kernel/sched/topology.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Scheduler topology setup/handling methods
   4  */
   5
   6 DEFINE_MUTEX(sched_domains_mutex);
   7
   8 /* Protected by sched_domains_mutex: */
   9 static cpumask_var_t sched_domains_tmpmask;
  10 static cpumask_var_t sched_domains_tmpmask2;
  11
  12 #ifdef CONFIG_SCHED_DEBUG
  13
  14 static int __init sched_debug_setup(char *str)
  15 {
  16         sched_debug_verbose = true;
  17
  18         return 0;
  19 }
  20 early_param("sched_verbose", sched_debug_setup);
  21
  22 static inline bool sched_debug(void)
  23 {
  24         return sched_debug_verbose;
  25 }
  26
  27 #define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name },
  28 const struct sd_flag_debug sd_flag_debug[] = {
  29 #include <linux/sched/sd_flags.h>
  30 };
  31 #undef SD_FLAG
  32
  33 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
  34                                   struct cpumask *groupmask)
  35 {
  36         struct sched_group *group = sd->groups;
  37         unsigned long flags = sd->flags;
  38         unsigned int idx;
  39
  40         cpumask_clear(groupmask);
  41
  42         printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
  43         printk(KERN_CONT "span=%*pbl level=%s\n",
  44                cpumask_pr_args(sched_domain_span(sd)), sd->name);
  45
  46         if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
  47                 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
  48         }
  49         if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) {
  50                 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
  51         }
  52
  53         for_each_set_bit(idx, &flags, __SD_FLAG_CNT) {
  54                 unsigned int flag = BIT(idx);
  55                 unsigned int meta_flags = sd_flag_debug[idx].meta_flags;
  56
  57                 if ((meta_flags & SDF_SHARED_CHILD) && sd->child &&
  58                     !(sd->child->flags & flag))
  59                         printk(KERN_ERR "ERROR: flag %s set here but not in child\n",
  60                                sd_flag_debug[idx].name);
  61
  62                 if ((meta_flags & SDF_SHARED_PARENT) && sd->parent &&
  63                     !(sd->parent->flags & flag))
  64                         printk(KERN_ERR "ERROR: flag %s set here but not in parent\n",
  65                                sd_flag_debug[idx].name);
  66         }
  67
  68         printk(KERN_DEBUG "%*s groups:", level + 1, "");
  69         do {
  70                 if (!group) {
  71                         printk("\n");
  72                         printk(KERN_ERR "ERROR: group is NULL\n");
  73                         break;
  74                 }
  75
  76                 if (cpumask_empty(sched_group_span(group))) {
  77                         printk(KERN_CONT "\n");
  78                         printk(KERN_ERR "ERROR: empty group\n");
  79                         break;
  80                 }
  81
  82                 if (!(sd->flags & SD_OVERLAP) &&
  83                     cpumask_intersects(groupmask, sched_group_span(group))) {
  84                         printk(KERN_CONT "\n");
  85                         printk(KERN_ERR "ERROR: repeated CPUs\n");
  86                         break;
  87                 }
  88
  89                 cpumask_or(groupmask, groupmask, sched_group_span(group));
  90
  91                 printk(KERN_CONT " %d:{ span=%*pbl",
  92                                 group->sgc->id,
  93                                 cpumask_pr_args(sched_group_span(group)));
  94
  95                 if ((sd->flags & SD_OVERLAP) &&
  96                     !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
  97                         printk(KERN_CONT " mask=%*pbl",
  98                                 cpumask_pr_args(group_balance_mask(group)));
  99                 }
 100
 101                 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
 102                         printk(KERN_CONT " cap=%lu", group->sgc->capacity);
 103
 104                 if (group == sd->groups && sd->child &&
 105                     !cpumask_equal(sched_domain_span(sd->child),
 106                                    sched_group_span(group))) {
 107                         printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
 108                 }
 109
 110                 printk(KERN_CONT " }");
 111
 112                 group = group->next;
 113
 114                 if (group != sd->groups)
 115                         printk(KERN_CONT ",");
 116
 117         } while (group != sd->groups);
 118         printk(KERN_CONT "\n");
 119
 120         if (!cpumask_equal(sched_domain_span(sd), groupmask))
 121                 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
 122
 123         if (sd->parent &&
 124             !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
 125                 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
 126         return 0;
 127 }
 128
 129 static void sched_domain_debug(struct sched_domain *sd, int cpu)
 130 {
 131         int level = 0;
 132
 133         if (!sched_debug_verbose)
 134                 return;
 135
 136         if (!sd) {
 137                 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
 138                 return;
 139         }
 140
 141         printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
 142
 143         for (;;) {
 144                 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
 145                         break;
 146                 level++;
 147                 sd = sd->parent;
 148                 if (!sd)
 149                         break;
 150         }
 151 }
 152 #else /* !CONFIG_SCHED_DEBUG */
 153
 154 # define sched_debug_verbose 0
 155 # define sched_domain_debug(sd, cpu) do { } while (0)
 156 static inline bool sched_debug(void)
 157 {
 158         return false;
 159 }
 160 #endif /* CONFIG_SCHED_DEBUG */
 161
 162 /* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */
 163 #define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) |
 164 static const unsigned int SD_DEGENERATE_GROUPS_MASK =
 165 #include <linux/sched/sd_flags.h>
 166 0;
 167 #undef SD_FLAG
 168
 169 static int sd_degenerate(struct sched_domain *sd)
 170 {
 171         if (cpumask_weight(sched_domain_span(sd)) == 1)
 172                 return 1;
 173
 174         /* Following flags need at least 2 groups */
 175         if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) &&
 176             (sd->groups != sd->groups->next))
 177                 return 0;
 178
 179         /* Following flags don't use groups */
 180         if (sd->flags & (SD_WAKE_AFFINE))
 181                 return 0;
 182
 183         return 1;
 184 }
 185
 186 static int
 187 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
 188 {
 189         unsigned long cflags = sd->flags, pflags = parent->flags;
 190
 191         if (sd_degenerate(parent))
 192                 return 1;
 193
 194         if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
 195                 return 0;
 196
 197         /* Flags needing groups don't count if only 1 group in parent */
 198         if (parent->groups == parent->groups->next)
 199                 pflags &= ~SD_DEGENERATE_GROUPS_MASK;
 200
 201         if (~cflags & pflags)
 202                 return 0;
 203
 204         return 1;
 205 }
 206
 207 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
 208 DEFINE_STATIC_KEY_FALSE(sched_energy_present);
 209 static unsigned int sysctl_sched_energy_aware = 1;
 210 DEFINE_MUTEX(sched_energy_mutex);
 211 bool sched_energy_update;
 212
 213 void rebuild_sched_domains_energy(void)
 214 {
 215         mutex_lock(&sched_energy_mutex);
 216         sched_energy_update = true;
 217         rebuild_sched_domains();
 218         sched_energy_update = false;
 219         mutex_unlock(&sched_energy_mutex);
 220 }
 221
 222 #ifdef CONFIG_PROC_SYSCTL
 223 static int sched_energy_aware_handler(struct ctl_table *table, int write,
 224                 void *buffer, size_t *lenp, loff_t *ppos)
 225 {
 226         int ret, state;
 227
 228         if (write && !capable(CAP_SYS_ADMIN))
 229                 return -EPERM;
 230
 231         ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 232         if (!ret && write) {
 233                 state = static_branch_unlikely(&sched_energy_present);
 234                 if (state != sysctl_sched_energy_aware)
 235                         rebuild_sched_domains_energy();
 236         }
 237
 238         return ret;
 239 }
 240
 241 static struct ctl_table sched_energy_aware_sysctls[] = {
 242         {
 243                 .procname       = "sched_energy_aware",
 244                 .data           = &sysctl_sched_energy_aware,
 245                 .maxlen         = sizeof(unsigned int),
 246                 .mode           = 0644,
 247                 .proc_handler   = sched_energy_aware_handler,
 248                 .extra1         = SYSCTL_ZERO,
 249                 .extra2         = SYSCTL_ONE,
 250         },
 251         {}
 252 };
 253
 254 static int __init sched_energy_aware_sysctl_init(void)
 255 {
 256         register_sysctl_init("kernel", sched_energy_aware_sysctls);
 257         return 0;
 258 }
 259
 260 late_initcall(sched_energy_aware_sysctl_init);
 261 #endif
 262
 263 static void free_pd(struct perf_domain *pd)
 264 {
 265         struct perf_domain *tmp;
 266
 267         while (pd) {
 268                 tmp = pd->next;
 269                 kfree(pd);
 270                 pd = tmp;
 271         }
 272 }
 273
 274 static struct perf_domain *find_pd(struct perf_domain *pd, int cpu)
 275 {
 276         while (pd) {
 277                 if (cpumask_test_cpu(cpu, perf_domain_span(pd)))
 278                         return pd;
 279                 pd = pd->next;
 280         }
 281
 282         return NULL;
 283 }
 284
 285 static struct perf_domain *pd_init(int cpu)
 286 {
 287         struct em_perf_domain *obj = em_cpu_get(cpu);
 288         struct perf_domain *pd;
 289
 290         if (!obj) {
 291                 if (sched_debug())
 292                         pr_info("%s: no EM found for CPU%d\n", __func__, cpu);
 293                 return NULL;
 294         }
 295
 296         pd = kzalloc(sizeof(*pd), GFP_KERNEL);
 297         if (!pd)
 298                 return NULL;
 299         pd->em_pd = obj;
 300
 301         return pd;
 302 }
 303
 304 static void perf_domain_debug(const struct cpumask *cpu_map,
 305                                                 struct perf_domain *pd)
 306 {
 307         if (!sched_debug() || !pd)
 308                 return;
 309
 310         printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map));
 311
 312         while (pd) {
 313                 printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }",
 314                                 cpumask_first(perf_domain_span(pd)),
 315                                 cpumask_pr_args(perf_domain_span(pd)),
 316                                 em_pd_nr_perf_states(pd->em_pd));
 317                 pd = pd->next;
 318         }
 319
 320         printk(KERN_CONT "\n");
 321 }
 322
 323 static void destroy_perf_domain_rcu(struct rcu_head *rp)
 324 {
 325         struct perf_domain *pd;
 326
 327         pd = container_of(rp, struct perf_domain, rcu);
 328         free_pd(pd);
 329 }
 330
 331 static void sched_energy_set(bool has_eas)
 332 {
 333         if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
 334                 if (sched_debug())
 335                         pr_info("%s: stopping EAS\n", __func__);
 336                 static_branch_disable_cpuslocked(&sched_energy_present);
 337         } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
 338                 if (sched_debug())
 339                         pr_info("%s: starting EAS\n", __func__);
 340                 static_branch_enable_cpuslocked(&sched_energy_present);
 341         }
 342 }
 343
 344 /*
 345  * EAS can be used on a root domain if it meets all the following conditions:
 346  *    1. an Energy Model (EM) is available;
 347  *    2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
 348  *    3. no SMT is detected.
