kernel/sched/topology.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Scheduler topology setup/handling methods
   4  */
   5
   6 #include <linux/bsearch.h>
   7
   8 DEFINE_MUTEX(sched_domains_mutex);
   9
  10 /* Protected by sched_domains_mutex: */
  11 static cpumask_var_t sched_domains_tmpmask;
  12 static cpumask_var_t sched_domains_tmpmask2;
  13
  14 #ifdef CONFIG_SCHED_DEBUG
  15
  16 static int __init sched_debug_setup(char *str)
  17 {
  18         sched_debug_verbose = true;
  19
  20         return 0;
  21 }
  22 early_param("sched_verbose", sched_debug_setup);
  23
  24 static inline bool sched_debug(void)
  25 {
  26         return sched_debug_verbose;
  27 }
  28
  29 #define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name },
  30 const struct sd_flag_debug sd_flag_debug[] = {
  31 #include <linux/sched/sd_flags.h>
  32 };
  33 #undef SD_FLAG
  34
  35 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
  36                                   struct cpumask *groupmask)
  37 {
  38         struct sched_group *group = sd->groups;
  39         unsigned long flags = sd->flags;
  40         unsigned int idx;
  41
  42         cpumask_clear(groupmask);
  43
  44         printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
  45         printk(KERN_CONT "span=%*pbl level=%s\n",
  46                cpumask_pr_args(sched_domain_span(sd)), sd->name);
  47
  48         if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
  49                 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
  50         }
  51         if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) {
  52                 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
  53         }
  54
  55         for_each_set_bit(idx, &flags, __SD_FLAG_CNT) {
  56                 unsigned int flag = BIT(idx);
  57                 unsigned int meta_flags = sd_flag_debug[idx].meta_flags;
  58
  59                 if ((meta_flags & SDF_SHARED_CHILD) && sd->child &&
  60                     !(sd->child->flags & flag))
  61                         printk(KERN_ERR "ERROR: flag %s set here but not in child\n",
  62                                sd_flag_debug[idx].name);
  63
  64                 if ((meta_flags & SDF_SHARED_PARENT) && sd->parent &&
  65                     !(sd->parent->flags & flag))
  66                         printk(KERN_ERR "ERROR: flag %s set here but not in parent\n",
  67                                sd_flag_debug[idx].name);
  68         }
  69
  70         printk(KERN_DEBUG "%*s groups:", level + 1, "");
  71         do {
  72                 if (!group) {
  73                         printk("\n");
  74                         printk(KERN_ERR "ERROR: group is NULL\n");
  75                         break;
  76                 }
  77
  78                 if (cpumask_empty(sched_group_span(group))) {
  79                         printk(KERN_CONT "\n");
  80                         printk(KERN_ERR "ERROR: empty group\n");
  81                         break;
  82                 }
  83
  84                 if (!(sd->flags & SD_OVERLAP) &&
  85                     cpumask_intersects(groupmask, sched_group_span(group))) {
  86                         printk(KERN_CONT "\n");
  87                         printk(KERN_ERR "ERROR: repeated CPUs\n");
  88                         break;
  89                 }
  90
  91                 cpumask_or(groupmask, groupmask, sched_group_span(group));
  92
  93                 printk(KERN_CONT " %d:{ span=%*pbl",
  94                                 group->sgc->id,
  95                                 cpumask_pr_args(sched_group_span(group)));
  96
  97                 if ((sd->flags & SD_OVERLAP) &&
  98                     !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
  99                         printk(KERN_CONT " mask=%*pbl",
 100                                 cpumask_pr_args(group_balance_mask(group)));
 101                 }
 102
 103                 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
 104                         printk(KERN_CONT " cap=%lu", group->sgc->capacity);
 105
 106                 if (group == sd->groups && sd->child &&
 107                     !cpumask_equal(sched_domain_span(sd->child),
 108                                    sched_group_span(group))) {
 109                         printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
 110                 }
 111
 112                 printk(KERN_CONT " }");
 113
 114                 group = group->next;
 115
 116                 if (group != sd->groups)
 117                         printk(KERN_CONT ",");
 118
 119         } while (group != sd->groups);
 120         printk(KERN_CONT "\n");
 121
 122         if (!cpumask_equal(sched_domain_span(sd), groupmask))
 123                 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
 124
 125         if (sd->parent &&
 126             !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
 127                 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
 128         return 0;
 129 }
 130
 131 static void sched_domain_debug(struct sched_domain *sd, int cpu)
 132 {
 133         int level = 0;
 134
 135         if (!sched_debug_verbose)
 136                 return;
 137
 138         if (!sd) {
 139                 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
 140                 return;
 141         }
 142
 143         printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
 144
 145         for (;;) {
 146                 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
 147                         break;
 148                 level++;
 149                 sd = sd->parent;
 150                 if (!sd)
 151                         break;
 152         }
 153 }
 154 #else /* !CONFIG_SCHED_DEBUG */
 155
 156 # define sched_debug_verbose 0
 157 # define sched_domain_debug(sd, cpu) do { } while (0)
 158 static inline bool sched_debug(void)
 159 {
 160         return false;
 161 }
 162 #endif /* CONFIG_SCHED_DEBUG */
 163
 164 /* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */
 165 #define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) |
 166 static const unsigned int SD_DEGENERATE_GROUPS_MASK =
 167 #include <linux/sched/sd_flags.h>
 168 0;
 169 #undef SD_FLAG
 170
 171 static int sd_degenerate(struct sched_domain *sd)
 172 {
 173         if (cpumask_weight(sched_domain_span(sd)) == 1)
 174                 return 1;
 175
 176         /* Following flags need at least 2 groups */
 177         if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) &&
 178             (sd->groups != sd->groups->next))
 179                 return 0;
 180
 181         /* Following flags don't use groups */
 182         if (sd->flags & (SD_WAKE_AFFINE))
 183                 return 0;
 184
 185         return 1;
 186 }
 187
 188 static int
 189 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
 190 {
 191         unsigned long cflags = sd->flags, pflags = parent->flags;
 192
 193         if (sd_degenerate(parent))
 194                 return 1;
 195
 196         if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
 197                 return 0;
 198
 199         /* Flags needing groups don't count if only 1 group in parent */
 200         if (parent->groups == parent->groups->next)
 201                 pflags &= ~SD_DEGENERATE_GROUPS_MASK;
 202
 203         if (~cflags & pflags)
 204                 return 0;
 205
 206         return 1;
 207 }
 208
 209 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
 210 DEFINE_STATIC_KEY_FALSE(sched_energy_present);
 211 static unsigned int sysctl_sched_energy_aware = 1;
 212 static DEFINE_MUTEX(sched_energy_mutex);
 213 static bool sched_energy_update;
 214
 215 static bool sched_is_eas_possible(const struct cpumask *cpu_mask)
 216 {
 217         bool any_asym_capacity = false;
 218         struct cpufreq_policy *policy;
 219         struct cpufreq_governor *gov;
 220         int i;
 221
 222         /* EAS is enabled for asymmetric CPU capacity topologies. */
 223         for_each_cpu(i, cpu_mask) {
 224                 if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, i))) {
 225                         any_asym_capacity = true;
 226                         break;
 227                 }
 228         }
 229         if (!any_asym_capacity) {
 230                 if (sched_debug()) {
 231                         pr_info("rd %*pbl: Checking EAS, CPUs do not have asymmetric capacities\n",
 232                                 cpumask_pr_args(cpu_mask));
 233                 }
 234                 return false;
 235         }
 236
 237         /* EAS definitely does *not* handle SMT */
 238         if (sched_smt_active()) {
 239                 if (sched_debug()) {
 240                         pr_info("rd %*pbl: Checking EAS, SMT is not supported\n",
 241                                 cpumask_pr_args(cpu_mask));
 242                 }
 243                 return false;
 244         }
 245
 246         if (!arch_scale_freq_invariant()) {
 247                 if (sched_debug()) {
 248                         pr_info("rd %*pbl: Checking EAS: frequency-invariant load tracking not yet supported",
 249                                 cpumask_pr_args(cpu_mask));
 250                 }
 251                 return false;
 252         }
 253
 254         /* Do not attempt EAS if schedutil is not being used. */
 255         for_each_cpu(i, cpu_mask) {
 256                 policy = cpufreq_cpu_get(i);
 257                 if (!policy) {
 258                         if (sched_debug()) {
 259                                 pr_info("rd %*pbl: Checking EAS, cpufreq policy not set for CPU: %d",
 260                                         cpumask_pr_args(cpu_mask), i);
 261                         }
 262                         return false;
 263                 }
 264                 gov = policy->governor;
 265                 cpufreq_cpu_put(policy);
 266                 if (gov != &schedutil_gov) {
 267                         if (sched_debug()) {
 268                                 pr_info("rd %*pbl: Checking EAS, schedutil is mandatory\n",
 269                                         cpumask_pr_args(cpu_mask));
 270                         }
 271                         return false;
 272                 }
 273         }
 274
 275         return true;
 276 }
 277
 278 void rebuild_sched_domains_energy(void)
 279 {
 280         mutex_lock(&sched_energy_mutex);
 281         sched_energy_update = true;
 282         rebuild_sched_domains();
 283         sched_energy_update = false;
 284         mutex_unlock(&sched_energy_mutex);
 285 }
 286
 287 #ifdef CONFIG_PROC_SYSCTL
 288 static int sched_energy_aware_handler(struct ctl_table *table, int write,
 289                 void *buffer, size_t *lenp, loff_t *ppos)
 290 {
 291         int ret, state;
 292
 293         if (write && !capable(CAP_SYS_ADMIN))
 294                 return -EPERM;
 295
 296         if (!sched_is_eas_possible(cpu_active_mask)) {
 297                 if (write) {
 298                         return -EOPNOTSUPP;
 299                 } else {
 300                         *lenp = 0;
 301                         return 0;
 302                 }
 303         }
 304
 305         ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 306         if (!ret && write) {
 307                 state = static_branch_unlikely(&sched_energy_present);
 308                 if (state != sysctl_sched_energy_aware)
 309                         rebuild_sched_domains_energy();
 310         }
 311
 312         return ret;
 313 }
 314
 315 static struct ctl_table sched_energy_aware_sysctls[] = {
 316         {
 317                 .procname       = "sched_energy_aware",
 318                 .data           = &sysctl_sched_energy_aware,
 319                 .maxlen         = sizeof(unsigned int),
 320                 .mode           = 0644,
 321                 .proc_handler   = sched_energy_aware_handler,
 322                 .extra1         = SYSCTL_ZERO,
 323                 .extra2         = SYSCTL_ONE,
 324         },
 325         {}
 326 };
 327
 328 static int __init sched_energy_aware_sysctl_init(void)
 329 {
 330         register_sysctl_init("kernel", sched_energy_aware_sysctls);
 331         return 0;
 332 }
 333
 334 late_initcall(sched_energy_aware_sysctl_init);
 335 #endif
 336
 337 static void free_pd(struct perf_domain *pd)
 338 {
 339         struct perf_domain *tmp;
 340
 341         while (pd) {
 342                 tmp = pd->next;
 343                 kfree(pd);
 344                 pd = tmp;
 345         }
 346 }
 347
 348 static struct perf_domain *find_pd(struct perf_domain *pd, int cpu)
 349 {
 350         while (pd) {
 351                 if (cpumask_test_cpu(cpu, perf_domain_span(pd)))
 352                         return pd;
 353                 pd = pd->next;
 354         }
 355
 356         return NULL;
 357 }
 358
 359 static struct perf_domain *pd_init(int cpu)
 360 {
 361         struct em_perf_domain *obj = em_cpu_get(cpu);
 362         struct perf_domain *pd;
 363
 364         if (!obj) {
 365                 if (sched_debug())
 366                         pr_info("%s: no EM found for CPU%d\n", __func__, cpu);
 367                 return NULL;
 368         }
 369
 370         pd = kzalloc(sizeof(*pd), GFP_KERNEL);
 371         if (!pd)
 372                 return NULL;
 373         pd->em_pd = obj;
 374
 375         return pd;
 376 }
 377
 378 static void perf_domain_debug(const struct cpumask *cpu_map,
 379                                                 struct perf_domain *pd)
 380 {
 381         if (!sched_debug() || !pd)
 382                 return;
 383
 384         printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map));
 385
 386         while (pd) {
 387                 printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }",
 388                                 cpumask_first(perf_domain_span(pd)),
 389                                 cpumask_pr_args(perf_domain_span(pd)),
 390                                 em_pd_nr_perf_states(pd->em_pd));
 391                 pd = pd->next;
 392         }
 393
 394         printk(KERN_CONT "\n");
 395 }
 396
 397 static void destroy_perf_domain_rcu(struct rcu_head *rp)
 398 {
 399         struct perf_domain *pd;
 400
 401         pd = container_of(rp, struct perf_domain, rcu);
 402         free_pd(pd);
 403 }
 404
 405 static void sched_energy_set(bool has_eas)
 406 {
 407         if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
 408                 if (sched_debug())
 409                         pr_info("%s: stopping EAS\n", __func__);
 410                 static_branch_disable_cpuslocked(&sched_energy_present);
 411         } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
 412                 if (sched_debug())
 413                         pr_info("%s: starting EAS\n", __func__);
 414                 static_branch_enable_cpuslocked(&sched_energy_present);
 415         }
 416 }
 417
 418 /*
 419  * EAS can be used on a root domain if it meets all the following conditions:
 420  *    1. an Energy Model (EM) is available;
 421  *    2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
 422  *    3. no SMT is detected.
