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