 349  *    4. the EM complexity is low enough to keep scheduling overheads low;
 350  *    5. schedutil is driving the frequency of all CPUs of the rd;
 351  *    6. frequency invariance support is present;
 352  *
 353  * The complexity of the Energy Model is defined as:
 354  *
 355  *              C = nr_pd * (nr_cpus + nr_ps)
 356  *
 357  * with parameters defined as:
 358  *  - nr_pd:    the number of performance domains
 359  *  - nr_cpus:  the number of CPUs
 360  *  - nr_ps:    the sum of the number of performance states of all performance
 361  *              domains (for example, on a system with 2 performance domains,
 362  *              with 10 performance states each, nr_ps = 2 * 10 = 20).
 363  *
 364  * It is generally not a good idea to use such a model in the wake-up path on
 365  * very complex platforms because of the associated scheduling overheads. The
 366  * arbitrary constraint below prevents that. It makes EAS usable up to 16 CPUs
 367  * with per-CPU DVFS and less than 8 performance states each, for example.
 368  */
 369 #define EM_MAX_COMPLEXITY 2048
 370
 371 extern struct cpufreq_governor schedutil_gov;
 372 static bool build_perf_domains(const struct cpumask *cpu_map)
 373 {
 374         int i, nr_pd = 0, nr_ps = 0, nr_cpus = cpumask_weight(cpu_map);
 375         struct perf_domain *pd = NULL, *tmp;
 376         int cpu = cpumask_first(cpu_map);
 377         struct root_domain *rd = cpu_rq(cpu)->rd;
 378         struct cpufreq_policy *policy;
 379         struct cpufreq_governor *gov;
 380
 381         if (!sysctl_sched_energy_aware)
 382                 goto free;
 383
 384         /* EAS is enabled for asymmetric CPU capacity topologies. */
 385         if (!per_cpu(sd_asym_cpucapacity, cpu)) {
 386                 if (sched_debug()) {
 387                         pr_info("rd %*pbl: CPUs do not have asymmetric capacities\n",
 388                                         cpumask_pr_args(cpu_map));
 389                 }
 390                 goto free;
 391         }
 392
 393         /* EAS definitely does *not* handle SMT */
 394         if (sched_smt_active()) {
 395                 pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n",
 396                         cpumask_pr_args(cpu_map));
 397                 goto free;
 398         }
 399
 400         if (!arch_scale_freq_invariant()) {
 401                 if (sched_debug()) {
 402                         pr_warn("rd %*pbl: Disabling EAS: frequency-invariant load tracking not yet supported",
 403                                 cpumask_pr_args(cpu_map));
 404                 }
 405                 goto free;
 406         }
 407
 408         for_each_cpu(i, cpu_map) {
 409                 /* Skip already covered CPUs. */
 410                 if (find_pd(pd, i))
 411                         continue;
 412
 413                 /* Do not attempt EAS if schedutil is not being used. */
 414                 policy = cpufreq_cpu_get(i);
 415                 if (!policy)
 416                         goto free;
 417                 gov = policy->governor;
 418                 cpufreq_cpu_put(policy);
 419                 if (gov != &schedutil_gov) {
 420                         if (rd->pd)
 421                                 pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n",
 422                                                 cpumask_pr_args(cpu_map));
 423                         goto free;
 424                 }
 425
 426                 /* Create the new pd and add it to the local list. */
 427                 tmp = pd_init(i);
 428                 if (!tmp)
 429                         goto free;
 430                 tmp->next = pd;
 431                 pd = tmp;
 432
 433                 /*
 434                  * Count performance domains and performance states for the
 435                  * complexity check.
 436                  */
 437                 nr_pd++;
 438                 nr_ps += em_pd_nr_perf_states(pd->em_pd);
 439         }
 440
 441         /* Bail out if the Energy Model complexity is too high. */
 442         if (nr_pd * (nr_ps + nr_cpus) > EM_MAX_COMPLEXITY) {
 443                 WARN(1, "rd %*pbl: Failed to start EAS, EM complexity is too high\n",
 444                                                 cpumask_pr_args(cpu_map));
 445                 goto free;
 446         }
 447
 448         perf_domain_debug(cpu_map, pd);
 449
 450         /* Attach the new list of performance domains to the root domain. */
 451         tmp = rd->pd;
 452         rcu_assign_pointer(rd->pd, pd);
 453         if (tmp)
 454                 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 455
 456         return !!pd;
 457
 458 free:
 459         free_pd(pd);
 460         tmp = rd->pd;
 461         rcu_assign_pointer(rd->pd, NULL);
 462         if (tmp)
 463                 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 464
 465         return false;
 466 }
 467 #else
 468 static void free_pd(struct perf_domain *pd) { }
 469 #endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL*/
 470
 471 static void free_rootdomain(struct rcu_head *rcu)
 472 {
 473         struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
 474
 475         cpupri_cleanup(&rd->cpupri);
 476         cpudl_cleanup(&rd->cpudl);
 477         free_cpumask_var(rd->dlo_mask);
 478         free_cpumask_var(rd->rto_mask);
 479         free_cpumask_var(rd->online);
 480         free_cpumask_var(rd->span);
 481         free_pd(rd->pd);
 482         kfree(rd);
 483 }
 484
 485 void rq_attach_root(struct rq *rq, struct root_domain *rd)
 486 {
 487         struct root_domain *old_rd = NULL;
 488         unsigned long flags;
 489
 490         raw_spin_rq_lock_irqsave(rq, flags);
 491
 492         if (rq->rd) {
 493                 old_rd = rq->rd;
 494
 495                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
 496                         set_rq_offline(rq);
 497
 498                 cpumask_clear_cpu(rq->cpu, old_rd->span);
 499
 500                 /*
 501                  * If we dont want to free the old_rd yet then
 502                  * set old_rd to NULL to skip the freeing later
 503                  * in this function:
 504                  */
 505                 if (!atomic_dec_and_test(&old_rd->refcount))
 506                         old_rd = NULL;
 507         }
 508
 509         atomic_inc(&rd->refcount);
 510         rq->rd = rd;
 511
 512         cpumask_set_cpu(rq->cpu, rd->span);
 513         if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
 514                 set_rq_online(rq);
 515
 516         raw_spin_rq_unlock_irqrestore(rq, flags);
 517
 518         if (old_rd)
 519                 call_rcu(&old_rd->rcu, free_rootdomain);
 520 }
 521
 522 void sched_get_rd(struct root_domain *rd)
 523 {
 524         atomic_inc(&rd->refcount);
 525 }
 526
 527 void sched_put_rd(struct root_domain *rd)
 528 {
 529         if (!atomic_dec_and_test(&rd->refcount))
 530                 return;
 531
 532         call_rcu(&rd->rcu, free_rootdomain);
 533 }
 534
 535 static int init_rootdomain(struct root_domain *rd)
 536 {
 537         if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
 538                 goto out;
 539         if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
 540                 goto free_span;
 541         if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
 542                 goto free_online;
 543         if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
 544                 goto free_dlo_mask;
 545
 546 #ifdef HAVE_RT_PUSH_IPI
 547         rd->rto_cpu = -1;
 548         raw_spin_lock_init(&rd->rto_lock);
 549         rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func);
 550 #endif
 551
 552         rd->visit_gen = 0;
 553         init_dl_bw(&rd->dl_bw);
 554         if (cpudl_init(&rd->cpudl) != 0)
 555                 goto free_rto_mask;
 556
 557         if (cpupri_init(&rd->cpupri) != 0)
 558                 goto free_cpudl;
 559         return 0;
 560
 561 free_cpudl:
 562         cpudl_cleanup(&rd->cpudl);
 563 free_rto_mask:
 564         free_cpumask_var(rd->rto_mask);
 565 free_dlo_mask:
 566         free_cpumask_var(rd->dlo_mask);
 567 free_online:
 568         free_cpumask_var(rd->online);
 569 free_span:
 570         free_cpumask_var(rd->span);
 571 out:
 572         return -ENOMEM;
 573 }
 574
 575 /*
 576  * By default the system creates a single root-domain with all CPUs as
 577  * members (mimicking the global state we have today).
 578  */
 579 struct root_domain def_root_domain;
 580
 581 void init_defrootdomain(void)
 582 {
 583         init_rootdomain(&def_root_domain);
 584
 585         atomic_set(&def_root_domain.refcount, 1);
 586 }
 587
 588 static struct root_domain *alloc_rootdomain(void)
 589 {
 590         struct root_domain *rd;
 591
 592         rd = kzalloc(sizeof(*rd), GFP_KERNEL);
 593         if (!rd)
 594                 return NULL;
 595
 596         if (init_rootdomain(rd) != 0) {
 597                 kfree(rd);
 598                 return NULL;
 599         }
 600
 601         return rd;
 602 }
 603
 604 static void free_sched_groups(struct sched_group *sg, int free_sgc)
 605 {
 606         struct sched_group *tmp, *first;
 607
 608         if (!sg)
 609                 return;
 610
 611         first = sg;
 612         do {
 613                 tmp = sg->next;
 614
 615                 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
 616                         kfree(sg->sgc);
 617
 618                 if (atomic_dec_and_test(&sg->ref))
 619                         kfree(sg);
 620                 sg = tmp;
 621         } while (sg != first);
 622 }
 623
 624 static void destroy_sched_domain(struct sched_domain *sd)
 625 {
 626         /*
 627          * A normal sched domain may have multiple group references, an
 628          * overlapping domain, having private groups, only one.  Iterate,
 629          * dropping group/capacity references, freeing where none remain.
 630          */
 631         free_sched_groups(sd->groups, 1);
 632
 633         if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
 634                 kfree(sd->shared);
 635         kfree(sd);
 636 }
 637
 638 static void destroy_sched_domains_rcu(struct rcu_head *rcu)
 639 {
 640         struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
 641
 642         while (sd) {
 643                 struct sched_domain *parent = sd->parent;
 644                 destroy_sched_domain(sd);
 645                 sd = parent;
 646         }
 647 }
 648
 649 static void destroy_sched_domains(struct sched_domain *sd)
 650 {
 651         if (sd)
 652                 call_rcu(&sd->rcu, destroy_sched_domains_rcu);
 653 }
 654
 655 /*
 656  * Keep a special pointer to the highest sched_domain that has
 657  * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
 658  * allows us to avoid some pointer chasing select_idle_sibling().
 659  *
 660  * Also keep a unique ID per domain (we use the first CPU number in
 661  * the cpumask of the domain), this allows us to quickly tell if
 662  * two CPUs are in the same cache domain, see cpus_share_cache().