 423  *    4. schedutil is driving the frequency of all CPUs of the rd;
 424  *    5. frequency invariance support is present;
 425  */
 426 static bool build_perf_domains(const struct cpumask *cpu_map)
 427 {
 428         int i;
 429         struct perf_domain *pd = NULL, *tmp;
 430         int cpu = cpumask_first(cpu_map);
 431         struct root_domain *rd = cpu_rq(cpu)->rd;
 432
 433         if (!sysctl_sched_energy_aware)
 434                 goto free;
 435
 436         if (!sched_is_eas_possible(cpu_map))
 437                 goto free;
 438
 439         for_each_cpu(i, cpu_map) {
 440                 /* Skip already covered CPUs. */
 441                 if (find_pd(pd, i))
 442                         continue;
 443
 444                 /* Create the new pd and add it to the local list. */
 445                 tmp = pd_init(i);
 446                 if (!tmp)
 447                         goto free;
 448                 tmp->next = pd;
 449                 pd = tmp;
 450         }
 451
 452         perf_domain_debug(cpu_map, pd);
 453
 454         /* Attach the new list of performance domains to the root domain. */
 455         tmp = rd->pd;
 456         rcu_assign_pointer(rd->pd, pd);
 457         if (tmp)
 458                 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 459
 460         return !!pd;
 461
 462 free:
 463         free_pd(pd);
 464         tmp = rd->pd;
 465         rcu_assign_pointer(rd->pd, NULL);
 466         if (tmp)
 467                 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
 468
 469         return false;
 470 }
 471 #else
 472 static void free_pd(struct perf_domain *pd) { }
 473 #endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL*/
 474
 475 static void free_rootdomain(struct rcu_head *rcu)
 476 {
 477         struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
 478
 479         cpupri_cleanup(&rd->cpupri);
 480         cpudl_cleanup(&rd->cpudl);
 481         free_cpumask_var(rd->dlo_mask);
 482         free_cpumask_var(rd->rto_mask);
 483         free_cpumask_var(rd->online);
 484         free_cpumask_var(rd->span);
 485         free_pd(rd->pd);
 486         kfree(rd);
 487 }
 488
 489 void rq_attach_root(struct rq *rq, struct root_domain *rd)
 490 {
 491         struct root_domain *old_rd = NULL;
 492         struct rq_flags rf;
 493
 494         rq_lock_irqsave(rq, &rf);
 495
 496         if (rq->rd) {
 497                 old_rd = rq->rd;
 498
 499                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
 500                         set_rq_offline(rq);
 501
 502                 cpumask_clear_cpu(rq->cpu, old_rd->span);
 503
 504                 /*
 505                  * If we dont want to free the old_rd yet then
 506                  * set old_rd to NULL to skip the freeing later
 507                  * in this function:
 508                  */
 509                 if (!atomic_dec_and_test(&old_rd->refcount))
 510                         old_rd = NULL;
 511         }
 512
 513         atomic_inc(&rd->refcount);
 514         rq->rd = rd;
 515
 516         cpumask_set_cpu(rq->cpu, rd->span);
 517         if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
 518                 set_rq_online(rq);
 519
 520         rq_unlock_irqrestore(rq, &rf);
 521
 522         if (old_rd)
 523                 call_rcu(&old_rd->rcu, free_rootdomain);
 524 }
 525
 526 void sched_get_rd(struct root_domain *rd)
 527 {
 528         atomic_inc(&rd->refcount);
 529 }
 530
 531 void sched_put_rd(struct root_domain *rd)
 532 {
 533         if (!atomic_dec_and_test(&rd->refcount))
 534                 return;
 535
 536         call_rcu(&rd->rcu, free_rootdomain);
 537 }
 538
 539 static int init_rootdomain(struct root_domain *rd)
 540 {
 541         if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
 542                 goto out;
 543         if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
 544                 goto free_span;
 545         if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
 546                 goto free_online;
 547         if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
 548                 goto free_dlo_mask;
 549
 550 #ifdef HAVE_RT_PUSH_IPI
 551         rd->rto_cpu = -1;
 552         raw_spin_lock_init(&rd->rto_lock);
 553         rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func);
 554 #endif
 555
 556         rd->visit_gen = 0;
 557         init_dl_bw(&rd->dl_bw);
 558         if (cpudl_init(&rd->cpudl) != 0)
 559                 goto free_rto_mask;
 560
 561         if (cpupri_init(&rd->cpupri) != 0)
 562                 goto free_cpudl;
 563         return 0;
 564
 565 free_cpudl:
 566         cpudl_cleanup(&rd->cpudl);
 567 free_rto_mask:
 568         free_cpumask_var(rd->rto_mask);
 569 free_dlo_mask:
 570         free_cpumask_var(rd->dlo_mask);
 571 free_online:
 572         free_cpumask_var(rd->online);
 573 free_span:
 574         free_cpumask_var(rd->span);
 575 out:
 576         return -ENOMEM;
 577 }
 578
 579 /*
 580  * By default the system creates a single root-domain with all CPUs as
 581  * members (mimicking the global state we have today).
 582  */
 583 struct root_domain def_root_domain;
 584
 585 void __init init_defrootdomain(void)
 586 {
 587         init_rootdomain(&def_root_domain);
 588
 589         atomic_set(&def_root_domain.refcount, 1);
 590 }
 591
 592 static struct root_domain *alloc_rootdomain(void)
 593 {
 594         struct root_domain *rd;
 595
 596         rd = kzalloc(sizeof(*rd), GFP_KERNEL);
 597         if (!rd)
 598                 return NULL;
 599
 600         if (init_rootdomain(rd) != 0) {
 601                 kfree(rd);
 602                 return NULL;
 603         }
 604
 605         return rd;
 606 }
 607
 608 static void free_sched_groups(struct sched_group *sg, int free_sgc)
 609 {
 610         struct sched_group *tmp, *first;
 611
 612         if (!sg)
 613                 return;
 614
 615         first = sg;
 616         do {
 617                 tmp = sg->next;
 618
 619                 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
 620                         kfree(sg->sgc);
 621
 622                 if (atomic_dec_and_test(&sg->ref))
 623                         kfree(sg);
 624                 sg = tmp;
 625         } while (sg != first);
 626 }
 627
 628 static void destroy_sched_domain(struct sched_domain *sd)
 629 {
 630         /*
 631          * A normal sched domain may have multiple group references, an
 632          * overlapping domain, having private groups, only one.  Iterate,
 633          * dropping group/capacity references, freeing where none remain.
 634          */
 635         free_sched_groups(sd->groups, 1);
 636
 637         if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
 638                 kfree(sd->shared);
 639         kfree(sd);
 640 }
 641
 642 static void destroy_sched_domains_rcu(struct rcu_head *rcu)
 643 {
 644         struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
 645
 646         while (sd) {
 647                 struct sched_domain *parent = sd->parent;
 648                 destroy_sched_domain(sd);
 649                 sd = parent;
 650         }
 651 }
 652
 653 static void destroy_sched_domains(struct sched_domain *sd)
 654 {
 655         if (sd)
 656                 call_rcu(&sd->rcu, destroy_sched_domains_rcu);
 657 }
 658
 659 /*
 660  * Keep a special pointer to the highest sched_domain that has SD_SHARE_LLC set
 661  * (Last Level Cache Domain) for this allows us to avoid some pointer chasing
 662  * select_idle_sibling().
 663  *
 664  * Also keep a unique ID per domain (we use the first CPU number in the cpumask
 665  * of the domain), this allows us to quickly tell if two CPUs are in the same
 666  * cache domain, see cpus_share_cache().
 667  */
 668 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
 669 DEFINE_PER_CPU(int, sd_llc_size);
 670 DEFINE_PER_CPU(int, sd_llc_id);
 671 DEFINE_PER_CPU(int, sd_share_id);
 672 DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
 673 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
 674 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 675 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
 676
 677 DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
 678 DEFINE_STATIC_KEY_FALSE(sched_cluster_active);
 679
 680 static void update_top_cache_domain(int cpu)
 681 {
 682         struct sched_domain_shared *sds = NULL;
 683         struct sched_domain *sd;
 684         int id = cpu;
 685         int size = 1;
 686
 687         sd = highest_flag_domain(cpu, SD_SHARE_LLC);
 688         if (sd) {
 689                 id = cpumask_first(sched_domain_span(sd));
 690                 size = cpumask_weight(sched_domain_span(sd));
 691                 sds = sd->shared;
 692         }
 693
 694         rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
 695         per_cpu(sd_llc_size, cpu) = size;
 696         per_cpu(sd_llc_id, cpu) = id;
 697         rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
 698
 699         sd = lowest_flag_domain(cpu, SD_CLUSTER);
 700         if (sd)
 701                 id = cpumask_first(sched_domain_span(sd));
 702
 703         /*
 704          * This assignment should be placed after the sd_llc_id as
 705          * we want this id equals to cluster id on cluster machines
 706          * but equals to LLC id on non-Cluster machines.
 707          */
 708         per_cpu(sd_share_id, cpu) = id;
 709
 710         sd = lowest_flag_domain(cpu, SD_NUMA);
 711         rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
 712
 713         sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
 714         rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);
 715
 716         sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY_FULL);
 717         rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
 718 }
 719
 720 /*
 721  * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
 722  * hold the hotplug lock.
 723  */
 724 static void
 725 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 726 {
 727         struct rq *rq = cpu_rq(cpu);
 728         struct sched_domain *tmp;
 729
 730         /* Remove the sched domains which do not contribute to scheduling. */
 731         for (tmp = sd; tmp; ) {
 732                 struct sched_domain *parent = tmp->parent;
 733                 if (!parent)
 734                         break;
 735
 736                 if (sd_parent_degenerate(tmp, parent)) {
 737                         tmp->parent = parent->parent;
 738
 739                         if (parent->parent) {
 740                                 parent->parent->child = tmp;
 741                                 parent->parent->groups->flags = tmp->flags;
 742                         }
 743
 744                         /*
 745                          * Transfer SD_PREFER_SIBLING down in case of a
 746                          * degenerate parent; the spans match for this
 747                          * so the property transfers.
