rfcp)) {
1885                                 schedule_timeout_interruptible(1);
1886                                 continue;
1887                         }
1888                         n_max_cbs++;
1889                         n_launders_sa = 0;
1890                         rfcp->rfc_gps = 0;
1891                 }
1892                 cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
1893                 rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
1894         }
1895         stoppedat = jiffies;
1896         n_launders_cb_snap = READ_ONCE(n_launders_cb);
1897         cver = READ_ONCE(rcu_torture_current_version) - cver;
1898         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1899         cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
1900         (void)rcu_torture_fwd_prog_cbfree();
1901 
1902         if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
1903             !shutdown_time_arrived()) {
1904                 WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
1905                 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",
1906                          __func__,
1907                          stoppedat - rcu_fwd_startat, jiffies - stoppedat,
1908                          n_launders + n_max_cbs - n_launders_cb_snap,
1909                          n_launders, n_launders_sa,
1910                          n_max_gps, n_max_cbs, cver, gps);
1911                 rcu_torture_fwd_cb_hist();
1912         }
1913         schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
1914         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1915 }
1916 
1917 
1918 /*
1919  * OOM notifier, but this only prints diagnostic information for the
1920  * current forward-progress test.
1921  */
1922 static int rcutorture_oom_notify(struct notifier_block *self,
1923                                  unsigned long notused, void *nfreed)
1924 {
1925         WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
1926              __func__);
1927         rcu_torture_fwd_cb_hist();
1928         rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat)) / 2);
1929         WRITE_ONCE(rcu_fwd_emergency_stop, true);
1930         smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
1931         pr_info("%s: Freed %lu RCU callbacks.\n",
1932                 __func__, rcu_torture_fwd_prog_cbfree());
1933         rcu_barrier();
1934         pr_info("%s: Freed %lu RCU callbacks.\n",
1935                 __func__, rcu_torture_fwd_prog_cbfree());
1936         rcu_barrier();
1937         pr_info("%s: Freed %lu RCU callbacks.\n",
1938                 __func__, rcu_torture_fwd_prog_cbfree());
1939         smp_mb(); /* Frees before return to avoid redoing OOM. */
1940         (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
1941         pr_info("%s returning after OOM processing.\n", __func__);
1942         return NOTIFY_OK;
1943 }
1944 
1945 static struct notifier_block rcutorture_oom_nb = {
1946         .notifier_call = rcutorture_oom_notify
1947 };
1948 
1949 /* Carry out grace-period forward-progress testing. */
1950 static int rcu_torture_fwd_prog(void *args)
1951 {
1952         int tested = 0;
1953         int tested_tries = 0;
1954 
1955         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1956         rcu_bind_current_to_nocb();
1957         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1958                 set_user_nice(current, MAX_NICE);
1959         do {
1960                 schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
1961                 WRITE_ONCE(rcu_fwd_emergency_stop, false);
1962                 register_oom_notifier(&rcutorture_oom_nb);
1963                 rcu_torture_fwd_prog_nr(&tested, &tested_tries);
1964                 rcu_torture_fwd_prog_cr();
1965                 unregister_oom_notifier(&rcutorture_oom_nb);
1966 
1967                 /* Avoid slow periods, better to test when busy. */
1968                 stutter_wait("rcu_torture_fwd_prog");
1969         } while (!torture_must_stop());
1970         /* Short runs might not contain a valid forward-progress attempt. */
1971         WARN_ON(!tested && tested_tries >= 5);
1972         pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
1973         torture_kthread_stopping("rcu_torture_fwd_prog");
1974         return 0;
1975 }
1976 
1977 /* If forward-progress checking is requested and feasible, spawn the thread. */
1978 static int __init rcu_torture_fwd_prog_init(void)
1979 {
1980         if (!fwd_progress)
1981                 return 0; /* Not requested, so don't do it. */
1982         if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
1983             cur_ops == &rcu_busted_ops) {
1984                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
1985                 return 0;
1986         }
1987         if (stall_cpu > 0) {
1988                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
1989                 if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
1990                         return -EINVAL; /* In module, can fail back to user. */
1991                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
1992                 return 0;
1993         }
1994         if (fwd_progress_holdoff <= 0)
1995                 fwd_progress_holdoff = 1;
1996         if (fwd_progress_div <= 0)
1997                 fwd_progress_div = 4;
1998         return torture_create_kthread(rcu_torture_fwd_prog,
1999                                       NULL, fwd_prog_task);
2000 }
2001 
2002 /* Callback function for RCU barrier testing. */
2003 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
2004 {
2005         atomic_inc(&barrier_cbs_invoked);
2006 }
2007 
2008 /* kthread function to register callbacks used to test RCU barriers. */
2009 static int rcu_torture_barrier_cbs(void *arg)
2010 {
2011         long myid = (long)arg;
2012         bool lastphase = 0;
2013         bool newphase;
2014         struct rcu_head rcu;
2015 
2016         init_rcu_head_on_stack(&rcu);
2017         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
2018         set_user_nice(current, MAX_NICE);
2019         do {
2020                 wait_event(barrier_cbs_wq[myid],
2021                            (newphase =
2022                             smp_load_acquire(&barrier_phase)) != lastphase ||
2023                            torture_must_stop());
2024                 lastphase = newphase;
2025                 if (torture_must_stop())
2026                         break;
2027                 /*
2028                  * The above smp_load_acquire() ensures barrier_phase load
2029                  * is ordered before the following ->call().
