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