 663  */
 664 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
 665 DEFINE_PER_CPU(int, sd_llc_size);
 666 DEFINE_PER_CPU(int, sd_llc_id);
 667 DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
 668 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
 669 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 670 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
 671 DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
 672
 673 static void update_top_cache_domain(int cpu)
 674 {
 675         struct sched_domain_shared *sds = NULL;
 676         struct sched_domain *sd;
 677         int id = cpu;
 678         int size = 1;
 679
 680         sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
 681         if (sd) {
 682                 id = cpumask_first(sched_domain_span(sd));
 683                 size = cpumask_weight(sched_domain_span(sd));
 684                 sds = sd->shared;
 685         }
 686
 687         rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
 688         per_cpu(sd_llc_size, cpu) = size;
 689         per_cpu(sd_llc_id, cpu) = id;
 690         rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
 691
 692         sd = lowest_flag_domain(cpu, SD_NUMA);
 693         rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
 694
 695         sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
 696         rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);
 697
 698         sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY_FULL);
 699         rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
 700 }
 701
 702 /*
 703  * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
 704  * hold the hotplug lock.
 705  */
 706 static void
 707 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 708 {
 709         struct rq *rq = cpu_rq(cpu);
 710         struct sched_domain *tmp;
 711
 712         /* Remove the sched domains which do not contribute to scheduling. */
 713         for (tmp = sd; tmp; ) {
 714                 struct sched_domain *parent = tmp->parent;
 715                 if (!parent)
 716                         break;
 717
 718                 if (sd_parent_degenerate(tmp, parent)) {
 719                         tmp->parent = parent->parent;
 720                         if (parent->parent)
 721                                 parent->parent->child = tmp;
 722                         /*
 723                          * Transfer SD_PREFER_SIBLING down in case of a
 724                          * degenerate parent; the spans match for this
 725                          * so the property transfers.
 726                          */
 727                         if (parent->flags & SD_PREFER_SIBLING)
 728                                 tmp->flags |= SD_PREFER_SIBLING;
 729                         destroy_sched_domain(parent);
 730                 } else
 731                         tmp = tmp->parent;
 732         }
 733
 734         if (sd && sd_degenerate(sd)) {
 735                 tmp = sd;
 736                 sd = sd->parent;
 737                 destroy_sched_domain(tmp);
 738                 if (sd) {
 739                         struct sched_group *sg = sd->groups;
 740
 741                         /*
 742                          * sched groups hold the flags of the child sched
 743                          * domain for convenience. Clear such flags since
 744                          * the child is being destroyed.
 745                          */
 746                         do {
 747                                 sg->flags = 0;
 748                         } while (sg != sd->groups);
 749
 750                         sd->child = NULL;
 751                 }
 752         }
 753
 754         sched_domain_debug(sd, cpu);
 755
 756         rq_attach_root(rq, rd);
 757         tmp = rq->sd;
 758         rcu_assign_pointer(rq->sd, sd);
 759         dirty_sched_domain_sysctl(cpu);
 760         destroy_sched_domains(tmp);
 761
 762         update_top_cache_domain(cpu);
 763 }
 764
 765 struct s_data {
 766         struct sched_domain * __percpu *sd;
 767         struct root_domain      *rd;
 768 };
 769
 770 enum s_alloc {
 771         sa_rootdomain,
 772         sa_sd,
 773         sa_sd_storage,
 774         sa_none,
 775 };
 776
 777 /*
 778  * Return the canonical balance CPU for this group, this is the first CPU
 779  * of this group that's also in the balance mask.
 780  *
 781  * The balance mask are all those CPUs that could actually end up at this
 782  * group. See build_balance_mask().
 783  *
 784  * Also see should_we_balance().
 785  */
 786 int group_balance_cpu(struct sched_group *sg)
 787 {
 788         return cpumask_first(group_balance_mask(sg));
 789 }
 790
 791
 792 /*
 793  * NUMA topology (first read the regular topology blurb below)
 794  *
 795  * Given a node-distance table, for example:
 796  *
 797  *   node   0   1   2   3
 798  *     0:  10  20  30  20
 799  *     1:  20  10  20  30
 800  *     2:  30  20  10  20
 801  *     3:  20  30  20  10
 802  *
 803  * which represents a 4 node ring topology like:
 804  *
 805  *   0 ----- 1
 806  *   |       |
 807  *   |       |
 808  *   |       |
 809  *   3 ----- 2
 810  *
 811  * We want to construct domains and groups to represent this. The way we go
 812  * about doing this is to build the domains on 'hops'. For each NUMA level we
 813  * construct the mask of all nodes reachable in @level hops.
 814  *
 815  * For the above NUMA topology that gives 3 levels:
 816  *
 817  * NUMA-2       0-3             0-3             0-3             0-3
 818  *  groups:     {0-1,3},{1-3}   {0-2},{0,2-3}   {1-3},{0-1,3}   {0,2-3},{0-2}
 819  *
 820  * NUMA-1       0-1,3           0-2             1-3             0,2-3
 821  *  groups:     {0},{1},{3}     {0},{1},{2}     {1},{2},{3}     {0},{2},{3}
 822  *
 823  * NUMA-0       0               1               2               3
 824  *
 825  *
 826  * As can be seen; things don't nicely line up as with the regular topology.
 827  * When we iterate a domain in child domain chunks some nodes can be
 828  * represented multiple times -- hence the "overlap" naming for this part of
 829  * the topology.
 830  *
 831  * In order to minimize this overlap, we only build enough groups to cover the
 832  * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
 833  *
 834  * Because:
 835  *
 836  *  - the first group of each domain is its child domain; this
 837  *    gets us the first 0-1,3
 838  *  - the only uncovered node is 2, who's child domain is 1-3.
 839  *
 840  * However, because of the overlap, computing a unique CPU for each group is
 841  * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
 842  * groups include the CPUs of Node-0, while those CPUs would not in fact ever
 843  * end up at those groups (they would end up in group: 0-1,3).
 844  *
 845  * To correct this we have to introduce the group balance mask. This mask
 846  * will contain those CPUs in the group that can reach this group given the
 847  * (child) domain tree.
 848  *
 849  * With this we can once again compute balance_cpu and sched_group_capacity
 850  * relations.
 851  *
 852  * XXX include words on how balance_cpu is unique and therefore can be
 853  * used for sched_group_capacity links.
 854  *
 855  *
 856  * Another 'interesting' topology is:
 857  *
 858  *   node   0   1   2   3
 859  *     0:  10  20  20  30
 860  *     1:  20  10  20  20
 861  *     2:  20  20  10  20
 862  *     3:  30  20  20  10
 863  *
 864  * Which looks a little like:
 865  *
 866  *   0 ----- 1
 867  *   |     / |
 868  *   |   /   |
 869  *   | /     |
 870  *   2 ----- 3
 871  *
 872  * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
 873  * are not.
 874  *
 875  * This leads to a few particularly weird cases where the sched_domain's are
 876  * not of the same number for each CPU. Consider:
 877  *
 878  * NUMA-2       0-3                                             0-3
 879  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
 880  *
 881  * NUMA-1       0-2             0-3             0-3             1-3
 882  *
 883  * NUMA-0       0               1               2               3
 884  *
 885  */
 886
 887
 888 /*
 889  * Build the balance mask; it contains only those CPUs that can arrive at this
 890  * group and should be considered to continue balancing.
 891  *
 892  * We do this during the group creation pass, therefore the group information
 893  * isn't complete yet, however since each group represents a (child) domain we
 894  * can fully construct this using the sched_domain bits (which are already
 895  * complete).
 896  */
 897 static void
 898 build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
 899 {
 900         const struct cpumask *sg_span = sched_group_span(sg);
 901         struct sd_data *sdd = sd->private;
 902         struct sched_domain *sibling;
 903         int i;
 904
 905         cpumask_clear(mask);
 906
 907         for_each_cpu(i, sg_span) {
 908                 sibling = *per_cpu_ptr(sdd->sd, i);
 909
 910                 /*
 911                  * Can happen in the asymmetric case, where these siblings are
 912                  * unused. The mask will not be empty because those CPUs that
 913                  * do have the top domain _should_ span the domain.
 914                  */
 915                 if (!sibling->child)
 916                         continue;
 917
 918                 /* If we would not end up here, we can't continue from here */
 919                 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
 920                         continue;
 921
 922                 cpumask_set_cpu(i, mask);
 923         }
 924
 925         /* We must not have empty masks here */
 926         WARN_ON_ONCE(cpumask_empty(mask));
 927 }
 928
 929 /*
 930  * XXX: This creates per-node group entries; since the load-balancer will
 931  * immediately access remote memory to construct this group's load-balance
 932  * statistics having the groups node local is of dubious benefit.
 933  */
 934 static struct sched_group *
 935 build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
 936 {
 937         struct sched_group *sg;
 938         struct cpumask *sg_span;
 939
 940         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
 941                         GFP_KERNEL, cpu_to_node(cpu));
 942
 943         if (!sg)
 944                 return NULL;
 945
 946         sg_span = sched_group_span(sg);
 947         if (sd->child) {
 948                 cpumask_copy(sg_span, sched_domain_span(sd->child));
 949                 sg->flags = sd->child->flags;
 950         } else {
 951                 cpumask_copy(sg_span, sched_domain_span(sd));
 952         }
 953
 954         atomic_inc(&sg->ref);
 955         return sg;
 956 }
 957
 958 static void init_overlap_sched_group(struct sched_domain *sd,
 959                                      struct sched_group *sg)
 960 {
 961         struct cpumask *mask = sched_domains_tmpmask2;
 962         struct sd_data *sdd = sd->private;
 963         struct cpumask *sg_span;
 964         int cpu;
 965
 966         build_balance_mask(sd, sg, mask);
 967         cpu = cpumask_first(mask);
 968
 969         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
 970         if (atomic_inc_return(&sg->sgc->ref) == 1)
 971                 cpumask_copy(group_balance_mask(sg), mask);
 972         else
 973                 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
 974
 975         /*
 976          * Initialize sgc->capacity such that even if we mess up the
 977          * domains and no possible iteration will get us here, we won't
 978          * die on a /0 trap.
 979          */
 980         sg_span = sched_group_span(sg);
 981         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
 982         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
 983         sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
 984 }
 985
 986 static struct sched_domain *
 987 find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling)
 988 {
 989         /*
 990          * The proper descendant would be the one whose child won't span out
 991          * of sd
 992          */
 993         while (sibling->child &&
 994                !cpumask_subset(sched_domain_span(sibling->child),
 995                                sched_domain_span(sd)))
 996                 sibling = sibling->child;
 997
 998         /*
 999          * As we are referencing sgc across different topology level, we need
1000          * to go down to skip those sched_domains which don't contribute to
1001          * scheduling because they will be degenerated in cpu_attach_domain
1002          */
1003         while (sibling->child &&
1004                cpumask_equal(sched_domain_span(sibling->child),
1005                              sched_domain_span(sibling)))
1006                 sibling = sibling->child;
1007
1008         return sibling;
1009 }
1010
1011 static int
1012 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
1013 {
1014         struct sched_group *first = NULL, *last = NULL, *sg;
1015         const struct cpumask *span = sched_domain_span(sd);
1016         struct cpumask *covered = sched_domains_tmpmask;
1017         struct sd_data *sdd = sd->private;
1018         struct sched_domain *sibling;
1019         int i;
1020
1021         cpumask_clear(covered);
1022
1023         for_each_cpu_wrap(i, span, cpu) {
1024                 struct cpumask *sg_span;
1025
1026                 if (cpumask_test_cpu(i, covered))
1027                         continue;
1028
1029                 sibling = *per_cpu_ptr(sdd->sd, i);
1030
1031                 /*
1032                  * Asymmetric node setups can result in situations where the
1033                  * domain tree is of unequal depth, make sure to skip domains
1034                  * that already cover the entire range.