2030                  */
2031                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
2032                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
2033                 local_irq_enable();
2034                 if (atomic_dec_and_test(&barrier_cbs_count))
2035                         wake_up(&barrier_wq);
2036         } while (!torture_must_stop());
2037         if (cur_ops->cb_barrier != NULL)
2038                 cur_ops->cb_barrier();
2039         destroy_rcu_head_on_stack(&rcu);
2040         torture_kthread_stopping("rcu_torture_barrier_cbs");
2041         return 0;
2042 }
2043 
2044 /* kthread function to drive and coordinate RCU barrier testing. */
2045 static int rcu_torture_barrier(void *arg)
2046 {
2047         int i;
2048 
2049         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
2050         do {
2051                 atomic_set(&barrier_cbs_invoked, 0);
2052                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
2053                 /* Ensure barrier_phase ordered after prior assignments. */
2054                 smp_store_release(&barrier_phase, !barrier_phase);
2055                 for (i = 0; i < n_barrier_cbs; i++)
2056                         wake_up(&barrier_cbs_wq[i]);
2057                 wait_event(barrier_wq,
2058                            atomic_read(&barrier_cbs_count) == 0 ||
2059                            torture_must_stop());
2060                 if (torture_must_stop())
2061                         break;
2062                 n_barrier_attempts++;
2063                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
2064                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
2065                         n_rcu_torture_barrier_error++;
2066                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
2067                                atomic_read(&barrier_cbs_invoked),
2068                                n_barrier_cbs);
2069                         WARN_ON_ONCE(1);
2070                 } else {
2071                         n_barrier_successes++;
2072                 }
2073                 schedule_timeout_interruptible(HZ / 10);
2074         } while (!torture_must_stop());
2075         torture_kthread_stopping("rcu_torture_barrier");
2076         return 0;
2077 }
2078 
2079 /* Initialize RCU barrier testing. */
2080 static int rcu_torture_barrier_init(void)
2081 {
2082         int i;
2083         int ret;
2084 
2085         if (n_barrier_cbs <= 0)
2086                 return 0;
2087         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2088                 pr_alert("%s" TORTURE_FLAG
2089                          " Call or barrier ops missing for %s,\n",
2090                          torture_type, cur_ops->name);
2091                 pr_alert("%s" TORTURE_FLAG
2092                          " RCU barrier testing omitted from run.\n",
2093                          torture_type);
2094                 return 0;
2095         }
2096         atomic_set(&barrier_cbs_count, 0);
2097         atomic_set(&barrier_cbs_invoked, 0);
2098         barrier_cbs_tasks =
2099                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2100                         GFP_KERNEL);
2101         barrier_cbs_wq =
2102                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2103         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2104                 return -ENOMEM;
2105         for (i = 0; i < n_barrier_cbs; i++) {
2106                 init_waitqueue_head(&barrier_cbs_wq[i]);
2107                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
2108                                              (void *)(long)i,
2109                                              barrier_cbs_tasks[i]);
2110                 if (ret)
2111                         return ret;
2112         }
2113         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2114 }
2115 
2116 /* Clean up after RCU barrier testing. */
2117 static void rcu_torture_barrier_cleanup(void)
2118 {
2119         int i;
2120 
2121         torture_stop_kthread(rcu_torture_barrier, barrier_task);
2122         if (barrier_cbs_tasks != NULL) {
2123                 for (i = 0; i < n_barrier_cbs; i++)
2124                         torture_stop_kthread(rcu_torture_barrier_cbs,
2125                                              barrier_cbs_tasks[i]);
2126                 kfree(barrier_cbs_tasks);
2127                 barrier_cbs_tasks = NULL;
2128         }
2129         if (barrier_cbs_wq != NULL) {
2130                 kfree(barrier_cbs_wq);
2131                 barrier_cbs_wq = NULL;
2132         }
2133 }
2134 
2135 static bool rcu_torture_can_boost(void)
2136 {
2137         static int boost_warn_once;
2138         int prio;
2139 
2140         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2141                 return false;
2142 
2143         prio = rcu_get_gp_kthreads_prio();
2144         if (!prio)
2145                 return false;
2146 