 748                          */
 749                         if (parent->flags & SD_PREFER_SIBLING)
 750                                 tmp->flags |= SD_PREFER_SIBLING;
 751                         destroy_sched_domain(parent);
 752                 } else
 753                         tmp = tmp->parent;
 754         }
 755
 756         if (sd && sd_degenerate(sd)) {
 757                 tmp = sd;
 758                 sd = sd->parent;
 759                 destroy_sched_domain(tmp);
 760                 if (sd) {
 761                         struct sched_group *sg = sd->groups;
 762
 763                         /*
 764                          * sched groups hold the flags of the child sched
 765                          * domain for convenience. Clear such flags since
 766                          * the child is being destroyed.
 767                          */
 768                         do {
 769                                 sg->flags = 0;
 770                         } while (sg != sd->groups);
 771
 772                         sd->child = NULL;
 773                 }
 774         }
 775
 776         sched_domain_debug(sd, cpu);
 777
 778         rq_attach_root(rq, rd);
 779         tmp = rq->sd;
 780         rcu_assign_pointer(rq->sd, sd);
 781         dirty_sched_domain_sysctl(cpu);
 782         destroy_sched_domains(tmp);
 783
 784         update_top_cache_domain(cpu);
 785 }
 786
 787 struct s_data {
 788         struct sched_domain * __percpu *sd;
 789         struct root_domain      *rd;
 790 };
 791
 792 enum s_alloc {
 793         sa_rootdomain,
 794         sa_sd,
 795         sa_sd_storage,
 796         sa_none,
 797 };
 798
 799 /*
 800  * Return the canonical balance CPU for this group, this is the first CPU
 801  * of this group that's also in the balance mask.
 802  *
 803  * The balance mask are all those CPUs that could actually end up at this
 804  * group. See build_balance_mask().
 805  *
 806  * Also see should_we_balance().
 807  */
 808 int group_balance_cpu(struct sched_group *sg)
 809 {
 810         return cpumask_first(group_balance_mask(sg));
 811 }
 812
 813
 814 /*
 815  * NUMA topology (first read the regular topology blurb below)
 816  *
 817  * Given a node-distance table, for example:
 818  *
 819  *   node   0   1   2   3
 820  *     0:  10  20  30  20
 821  *     1:  20  10  20  30
 822  *     2:  30  20  10  20
 823  *     3:  20  30  20  10
 824  *
 825  * which represents a 4 node ring topology like:
 826  *
 827  *   0 ----- 1
 828  *   |       |
 829  *   |       |
 830  *   |       |
 831  *   3 ----- 2
 832  *
 833  * We want to construct domains and groups to represent this. The way we go
 834  * about doing this is to build the domains on 'hops'. For each NUMA level we
 835  * construct the mask of all nodes reachable in @level hops.
 836  *
 837  * For the above NUMA topology that gives 3 levels:
 838  *
 839  * NUMA-2       0-3             0-3             0-3             0-3
 840  *  groups:     {0-1,3},{1-3}   {0-2},{0,2-3}   {1-3},{0-1,3}   {0,2-3},{0-2}
 841  *
 842  * NUMA-1       0-1,3           0-2             1-3             0,2-3
 843  *  groups:     {0},{1},{3}     {0},{1},{2}     {1},{2},{3}     {0},{2},{3}
 844  *
 845  * NUMA-0       0               1               2               3
 846  *
 847  *
 848  * As can be seen; things don't nicely line up as with the regular topology.
 849  * When we iterate a domain in child domain chunks some nodes can be
 850  * represented multiple times -- hence the "overlap" naming for this part of
 851  * the topology.
 852  *
 853  * In order to minimize this overlap, we only build enough groups to cover the
 854  * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
 855  *
 856  * Because:
 857  *
 858  *  - the first group of each domain is its child domain; this
 859  *    gets us the first 0-1,3
 860  *  - the only uncovered node is 2, who's child domain is 1-3.
 861  *
 862  * However, because of the overlap, computing a unique CPU for each group is
 863  * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
 864  * groups include the CPUs of Node-0, while those CPUs would not in fact ever
 865  * end up at those groups (they would end up in group: 0-1,3).
 866  *
 867  * To correct this we have to introduce the group balance mask. This mask
 868  * will contain those CPUs in the group that can reach this group given the
 869  * (child) domain tree.
 870  *
 871  * With this we can once again compute balance_cpu and sched_group_capacity
 872  * relations.
 873  *
 874  * XXX include words on how balance_cpu is unique and therefore can be
 875  * used for sched_group_capacity links.
 876  *
 877  *
 878  * Another 'interesting' topology is:
 879  *
 880  *   node   0   1   2   3
 881  *     0:  10  20  20  30
 882  *     1:  20  10  20  20
 883  *     2:  20  20  10  20
 884  *     3:  30  20  20  10
 885  *
 886  * Which looks a little like:
 887  *
 888  *   0 ----- 1
 889  *   |     / |
 890  *   |   /   |
 891  *   | /     |
 892  *   2 ----- 3
 893  *
 894  * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
 895  * are not.
 896  *
 897  * This leads to a few particularly weird cases where the sched_domain's are
 898  * not of the same number for each CPU. Consider:
 899  *
 900  * NUMA-2       0-3                                             0-3
 901  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
 902  *
 903  * NUMA-1       0-2             0-3             0-3             1-3
 904  *
 905  * NUMA-0       0               1               2               3
 906  *
 907  */
 908
 909
 910 /*
 911  * Build the balance mask; it contains only those CPUs that can arrive at this
 912  * group and should be considered to continue balancing.
 913  *
 914  * We do this during the group creation pass, therefore the group information
 915  * isn't complete yet, however since each group represents a (child) domain we
 916  * can fully construct this using the sched_domain bits (which are already
 917  * complete).
 918  */
 919 static void
 920 build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
 921 {
 922         const struct cpumask *sg_span = sched_group_span(sg);
 923         struct sd_data *sdd = sd->private;
 924         struct sched_domain *sibling;
 925         int i;
 926
 927         cpumask_clear(mask);
 928
 929         for_each_cpu(i, sg_span) {
 930                 sibling = *per_cpu_ptr(sdd->sd, i);
 931
 932                 /*
 933                  * Can happen in the asymmetric case, where these siblings are
 934                  * unused. The mask will not be empty because those CPUs that
 935                  * do have the top domain _should_ span the domain.
 936                  */
 937                 if (!sibling->child)
 938                         continue;
 939
 940                 /* If we would not end up here, we can't continue from here */
 941                 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
 942                         continue;
 943
 944                 cpumask_set_cpu(i, mask);
 945         }
 946
 947         /* We must not have empty masks here */
 948         WARN_ON_ONCE(cpumask_empty(mask));
 949 }
 950
 951 /*
 952  * XXX: This creates per-node group entries; since the load-balancer will
 953  * immediately access remote memory to construct this group's load-balance
 954  * statistics having the groups node local is of dubious benefit.
 955  */
 956 static struct sched_group *
 957 build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
 958 {
 959         struct sched_group *sg;
 960         struct cpumask *sg_span;
 961
 962         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
 963                         GFP_KERNEL, cpu_to_node(cpu));
 964
 965         if (!sg)
 966                 return NULL;
 967
 968         sg_span = sched_group_span(sg);
 969         if (sd->child) {
 970                 cpumask_copy(sg_span, sched_domain_span(sd->child));
 971                 sg->flags = sd->child->flags;
 972         } else {
 973                 cpumask_copy(sg_span, sched_domain_span(sd));
 974         }
 975
 976         atomic_inc(&sg->ref);
 977         return sg;
 978 }
 979
 980 static void init_overlap_sched_group(struct sched_domain *sd,
 981                                      struct sched_group *sg)
 982 {
 983         struct cpumask *mask = sched_domains_tmpmask2;
 984         struct sd_data *sdd = sd->private;
 985         struct cpumask *sg_span;
 986         int cpu;
 987
 988         build_balance_mask(sd, sg, mask);
 989         cpu = cpumask_first(mask);
 990
 991         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
 992         if (atomic_inc_return(&sg->sgc->ref) == 1)
 993                 cpumask_copy(group_balance_mask(sg), mask);
 994         else
 995                 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
 996
 997         /*
 998          * Initialize sgc->capacity such that even if we mess up the
 999          * domains and no possible iteration will get us here, we won't
1000          * die on a /0 trap.
1001          */
1002         sg_span = sched_group_span(sg);
1003         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
1004         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
1005         sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
1006 }
1007
1008 static struct sched_domain *
1009 find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling)
1010 {
1011         /*
1012          * The proper descendant would be the one whose child won't span out
1013          * of sd
1014          */
1015         while (sibling->child &&
1016                !cpumask_subset(sched_domain_span(sibling->child),
1017                                sched_domain_span(sd)))
1018                 sibling = sibling->child;
1019
1020         /*
1021          * As we are referencing sgc across different topology level, we need
1022          * to go down to skip those sched_domains which don't contribute to
1023          * scheduling because they will be degenerated in cpu_attach_domain
1024          */
1025         while (sibling->child &&
1026                cpumask_equal(sched_domain_span(sibling->child),
1027                              sched_domain_span(sibling)))
1028                 sibling = sibling->child;
1029
1030         return sibling;
1031 }
1032
1033 static int
1034 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
1035 {
1036         struct sched_group *first = NULL, *last = NULL, *sg;
1037         const struct cpumask *span = sched_domain_span(sd);
1038         struct cpumask *covered = sched_domains_tmpmask;
1039         struct sd_data *sdd = sd->private;
1040         struct sched_domain *sibling;
1041         int i;
1042
1043         cpumask_clear(covered);
1044
1045         for_each_cpu_wrap(i, span, cpu) {
1046                 struct cpumask *sg_span;
1047
1048                 if (cpumask_test_cpu(i, covered))
1049                         continue;
1050
1051                 sibling = *per_cpu_ptr(sdd->sd, i);
1052
1053                 /*
1054                  * Asymmetric node setups can result in situations where the
1055                  * domain tree is of unequal depth, make sure to skip domains
1056                  * that already cover the entire range.
1057                  *
1058                  * In that case build_sched_domains() will have terminated the
1059                  * iteration early and our sibling sd spans will be empty.
1060                  * Domains should always include the CPU they're built on, so
1061                  * check that.
1062                  */
1063                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
1064                         continue;
1065
1066                 /*
1067                  * Usually we build sched_group by sibling's child sched_domain
1068                  * But for machines whose NUMA diameter are 3 or above, we move
1069                  * to build sched_group by sibling's proper descendant's child
1070                  * domain because sibling's child sched_domain will span out of
1071                  * the sched_domain being built as below.
1072                  *
1073                  * Smallest diameter=3 topology is:
1074                  *
1075                  *   node   0   1   2   3
1076                  *     0:  10  20  30  40
1077                  *     1:  20  10  20  30
1078                  *     2:  30  20  10  20
1079                  *     3:  40  30  20  10
1080                  *
1081                  *   0 --- 1 --- 2 --- 3
1082                  *
1083                  * NUMA-3       0-3             N/A             N/A             0-3
1084                  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
1085                  *
1086                  * NUMA-2       0-2             0-3             0-3             1-3
1087                  *  groups:     {0-1},{1-3}     {0-2},{2-3}     {1-3},{0-1}     {2-3},{0-2}
1088                  *
1089                  * NUMA-1       0-1             0-2             1-3             2-3
1090                  *  groups:     {0},{1}         {1},{2},{0}     {2},{3},{1}     {3},{2}
1091                  *
1092                  * NUMA-0       0               1               2               3
1093                  *
1094                  * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the
1095                  * group span isn't a subset of the domain span.