1035                  *
1036                  * In that case build_sched_domains() will have terminated the
1037                  * iteration early and our sibling sd spans will be empty.
1038                  * Domains should always include the CPU they're built on, so
1039                  * check that.
1040                  */
1041                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
1042                         continue;
1043
1044                 /*
1045                  * Usually we build sched_group by sibling's child sched_domain
1046                  * But for machines whose NUMA diameter are 3 or above, we move
1047                  * to build sched_group by sibling's proper descendant's child
1048                  * domain because sibling's child sched_domain will span out of
1049                  * the sched_domain being built as below.
1050                  *
1051                  * Smallest diameter=3 topology is:
1052                  *
1053                  *   node   0   1   2   3
1054                  *     0:  10  20  30  40
1055                  *     1:  20  10  20  30
1056                  *     2:  30  20  10  20
1057                  *     3:  40  30  20  10
1058                  *
1059                  *   0 --- 1 --- 2 --- 3
1060                  *
1061                  * NUMA-3       0-3             N/A             N/A             0-3
1062                  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
1063                  *
1064                  * NUMA-2       0-2             0-3             0-3             1-3
1065                  *  groups:     {0-1},{1-3}     {0-2},{2-3}     {1-3},{0-1}     {2-3},{0-2}
1066                  *
1067                  * NUMA-1       0-1             0-2             1-3             2-3
1068                  *  groups:     {0},{1}         {1},{2},{0}     {2},{3},{1}     {3},{2}
1069                  *
1070                  * NUMA-0       0               1               2               3
1071                  *
1072                  * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the
1073                  * group span isn't a subset of the domain span.
1074                  */
1075                 if (sibling->child &&
1076                     !cpumask_subset(sched_domain_span(sibling->child), span))
1077                         sibling = find_descended_sibling(sd, sibling);
1078
1079                 sg = build_group_from_child_sched_domain(sibling, cpu);
1080                 if (!sg)
1081                         goto fail;
1082
1083                 sg_span = sched_group_span(sg);
1084                 cpumask_or(covered, covered, sg_span);
1085
1086                 init_overlap_sched_group(sibling, sg);
1087
1088                 if (!first)
1089                         first = sg;
1090                 if (last)
1091                         last->next = sg;
1092                 last = sg;
1093                 last->next = first;
1094         }
1095         sd->groups = first;
1096
1097         return 0;
1098
1099 fail:
1100         free_sched_groups(first, 0);
1101
1102         return -ENOMEM;
1103 }
1104
1105
1106 /*
1107  * Package topology (also see the load-balance blurb in fair.c)
1108  *
1109  * The scheduler builds a tree structure to represent a number of important
1110  * topology features. By default (default_topology[]) these include:
1111  *
1112  *  - Simultaneous multithreading (SMT)
1113  *  - Multi-Core Cache (MC)
1114  *  - Package (DIE)
1115  *
1116  * Where the last one more or less denotes everything up to a NUMA node.
1117  *
1118  * The tree consists of 3 primary data structures:
1119  *
1120  *      sched_domain -> sched_group -> sched_group_capacity
1121  *          ^ ^             ^ ^
1122  *          `-'             `-'
1123  *
1124  * The sched_domains are per-CPU and have a two way link (parent & child) and
1125  * denote the ever growing mask of CPUs belonging to that level of topology.
1126  *
1127  * Each sched_domain has a circular (double) linked list of sched_group's, each
1128  * denoting the domains of the level below (or individual CPUs in case of the
1129  * first domain level). The sched_group linked by a sched_domain includes the
1130  * CPU of that sched_domain [*].
1131  *
1132  * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
1133  *
1134  * CPU   0   1   2   3   4   5   6   7
1135  *
1136  * DIE  [                             ]
1137  * MC   [             ] [             ]
1138  * SMT  [     ] [     ] [     ] [     ]
1139  *
1140  *  - or -
1141  *
1142  * DIE  0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
1143  * MC   0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
1144  * SMT  0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
1145  *
1146  * CPU   0   1   2   3   4   5   6   7
1147  *
1148  * One way to think about it is: sched_domain moves you up and down among these
1149  * topology levels, while sched_group moves you sideways through it, at child
1150  * domain granularity.
1151  *
1152  * sched_group_capacity ensures each unique sched_group has shared storage.
1153  *
1154  * There are two related construction problems, both require a CPU that
1155  * uniquely identify each group (for a given domain):
1156  *
1157  *  - The first is the balance_cpu (see should_we_balance() and the
1158  *    load-balance blub in fair.c); for each group we only want 1 CPU to
1159  *    continue balancing at a higher domain.
1160  *
1161  *  - The second is the sched_group_capacity; we want all identical groups
1162  *    to share a single sched_group_capacity.
1163  *
1164  * Since these topologies are exclusive by construction. That is, its
1165  * impossible for an SMT thread to belong to multiple cores, and cores to
1166  * be part of multiple caches. There is a very clear and unique location
1167  * for each CPU in the hierarchy.
1168  *
1169  * Therefore computing a unique CPU for each group is trivial (the iteration
1170  * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
1171  * group), we can simply pick the first CPU in each group.
1172  *
1173  *
1174  * [*] in other words, the first group of each domain is its child domain.
1175  */
1176
1177 static struct sched_group *get_group(int cpu, struct sd_data *sdd)
1178 {
1179         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1180         struct sched_domain *child = sd->child;
1181         struct sched_group *sg;
1182         bool already_visited;
1183
1184         if (child)
1185                 cpu = cpumask_first(sched_domain_span(child));
1186
1187         sg = *per_cpu_ptr(sdd->sg, cpu);
1188         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
1189
1190         /* Increase refcounts for claim_allocations: */
1191         already_visited = atomic_inc_return(&sg->ref) > 1;
1192         /* sgc visits should follow a similar trend as sg */
1193         WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1));
1194
1195         /* If we have already visited that group, it's already initialized. */
1196         if (already_visited)
1197                 return sg;
1198
1199         if (child) {
1200                 cpumask_copy(sched_group_span(sg), sched_domain_span(child));
1201                 cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
1202                 sg->flags = child->flags;
1203         } else {
1204                 cpumask_set_cpu(cpu, sched_group_span(sg));
1205                 cpumask_set_cpu(cpu, group_balance_mask(sg));
1206         }
1207
1208         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
1209         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
1210         sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
1211
1212         return sg;
1213 }
1214
1215 /*
1216  * build_sched_groups will build a circular linked list of the groups
1217  * covered by the given span, will set each group's ->cpumask correctly,
1218  * and will initialize their ->sgc.
1219  *
1220  * Assumes the sched_domain tree is fully constructed
1221  */
1222 static int
1223 build_sched_groups(struct sched_domain *sd, int cpu)
1224 {
1225         struct sched_group *first = NULL, *last = NULL;
1226         struct sd_data *sdd = sd->private;
1227         const struct cpumask *span = sched_domain_span(sd);
1228         struct cpumask *covered;
1229         int i;
1230
1231         lockdep_assert_held(&sched_domains_mutex);
1232         covered = sched_domains_tmpmask;
1233
1234         cpumask_clear(covered);
1235
1236         for_each_cpu_wrap(i, span, cpu) {
1237                 struct sched_group *sg;
1238
1239                 if (cpumask_test_cpu(i, covered))
1240                         continue;
1241
1242                 sg = get_group(i, sdd);
1243
1244                 cpumask_or(covered, covered, sched_group_span(sg));
1245
1246                 if (!first)
1247                         first = sg;
1248                 if (last)
1249                         last->next = sg;
1250                 last = sg;
1251         }
1252         last->next = first;
1253         sd->groups = first;
1254
1255         return 0;
1256 }
1257
1258 /*
1259  * Initialize sched groups cpu_capacity.
1260  *
1261  * cpu_capacity indicates the capacity of sched group, which is used while
1262  * distributing the load between different sched groups in a sched domain.
1263  * Typically cpu_capacity for all the groups in a sched domain will be same
1264  * unless there are asymmetries in the topology. If there are asymmetries,
1265  * group having more cpu_capacity will pickup more load compared to the
1266  * group having less cpu_capacity.
1267  */
1268 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
1269 {
1270         struct sched_group *sg = sd->groups;
1271
1272         WARN_ON(!sg);
1273
1274         do {
1275                 int cpu, max_cpu = -1;
1276
1277                 sg->group_weight = cpumask_weight(sched_group_span(sg));
1278
1279                 if (!(sd->flags & SD_ASYM_PACKING))
1280                         goto next;
1281
1282                 for_each_cpu(cpu, sched_group_span(sg)) {
1283                         if (max_cpu < 0)
1284                                 max_cpu = cpu;
1285                         else if (sched_asym_prefer(cpu, max_cpu))
1286                                 max_cpu = cpu;
1287                 }
1288                 sg->asym_prefer_cpu = max_cpu;
1289
1290 next:
1291                 sg = sg->next;
1292         } while (sg != sd->groups);
1293
1294         if (cpu != group_balance_cpu(sg))
1295                 return;
1296
1297         update_group_capacity(sd, cpu);
1298 }
1299
1300 /*
1301  * Asymmetric CPU capacity bits
1302  */
1303 struct asym_cap_data {
1304         struct list_head link;
1305         unsigned long capacity;
1306         unsigned long cpus[];
1307 };
1308
1309 /*
1310  * Set of available CPUs grouped by their corresponding capacities
1311  * Each list entry contains a CPU mask reflecting CPUs that share the same
1312  * capacity.
1313  * The lifespan of data is unlimited.
1314  */
1315 static LIST_HEAD(asym_cap_list);
1316
1317 #define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus)
1318
1319 /*
1320  * Verify whether there is any CPU capacity asymmetry in a given sched domain.
1321  * Provides sd_flags reflecting the asymmetry scope.
1322  */
1323 static inline int
1324 asym_cpu_capacity_classify(const struct cpumask *sd_span,
1325                            const struct cpumask *cpu_map)
1326 {
1327         struct asym_cap_data *entry;
1328         int count = 0, miss = 0;
1329
1330         /*
1331          * Count how many unique CPU capacities this domain spans across
1332          * (compare sched_domain CPUs mask with ones representing  available
1333          * CPUs capacities). Take into account CPUs that might be offline:
1334          * skip those.