2147         if (prio < 2) {
2148                 if (boost_warn_once  == 1)
2149                         return false;
2150 
2151                 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);
2152                 boost_warn_once = 1;
2153                 return false;
2154         }
2155 
2156         return true;
2157 }
2158 
2159 static enum cpuhp_state rcutor_hp;
2160 
2161 static void
2162 rcu_torture_cleanup(void)
2163 {
2164         int firsttime;
2165         int flags = 0;
2166         unsigned long gp_seq = 0;
2167         int i;
2168 
2169         if (torture_cleanup_begin()) {
2170                 if (cur_ops->cb_barrier != NULL)
2171                         cur_ops->cb_barrier();
2172                 return;
2173         }
2174         if (!cur_ops) {
2175                 torture_cleanup_end();
2176                 return;
2177         }
2178 
2179         show_rcu_gp_kthreads();
2180         rcu_torture_barrier_cleanup();
2181         torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2182         torture_stop_kthread(rcu_torture_stall, stall_task);
2183         torture_stop_kthread(rcu_torture_writer, writer_task);
2184 
2185         if (reader_tasks) {
2186                 for (i = 0; i < nrealreaders; i++)
2187                         torture_stop_kthread(rcu_torture_reader,
2188                                              reader_tasks[i]);
2189                 kfree(reader_tasks);
2190         }
2191         rcu_torture_current = NULL;
2192 
2193         if (fakewriter_tasks) {
2194                 for (i = 0; i < nfakewriters; i++) {
2195                         torture_stop_kthread(rcu_torture_fakewriter,
2196                                              fakewriter_tasks[i]);
2197                 }
2198                 kfree(fakewriter_tasks);
2199                 fakewriter_tasks = NULL;
2200         }
2201 
2202         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2203         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2204         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2205                  cur_ops->name, gp_seq, flags);
2206         torture_stop_kthread(rcu_torture_stats, stats_task);
2207         torture_stop_kthread(rcu_torture_fqs, fqs_task);
2208         if (rcu_torture_can_boost())
2209                 cpuhp_remove_state(rcutor_hp);
2210 
2211         /*
2212          * Wait for all RCU callbacks to fire, then do torture-type-specific
2213          * cleanup operations.
2214          */
2215         if (cur_ops->cb_barrier != NULL)
2216                 cur_ops->cb_barrier();
2217         if (cur_ops->cleanup != NULL)
2218                 cur_ops->cleanup();
2219 
2220         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2221 
2222         if (err_segs_recorded) {
2223                 pr_alert("Failure/close-call rcutorture reader segments:\n");
2224                 if (rt_read_nsegs == 0)
2225                         pr_alert("\t: No segments recorded!!!\n");
2226                 firsttime = 1;
2227                 for (i = 0; i < rt_read_nsegs; i++) {
2228                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2229                         if (err_segs[i].rt_delay_jiffies != 0) {
2230                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2231                                         err_segs[i].rt_delay_jiffies);
2232                                 firsttime = 0;
2233                         }
2234                         if (err_segs[i].rt_delay_ms != 0) {
2235                                 pr_cont("%s%ldms", firsttime ? "" : "+",
2236                                         err_segs[i].rt_delay_ms);
2237                                 firsttime = 0;
2238                         }
2239                         if (err_segs[i].rt_delay_us != 0) {
2240                                 pr_cont("%s%ldus", firsttime ? "" : "+",
2241                                         err_segs[i].rt_delay_us);
2242                                 firsttime = 0;
2243                         }
2244                         pr_cont("%s\n",
2245                                 err_segs[i].rt_preempted ? "preempted" : "");
2246 
2247                 }
2248         }
2249         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2250                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2251         else if (torture_onoff_failures())
2252                 rcu_torture_print_module_parms(cur_ops,
2253                                                "End of test: RCU_HOTPLUG");
2254         else
2255                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2256         torture_cleanup_end();
2257 }
2258 
2259 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2260 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2261 {
2262 }
2263 
2264 static void rcu_torture_err_cb(struct rcu_head *rhp)
2265 {
2266         /*
2267          * This -might- happen due to race conditions, but is unlikely.
