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
1326 #define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)
1327
1328 void sched_init_numa(void)
1329 {
1330         struct sched_domain_topology_level *tl;
1331         unsigned long *distance_map;
1332         int nr_levels = 0;
1333         int i, j;
1334
1335         /*
1336          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1337          * unique distances in the node_distance() table.
1338          */
1339         distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL);
1340         if (!distance_map)
1341                 return;
1342
1343         bitmap_zero(distance_map, NR_DISTANCE_VALUES);
1344         for (i = 0; i < nr_node_ids; i++) {
1345                 for (j = 0; j < nr_node_ids; j++) {
1346                         int distance = node_distance(i, j);
1347
1348                         if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
1349                                 sched_numa_warn("Invalid distance value range");
1350                                 return;
1351                         }
1352
1353                         bitmap_set(distance_map, distance, 1);
1354                 }
1355         }
1356         /*
1357          * We can now figure out how many unique distance values there are and
1358          * allocate memory accordingly.
1359          */
1360         nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES);
1361
1362         sched_domains_numa_distance = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
1363         if (!sched_domains_numa_distance) {
1364                 bitmap_free(distance_map);
1365                 return;
1366         }
1367
1368         for (i = 0, j = 0; i < nr_levels; i++, j++) {
1369                 j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
1370                 sched_domains_numa_distance[i] = j;
1371         }
1372
1373         bitmap_free(distance_map);
1374
1375         /*
1376          * 'nr_levels' contains the number of unique distances
1377          *
1378          * The sched_domains_numa_distance[] array includes the actual distance
1379          * numbers.
1380          */
1381
1382         /*
1383          * Here, we should temporarily reset sched_domains_numa_levels to 0.
1384          * If it fails to allocate memory for array sched_domains_numa_masks[][],
1385          * the array will contain less then 'nr_levels' members. This could be
1386          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1387          * in other functions.
1388          *
1389          * We reset it to 'nr_levels' at the end of this function.
1390          */
1391         sched_domains_numa_levels = 0;
1392
1393         sched_domains_numa_masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
1394         if (!sched_domains_numa_masks)
1395                 return;
1396
1397         /*
1398          * Now for each level, construct a mask per node which contains all
1399          * CPUs of nodes that are that many hops away from us.
1400          */
1401         for (i = 0; i < nr_levels; i++) {
1402                 sched_domains_numa_masks[i] =
1403                         kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1404                 if (!sched_domains_numa_masks[i])
1405                         return;
1406
1407                 for (j = 0; j < nr_node_ids; j++) {
1408                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1409                         int k;
1410
1411                         if (!mask)
1412                                 return;
1413
1414                         sched_domains_numa_masks[i][j] = mask;
1415
1416                         for_each_node(k) {
1417                                 if (sched_debug() && (node_distance(j, k) != node_distance(k, j)))
1418                                         sched_numa_warn("Node-distance not symmetric");
1419
1420                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
1421                                         continue;
1422
1423                                 cpumask_or(mask, mask, cpumask_of_node(k));
1424                         }
1425                 }
1426         }
1427
1428         /* Compute default topology size */
1429         for (i = 0; sched_domain_topology[i].mask; i++);
1430
1431         tl = kzalloc((i + nr_levels + 1) *
1432                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1433         if (!tl)
1434                 return;
1435
1436         /*
1437          * Copy the default topology bits..
1438          */
1439         for (i = 0; sched_domain_topology[i].mask; i++)
1440                 tl[i] = sched_domain_topology[i];
1441
1442         /*
1443          * Add the NUMA identity distance, aka single NODE.
1444          */
1445         tl[i++] = (struct sched_domain_topology_level){
1446                 .mask = sd_numa_mask,
1447                 .numa_level = 0,
1448                 SD_INIT_NAME(NODE)
1449         };
1450
1451         /*
1452          * .. and append 'j' levels of NUMA goodness.