1335          */
1336         list_for_each_entry(entry, &asym_cap_list, link) {
1337                 if (cpumask_intersects(sd_span, cpu_capacity_span(entry)))
1338                         ++count;
1339                 else if (cpumask_intersects(cpu_map, cpu_capacity_span(entry)))
1340                         ++miss;
1341         }
1342
1343         WARN_ON_ONCE(!count && !list_empty(&asym_cap_list));
1344
1345         /* No asymmetry detected */
1346         if (count < 2)
1347                 return 0;
1348         /* Some of the available CPU capacity values have not been detected */
1349         if (miss)
1350                 return SD_ASYM_CPUCAPACITY;
1351
1352         /* Full asymmetry */
1353         return SD_ASYM_CPUCAPACITY | SD_ASYM_CPUCAPACITY_FULL;
1354
1355 }
1356
1357 static inline void asym_cpu_capacity_update_data(int cpu)
1358 {
1359         unsigned long capacity = arch_scale_cpu_capacity(cpu);
1360         struct asym_cap_data *entry = NULL;
1361
1362         list_for_each_entry(entry, &asym_cap_list, link) {
1363                 if (capacity == entry->capacity)
1364                         goto done;
1365         }
1366
1367         entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL);
1368         if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n"))
1369                 return;
1370         entry->capacity = capacity;
1371         list_add(&entry->link, &asym_cap_list);
1372 done:
1373         __cpumask_set_cpu(cpu, cpu_capacity_span(entry));
1374 }
1375
1376 /*
1377  * Build-up/update list of CPUs grouped by their capacities
1378  * An update requires explicit request to rebuild sched domains
1379  * with state indicating CPU topology changes.
1380  */
1381 static void asym_cpu_capacity_scan(void)
1382 {
1383         struct asym_cap_data *entry, *next;
1384         int cpu;
1385
1386         list_for_each_entry(entry, &asym_cap_list, link)
1387                 cpumask_clear(cpu_capacity_span(entry));
1388
1389         for_each_cpu_and(cpu, cpu_possible_mask, housekeeping_cpumask(HK_TYPE_DOMAIN))
1390                 asym_cpu_capacity_update_data(cpu);
1391
1392         list_for_each_entry_safe(entry, next, &asym_cap_list, link) {
1393                 if (cpumask_empty(cpu_capacity_span(entry))) {
1394                         list_del(&entry->link);
1395                         kfree(entry);
1396                 }
1397         }
1398
1399         /*
1400          * Only one capacity value has been detected i.e. this system is symmetric.
1401          * No need to keep this data around.
1402          */
1403         if (list_is_singular(&asym_cap_list)) {
1404                 entry = list_first_entry(&asym_cap_list, typeof(*entry), link);
1405                 list_del(&entry->link);
1406                 kfree(entry);
1407         }
1408 }
1409
1410 /*
1411  * Initializers for schedule domains
1412  * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
1413  */
1414
1415 static int default_relax_domain_level = -1;
1416 int sched_domain_level_max;
1417
1418 static int __init setup_relax_domain_level(char *str)
1419 {
1420         if (kstrtoint(str, 0, &default_relax_domain_level))
1421                 pr_warn("Unable to set relax_domain_level\n");
1422
1423         return 1;
1424 }
1425 __setup("relax_domain_level=", setup_relax_domain_level);
1426
1427 static void set_domain_attribute(struct sched_domain *sd,
1428                                  struct sched_domain_attr *attr)
1429 {
1430         int request;
1431
1432         if (!attr || attr->relax_domain_level < 0) {
1433                 if (default_relax_domain_level < 0)
1434                         return;
1435                 request = default_relax_domain_level;
1436         } else
1437                 request = attr->relax_domain_level;
1438
1439         if (sd->level > request) {
1440                 /* Turn off idle balance on this domain: */
1441                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
1442         }
1443 }
1444
1445 static void __sdt_free(const struct cpumask *cpu_map);
1446 static int __sdt_alloc(const struct cpumask *cpu_map);
1447
1448 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
1449                                  const struct cpumask *cpu_map)
1450 {
1451         switch (what) {
1452         case sa_rootdomain:
1453                 if (!atomic_read(&d->rd->refcount))
1454                         free_rootdomain(&d->rd->rcu);
1455                 fallthrough;
1456         case sa_sd:
1457                 free_percpu(d->sd);
1458                 fallthrough;
1459         case sa_sd_storage:
1460                 __sdt_free(cpu_map);
1461                 fallthrough;
1462         case sa_none:
1463                 break;
1464         }
1465 }
1466
1467 static enum s_alloc
1468 __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1469 {
1470         memset(d, 0, sizeof(*d));
1471
1472         if (__sdt_alloc(cpu_map))
1473                 return sa_sd_storage;
1474         d->sd = alloc_percpu(struct sched_domain *);
1475         if (!d->sd)
1476                 return sa_sd_storage;
1477         d->rd = alloc_rootdomain();
1478         if (!d->rd)
1479                 return sa_sd;
1480
1481         return sa_rootdomain;
1482 }
1483
1484 /*
1485  * NULL the sd_data elements we've used to build the sched_domain and
1486  * sched_group structure so that the subsequent __free_domain_allocs()
1487  * will not free the data we're using.
1488  */
1489 static void claim_allocations(int cpu, struct sched_domain *sd)
1490 {
1491         struct sd_data *sdd = sd->private;
1492
1493         WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1494         *per_cpu_ptr(sdd->sd, cpu) = NULL;
1495
1496         if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1497                 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1498
1499         if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1500                 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1501
1502         if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1503                 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1504 }
1505
1506 #ifdef CONFIG_NUMA
1507 enum numa_topology_type sched_numa_topology_type;
1508
1509 static int                      sched_domains_numa_levels;
1510 static int                      sched_domains_curr_level;
1511
1512 int                             sched_max_numa_distance;
1513 static int                      *sched_domains_numa_distance;
1514 static struct cpumask           ***sched_domains_numa_masks;
1515 #endif
1516
1517 /*
1518  * SD_flags allowed in topology descriptions.
1519  *
1520  * These flags are purely descriptive of the topology and do not prescribe
1521  * behaviour. Behaviour is artificial and mapped in the below sd_init()
1522  * function:
1523  *
1524  *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
1525  *   SD_SHARE_PKG_RESOURCES - describes shared caches
1526  *   SD_NUMA                - describes NUMA topologies
1527  *
1528  * Odd one out, which beside describing the topology has a quirk also
1529  * prescribes the desired behaviour that goes along with it:
1530  *
1531  *   SD_ASYM_PACKING        - describes SMT quirks
1532  */
1533 #define TOPOLOGY_SD_FLAGS               \
1534         (SD_SHARE_CPUCAPACITY   |       \
1535          SD_SHARE_PKG_RESOURCES |       \
1536          SD_NUMA                |       \
1537          SD_ASYM_PACKING)
1538
1539 static struct sched_domain *
1540 sd_init(struct sched_domain_topology_level *tl,
1541         const struct cpumask *cpu_map,
1542         struct sched_domain *child, int cpu)
1543 {
1544         struct sd_data *sdd = &tl->data;
1545         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1546         int sd_id, sd_weight, sd_flags = 0;
1547         struct cpumask *sd_span;
1548
1549 #ifdef CONFIG_NUMA
1550         /*
1551          * Ugly hack to pass state to sd_numa_mask()...
1552          */
1553         sched_domains_curr_level = tl->numa_level;
1554 #endif
1555
1556         sd_weight = cpumask_weight(tl->mask(cpu));
1557
1558         if (tl->sd_flags)
1559                 sd_flags = (*tl->sd_flags)();
1560         if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1561                         "wrong sd_flags in topology description\n"))
1562                 sd_flags &= TOPOLOGY_SD_FLAGS;
1563
1564         *sd = (struct sched_domain){
1565                 .min_interval           = sd_weight,
1566                 .max_interval           = 2*sd_weight,
1567                 .busy_factor            = 16,
1568                 .imbalance_pct          = 117,
1569
1570                 .cache_nice_tries       = 0,
1571
1572                 .flags                  = 1*SD_BALANCE_NEWIDLE
1573                                         | 1*SD_BALANCE_EXEC
1574                                         | 1*SD_BALANCE_FORK
1575                                         | 0*SD_BALANCE_WAKE
1576                                         | 1*SD_WAKE_AFFINE
1577                                         | 0*SD_SHARE_CPUCAPACITY
1578                                         | 0*SD_SHARE_PKG_RESOURCES
1579                                         | 0*SD_SERIALIZE
1580                                         | 1*SD_PREFER_SIBLING
1581                                         | 0*SD_NUMA
1582                                         | sd_flags
1583                                         ,
1584
1585                 .last_balance           = jiffies,
1586                 .balance_interval       = sd_weight,
1587                 .max_newidle_lb_cost    = 0,
1588                 .last_decay_max_lb_cost = jiffies,
1589                 .child                  = child,
1590 #ifdef CONFIG_SCHED_DEBUG
1591                 .name                   = tl->name,
1592 #endif
1593         };
1594
1595         sd_span = sched_domain_span(sd);
1596         cpumask_and(sd_span, cpu_map, tl->mask(cpu));
1597         sd_id = cpumask_first(sd_span);
1598
1599         sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map);
1600
1601         WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) ==
1602                   (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY),
1603                   "CPU capacity asymmetry not supported on SMT\n");
1604
1605         /*
1606          * Convert topological properties into behaviour.
1607          */
1608         /* Don't attempt to spread across CPUs of different capacities. */
1609         if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child)
1610                 sd->child->flags &= ~SD_PREFER_SIBLING;
1611
1612         if (sd->flags & SD_SHARE_CPUCAPACITY) {
1613                 sd->imbalance_pct = 110;
1614
1615         } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1616                 sd->imbalance_pct = 117;
1617                 sd->cache_nice_tries = 1;
1618
1619 #ifdef CONFIG_NUMA
1620         } else if (sd->flags & SD_NUMA) {
1621                 sd->cache_nice_tries = 2;
1622
1623                 sd->flags &= ~SD_PREFER_SIBLING;
1624                 sd->flags |= SD_SERIALIZE;
1625                 if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) {
1626                         sd->flags &= ~(SD_BALANCE_EXEC |
1627                                        SD_BALANCE_FORK |
1628                                        SD_WAKE_AFFINE);
1629                 }
1630
1631 #endif
1632         } else {
1633                 sd->cache_nice_tries = 1;
1634         }
1635
1636         /*
1637          * For all levels sharing cache; connect a sched_domain_shared
1638          * instance.
1639          */
1640         if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1641                 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1642                 atomic_inc(&sd->shared->ref);
1643                 atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1644         }
1645
1646         sd->private = sdd;
1647
1648         return sd;
1649 }
1650
1651 /*
1652  * Topology list, bottom-up.