2268          * The scenario that leads to this happening is that the
2269          * first of the pair of duplicate callbacks is queued,
2270          * someone else starts a grace period that includes that
2271          * callback, then the second of the pair must wait for the
2272          * next grace period.  Unlikely, but can happen.  If it
2273          * does happen, the debug-objects subsystem won't have splatted.
2274          */
2275         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2276 }
2277 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2278 
2279 /*
2280  * Verify that double-free causes debug-objects to complain, but only
2281  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2282  * cannot be carried out.
2283  */
2284 static void rcu_test_debug_objects(void)
2285 {
2286 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2287         struct rcu_head rh1;
2288         struct rcu_head rh2;
2289 
2290         init_rcu_head_on_stack(&rh1);
2291         init_rcu_head_on_stack(&rh2);
2292         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2293 
2294         /* Try to queue the rh2 pair of callbacks for the same grace period. */
2295         preempt_disable(); /* Prevent preemption from interrupting test. */
2296         rcu_read_lock(); /* Make it impossible to finish a grace period. */
2297         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2298         local_irq_disable(); /* Make it harder to start a new grace period. */
2299         call_rcu(&rh2, rcu_torture_leak_cb);
2300         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2301         local_irq_enable();
2302         rcu_read_unlock();
2303         preempt_enable();
2304 
2305         /* Wait for them all to get done so we can safely return. */
2306         rcu_barrier();
2307         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2308         destroy_rcu_head_on_stack(&rh1);
2309         destroy_rcu_head_on_stack(&rh2);
2310 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2311         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2312 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2313 }
2314 
2315 static void rcutorture_sync(void)
2316 {
2317         static unsigned long n;
2318 
2319         if (cur_ops->sync && !(++n & 0xfff))
2320                 cur_ops->sync();
2321 }
2322 
2323 static int __init
2324 rcu_torture_init(void)
2325 {
2326         long i;
2327         int cpu;
2328         int firsterr = 0;
2329         static struct rcu_torture_ops *torture_ops[] = {
2330                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2331                 &busted_srcud_ops, &tasks_ops, &trivial_ops,
2332         };
2333 
2334         if (!torture_init_begin(torture_type, verbose))
2335                 return -EBUSY;
2336 
2337         /* Process args and tell the world that the torturer is on the job. */
2338         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2339                 cur_ops = torture_ops[i];
2340                 if (strcmp(torture_type, cur_ops->name) == 0)
2341                         break;
2342         }
2343         if (i == ARRAY_SIZE(torture_ops)) {
2344                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2345                          torture_type);
2346                 pr_alert("rcu-torture types:");
2347                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2348                         pr_cont(" %s", torture_ops[i]->name);
2349                 pr_cont("\n");
2350                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2351                 firsterr = -EINVAL;
2352                 cur_ops = NULL;
2353                 goto unwind;
2354         }
2355         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2356                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2357                 fqs_duration = 0;
2358         }
2359         if (cur_ops->init)
2360                 cur_ops->init();
2361 
2362         if (nreaders >= 0) {
2363                 nrealreaders = nreaders;
2364         } else {
2365                 nrealreaders = num_online_cpus() - 2 - nreaders;
2366                 if (nrealreaders <= 0)
2367                         nrealreaders = 1;
2368         }
2369         rcu_torture_print_module_parms(cur_ops, "Start of test");
2370 
2371         /* Set up the freelist. */
2372 
2373         INIT_LIST_HEAD(&rcu_torture_freelist);
2374         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2375                 rcu_tortures[i].rtort_mbtest = 0;
2376                 list_add_tail(&rcu_tortures[i].rtort_free,
2377                               &rcu_torture_freelist);
2378         }
2379 
2380         /* Initialize the statistics so that each run gets its own numbers. */
2381 
2382         rcu_torture_current = NULL;
2383         rcu_torture_current_version = 0;
2384         atomic_set(&n_rcu_torture_alloc, 0);
2385         atomic_set(&n_rcu_torture_alloc_fail, 0);
2386         atomic_set(&n_rcu_torture_free, 0);
2387         atomic_set(&n_rcu_torture_mberror, 0);
2388         atomic_set(&n_rcu_torture_error, 0);
2389         n_rcu_torture_barrier_error = 0;
2390         n_rcu_torture_boost_ktrerror = 0;
2391         n_rcu_torture_boost_rterror = 0;
