kernel/sched/topology.c

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