1653  */
1654 static struct sched_domain_topology_level default_topology[] = {
1655 #ifdef CONFIG_SCHED_SMT
1656         { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1657 #endif
1658
1659 #ifdef CONFIG_SCHED_CLUSTER
1660         { cpu_clustergroup_mask, cpu_cluster_flags, SD_INIT_NAME(CLS) },
1661 #endif
1662
1663 #ifdef CONFIG_SCHED_MC
1664         { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1665 #endif
1666         { cpu_cpu_mask, SD_INIT_NAME(DIE) },
1667         { NULL, },
1668 };
1669
1670 static struct sched_domain_topology_level *sched_domain_topology =
1671         default_topology;
1672 static struct sched_domain_topology_level *sched_domain_topology_saved;
1673
1674 #define for_each_sd_topology(tl)                        \
1675         for (tl = sched_domain_topology; tl->mask; tl++)
1676
1677 void set_sched_topology(struct sched_domain_topology_level *tl)
1678 {
1679         if (WARN_ON_ONCE(sched_smp_initialized))
1680                 return;
1681
1682         sched_domain_topology = tl;
1683         sched_domain_topology_saved = NULL;
1684 }
1685
1686 #ifdef CONFIG_NUMA
1687
1688 static const struct cpumask *sd_numa_mask(int cpu)
1689 {
1690         return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1691 }
1692
1693 static void sched_numa_warn(const char *str)
1694 {
1695         static int done = false;
1696         int i,j;
1697
1698         if (done)
1699                 return;
1700
1701         done = true;
1702
1703         printk(KERN_WARNING "ERROR: %s\n\n", str);
1704
1705         for (i = 0; i < nr_node_ids; i++) {
1706                 printk(KERN_WARNING "  ");
1707                 for (j = 0; j < nr_node_ids; j++) {
1708                         if (!node_state(i, N_CPU) || !node_state(j, N_CPU))
1709                                 printk(KERN_CONT "(%02d) ", node_distance(i,j));
1710                         else
1711                                 printk(KERN_CONT " %02d  ", node_distance(i,j));
1712                 }
1713                 printk(KERN_CONT "\n");
1714         }
1715         printk(KERN_WARNING "\n");
1716 }
1717
1718 bool find_numa_distance(int distance)
1719 {
1720         bool found = false;
1721         int i, *distances;
1722
1723         if (distance == node_distance(0, 0))
1724                 return true;
1725
1726         rcu_read_lock();
1727         distances = rcu_dereference(sched_domains_numa_distance);
1728         if (!distances)
1729                 goto unlock;
1730         for (i = 0; i < sched_domains_numa_levels; i++) {
1731                 if (distances[i] == distance) {
1732                         found = true;
1733                         break;
1734                 }
1735         }
1736 unlock:
1737         rcu_read_unlock();
1738
1739         return found;
1740 }
1741
1742 #define for_each_cpu_node_but(n, nbut)          \
1743         for_each_node_state(n, N_CPU)           \
1744                 if (n == nbut)                  \
1745                         continue;               \
1746                 else
1747
1748 /*
1749  * A system can have three types of NUMA topology:
1750  * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1751  * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1752  * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1753  *
1754  * The difference between a glueless mesh topology and a backplane
1755  * topology lies in whether communication between not directly
1756  * connected nodes goes through intermediary nodes (where programs
1757  * could run), or through backplane controllers. This affects
1758  * placement of programs.
1759  *
1760  * The type of topology can be discerned with the following tests:
1761  * - If the maximum distance between any nodes is 1 hop, the system
1762  *   is directly connected.
1763  * - If for two nodes A and B, located N > 1 hops away from each other,
1764  *   there is an intermediary node C, which is < N hops away from both
1765  *   nodes A and B, the system is a glueless mesh.
1766  */
1767 static void init_numa_topology_type(int offline_node)
1768 {
1769         int a, b, c, n;
1770
1771         n = sched_max_numa_distance;
1772
1773         if (sched_domains_numa_levels <= 2) {
1774                 sched_numa_topology_type = NUMA_DIRECT;
1775                 return;
1776         }
1777
1778         for_each_cpu_node_but(a, offline_node) {
1779                 for_each_cpu_node_but(b, offline_node) {
1780                         /* Find two nodes furthest removed from each other. */
1781                         if (node_distance(a, b) < n)
1782                                 continue;
1783
1784                         /* Is there an intermediary node between a and b? */
1785                         for_each_cpu_node_but(c, offline_node) {
1786                                 if (node_distance(a, c) < n &&
1787                                     node_distance(b, c) < n) {
1788                                         sched_numa_topology_type =
1789                                                         NUMA_GLUELESS_MESH;
1790                                         return;
1791                                 }
1792                         }
1793
1794                         sched_numa_topology_type = NUMA_BACKPLANE;
1795                         return;
1796                 }
1797         }
1798
1799         pr_err("Failed to find a NUMA topology type, defaulting to DIRECT\n");
1800         sched_numa_topology_type = NUMA_DIRECT;
1801 }
1802
1803
1804 #define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)
1805
1806 void sched_init_numa(int offline_node)
1807 {
1808         struct sched_domain_topology_level *tl;
1809         unsigned long *distance_map;
1810         int nr_levels = 0;
1811         int i, j;
1812         int *distances;
1813         struct cpumask ***masks;
1814
1815         /*
1816          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1817          * unique distances in the node_distance() table.
1818          */
1819         distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL);
1820         if (!distance_map)
1821                 return;
1822
1823         bitmap_zero(distance_map, NR_DISTANCE_VALUES);
1824         for_each_cpu_node_but(i, offline_node) {
1825                 for_each_cpu_node_but(j, offline_node) {
1826                         int distance = node_distance(i, j);
1827
1828                         if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
1829                                 sched_numa_warn("Invalid distance value range");
1830                                 bitmap_free(distance_map);
1831                                 return;
1832                         }
1833
1834                         bitmap_set(distance_map, distance, 1);
1835                 }
1836         }
1837         /*
1838          * We can now figure out how many unique distance values there are and
1839          * allocate memory accordingly.
1840          */
1841         nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES);
1842
1843         distances = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
1844         if (!distances) {
1845                 bitmap_free(distance_map);
1846                 return;
1847         }
1848
1849         for (i = 0, j = 0; i < nr_levels; i++, j++) {
1850                 j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
1851                 distances[i] = j;
1852         }
1853         rcu_assign_pointer(sched_domains_numa_distance, distances);
1854
1855         bitmap_free(distance_map);
1856
1857         /*
1858          * 'nr_levels' contains the number of unique distances
1859          *
1860          * The sched_domains_numa_distance[] array includes the actual distance
1861          * numbers.
1862          */
1863
1864         /*
1865          * Here, we should temporarily reset sched_domains_numa_levels to 0.
1866          * If it fails to allocate memory for array sched_domains_numa_masks[][],
1867          * the array will contain less then 'nr_levels' members. This could be
1868          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1869          * in other functions.
1870          *
1871          * We reset it to 'nr_levels' at the end of this function.
1872          */
1873         sched_domains_numa_levels = 0;
1874
1875         masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
1876         if (!masks)
1877                 return;
1878
1879         /*
1880          * Now for each level, construct a mask per node which contains all
1881          * CPUs of nodes that are that many hops away from us.
1882          */
1883         for (i = 0; i < nr_levels; i++) {
1884                 masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1885                 if (!masks[i])
1886                         return;
1887
1888                 for_each_cpu_node_but(j, offline_node) {
1889                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1890                         int k;
1891
1892                         if (!mask)
1893                                 return;
1894
1895                         masks[i][j] = mask;
1896
1897                         for_each_cpu_node_but(k, offline_node) {
1898                                 if (sched_debug() && (node_distance(j, k) != node_distance(k, j)))
1899                                         sched_numa_warn("Node-distance not symmetric");
1900
1901                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
1902                                         continue;
1903
1904                                 cpumask_or(mask, mask, cpumask_of_node(k));
1905                         }
1906                 }
1907         }
1908         rcu_assign_pointer(sched_domains_numa_masks, masks);
1909
1910         /* Compute default topology size */
1911         for (i = 0; sched_domain_topology[i].mask; i++);
1912
1913         tl = kzalloc((i + nr_levels + 1) *
1914                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1915         if (!tl)
1916                 return;
1917
1918         /*
1919          * Copy the default topology bits..
1920          */
1921         for (i = 0; sched_domain_topology[i].mask; i++)
1922                 tl[i] = sched_domain_topology[i];
1923
1924         /*
1925          * Add the NUMA identity distance, aka single NODE.
1926          */
1927         tl[i++] = (struct sched_domain_topology_level){
1928                 .mask = sd_numa_mask,
1929                 .numa_level = 0,
1930                 SD_INIT_NAME(NODE)
1931         };
1932
1933         /*
1934          * .. and append 'j' levels of NUMA goodness.
1935          */
1936         for (j = 1; j < nr_levels; i++, j++) {
1937                 tl[i] = (struct sched_domain_topology_level){
1938                         .mask = sd_numa_mask,
1939                         .sd_flags = cpu_numa_flags,
1940                         .flags = SDTL_OVERLAP,
1941                         .numa_level = j,
1942                         SD_INIT_NAME(NUMA)
1943                 };
1944         }
1945
1946         sched_domain_topology_saved = sched_domain_topology;
1947         sched_domain_topology = tl;
1948
1949         sched_domains_numa_levels = nr_levels;
1950         WRITE_ONCE(sched_max_numa_distance, sched_domains_numa_distance[nr_levels - 1]);
1951
1952         init_numa_topology_type(offline_node);
1953 }
1954
1955
1956 static void sched_reset_numa(void)
1957 {
1958         int nr_levels, *distances;
1959         struct cpumask ***masks;
1960
1961         nr_levels = sched_domains_numa_levels;
1962         sched_domains_numa_levels = 0;
1963         sched_max_numa_distance = 0;
1964         sched_numa_topology_type = NUMA_DIRECT;
1965         distances = sched_domains_numa_distance;
1966         rcu_assign_pointer(sched_domains_numa_distance, NULL);
1967         masks = sched_domains_numa_masks;
1968         rcu_assign_pointer(sched_domains_numa_masks, NULL);
1969         if (distances || masks) {
1970                 int i, j;
1971
1972                 synchronize_rcu();
1973                 kfree(distances);
1974                 for (i = 0; i < nr_levels && masks; i++) {
1975                         if (!masks[i])
1976                                 continue;
1977                         for_each_node(j)
1978                                 kfree(masks[i][j]);
1979                         kfree(masks[i]);
1980                 }
1981                 kfree(masks);
1982         }
1983         if (sched_domain_topology_saved) {
1984                 kfree(sched_domain_topology);
1985                 sched_domain_topology = sched_domain_topology_saved;
1986                 sched_domain_topology_saved = NULL;
1987         }
1988 }
1989
1990 /*
1991  * Call with hotplug lock held
1992  */
1993 void sched_update_numa(int cpu, bool online)
1994 {
1995         int node;
1996
1997         node = cpu_to_node(cpu);
1998         /*
1999          * Scheduler NUMA topology is updated when the first CPU of a
2000          * node is onlined or the last CPU of a node is offlined.