1096                  */
1097                 if (sibling->child &&
1098                     !cpumask_subset(sched_domain_span(sibling->child), span))
1099                         sibling = find_descended_sibling(sd, sibling);
1100
1101                 sg = build_group_from_child_sched_domain(sibling, cpu);
1102                 if (!sg)
1103                         goto fail;
1104
1105                 sg_span = sched_group_span(sg);
1106                 cpumask_or(covered, covered, sg_span);
1107
1108                 init_overlap_sched_group(sibling, sg);
1109
1110                 if (!first)
1111                         first = sg;
1112                 if (last)
1113                         last->next = sg;
1114                 last = sg;
1115                 last->next = first;
1116         }
1117         sd->groups = first;
1118
1119         return 0;
1120
1121 fail:
1122         free_sched_groups(first, 0);
1123
1124         return -ENOMEM;
1125 }
1126
1127
1128 /*
1129  * Package topology (also see the load-balance blurb in fair.c)
1130  *
1131  * The scheduler builds a tree structure to represent a number of important
1132  * topology features. By default (default_topology[]) these include:
1133  *
1134  *  - Simultaneous multithreading (SMT)
1135  *  - Multi-Core Cache (MC)
1136  *  - Package (PKG)
1137  *
1138  * Where the last one more or less denotes everything up to a NUMA node.
1139  *
1140  * The tree consists of 3 primary data structures:
1141  *
1142  *      sched_domain -> sched_group -> sched_group_capacity
1143  *          ^ ^             ^ ^
1144  *          `-'             `-'
1145  *
1146  * The sched_domains are per-CPU and have a two way link (parent & child) and
1147  * denote the ever growing mask of CPUs belonging to that level of topology.
1148  *
1149  * Each sched_domain has a circular (double) linked list of sched_group's, each
1150  * denoting the domains of the level below (or individual CPUs in case of the
1151  * first domain level). The sched_group linked by a sched_domain includes the
1152  * CPU of that sched_domain [*].
1153  *
1154  * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
1155  *
1156  * CPU   0   1   2   3   4   5   6   7
1157  *
1158  * PKG  [                             ]
1159  * MC   [             ] [             ]
1160  * SMT  [     ] [     ] [     ] [     ]
1161  *
1162  *  - or -
1163  *
1164  * PKG  0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
1165  * MC   0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
1166  * SMT  0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
1167  *
1168  * CPU   0   1   2   3   4   5   6   7
1169  *
1170  * One way to think about it is: sched_domain moves you up and down among these
1171  * topology levels, while sched_group moves you sideways through it, at child
1172  * domain granularity.
1173  *
1174  * sched_group_capacity ensures each unique sched_group has shared storage.
1175  *
1176  * There are two related construction problems, both require a CPU that
1177  * uniquely identify each group (for a given domain):
1178  *
1179  *  - The first is the balance_cpu (see should_we_balance() and the
1180  *    load-balance blub in fair.c); for each group we only want 1 CPU to
1181  *    continue balancing at a higher domain.
1182  *
1183  *  - The second is the sched_group_capacity; we want all identical groups
1184  *    to share a single sched_group_capacity.
1185  *
1186  * Since these topologies are exclusive by construction. That is, its
1187  * impossible for an SMT thread to belong to multiple cores, and cores to
1188  * be part of multiple caches. There is a very clear and unique location
1189  * for each CPU in the hierarchy.
1190  *
1191  * Therefore computing a unique CPU for each group is trivial (the iteration
1192  * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
1193  * group), we can simply pick the first CPU in each group.
1194  *
1195  *
1196  * [*] in other words, the first group of each domain is its child domain.
1197  */
1198
1199 static struct sched_group *get_group(int cpu, struct sd_data *sdd)
1200 {
1201         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1202         struct sched_domain *child = sd->child;
1203         struct sched_group *sg;
1204         bool already_visited;
1205
1206         if (child)
1207                 cpu = cpumask_first(sched_domain_span(child));
1208
1209         sg = *per_cpu_ptr(sdd->sg, cpu);
1210         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
1211
1212         /* Increase refcounts for claim_allocations: */
1213         already_visited = atomic_inc_return(&sg->ref) > 1;
1214         /* sgc visits should follow a similar trend as sg */
1215         WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1));
1216
1217         /* If we have already visited that group, it's already initialized. */
1218         if (already_visited)
1219                 return sg;
1220
1221         if (child) {
1222                 cpumask_copy(sched_group_span(sg), sched_domain_span(child));
1223                 cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
1224                 sg->flags = child->flags;
1225         } else {
1226                 cpumask_set_cpu(cpu, sched_group_span(sg));
1227                 cpumask_set_cpu(cpu, group_balance_mask(sg));
1228         }
1229
1230         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
1231         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
1232         sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
1233
1234         return sg;
1235 }
1236
1237 /*
1238  * build_sched_groups will build a circular linked list of the groups
1239  * covered by the given span, will set each group's ->cpumask correctly,
1240  * and will initialize their ->sgc.
1241  *
1242  * Assumes the sched_domain tree is fully constructed
1243  */
1244 static int
1245 build_sched_groups(struct sched_domain *sd, int cpu)
1246 {
1247         struct sched_group *first = NULL, *last = NULL;
1248         struct sd_data *sdd = sd->private;
1249         const struct cpumask *span = sched_domain_span(sd);
1250         struct cpumask *covered;
1251         int i;
1252
1253         lockdep_assert_held(&sched_domains_mutex);
1254         covered = sched_domains_tmpmask;
1255
1256         cpumask_clear(covered);
1257
1258         for_each_cpu_wrap(i, span, cpu) {
1259                 struct sched_group *sg;
1260
1261                 if (cpumask_test_cpu(i, covered))
1262                         continue;
1263
1264                 sg = get_group(i, sdd);
1265
1266                 cpumask_or(covered, covered, sched_group_span(sg));
1267
1268                 if (!first)
1269                         first = sg;
1270                 if (last)
1271                         last->next = sg;
1272                 last = sg;
1273         }
1274         last->next = first;
1275         sd->groups = first;
1276
1277         return 0;
1278 }
1279
1280 /*
1281  * Initialize sched groups cpu_capacity.
1282  *
1283  * cpu_capacity indicates the capacity of sched group, which is used while
1284  * distributing the load between different sched groups in a sched domain.
1285  * Typically cpu_capacity for all the groups in a sched domain will be same
1286  * unless there are asymmetries in the topology. If there are asymmetries,
1287  * group having more cpu_capacity will pickup more load compared to the
1288  * group having less cpu_capacity.
1289  */
1290 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
1291 {
1292         struct sched_group *sg = sd->groups;
1293         struct cpumask *mask = sched_domains_tmpmask2;
1294
1295         WARN_ON(!sg);
1296
1297         do {
1298                 int cpu, cores = 0, max_cpu = -1;
1299
1300                 sg->group_weight = cpumask_weight(sched_group_span(sg));
1301
1302                 cpumask_copy(mask, sched_group_span(sg));
1303                 for_each_cpu(cpu, mask) {
1304                         cores++;
1305 #ifdef CONFIG_SCHED_SMT
1306                         cpumask_andnot(mask, mask, cpu_smt_mask(cpu));
1307 #endif
1308                 }
1309                 sg->cores = cores;
1310
1311                 if (!(sd->flags & SD_ASYM_PACKING))
1312                         goto next;
1313
1314                 for_each_cpu(cpu, sched_group_span(sg)) {
1315                         if (max_cpu < 0)
1316                                 max_cpu = cpu;
1317                         else if (sched_asym_prefer(cpu, max_cpu))
1318                                 max_cpu = cpu;
1319                 }
1320                 sg->asym_prefer_cpu = max_cpu;
1321
1322 next:
1323                 sg = sg->next;
1324         } while (sg != sd->groups);
1325
1326         if (cpu != group_balance_cpu(sg))
1327                 return;
1328
1329         update_group_capacity(sd, cpu);
1330 }
1331
1332 /*
1333  * Asymmetric CPU capacity bits
1334  */
1335 struct asym_cap_data {
1336         struct list_head link;
1337         unsigned long capacity;
1338         unsigned long cpus[];
1339 };
1340
1341 /*
1342  * Set of available CPUs grouped by their corresponding capacities
1343  * Each list entry contains a CPU mask reflecting CPUs that share the same
1344  * capacity.
1345  * The lifespan of data is unlimited.
1346  */
1347 static LIST_HEAD(asym_cap_list);
1348
1349 #define cpu_capacity_span(asym_data) to_cpumask((asym_data)->cpus)
1350
1351 /*
1352  * Verify whether there is any CPU capacity asymmetry in a given sched domain.
1353  * Provides sd_flags reflecting the asymmetry scope.
1354  */
1355 static inline int
1356 asym_cpu_capacity_classify(const struct cpumask *sd_span,
1357                            const struct cpumask *cpu_map)
1358 {
1359         struct asym_cap_data *entry;
1360         int count = 0, miss = 0;
1361
1362         /*
1363          * Count how many unique CPU capacities this domain spans across
1364          * (compare sched_domain CPUs mask with ones representing  available
1365          * CPUs capacities). Take into account CPUs that might be offline:
1366          * skip those.
1367          */
1368         list_for_each_entry(entry, &asym_cap_list, link) {
1369                 if (cpumask_intersects(sd_span, cpu_capacity_span(entry)))
1370                         ++count;
1371                 else if (cpumask_intersects(cpu_map, cpu_capacity_span(entry)))
1372                         ++miss;
1373         }
1374
1375         WARN_ON_ONCE(!count && !list_empty(&asym_cap_list));
1376
1377         /* No asymmetry detected */
1378         if (count < 2)
1379                 return 0;
1380         /* Some of the available CPU capacity values have not been detected */
1381         if (miss)
1382                 return SD_ASYM_CPUCAPACITY;
1383
1384         /* Full asymmetry */
1385         return SD_ASYM_CPUCAPACITY | SD_ASYM_CPUCAPACITY_FULL;
1386
1387 }
1388
1389 static inline void asym_cpu_capacity_update_data(int cpu)
1390 {
1391         unsigned long capacity = arch_scale_cpu_capacity(cpu);
1392         struct asym_cap_data *entry = NULL;
1393
1394         list_for_each_entry(entry, &asym_cap_list, link) {
1395                 if (capacity == entry->capacity)
1396                         goto done;
1397         }
1398
1399         entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL);
1400         if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n"))
1401                 return;
1402         entry->capacity = capacity;
1403         list_add(&entry->link, &asym_cap_list);
1404 done:
1405         __cpumask_set_cpu(cpu, cpu_capacity_span(entry));
1406 }
1407
1408 /*
1409  * Build-up/update list of CPUs grouped by their capacities
1410  * An update requires explicit request to rebuild sched domains
1411  * with state indicating CPU topology changes.
1412  */
1413 static void asym_cpu_capacity_scan(void)
1414 {
1415         struct asym_cap_data *entry, *next;
1416         int cpu;
1417
1418         list_for_each_entry(entry, &asym_cap_list, link)
1419                 cpumask_clear(cpu_capacity_span(entry));
1420
1421         for_each_cpu_and(cpu, cpu_possible_mask, housekeeping_cpumask(HK_TYPE_DOMAIN))
1422                 asym_cpu_capacity_update_data(cpu);
1423
1424         list_for_each_entry_safe(entry, next, &asym_cap_list, link) {
1425                 if (cpumask_empty(cpu_capacity_span(entry))) {
1426                         list_del(&entry->link);
1427                         kfree(entry);
1428                 }
1429         }
1430
1431         /*
1432          * Only one capacity value has been detected i.e. this system is symmetric.