1453          */
1454         for (j = 1; j < nr_levels; i++, j++) {
1455                 tl[i] = (struct sched_domain_topology_level){
1456                         .mask = sd_numa_mask,
1457                         .sd_flags = cpu_numa_flags,
1458                         .flags = SDTL_OVERLAP,
1459                         .numa_level = j,
1460                         SD_INIT_NAME(NUMA)
1461                 };
1462         }
1463
1464         sched_domain_topology = tl;
1465
1466         sched_domains_numa_levels = nr_levels;
1467         sched_max_numa_distance = sched_domains_numa_distance[nr_levels - 1];
1468
1469         init_numa_topology_type();
1470 }
1471
1472 void sched_domains_numa_masks_set(unsigned int cpu)
1473 {
1474         int node = cpu_to_node(cpu);
1475         int i, j;
1476
1477         for (i = 0; i < sched_domains_numa_levels; i++) {
1478                 for (j = 0; j < nr_node_ids; j++) {
1479                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
1480                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
1481                 }
1482         }
1483 }
1484
1485 void sched_domains_numa_masks_clear(unsigned int cpu)
1486 {
1487         int i, j;
1488
1489         for (i = 0; i < sched_domains_numa_levels; i++) {
1490                 for (j = 0; j < nr_node_ids; j++)
1491                         cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
1492         }
1493 }
1494
1495 #endif /* CONFIG_NUMA */
1496
1497 static int __sdt_alloc(const struct cpumask *cpu_map)
1498 {
1499         struct sched_domain_topology_level *tl;
1500         int j;
1501
1502         for_each_sd_topology(tl) {
1503                 struct sd_data *sdd = &tl->data;
1504
1505                 sdd->sd = alloc_percpu(struct sched_domain *);
1506                 if (!sdd->sd)
1507                         return -ENOMEM;
1508
1509                 sdd->sds = alloc_percpu(struct sched_domain_shared *);
1510                 if (!sdd->sds)
1511                         return -ENOMEM;
1512
1513                 sdd->sg = alloc_percpu(struct sched_group *);
1514                 if (!sdd->sg)
1515                         return -ENOMEM;
1516
1517                 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
1518                 if (!sdd->sgc)
1519                         return -ENOMEM;
1520
1521                 for_each_cpu(j, cpu_map) {
1522                         struct sched_domain *sd;
1523                         struct sched_domain_shared *sds;
1524                         struct sched_group *sg;
1525                         struct sched_group_capacity *sgc;
1526
1527                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
1528                                         GFP_KERNEL, cpu_to_node(j));
1529                         if (!sd)
1530                                 return -ENOMEM;
1531
1532                         *per_cpu_ptr(sdd->sd, j) = sd;
1533
1534                         sds = kzalloc_node(sizeof(struct sched_domain_shared),
1535                                         GFP_KERNEL, cpu_to_node(j));
1536                         if (!sds)
1537                                 return -ENOMEM;
1538
1539                         *per_cpu_ptr(sdd->sds, j) = sds;
1540
1541                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
1542                                         GFP_KERNEL, cpu_to_node(j));
1543                         if (!sg)
1544                                 return -ENOMEM;
1545
1546                         sg->next = sg;
1547
1548                         *per_cpu_ptr(sdd->sg, j) = sg;
1549
1550                         sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
1551                                         GFP_KERNEL, cpu_to_node(j));
1552                         if (!sgc)
1553                                 return -ENOMEM;
1554
1555 #ifdef CONFIG_SCHED_DEBUG
1556                         sgc->id = j;
1557 #endif
1558
1559                         *per_cpu_ptr(sdd->sgc, j) = sgc;
1560                 }
1561         }
1562
1563         return 0;
1564 }
1565
1566 static void __sdt_free(const struct cpumask *cpu_map)
1567 {
1568         struct sched_domain_topology_level *tl;
1569         int j;
1570
1571         for_each_sd_topology(tl) {
1572                 struct sd_data *sdd = &tl->data;
1573
1574                 for_each_cpu(j, cpu_map) {
1575                         struct sched_domain *sd;
1576
1577                         if (sdd->sd) {
1578                                 sd = *per_cpu_ptr(sdd->sd, j);