2001          */
2002         if (cpumask_weight(cpumask_of_node(node)) != 1)
2003                 return;
2004
2005         sched_reset_numa();
2006         sched_init_numa(online ? NUMA_NO_NODE : node);
2007 }
2008
2009 void sched_domains_numa_masks_set(unsigned int cpu)
2010 {
2011         int node = cpu_to_node(cpu);
2012         int i, j;
2013
2014         for (i = 0; i < sched_domains_numa_levels; i++) {
2015                 for (j = 0; j < nr_node_ids; j++) {
2016                         if (!node_state(j, N_CPU))
2017                                 continue;
2018
2019                         /* Set ourselves in the remote node's masks */
2020                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
2021                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
2022                 }
2023         }
2024 }
2025
2026 void sched_domains_numa_masks_clear(unsigned int cpu)
2027 {
2028         int i, j;
2029
2030         for (i = 0; i < sched_domains_numa_levels; i++) {
2031                 for (j = 0; j < nr_node_ids; j++) {
2032                         if (sched_domains_numa_masks[i][j])
2033                                 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
2034                 }
2035         }
2036 }
2037
2038 /*
2039  * sched_numa_find_closest() - given the NUMA topology, find the cpu
2040  *                             closest to @cpu from @cpumask.
2041  * cpumask: cpumask to find a cpu from
2042  * cpu: cpu to be close to
2043  *
2044  * returns: cpu, or nr_cpu_ids when nothing found.
2045  */
2046 int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
2047 {
2048         int i, j = cpu_to_node(cpu), found = nr_cpu_ids;
2049         struct cpumask ***masks;
2050
2051         rcu_read_lock();
2052         masks = rcu_dereference(sched_domains_numa_masks);
2053         if (!masks)
2054                 goto unlock;
2055         for (i = 0; i < sched_domains_numa_levels; i++) {
2056                 if (!masks[i][j])
2057                         break;
2058                 cpu = cpumask_any_and(cpus, masks[i][j]);
2059                 if (cpu < nr_cpu_ids) {
2060                         found = cpu;
2061                         break;
2062                 }
2063         }
2064 unlock:
2065         rcu_read_unlock();
2066
2067         return found;
2068 }
2069
2070 #endif /* CONFIG_NUMA */
2071
2072 static int __sdt_alloc(const struct cpumask *cpu_map)
2073 {
2074         struct sched_domain_topology_level *tl;
2075         int j;
2076
2077         for_each_sd_topology(tl) {
2078                 struct sd_data *sdd = &tl->data;
2079
2080                 sdd->sd = alloc_percpu(struct sched_domain *);
2081                 if (!sdd->sd)
2082                         return -ENOMEM;
2083
2084                 sdd->sds = alloc_percpu(struct sched_domain_shared *);
2085                 if (!sdd->sds)
2086                         return -ENOMEM;
2087
2088                 sdd->sg = alloc_percpu(struct sched_group *);
2089                 if (!sdd->sg)
2090                         return -ENOMEM;
2091
2092                 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
2093                 if (!sdd->sgc)
2094                         return -ENOMEM;
2095
2096                 for_each_cpu(j, cpu_map) {
2097                         struct sched_domain *sd;
2098                         struct sched_domain_shared *sds;
2099                         struct sched_group *sg;
2100                         struct sched_group_capacity *sgc;
2101
2102                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
2103                                         GFP_KERNEL, cpu_to_node(j));
2104                         if (!sd)
2105                                 return -ENOMEM;
2106
2107                         *per_cpu_ptr(sdd->sd, j) = sd;
2108
2109                         sds = kzalloc_node(sizeof(struct sched_domain_shared),
2110                                         GFP_KERNEL, cpu_to_node(j));
2111                         if (!sds)
2112                                 return -ENOMEM;
2113
2114                         *per_cpu_ptr(sdd->sds, j) = sds;
2115
2116                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
2117                                         GFP_KERNEL, cpu_to_node(j));
2118                         if (!sg)
2119                                 return -ENOMEM;
2120
2121                         sg->next = sg;
2122
2123                         *per_cpu_ptr(sdd->sg, j) = sg;
2124
2125                         sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
2126                                         GFP_KERNEL, cpu_to_node(j));
2127                         if (!sgc)
2128                                 return -ENOMEM;
2129
2130 #ifdef CONFIG_SCHED_DEBUG
2131                         sgc->id = j;
2132 #endif
2133
2134                         *per_cpu_ptr(sdd->sgc, j) = sgc;
2135                 }
2136         }
2137
2138         return 0;
2139 }
2140
2141 static void __sdt_free(const struct cpumask *cpu_map)
2142 {
2143         struct sched_domain_topology_level *tl;
2144         int j;
2145
2146         for_each_sd_topology(tl) {
2147                 struct sd_data *sdd = &tl->data;
2148
2149                 for_each_cpu(j, cpu_map) {
2150                         struct sched_domain *sd;
2151
2152                         if (sdd->sd) {
2153                                 sd = *per_cpu_ptr(sdd->sd, j);
2154                                 if (sd && (sd->flags & SD_OVERLAP))
2155                                         free_sched_groups(sd->groups, 0);
2156                                 kfree(*per_cpu_ptr(sdd->sd, j));
2157                         }
2158
2159                         if (sdd->sds)
2160                                 kfree(*per_cpu_ptr(sdd->sds, j));
2161                         if (sdd->sg)
2162                                 kfree(*per_cpu_ptr(sdd->sg, j));
2163                         if (sdd->sgc)
2164                                 kfree(*per_cpu_ptr(sdd->sgc, j));
2165                 }
2166                 free_percpu(sdd->sd);
2167                 sdd->sd = NULL;
2168                 free_percpu(sdd->sds);
2169                 sdd->sds = NULL;
2170                 free_percpu(sdd->sg);
2171                 sdd->sg = NULL;
2172                 free_percpu(sdd->sgc);
2173                 sdd->sgc = NULL;
2174         }
2175 }
2176
2177 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
2178                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
2179                 struct sched_domain *child, int cpu)
2180 {
2181         struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
2182
2183         if (child) {
2184                 sd->level = child->level + 1;
2185                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
2186                 child->parent = sd;
2187
2188                 if (!cpumask_subset(sched_domain_span(child),
2189                                     sched_domain_span(sd))) {
2190                         pr_err("BUG: arch topology borken\n");
2191 #ifdef CONFIG_SCHED_DEBUG
2192                         pr_err("     the %s domain not a subset of the %s domain\n",
2193                                         child->name, sd->name);
2194 #endif
2195                         /* Fixup, ensure @sd has at least @child CPUs. */
2196                         cpumask_or(sched_domain_span(sd),
2197                                    sched_domain_span(sd),
2198                                    sched_domain_span(child));
2199                 }
2200
2201         }
2202         set_domain_attribute(sd, attr);
2203
2204         return sd;
2205 }
2206
2207 /*
2208  * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
2209  * any two given CPUs at this (non-NUMA) topology level.
2210  */
2211 static bool topology_span_sane(struct sched_domain_topology_level *tl,
2212                               const struct cpumask *cpu_map, int cpu)
2213 {
2214         int i;
2215
2216         /* NUMA levels are allowed to overlap */
2217         if (tl->flags & SDTL_OVERLAP)
2218                 return true;
2219
2220         /*
2221          * Non-NUMA levels cannot partially overlap - they must be either
2222          * completely equal or completely disjoint. Otherwise we can end up
2223          * breaking the sched_group lists - i.e. a later get_group() pass
2224          * breaks the linking done for an earlier span.
2225          */
2226         for_each_cpu(i, cpu_map) {
2227                 if (i == cpu)
2228                         continue;
2229                 /*
2230                  * We should 'and' all those masks with 'cpu_map' to exactly
2231                  * match the topology we're about to build, but that can only
2232                  * remove CPUs, which only lessens our ability to detect
2233                  * overlaps
2234                  */
2235                 if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) &&
2236                     cpumask_intersects(tl->mask(cpu), tl->mask(i)))
2237                         return false;
2238         }
2239
2240         return true;
2241 }
2242
2243 /*
2244  * Build sched domains for a given set of CPUs and attach the sched domains
2245  * to the individual CPUs
2246  */
2247 static int
2248 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
2249 {
2250         enum s_alloc alloc_state = sa_none;
2251         struct sched_domain *sd;
2252         struct s_data d;
2253         struct rq *rq = NULL;
2254         int i, ret = -ENOMEM;
2255         bool has_asym = false;
2256
2257         if (WARN_ON(cpumask_empty(cpu_map)))
2258                 goto error;
2259
2260         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
2261         if (alloc_state != sa_rootdomain)
2262                 goto error;
2263
2264         /* Set up domains for CPUs specified by the cpu_map: */
2265         for_each_cpu(i, cpu_map) {
2266                 struct sched_domain_topology_level *tl;
2267
2268                 sd = NULL;
2269                 for_each_sd_topology(tl) {
2270
2271                         if (WARN_ON(!topology_span_sane(tl, cpu_map, i)))
2272                                 goto error;
2273
2274                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
2275
2276                         has_asym |= sd->flags & SD_ASYM_CPUCAPACITY;
2277
2278                         if (tl == sched_domain_topology)
2279                                 *per_cpu_ptr(d.sd, i) = sd;
2280                         if (tl->flags & SDTL_OVERLAP)
2281                                 sd->flags |= SD_OVERLAP;
2282                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
2283                                 break;
2284                 }
2285         }
2286
2287         /* Build the groups for the domains */
2288         for_each_cpu(i, cpu_map) {
2289                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2290                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
2291                         if (sd->flags & SD_OVERLAP) {
2292                                 if (build_overlap_sched_groups(sd, i))
2293                                         goto error;
2294                         } else {
2295                                 if (build_sched_groups(sd, i))
2296                                         goto error;
2297                         }
2298                 }
2299         }
2300
2301         /*
2302          * Calculate an allowed NUMA imbalance such that LLCs do not get
2303          * imbalanced.
2304          */
2305         for_each_cpu(i, cpu_map) {
2306                 unsigned int imb = 0;
2307                 unsigned int imb_span = 1;
2308
2309                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2310                         struct sched_domain *child = sd->child;
2311
2312                         if (!(sd->flags & SD_SHARE_PKG_RESOURCES) && child &&
2313                             (child->flags & SD_SHARE_PKG_RESOURCES)) {
2314                                 struct sched_domain __rcu *top_p;
2315                                 unsigned int nr_llcs;
2316
2317                                 /*
2318                                  * For a single LLC per node, allow an
2319                                  * imbalance up to 25% of the node. This is an
2320                                  * arbitrary cutoff based on SMT-2 to balance
2321                                  * between memory bandwidth and avoiding
2322                                  * premature sharing of HT resources and SMT-4
2323                                  * or SMT-8 *may* benefit from a different
2324                                  * cutoff.