1433          * No need to keep this data around.
1434          */
1435         if (list_is_singular(&asym_cap_list)) {
1436                 entry = list_first_entry(&asym_cap_list, typeof(*entry), link);
1437                 list_del(&entry->link);
1438                 kfree(entry);
1439         }
1440 }
1441
1442 /*
1443  * Initializers for schedule domains
1444  * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
1445  */
1446
1447 static int default_relax_domain_level = -1;
1448 int sched_domain_level_max;
1449
1450 static int __init setup_relax_domain_level(char *str)
1451 {
1452         if (kstrtoint(str, 0, &default_relax_domain_level))
1453                 pr_warn("Unable to set relax_domain_level\n");
1454
1455         return 1;
1456 }
1457 __setup("relax_domain_level=", setup_relax_domain_level);
1458
1459 static void set_domain_attribute(struct sched_domain *sd,
1460                                  struct sched_domain_attr *attr)
1461 {
1462         int request;
1463
1464         if (!attr || attr->relax_domain_level < 0) {
1465                 if (default_relax_domain_level < 0)
1466                         return;
1467                 request = default_relax_domain_level;
1468         } else
1469                 request = attr->relax_domain_level;
1470
1471         if (sd->level > request) {
1472                 /* Turn off idle balance on this domain: */
1473                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
1474         }
1475 }
1476
1477 static void __sdt_free(const struct cpumask *cpu_map);
1478 static int __sdt_alloc(const struct cpumask *cpu_map);
1479
1480 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
1481                                  const struct cpumask *cpu_map)
1482 {
1483         switch (what) {
1484         case sa_rootdomain:
1485                 if (!atomic_read(&d->rd->refcount))
1486                         free_rootdomain(&d->rd->rcu);
1487                 fallthrough;
1488         case sa_sd:
1489                 free_percpu(d->sd);
1490                 fallthrough;
1491         case sa_sd_storage:
1492                 __sdt_free(cpu_map);
1493                 fallthrough;
1494         case sa_none:
1495                 break;
1496         }
1497 }
1498
1499 static enum s_alloc
1500 __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1501 {
1502         memset(d, 0, sizeof(*d));
1503
1504         if (__sdt_alloc(cpu_map))
1505                 return sa_sd_storage;
1506         d->sd = alloc_percpu(struct sched_domain *);
1507         if (!d->sd)
1508                 return sa_sd_storage;
1509         d->rd = alloc_rootdomain();
1510         if (!d->rd)
1511                 return sa_sd;
1512
1513         return sa_rootdomain;
1514 }
1515
1516 /*
1517  * NULL the sd_data elements we've used to build the sched_domain and
1518  * sched_group structure so that the subsequent __free_domain_allocs()
1519  * will not free the data we're using.
1520  */
1521 static void claim_allocations(int cpu, struct sched_domain *sd)
1522 {
1523         struct sd_data *sdd = sd->private;
1524
1525         WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1526         *per_cpu_ptr(sdd->sd, cpu) = NULL;
1527
1528         if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1529                 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1530
1531         if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1532                 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1533
1534         if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1535                 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1536 }
1537
1538 #ifdef CONFIG_NUMA
1539 enum numa_topology_type sched_numa_topology_type;
1540
1541 static int                      sched_domains_numa_levels;
1542 static int                      sched_domains_curr_level;
1543
1544 int                             sched_max_numa_distance;
1545 static int                      *sched_domains_numa_distance;
1546 static struct cpumask           ***sched_domains_numa_masks;
1547 #endif
1548
1549 /*
1550  * SD_flags allowed in topology descriptions.
1551  *
1552  * These flags are purely descriptive of the topology and do not prescribe
1553  * behaviour. Behaviour is artificial and mapped in the below sd_init()
1554  * function. For details, see include/linux/sched/sd_flags.h.
1555  *
1556  *   SD_SHARE_CPUCAPACITY
1557  *   SD_SHARE_LLC
1558  *   SD_CLUSTER
1559  *   SD_NUMA
1560  *
1561  * Odd one out, which beside describing the topology has a quirk also
1562  * prescribes the desired behaviour that goes along with it:
1563  *
1564  *   SD_ASYM_PACKING        - describes SMT quirks
1565  */
1566 #define TOPOLOGY_SD_FLAGS               \
1567         (SD_SHARE_CPUCAPACITY   |       \
1568          SD_CLUSTER             |       \
1569          SD_SHARE_LLC           |       \
1570          SD_NUMA                |       \
1571          SD_ASYM_PACKING)
1572
1573 static struct sched_domain *
1574 sd_init(struct sched_domain_topology_level *tl,
1575         const struct cpumask *cpu_map,
1576         struct sched_domain *child, int cpu)
1577 {
1578         struct sd_data *sdd = &tl->data;
1579         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1580         int sd_id, sd_weight, sd_flags = 0;
1581         struct cpumask *sd_span;
1582
1583 #ifdef CONFIG_NUMA
1584         /*
1585          * Ugly hack to pass state to sd_numa_mask()...
1586          */
1587         sched_domains_curr_level = tl->numa_level;
1588 #endif
1589
1590         sd_weight = cpumask_weight(tl->mask(cpu));
1591
1592         if (tl->sd_flags)
1593                 sd_flags = (*tl->sd_flags)();
1594         if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1595                         "wrong sd_flags in topology description\n"))
1596                 sd_flags &= TOPOLOGY_SD_FLAGS;
1597
1598         *sd = (struct sched_domain){
1599                 .min_interval           = sd_weight,
1600                 .max_interval           = 2*sd_weight,
1601                 .busy_factor            = 16,
1602                 .imbalance_pct          = 117,
1603
1604                 .cache_nice_tries       = 0,
1605
1606                 .flags                  = 1*SD_BALANCE_NEWIDLE
1607                                         | 1*SD_BALANCE_EXEC
1608                                         | 1*SD_BALANCE_FORK
1609                                         | 0*SD_BALANCE_WAKE
1610                                         | 1*SD_WAKE_AFFINE
1611                                         | 0*SD_SHARE_CPUCAPACITY
1612                                         | 0*SD_SHARE_LLC
1613                                         | 0*SD_SERIALIZE
1614                                         | 1*SD_PREFER_SIBLING
1615                                         | 0*SD_NUMA
1616                                         | sd_flags
1617                                         ,
1618
1619                 .last_balance           = jiffies,
1620                 .balance_interval       = sd_weight,
1621                 .max_newidle_lb_cost    = 0,
1622                 .last_decay_max_lb_cost = jiffies,
1623                 .child                  = child,
1624 #ifdef CONFIG_SCHED_DEBUG
1625                 .name                   = tl->name,
1626 #endif
1627         };
1628
1629         sd_span = sched_domain_span(sd);
1630         cpumask_and(sd_span, cpu_map, tl->mask(cpu));
1631         sd_id = cpumask_first(sd_span);
1632
1633         sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map);
1634
1635         WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) ==
1636                   (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY),
1637                   "CPU capacity asymmetry not supported on SMT\n");
1638
1639         /*
1640          * Convert topological properties into behaviour.
1641          */
1642         /* Don't attempt to spread across CPUs of different capacities. */
1643         if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child)
1644                 sd->child->flags &= ~SD_PREFER_SIBLING;
1645
1646         if (sd->flags & SD_SHARE_CPUCAPACITY) {
1647                 sd->imbalance_pct = 110;
1648
1649         } else if (sd->flags & SD_SHARE_LLC) {
1650                 sd->imbalance_pct = 117;
1651                 sd->cache_nice_tries = 1;
1652
1653 #ifdef CONFIG_NUMA
1654         } else if (sd->flags & SD_NUMA) {
1655                 sd->cache_nice_tries = 2;
1656
1657                 sd->flags &= ~SD_PREFER_SIBLING;
1658                 sd->flags |= SD_SERIALIZE;
1659                 if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) {
1660                         sd->flags &= ~(SD_BALANCE_EXEC |
1661                                        SD_BALANCE_FORK |
1662                                        SD_WAKE_AFFINE);
1663                 }
1664
1665 #endif
1666         } else {
1667                 sd->cache_nice_tries = 1;
1668         }
1669
1670         /*
1671          * For all levels sharing cache; connect a sched_domain_shared
1672          * instance.
1673          */
1674         if (sd->flags & SD_SHARE_LLC) {
1675                 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1676                 atomic_inc(&sd->shared->ref);
1677                 atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1678         }
1679
1680         sd->private = sdd;
1681
1682         return sd;
1683 }
1684
1685 /*
1686  * Topology list, bottom-up.
1687  */
1688 static struct sched_domain_topology_level default_topology[] = {
1689 #ifdef CONFIG_SCHED_SMT
1690         { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1691 #endif
1692
1693 #ifdef CONFIG_SCHED_CLUSTER
1694         { cpu_clustergroup_mask, cpu_cluster_flags, SD_INIT_NAME(CLS) },
1695 #endif
1696
1697 #ifdef CONFIG_SCHED_MC
1698         { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1699 #endif
1700         { cpu_cpu_mask, SD_INIT_NAME(PKG) },
1701         { NULL, },
1702 };
1703
1704 static struct sched_domain_topology_level *sched_domain_topology =
1705         default_topology;
1706 static struct sched_domain_topology_level *sched_domain_topology_saved;
1707
1708 #define for_each_sd_topology(tl)                        \
1709         for (tl = sched_domain_topology; tl->mask; tl++)
1710
1711 void __init set_sched_topology(struct sched_domain_topology_level *tl)
1712 {
1713         if (WARN_ON_ONCE(sched_smp_initialized))
1714                 return;
1715
1716         sched_domain_topology = tl;
1717         sched_domain_topology_saved = NULL;
1718 }
1719
1720 #ifdef CONFIG_NUMA
1721
1722 static const struct cpumask *sd_numa_mask(int cpu)
1723 {
1724         return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1725 }
1726
1727 static void sched_numa_warn(const char *str)
1728 {
1729         static int done = false;
1730         int i,j;
1731
1732         if (done)
1733                 return;
1734
1735         done = true;
1736
1737         printk(KERN_WARNING "ERROR: %s\n\n", str);
1738
1739         for (i = 0; i < nr_node_ids; i++) {
1740                 printk(KERN_WARNING "  ");
1741                 for (j = 0; j < nr_node_ids; j++) {
1742                         if (!node_state(i, N_CPU) || !node_state(j, N_CPU))
1743                                 printk(KERN_CONT "(%02d) ", node_distance(i,j));
1744                         else
1745                                 printk(KERN_CONT " %02d  ", node_distance(i,j));
1746                 }
1747                 printk(KERN_CONT "\n");
1748         }
1749         printk(KERN_WARNING "\n");
1750 }
1751
1752 bool find_numa_distance(int distance)
1753 {
1754         bool found = false;
1755         int i, *distances;
1756
1757         if (distance == node_distance(0, 0))
1758                 return true;
1759
1760         rcu_read_lock();
1761         distances = rcu_dereference(sched_domains_numa_distance);
1762         if (!distances)
1763                 goto unlock;
1764         for (i = 0; i < sched_domains_numa_levels; i++) {
1765                 if (distances[i] == distance) {
1766                         found = true;
1767                         break;
1768                 }
1769         }
1770 unlock:
1771         rcu_read_unlock();
1772
1773         return found;
1774 }
1775
1776 #define for_each_cpu_node_but(n, nbut)          \
1777         for_each_node_state(n, N_CPU)           \
1778                 if (n == nbut)                  \
1779                         continue;               \
1780                 else
1781
1782 /*
1783  * A system can have three types of NUMA topology:
1784  * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1785  * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1786  * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1787  *
1788  * The difference between a glueless mesh topology and a backplane
1789  * topology lies in whether communication between not directly
1790  * connected nodes goes through intermediary nodes (where programs
1791  * could run), or through backplane controllers. This affects
1792  * placement of programs.