2392         n_rcu_torture_boost_failure = 0;
2393         n_rcu_torture_boosts = 0;
2394         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2395                 atomic_set(&rcu_torture_wcount[i], 0);
2396         for_each_possible_cpu(cpu) {
2397                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2398                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2399                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2400                 }
2401         }
2402         err_segs_recorded = 0;
2403         rt_read_nsegs = 0;
2404 
2405         /* Start up the kthreads. */
2406 
2407         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2408                                           writer_task);
2409         if (firsterr)
2410                 goto unwind;
2411         if (nfakewriters > 0) {
2412                 fakewriter_tasks = kcalloc(nfakewriters,
2413                                            sizeof(fakewriter_tasks[0]),
2414                                            GFP_KERNEL);
2415                 if (fakewriter_tasks == NULL) {
2416                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2417                         firsterr = -ENOMEM;
2418                         goto unwind;
2419                 }
2420         }
2421         for (i = 0; i < nfakewriters; i++) {
2422                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2423                                                   NULL, fakewriter_tasks[i]);
2424                 if (firsterr)
2425                         goto unwind;
2426         }
2427         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2428                                GFP_KERNEL);
2429         if (reader_tasks == NULL) {
2430                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2431                 firsterr = -ENOMEM;
2432                 goto unwind;
2433         }
2434         for (i = 0; i < nrealreaders; i++) {
2435                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2436                                                   reader_tasks[i]);
2437                 if (firsterr)
2438                         goto unwind;
2439         }
2440         if (stat_interval > 0) {
2441                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2442                                                   stats_task);
2443                 if (firsterr)
2444                         goto unwind;
2445         }
2446         if (test_no_idle_hz && shuffle_interval > 0) {
2447                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2448                 if (firsterr)
2449                         goto unwind;
2450         }
2451         if (stutter < 0)
2452                 stutter = 0;
2453         if (stutter) {
2454                 int t;
2455 
2456                 t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
2457                 firsterr = torture_stutter_init(stutter * HZ, t);
2458                 if (firsterr)
2459                         goto unwind;
2460         }
2461         if (fqs_duration < 0)
2462                 fqs_duration = 0;
2463         if (fqs_duration) {
2464                 /* Create the fqs thread */
2465                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2466                                                   fqs_task);
2467                 if (firsterr)
2468                         goto unwind;
2469         }
2470         if (test_boost_interval < 1)
2471                 test_boost_interval = 1;
2472         if (test_boost_duration < 2)
2473                 test_boost_duration = 2;
2474         if (rcu_torture_can_boost()) {
2475 
2476                 boost_starttime = jiffies + test_boost_interval * HZ;
2477 
2478                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2479                                              rcutorture_booster_init,
2480                                              rcutorture_booster_cleanup);
2481                 if (firsterr < 0)
2482                         goto unwind;
2483                 rcutor_hp = firsterr;
2484         }
2485         shutdown_jiffies = jiffies + shutdown_secs * HZ;
2486         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2487         if (firsterr)
2488                 goto unwind;
2489         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
2490                                       rcutorture_sync);
2491         if (firsterr)
2492                 goto unwind;
2493         firsterr = rcu_torture_stall_init();
2494         if (firsterr)
2495                 goto unwind;
2496         firsterr = rcu_torture_fwd_prog_init();
2497         if (firsterr)
2498                 goto unwind;
2499         firsterr = rcu_torture_barrier_init();
2500         if (firsterr)
2501                 goto unwind;
2502         if (object_debug)
2503                 rcu_test_debug_objects();
2504         torture_init_end();
2505         return 0;
2506 
2507 unwind:
2508         torture_init_end();
2509         rcu_torture_cleanup();
2510         return firsterr;
2511 }
2512 
2513 module_init(rcu_torture_init);
2514 module_exit(rcu_torture_cleanup);
/* [<][>][^][v][top][bottom][index][help] */
root/kernel/rcu/rcutorture.c

DEFINITIONS