2325                                  *
2326                                  * For multiple LLCs, allow an imbalance
2327                                  * until multiple tasks would share an LLC
2328                                  * on one node while LLCs on another node
2329                                  * remain idle.
2330                                  */
2331                                 nr_llcs = sd->span_weight / child->span_weight;
2332                                 if (nr_llcs == 1)
2333                                         imb = sd->span_weight >> 2;
2334                                 else
2335                                         imb = nr_llcs;
2336                                 sd->imb_numa_nr = imb;
2337
2338                                 /* Set span based on the first NUMA domain. */
2339                                 top_p = sd->parent;
2340                                 while (top_p && !(top_p->flags & SD_NUMA)) {
2341                                         top_p = top_p->parent;
2342                                 }
2343                                 imb_span = top_p ? top_p->span_weight : sd->span_weight;
2344                         } else {
2345                                 int factor = max(1U, (sd->span_weight / imb_span));
2346
2347                                 sd->imb_numa_nr = imb * factor;
2348                         }
2349                 }
2350         }
2351
2352         /* Calculate CPU capacity for physical packages and nodes */
2353         for (i = nr_cpumask_bits-1; i >= 0; i--) {
2354                 if (!cpumask_test_cpu(i, cpu_map))
2355                         continue;
2356
2357                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2358                         claim_allocations(i, sd);
2359                         init_sched_groups_capacity(i, sd);
2360                 }
2361         }
2362
2363         /* Attach the domains */
2364         rcu_read_lock();
2365         for_each_cpu(i, cpu_map) {
2366                 rq = cpu_rq(i);
2367                 sd = *per_cpu_ptr(d.sd, i);
2368
2369                 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
2370                 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
2371                         WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
2372
2373                 cpu_attach_domain(sd, d.rd, i);
2374         }
2375         rcu_read_unlock();
2376
2377         if (has_asym)
2378                 static_branch_inc_cpuslocked(&sched_asym_cpucapacity);
2379
2380         if (rq && sched_debug_verbose) {
2381                 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
2382                         cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
2383         }
2384
2385         ret = 0;
2386 error:
2387         __free_domain_allocs(&d, alloc_state, cpu_map);
2388
2389         return ret;
2390 }
2391
2392 /* Current sched domains: */
2393 static cpumask_var_t                    *doms_cur;
2394
2395 /* Number of sched domains in 'doms_cur': */
2396 static int                              ndoms_cur;
2397
2398 /* Attributes of custom domains in 'doms_cur' */
2399 static struct sched_domain_attr         *dattr_cur;
2400
2401 /*
2402  * Special case: If a kmalloc() of a doms_cur partition (array of
2403  * cpumask) fails, then fallback to a single sched domain,
2404  * as determined by the single cpumask fallback_doms.
2405  */
2406 static cpumask_var_t                    fallback_doms;
2407
2408 /*
2409  * arch_update_cpu_topology lets virtualized architectures update the
2410  * CPU core maps. It is supposed to return 1 if the topology changed
2411  * or 0 if it stayed the same.
2412  */
2413 int __weak arch_update_cpu_topology(void)
2414 {
2415         return 0;
2416 }
2417
2418 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
2419 {
2420         int i;
2421         cpumask_var_t *doms;
2422
2423         doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
2424         if (!doms)
2425                 return NULL;
2426         for (i = 0; i < ndoms; i++) {
2427                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
2428                         free_sched_domains(doms, i);
2429                         return NULL;
2430                 }
2431         }
2432         return doms;
2433 }
2434
2435 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
2436 {
2437         unsigned int i;
2438         for (i = 0; i < ndoms; i++)
2439                 free_cpumask_var(doms[i]);
2440         kfree(doms);
2441 }
2442
2443 /*
2444  * Set up scheduler domains and groups.  For now this just excludes isolated
2445  * CPUs, but could be used to exclude other special cases in the future.
2446  */
2447 int sched_init_domains(const struct cpumask *cpu_map)
2448 {
2449         int err;
2450
2451         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
2452         zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
2453         zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
2454
2455         arch_update_cpu_topology();
2456         asym_cpu_capacity_scan();
2457         ndoms_cur = 1;
2458         doms_cur = alloc_sched_domains(ndoms_cur);
2459         if (!doms_cur)
2460                 doms_cur = &fallback_doms;
2461         cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_TYPE_DOMAIN));
2462         err = build_sched_domains(doms_cur[0], NULL);
2463
2464         return err;
2465 }
2466
2467 /*
2468  * Detach sched domains from a group of CPUs specified in cpu_map
2469  * These CPUs will now be attached to the NULL domain
2470  */
2471 static void detach_destroy_domains(const struct cpumask *cpu_map)
2472 {
2473         unsigned int cpu = cpumask_any(cpu_map);
2474         int i;
2475
2476         if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
2477                 static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
2478
2479         rcu_read_lock();
2480         for_each_cpu(i, cpu_map)
2481                 cpu_attach_domain(NULL, &def_root_domain, i);
2482         rcu_read_unlock();
2483 }
2484
2485 /* handle null as "default" */
2486 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
2487                         struct sched_domain_attr *new, int idx_new)
2488 {
2489         struct sched_domain_attr tmp;
2490
2491         /* Fast path: */
2492         if (!new && !cur)
2493                 return 1;
2494
2495         tmp = SD_ATTR_INIT;
2496
2497         return !memcmp(cur ? (cur + idx_cur) : &tmp,
2498                         new ? (new + idx_new) : &tmp,
2499                         sizeof(struct sched_domain_attr));
2500 }
2501
2502 /*
2503  * Partition sched domains as specified by the 'ndoms_new'
2504  * cpumasks in the array doms_new[] of cpumasks. This compares
2505  * doms_new[] to the current sched domain partitioning, doms_cur[].
2506  * It destroys each deleted domain and builds each new domain.
2507  *
2508  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
2509  * The masks don't intersect (don't overlap.) We should setup one
2510  * sched domain for each mask. CPUs not in any of the cpumasks will
2511  * not be load balanced. If the same cpumask appears both in the
2512  * current 'doms_cur' domains and in the new 'doms_new', we can leave
2513  * it as it is.
2514  *
2515  * The passed in 'doms_new' should be allocated using
2516  * alloc_sched_domains.  This routine takes ownership of it and will
2517  * free_sched_domains it when done with it. If the caller failed the
2518  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
2519  * and partition_sched_domains() will fallback to the single partition
2520  * 'fallback_doms', it also forces the domains to be rebuilt.
2521  *
2522  * If doms_new == NULL it will be replaced with cpu_online_mask.
2523  * ndoms_new == 0 is a special case for destroying existing domains,
2524  * and it will not create the default domain.
2525  *
2526  * Call with hotplug lock and sched_domains_mutex held
2527  */
2528 void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
2529                                     struct sched_domain_attr *dattr_new)
2530 {
2531         bool __maybe_unused has_eas = false;
2532         int i, j, n;
2533         int new_topology;
2534
2535         lockdep_assert_held(&sched_domains_mutex);
2536
2537         /* Let the architecture update CPU core mappings: */
2538         new_topology = arch_update_cpu_topology();
2539         /* Trigger rebuilding CPU capacity asymmetry data */
2540         if (new_topology)
2541                 asym_cpu_capacity_scan();
2542
2543         if (!doms_new) {
2544                 WARN_ON_ONCE(dattr_new);
2545                 n = 0;
2546                 doms_new = alloc_sched_domains(1);
2547                 if (doms_new) {
2548                         n = 1;
2549                         cpumask_and(doms_new[0], cpu_active_mask,
2550                                     housekeeping_cpumask(HK_TYPE_DOMAIN));
2551                 }
2552         } else {
2553                 n = ndoms_new;
2554         }
2555
2556         /* Destroy deleted domains: */
2557         for (i = 0; i < ndoms_cur; i++) {
2558                 for (j = 0; j < n && !new_topology; j++) {
2559                         if (cpumask_equal(doms_cur[i], doms_new[j]) &&
2560                             dattrs_equal(dattr_cur, i, dattr_new, j)) {
2561                                 struct root_domain *rd;
2562
2563                                 /*
2564                                  * This domain won't be destroyed and as such
2565                                  * its dl_bw->total_bw needs to be cleared.  It
2566                                  * will be recomputed in function
2567                                  * update_tasks_root_domain().
2568                                  */
2569                                 rd = cpu_rq(cpumask_any(doms_cur[i]))->rd;
2570                                 dl_clear_root_domain(rd);
2571                                 goto match1;
2572                         }
2573                 }
2574                 /* No match - a current sched domain not in new doms_new[] */
2575                 detach_destroy_domains(doms_cur[i]);
2576 match1:
2577                 ;
2578         }
2579
2580         n = ndoms_cur;
2581         if (!doms_new) {
2582                 n = 0;
2583                 doms_new = &fallback_doms;
2584                 cpumask_and(doms_new[0], cpu_active_mask,
2585                             housekeeping_cpumask(HK_TYPE_DOMAIN));
2586         }
2587
2588         /* Build new domains: */
2589         for (i = 0; i < ndoms_new; i++) {
2590                 for (j = 0; j < n && !new_topology; j++) {
2591                         if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2592                             dattrs_equal(dattr_new, i, dattr_cur, j))
2593                                 goto match2;
2594                 }
2595                 /* No match - add a new doms_new */
2596                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
2597 match2:
2598                 ;
2599         }
2600
2601 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
2602         /* Build perf. domains: */
2603         for (i = 0; i < ndoms_new; i++) {
2604                 for (j = 0; j < n && !sched_energy_update; j++) {
2605                         if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2606                             cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) {
2607                                 has_eas = true;
2608                                 goto match3;
2609                         }
2610                 }
2611                 /* No match - add perf. domains for a new rd */
2612                 has_eas |= build_perf_domains(doms_new[i]);
2613 match3:
2614                 ;
2615         }
2616         sched_energy_set(has_eas);
2617 #endif
2618
2619         /* Remember the new sched domains: */
2620         if (doms_cur != &fallback_doms)
2621                 free_sched_domains(doms_cur, ndoms_cur);
2622
2623         kfree(dattr_cur);
2624         doms_cur = doms_new;
2625         dattr_cur = dattr_new;
2626         ndoms_cur = ndoms_new;
2627
2628         update_sched_domain_debugfs();
2629 }
2630
2631 /*
2632  * Call with hotplug lock held
2633  */
2634 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
2635                              struct sched_domain_attr *dattr_new)
2636 {
2637         mutex_lock(&sched_domains_mutex);
2638         partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
2639         mutex_unlock(&sched_domains_mutex);
2640 }