1793  *
1794  * The type of topology can be discerned with the following tests:
1795  * - If the maximum distance between any nodes is 1 hop, the system
1796  *   is directly connected.
1797  * - If for two nodes A and B, located N > 1 hops away from each other,
1798  *   there is an intermediary node C, which is < N hops away from both
1799  *   nodes A and B, the system is a glueless mesh.
1800  */
1801 static void init_numa_topology_type(int offline_node)
1802 {
1803         int a, b, c, n;
1804
1805         n = sched_max_numa_distance;
1806
1807         if (sched_domains_numa_levels <= 2) {
1808                 sched_numa_topology_type = NUMA_DIRECT;
1809                 return;
1810         }
1811
1812         for_each_cpu_node_but(a, offline_node) {
1813                 for_each_cpu_node_but(b, offline_node) {
1814                         /* Find two nodes furthest removed from each other. */
1815                         if (node_distance(a, b) < n)
1816                                 continue;
1817
1818                         /* Is there an intermediary node between a and b? */
1819                         for_each_cpu_node_but(c, offline_node) {
1820                                 if (node_distance(a, c) < n &&
1821                                     node_distance(b, c) < n) {
1822                                         sched_numa_topology_type =
1823                                                         NUMA_GLUELESS_MESH;
1824                                         return;
1825                                 }
1826                         }
1827
1828                         sched_numa_topology_type = NUMA_BACKPLANE;
1829                         return;
1830                 }
1831         }
1832
1833         pr_err("Failed to find a NUMA topology type, defaulting to DIRECT\n");
1834         sched_numa_topology_type = NUMA_DIRECT;
1835 }
1836
1837
1838 #define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)
1839
1840 void sched_init_numa(int offline_node)
1841 {
1842         struct sched_domain_topology_level *tl;
1843         unsigned long *distance_map;
1844         int nr_levels = 0;
1845         int i, j;
1846         int *distances;
1847         struct cpumask ***masks;
1848
1849         /*
1850          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1851          * unique distances in the node_distance() table.
1852          */
1853         distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL);
1854         if (!distance_map)
1855                 return;
1856
1857         bitmap_zero(distance_map, NR_DISTANCE_VALUES);
1858         for_each_cpu_node_but(i, offline_node) {
1859                 for_each_cpu_node_but(j, offline_node) {
1860                         int distance = node_distance(i, j);
1861
1862                         if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
1863                                 sched_numa_warn("Invalid distance value range");
1864                                 bitmap_free(distance_map);
1865                                 return;
1866                         }
1867
1868                         bitmap_set(distance_map, distance, 1);
1869                 }
1870         }
1871         /*
1872          * We can now figure out how many unique distance values there are and
1873          * allocate memory accordingly.
1874          */
1875         nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES);
1876
1877         distances = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
1878         if (!distances) {
1879                 bitmap_free(distance_map);
1880                 return;
1881         }
1882
1883         for (i = 0, j = 0; i < nr_levels; i++, j++) {
1884                 j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
1885                 distances[i] = j;
1886         }
1887         rcu_assign_pointer(sched_domains_numa_distance, distances);
1888
1889         bitmap_free(distance_map);
1890
1891         /*
1892          * 'nr_levels' contains the number of unique distances
1893          *
1894          * The sched_domains_numa_distance[] array includes the actual distance
1895          * numbers.
1896          */
1897
1898         /*
1899          * Here, we should temporarily reset sched_domains_numa_levels to 0.
1900          * If it fails to allocate memory for array sched_domains_numa_masks[][],
1901          * the array will contain less then 'nr_levels' members. This could be
1902          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1903          * in other functions.
1904          *
1905          * We reset it to 'nr_levels' at the end of this function.
1906          */
1907         sched_domains_numa_levels = 0;
1908
1909         masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
1910         if (!masks)
1911                 return;
1912
1913         /*
1914          * Now for each level, construct a mask per node which contains all
1915          * CPUs of nodes that are that many hops away from us.
1916          */
1917         for (i = 0; i < nr_levels; i++) {
1918                 masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1919                 if (!masks[i])
1920                         return;
1921
1922                 for_each_cpu_node_but(j, offline_node) {
1923                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1924                         int k;
1925
1926                         if (!mask)
1927                                 return;
1928
1929                         masks[i][j] = mask;
1930
1931                         for_each_cpu_node_but(k, offline_node) {
1932                                 if (sched_debug() && (node_distance(j, k) != node_distance(k, j)))
1933                                         sched_numa_warn("Node-distance not symmetric");
1934
1935                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
1936                                         continue;
1937
1938                                 cpumask_or(mask, mask, cpumask_of_node(k));
1939                         }
1940                 }
1941         }
1942         rcu_assign_pointer(sched_domains_numa_masks, masks);
1943
1944         /* Compute default topology size */
1945         for (i = 0; sched_domain_topology[i].mask; i++);
1946
1947         tl = kzalloc((i + nr_levels + 1) *
1948                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1949         if (!tl)
1950                 return;
1951
1952         /*
1953          * Copy the default topology bits..
1954          */
1955         for (i = 0; sched_domain_topology[i].mask; i++)
1956                 tl[i] = sched_domain_topology[i];
1957
1958         /*
1959          * Add the NUMA identity distance, aka single NODE.
1960          */
1961         tl[i++] = (struct sched_domain_topology_level){
1962                 .mask = sd_numa_mask,
1963                 .numa_level = 0,
1964                 SD_INIT_NAME(NODE)
1965         };
1966
1967         /*
1968          * .. and append 'j' levels of NUMA goodness.
1969          */
1970         for (j = 1; j < nr_levels; i++, j++) {
1971                 tl[i] = (struct sched_domain_topology_level){
1972                         .mask = sd_numa_mask,
1973                         .sd_flags = cpu_numa_flags,
1974                         .flags = SDTL_OVERLAP,
1975                         .numa_level = j,
1976                         SD_INIT_NAME(NUMA)
1977                 };
1978         }
1979
1980         sched_domain_topology_saved = sched_domain_topology;
1981         sched_domain_topology = tl;
1982
1983         sched_domains_numa_levels = nr_levels;
1984         WRITE_ONCE(sched_max_numa_distance, sched_domains_numa_distance[nr_levels - 1]);
1985
1986         init_numa_topology_type(offline_node);
1987 }
1988
1989
1990 static void sched_reset_numa(void)
1991 {
1992         int nr_levels, *distances;
1993         struct cpumask ***masks;
1994
1995         nr_levels = sched_domains_numa_levels;
1996         sched_domains_numa_levels = 0;
1997         sched_max_numa_distance = 0;
1998         sched_numa_topology_type = NUMA_DIRECT;
1999         distances = sched_domains_numa_distance;
2000         rcu_assign_pointer(sched_domains_numa_distance, NULL);
2001         masks = sched_domains_numa_masks;
2002         rcu_assign_pointer(sched_domains_numa_masks, NULL);
2003         if (distances || masks) {
2004                 int i, j;
2005
2006                 synchronize_rcu();
2007                 kfree(distances);
2008                 for (i = 0; i < nr_levels && masks; i++) {
2009                         if (!masks[i])
2010                                 continue;
2011                         for_each_node(j)
2012                                 kfree(masks[i][j]);
2013                         kfree(masks[i]);
2014                 }
2015                 kfree(masks);
2016         }
2017         if (sched_domain_topology_saved) {
2018                 kfree(sched_domain_topology);
2019                 sched_domain_topology = sched_domain_topology_saved;
2020                 sched_domain_topology_saved = NULL;
2021         }
2022 }
2023
2024 /*
2025  * Call with hotplug lock held
2026  */
2027 void sched_update_numa(int cpu, bool online)
2028 {
2029         int node;
2030
2031         node = cpu_to_node(cpu);
2032         /*
2033          * Scheduler NUMA topology is updated when the first CPU of a
2034          * node is onlined or the last CPU of a node is offlined.
2035          */
2036         if (cpumask_weight(cpumask_of_node(node)) != 1)
2037                 return;
2038
2039         sched_reset_numa();
2040         sched_init_numa(online ? NUMA_NO_NODE : node);
2041 }
2042
2043 void sched_domains_numa_masks_set(unsigned int cpu)
2044 {
2045         int node = cpu_to_node(cpu);
2046         int i, j;
2047
2048         for (i = 0; i < sched_domains_numa_levels; i++) {
2049                 for (j = 0; j < nr_node_ids; j++) {
2050                         if (!node_state(j, N_CPU))
2051                                 continue;
2052
2053                         /* Set ourselves in the remote node's masks */
2054                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
2055                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
2056                 }
2057         }
2058 }
2059
2060 void sched_domains_numa_masks_clear(unsigned int cpu)
2061 {
2062         int i, j;
2063
2064         for (i = 0; i < sched_domains_numa_levels; i++) {
2065                 for (j = 0; j < nr_node_ids; j++) {
2066                         if (sched_domains_numa_masks[i][j])
2067                                 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
2068                 }
2069         }
2070 }
2071
2072 /*
2073  * sched_numa_find_closest() - given the NUMA topology, find the cpu
2074  *                             closest to @cpu from @cpumask.
2075  * cpumask: cpumask to find a cpu from
2076  * cpu: cpu to be close to
2077  *
2078  * returns: cpu, or nr_cpu_ids when nothing found.
2079  */
2080 int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
2081 {
2082         int i, j = cpu_to_node(cpu), found = nr_cpu_ids;
2083         struct cpumask ***masks;
2084
2085         rcu_read_lock();
2086         masks = rcu_dereference(sched_domains_numa_masks);
2087         if (!masks)
2088                 goto unlock;
2089         for (i = 0; i < sched_domains_numa_levels; i++) {
2090                 if (!masks[i][j])
2091                         break;
2092                 cpu = cpumask_any_and(cpus, masks[i][j]);
2093                 if (cpu < nr_cpu_ids) {
2094                         found = cpu;
2095                         break;
2096                 }
2097         }
2098 unlock:
2099         rcu_read_unlock();
2100
2101         return found;
2102 }
2103
2104 struct __cmp_key {
2105         const struct cpumask *cpus;
2106         struct cpumask ***masks;
2107         int node;
2108         int cpu;
2109         int w;
2110 };
2111
2112 static int hop_cmp(const void *a, const void *b)
2113 {
2114         struct cpumask **prev_hop, **cur_hop = *(struct cpumask ***)b;
2115         struct __cmp_key *k = (struct __cmp_key *)a;
2116
2117         if (cpumask_weight_and(k->cpus, cur_hop[k->node]) <= k->cpu)
2118                 return 1;
2119
2120         if (b == k->masks) {
2121                 k->w = 0;
2122                 return 0;
2123         }
2124
2125         prev_hop = *((struct cpumask ***)b - 1);
2126         k->w = cpumask_weight_and(k->cpus, prev_hop[k->node]);
2127         if (k->w <= k->cpu)
2128                 return 0;
2129
2130         return -1;
2131 }
2132
2133 /**
2134  * sched_numa_find_nth_cpu() - given the NUMA topology, find the Nth closest CPU
2135  *                             from @cpus to @cpu, taking into account distance
2136  *                             from a given @node.
