kernel/sched/topology.c

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