2137  * @cpus: cpumask to find a cpu from
2138  * @cpu: CPU to start searching
2139  * @node: NUMA node to order CPUs by distance
2140  *
2141  * Return: cpu, or nr_cpu_ids when nothing found.
2142  */
2143 int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node)
2144 {
2145         struct __cmp_key k = { .cpus = cpus, .cpu = cpu };
2146         struct cpumask ***hop_masks;
2147         int hop, ret = nr_cpu_ids;
2148
2149         if (node == NUMA_NO_NODE)
2150                 return cpumask_nth_and(cpu, cpus, cpu_online_mask);
2151
2152         rcu_read_lock();
2153
2154         /* CPU-less node entries are uninitialized in sched_domains_numa_masks */
2155         node = numa_nearest_node(node, N_CPU);
2156         k.node = node;
2157
2158         k.masks = rcu_dereference(sched_domains_numa_masks);
2159         if (!k.masks)
2160                 goto unlock;
2161
2162         hop_masks = bsearch(&k, k.masks, sched_domains_numa_levels, sizeof(k.masks[0]), hop_cmp);
2163         hop = hop_masks - k.masks;
2164
2165         ret = hop ?
2166                 cpumask_nth_and_andnot(cpu - k.w, cpus, k.masks[hop][node], k.masks[hop-1][node]) :
2167                 cpumask_nth_and(cpu, cpus, k.masks[0][node]);
2168 unlock:
2169         rcu_read_unlock();
2170         return ret;
2171 }
2172 EXPORT_SYMBOL_GPL(sched_numa_find_nth_cpu);
2173
2174 /**
2175  * sched_numa_hop_mask() - Get the cpumask of CPUs at most @hops hops away from
2176  *                         @node
2177  * @node: The node to count hops from.
2178  * @hops: Include CPUs up to that many hops away. 0 means local node.
2179  *
2180  * Return: On success, a pointer to a cpumask of CPUs at most @hops away from
2181  * @node, an error value otherwise.
2182  *
2183  * Requires rcu_lock to be held. Returned cpumask is only valid within that
2184  * read-side section, copy it if required beyond that.
2185  *
2186  * Note that not all hops are equal in distance; see sched_init_numa() for how
2187  * distances and masks are handled.
2188  * Also note that this is a reflection of sched_domains_numa_masks, which may change
2189  * during the lifetime of the system (offline nodes are taken out of the masks).
2190  */
2191 const struct cpumask *sched_numa_hop_mask(unsigned int node, unsigned int hops)
2192 {
2193         struct cpumask ***masks;
2194
2195         if (node >= nr_node_ids || hops >= sched_domains_numa_levels)
2196                 return ERR_PTR(-EINVAL);
2197
2198         masks = rcu_dereference(sched_domains_numa_masks);
2199         if (!masks)
2200                 return ERR_PTR(-EBUSY);
2201
2202         return masks[hops][node];
2203 }
2204 EXPORT_SYMBOL_GPL(sched_numa_hop_mask);
2205
2206 #endif /* CONFIG_NUMA */
2207
2208 static int __sdt_alloc(const struct cpumask *cpu_map)
2209 {
2210         struct sched_domain_topology_level *tl;
2211         int j;
2212
2213         for_each_sd_topology(tl) {
2214                 struct sd_data *sdd = &tl->data;
2215
2216                 sdd->sd = alloc_percpu(struct sched_domain *);
2217                 if (!sdd->sd)
2218                         return -ENOMEM;
2219
2220                 sdd->sds = alloc_percpu(struct sched_domain_shared *);
2221                 if (!sdd->sds)
2222                         return -ENOMEM;
2223
2224                 sdd->sg = alloc_percpu(struct sched_group *);
2225                 if (!sdd->sg)
2226                         return -ENOMEM;
2227
2228                 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
2229                 if (!sdd->sgc)
2230                         return -ENOMEM;
2231
2232                 for_each_cpu(j, cpu_map) {
2233                         struct sched_domain *sd;
2234                         struct sched_domain_shared *sds;
2235                         struct sched_group *sg;
2236                         struct sched_group_capacity *sgc;
2237
2238                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
2239                                         GFP_KERNEL, cpu_to_node(j));
2240                         if (!sd)
2241                                 return -ENOMEM;
2242
2243                         *per_cpu_ptr(sdd->sd, j) = sd;
2244
2245                         sds = kzalloc_node(sizeof(struct sched_domain_shared),
2246                                         GFP_KERNEL, cpu_to_node(j));
2247                         if (!sds)
2248                                 return -ENOMEM;
2249
2250                         *per_cpu_ptr(sdd->sds, j) = sds;
2251
2252                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
2253                                         GFP_KERNEL, cpu_to_node(j));
2254                         if (!sg)
2255                                 return -ENOMEM;
2256
2257                         sg->next = sg;
2258
2259                         *per_cpu_ptr(sdd->sg, j) = sg;
2260
2261                         sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
2262                                         GFP_KERNEL, cpu_to_node(j));
2263                         if (!sgc)
2264                                 return -ENOMEM;
2265
2266 #ifdef CONFIG_SCHED_DEBUG
2267                         sgc->id = j;
2268 #endif
2269
2270                         *per_cpu_ptr(sdd->sgc, j) = sgc;
2271                 }
2272         }
2273
2274         return 0;
2275 }
2276
2277 static void __sdt_free(const struct cpumask *cpu_map)
2278 {
2279         struct sched_domain_topology_level *tl;
2280         int j;
2281
2282         for_each_sd_topology(tl) {
2283                 struct sd_data *sdd = &tl->data;
2284
2285                 for_each_cpu(j, cpu_map) {
2286                         struct sched_domain *sd;
2287
2288                         if (sdd->sd) {
2289                                 sd = *per_cpu_ptr(sdd->sd, j);
2290                                 if (sd && (sd->flags & SD_OVERLAP))
2291                                         free_sched_groups(sd->groups, 0);
2292                                 kfree(*per_cpu_ptr(sdd->sd, j));
2293                         }
2294
2295                         if (sdd->sds)
2296                                 kfree(*per_cpu_ptr(sdd->sds, j));
2297                         if (sdd->sg)
2298                                 kfree(*per_cpu_ptr(sdd->sg, j));
2299                         if (sdd->sgc)
2300                                 kfree(*per_cpu_ptr(sdd->sgc, j));
2301                 }
2302                 free_percpu(sdd->sd);
2303                 sdd->sd = NULL;
2304                 free_percpu(sdd->sds);
2305                 sdd->sds = NULL;
2306                 free_percpu(sdd->sg);
2307                 sdd->sg = NULL;
2308                 free_percpu(sdd->sgc);
2309                 sdd->sgc = NULL;
2310         }
2311 }
2312
2313 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
2314                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
2315                 struct sched_domain *child, int cpu)
2316 {
2317         struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
2318
2319         if (child) {
2320                 sd->level = child->level + 1;
2321                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
2322                 child->parent = sd;
2323
2324                 if (!cpumask_subset(sched_domain_span(child),
2325                                     sched_domain_span(sd))) {
2326                         pr_err("BUG: arch topology borken\n");
2327 #ifdef CONFIG_SCHED_DEBUG
2328                         pr_err("     the %s domain not a subset of the %s domain\n",
2329                                         child->name, sd->name);
2330 #endif
2331                         /* Fixup, ensure @sd has at least @child CPUs. */
2332                         cpumask_or(sched_domain_span(sd),
2333                                    sched_domain_span(sd),
2334                                    sched_domain_span(child));
2335                 }
2336
2337         }
2338         set_domain_attribute(sd, attr);
2339
2340         return sd;
2341 }
2342
2343 /*
2344  * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
2345  * any two given CPUs at this (non-NUMA) topology level.
2346  */
2347 static bool topology_span_sane(struct sched_domain_topology_level *tl,
2348                               const struct cpumask *cpu_map, int cpu)
2349 {
2350         int i;
2351
2352         /* NUMA levels are allowed to overlap */
2353         if (tl->flags & SDTL_OVERLAP)
2354                 return true;
2355
2356         /*
2357          * Non-NUMA levels cannot partially overlap - they must be either
2358          * completely equal or completely disjoint. Otherwise we can end up
2359          * breaking the sched_group lists - i.e. a later get_group() pass
2360          * breaks the linking done for an earlier span.
2361          */
2362         for_each_cpu(i, cpu_map) {
2363                 if (i == cpu)
2364                         continue;
2365                 /*
2366                  * We should 'and' all those masks with 'cpu_map' to exactly
2367                  * match the topology we're about to build, but that can only
2368                  * remove CPUs, which only lessens our ability to detect
2369                  * overlaps
2370                  */
2371                 if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) &&
2372                     cpumask_intersects(tl->mask(cpu), tl->mask(i)))
2373                         return false;
2374         }
2375
2376         return true;
2377 }
2378
2379 /*
2380  * Build sched domains for a given set of CPUs and attach the sched domains
2381  * to the individual CPUs
2382  */
2383 static int
2384 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
2385 {
2386         enum s_alloc alloc_state = sa_none;
2387         struct sched_domain *sd;
2388         struct s_data d;
2389         struct rq *rq = NULL;
2390         int i, ret = -ENOMEM;
2391         bool has_asym = false;
2392         bool has_cluster = false;
2393
2394         if (WARN_ON(cpumask_empty(cpu_map)))
2395                 goto error;
2396
2397         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
2398         if (alloc_state != sa_rootdomain)
2399                 goto error;
2400
2401         /* Set up domains for CPUs specified by the cpu_map: */
2402         for_each_cpu(i, cpu_map) {
2403                 struct sched_domain_topology_level *tl;
2404
2405                 sd = NULL;
2406                 for_each_sd_topology(tl) {
2407
2408                         if (WARN_ON(!topology_span_sane(tl, cpu_map, i)))
2409                                 goto error;
2410
2411                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
2412
2413                         has_asym |= sd->flags & SD_ASYM_CPUCAPACITY;
2414
2415                         if (tl == sched_domain_topology)
2416                                 *per_cpu_ptr(d.sd, i) = sd;
2417                         if (tl->flags & SDTL_OVERLAP)
2418                                 sd->flags |= SD_OVERLAP;
2419                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
2420                                 break;
2421                 }
2422         }
2423
2424         /* Build the groups for the domains */
2425         for_each_cpu(i, cpu_map) {
2426                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2427                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
2428                         if (sd->flags & SD_OVERLAP) {
2429                                 if (build_overlap_sched_groups(sd, i))
2430                                         goto error;
2431                         } else {
2432                                 if (build_sched_groups(sd, i))
2433                                         goto error;
2434                         }
2435                 }
2436         }
2437
2438         /*
2439          * Calculate an allowed NUMA imbalance such that LLCs do not get
2440          * imbalanced.
2441          */
2442         for_each_cpu(i, cpu_map) {
2443                 unsigned int imb = 0;
2444                 unsigned int imb_span = 1;
2445
2446                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2447                         struct sched_domain *child = sd->child;
2448
2449                         if (!(sd->flags & SD_SHARE_LLC) && child &&
2450                             (child->flags & SD_SHARE_LLC)) {
2451                                 struct sched_domain __rcu *top_p;
2452                                 unsigned int nr_llcs;
2453
2454                                 /*
2455                                  * For a single LLC per node, allow an
2456                                  * imbalance up to 12.5% of the node. This is
2457                                  * arbitrary cutoff based two factors -- SMT and
2458                                  * memory channels. For SMT-2, the intent is to
2459                                  * avoid premature sharing of HT resources but
2460                                  * SMT-4 or SMT-8 *may* benefit from a different
2461                                  * cutoff. For memory channels, this is a very
2462                                  * rough estimate of how many channels may be
2463                                  * active and is based on recent CPUs with
2464                                  * many cores.
2465                                  *
2466                                  * For multiple LLCs, allow an imbalance
2467                                  * until multiple tasks would share an LLC
2468                                  * on one node while LLCs on another node
2469                                  * remain idle. This assumes that there are
2470                                  * enough logical CPUs per LLC to avoid SMT
2471                                  * factors and that there is a correlation
2472                                  * between LLCs and memory channels.
2473                                  */
2474                                 nr_llcs = sd->span_weight / child->span_weight;
2475                                 if (nr_llcs == 1)
2476                                         imb = sd->span_weight >> 3;
2477                                 else
2478                                         imb = nr_llcs;
2479                                 imb = max(1U, imb);
2480                                 sd->imb_numa_nr = imb;
2481
2482                                 /* Set span based on the first NUMA domain. */
2483                                 top_p = sd->parent;
2484                                 while (top_p && !(top_p->flags & SD_NUMA)) {
2485                                         top_p = top_p->parent;
2486                                 }
2487                                 imb_span = top_p ? top_p->span_weight : sd->span_weight;
2488                         } else {
2489                                 int factor = max(1U, (sd->span_weight / imb_span));
2490
2491                                 sd->imb_numa_nr = imb * factor;
2492                         }
2493                 }
2494         }
2495
2496         /* Calculate CPU capacity for physical packages and nodes */
2497         for (i = nr_cpumask_bits-1; i >= 0; i--) {
2498                 if (!cpumask_test_cpu(i, cpu_map))
2499                         continue;
2500
2501                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2502                         claim_allocations(i, sd);
2503                         init_sched_groups_capacity(i, sd);
2504                 }
2505         }
2506
2507         /* Attach the domains */
2508         rcu_read_lock();
2509         for_each_cpu(i, cpu_map) {
2510                 unsigned long capacity;
2511
2512                 rq = cpu_rq(i);
2513                 sd = *per_cpu_ptr(d.sd, i);
2514
2515                 capacity = arch_scale_cpu_capacity(i);
2516                 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
2517                 if (capacity > READ_ONCE(d.rd->max_cpu_capacity))
2518                         WRITE_ONCE(d.rd->max_cpu_capacity, capacity);
2519
2520                 cpu_attach_domain(sd, d.rd, i);
2521
2522                 if (lowest_flag_domain(i, SD_CLUSTER))
2523                         has_cluster = true;
2524         }
2525         rcu_read_unlock();
2526
2527         if (has_asym)
2528                 static_branch_inc_cpuslocked(&sched_asym_cpucapacity);
2529
2530         if (has_cluster)
2531                 static_branch_inc_cpuslocked(&sched_cluster_active);
2532
2533         if (rq && sched_debug_verbose) {
2534                 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
2535                         cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
2536         }
2537
2538         ret = 0;
2539 error:
2540         __free_domain_allocs(&d, alloc_state, cpu_map);
2541
2542         return ret;
2543 }
2544
2545 /* Current sched domains: */
2546 static cpumask_var_t                    *doms_cur;
2547
2548 /* Number of sched domains in 'doms_cur': */
2549 static int                              ndoms_cur;
2550
2551 /* Attributes of custom domains in 'doms_cur' */
2552 static struct sched_domain_attr         *dattr_cur;
2553
2554 /*
2555  * Special case: If a kmalloc() of a doms_cur partition (array of
2556  * cpumask) fails, then fallback to a single sched domain,
2557  * as determined by the single cpumask fallback_doms.
2558  */
2559 static cpumask_var_t                    fallback_doms;
2560
2561 /*
2562  * arch_update_cpu_topology lets virtualized architectures update the
2563  * CPU core maps. It is supposed to return 1 if the topology changed
2564  * or 0 if it stayed the same.
2565  */
2566 int __weak arch_update_cpu_topology(void)
2567 {
2568         return 0;
2569 }
2570
2571 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
2572 {
2573         int i;
2574         cpumask_var_t *doms;
2575
2576         doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
2577         if (!doms)
2578                 return NULL;
2579         for (i = 0; i < ndoms; i++) {
2580                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
2581                         free_sched_domains(doms, i);
2582                         return NULL;
2583                 }
2584         }
2585         return doms;
2586 }
2587
2588 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
2589 {
2590         unsigned int i;
2591         for (i = 0; i < ndoms; i++)
2592                 free_cpumask_var(doms[i]);
2593         kfree(doms);
2594 }
2595
2596 /*
2597  * Set up scheduler domains and groups.  For now this just excludes isolated
2598  * CPUs, but could be used to exclude other special cases in the future.
2599  */
2600 int __init sched_init_domains(const struct cpumask *cpu_map)
2601 {
2602         int err;
2603
2604         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
2605         zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
2606         zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
2607
2608         arch_update_cpu_topology();
2609         asym_cpu_capacity_scan();
2610         ndoms_cur = 1;
2611         doms_cur = alloc_sched_domains(ndoms_cur);
2612         if (!doms_cur)
2613                 doms_cur = &fallback_doms;
2614         cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_TYPE_DOMAIN));
2615         err = build_sched_domains(doms_cur[0], NULL);
2616
2617         return err;
2618 }
2619
2620 /*
2621  * Detach sched domains from a group of CPUs specified in cpu_map
2622  * These CPUs will now be attached to the NULL domain
2623  */
2624 static void detach_destroy_domains(const struct cpumask *cpu_map)
2625 {
2626         unsigned int cpu = cpumask_any(cpu_map);
2627         int i;
2628
2629         if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
2630                 static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
2631
2632         if (static_branch_unlikely(&sched_cluster_active))
2633                 static_branch_dec_cpuslocked(&sched_cluster_active);
2634
2635         rcu_read_lock();
2636         for_each_cpu(i, cpu_map)
2637                 cpu_attach_domain(NULL, &def_root_domain, i);
2638         rcu_read_unlock();
2639 }
2640
2641 /* handle null as "default" */
2642 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
2643                         struct sched_domain_attr *new, int idx_new)
2644 {
2645         struct sched_domain_attr tmp;
2646
2647         /* Fast path: */
2648         if (!new && !cur)
2649                 return 1;
2650
2651         tmp = SD_ATTR_INIT;
2652
2653         return !memcmp(cur ? (cur + idx_cur) : &tmp,
2654                         new ? (new + idx_new) : &tmp,
2655                         sizeof(struct sched_domain_attr));
2656 }
2657
2658 /*
2659  * Partition sched domains as specified by the 'ndoms_new'
2660  * cpumasks in the array doms_new[] of cpumasks. This compares
2661  * doms_new[] to the current sched domain partitioning, doms_cur[].
2662  * It destroys each deleted domain and builds each new domain.
2663  *
2664  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
2665  * The masks don't intersect (don't overlap.) We should setup one
2666  * sched domain for each mask. CPUs not in any of the cpumasks will
2667  * not be load balanced. If the same cpumask appears both in the
2668  * current 'doms_cur' domains and in the new 'doms_new', we can leave
2669  * it as it is.
2670  *
2671  * The passed in 'doms_new' should be allocated using
2672  * alloc_sched_domains.  This routine takes ownership of it and will
2673  * free_sched_domains it when done with it. If the caller failed the
2674  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
2675  * and partition_sched_domains() will fallback to the single partition
2676  * 'fallback_doms', it also forces the domains to be rebuilt.
2677  *
2678  * If doms_new == NULL it will be replaced with cpu_online_mask.
2679  * ndoms_new == 0 is a special case for destroying existing domains,
2680  * and it will not create the default domain.
2681  *
2682  * Call with hotplug lock and sched_domains_mutex held
2683  */
2684 void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
2685                                     struct sched_domain_attr *dattr_new)
2686 {
2687         bool __maybe_unused has_eas = false;
2688         int i, j, n;
2689         int new_topology;
2690
2691         lockdep_assert_held(&sched_domains_mutex);
2692
2693         /* Let the architecture update CPU core mappings: */
2694         new_topology = arch_update_cpu_topology();
2695         /* Trigger rebuilding CPU capacity asymmetry data */
2696         if (new_topology)
2697                 asym_cpu_capacity_scan();
2698
2699         if (!doms_new) {
2700                 WARN_ON_ONCE(dattr_new);
2701                 n = 0;
2702                 doms_new = alloc_sched_domains(1);
2703                 if (doms_new) {
2704                         n = 1;
2705                         cpumask_and(doms_new[0], cpu_active_mask,
2706                                     housekeeping_cpumask(HK_TYPE_DOMAIN));
2707                 }
2708         } else {
2709                 n = ndoms_new;
2710         }
2711
2712         /* Destroy deleted domains: */
2713         for (i = 0; i < ndoms_cur; i++) {
2714                 for (j = 0; j < n && !new_topology; j++) {
2715                         if (cpumask_equal(doms_cur[i], doms_new[j]) &&
2716                             dattrs_equal(dattr_cur, i, dattr_new, j)) {
2717                                 struct root_domain *rd;
2718
2719                                 /*
2720                                  * This domain won't be destroyed and as such
2721                                  * its dl_bw->total_bw needs to be cleared.  It
2722                                  * will be recomputed in function
2723                                  * update_tasks_root_domain().
2724                                  */
2725                                 rd = cpu_rq(cpumask_any(doms_cur[i]))->rd;
2726                                 dl_clear_root_domain(rd);
2727                                 goto match1;
2728                         }
2729                 }
2730                 /* No match - a current sched domain not in new doms_new[] */
2731                 detach_destroy_domains(doms_cur[i]);
2732 match1:
2733                 ;
2734         }
2735
2736         n = ndoms_cur;
2737         if (!doms_new) {
2738                 n = 0;
2739                 doms_new = &fallback_doms;
2740                 cpumask_and(doms_new[0], cpu_active_mask,
2741                             housekeeping_cpumask(HK_TYPE_DOMAIN));
2742         }
2743
2744         /* Build new domains: */
2745         for (i = 0; i < ndoms_new; i++) {
2746                 for (j = 0; j < n && !new_topology; j++) {
2747                         if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2748                             dattrs_equal(dattr_new, i, dattr_cur, j))
2749                                 goto match2;
2750                 }
2751                 /* No match - add a new doms_new */
2752                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
2753 match2:
2754                 ;
2755         }
2756
2757 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
2758         /* Build perf. domains: */
2759         for (i = 0; i < ndoms_new; i++) {
2760                 for (j = 0; j < n && !sched_energy_update; j++) {
2761                         if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2762                             cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) {
2763                                 has_eas = true;
2764                                 goto match3;
2765                         }
2766                 }
2767                 /* No match - add perf. domains for a new rd */
2768                 has_eas |= build_perf_domains(doms_new[i]);
2769 match3:
2770                 ;
2771         }
2772         sched_energy_set(has_eas);
2773 #endif
2774
2775         /* Remember the new sched domains: */
2776         if (doms_cur != &fallback_doms)
2777                 free_sched_domains(doms_cur, ndoms_cur);
2778
2779         kfree(dattr_cur);
2780         doms_cur = doms_new;
2781         dattr_cur = dattr_new;
2782         ndoms_cur = ndoms_new;
2783
2784         update_sched_domain_debugfs();
2785 }
2786
2787 /*
2788  * Call with hotplug lock held
2789  */
2790 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
2791                              struct sched_domain_attr *dattr_new)
2792 {
2793         mutex_lock(&sched_domains_mutex);
2794         partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
2795         mutex_unlock(&sched_domains_mutex);
2796 }