1579                                 if (sd && (sd->flags & SD_OVERLAP))
1580                                         free_sched_groups(sd->groups, 0);
1581                                 kfree(*per_cpu_ptr(sdd->sd, j));
1582                         }
1583
1584                         if (sdd->sds)
1585                                 kfree(*per_cpu_ptr(sdd->sds, j));
1586                         if (sdd->sg)
1587                                 kfree(*per_cpu_ptr(sdd->sg, j));
1588                         if (sdd->sgc)
1589                                 kfree(*per_cpu_ptr(sdd->sgc, j));
1590                 }
1591                 free_percpu(sdd->sd);
1592                 sdd->sd = NULL;
1593                 free_percpu(sdd->sds);
1594                 sdd->sds = NULL;
1595                 free_percpu(sdd->sg);
1596                 sdd->sg = NULL;
1597                 free_percpu(sdd->sgc);
1598                 sdd->sgc = NULL;
1599         }
1600 }
1601
1602 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
1603                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
1604                 struct sched_domain *child, int cpu)
1605 {
1606         struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
1607
1608         if (child) {
1609                 sd->level = child->level + 1;
1610                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
1611                 child->parent = sd;
1612
1613                 if (!cpumask_subset(sched_domain_span(child),
1614                                     sched_domain_span(sd))) {
1615                         pr_err("BUG: arch topology borken\n");
1616 #ifdef CONFIG_SCHED_DEBUG
1617                         pr_err("     the %s domain not a subset of the %s domain\n",
1618                                         child->name, sd->name);
1619 #endif
1620                         /* Fixup, ensure @sd has at least @child CPUs. */
1621                         cpumask_or(sched_domain_span(sd),
1622                                    sched_domain_span(sd),
1623                                    sched_domain_span(child));
1624                 }
1625
1626         }
1627         set_domain_attribute(sd, attr);
1628
1629         return sd;
1630 }
1631
1632 /*
1633  * Build sched domains for a given set of CPUs and attach the sched domains
1634  * to the individual CPUs
1635  */
1636 static int
1637 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
1638 {
1639         enum s_alloc alloc_state;
1640         struct sched_domain *sd;
1641         struct s_data d;
1642         struct rq *rq = NULL;
1643         int i, ret = -ENOMEM;
1644
1645         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
1646         if (alloc_state != sa_rootdomain)
1647                 goto error;
1648
1649         /* Set up domains for CPUs specified by the cpu_map: */
1650         for_each_cpu(i, cpu_map) {
1651                 struct sched_domain_topology_level *tl;
1652
1653                 sd = NULL;
1654                 for_each_sd_topology(tl) {
1655                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
1656                         if (tl == sched_domain_topology)
1657                                 *per_cpu_ptr(d.sd, i) = sd;
1658                         if (tl->flags & SDTL_OVERLAP)
1659                                 sd->flags |= SD_OVERLAP;
1660                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
1661                                 break;
1662                 }
1663         }
1664
1665         /* Build the groups for the domains */
1666         for_each_cpu(i, cpu_map) {
1667                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
1668                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
1669                         if (sd->flags & SD_OVERLAP) {
1670                                 if (build_overlap_sched_groups(sd, i))
1671                                         goto error;
1672                         } else {
1673                                 if (build_sched_groups(sd, i))
1674                                         goto error;
1675                         }
1676                 }
1677         }
1678
1679         /* Calculate CPU capacity for physical packages and nodes */
1680         for (i = nr_cpumask_bits-1; i >= 0; i--) {
1681                 if (!cpumask_test_cpu(i, cpu_map))
1682                         continue;
1683
1684                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
1685                         claim_allocations(i, sd);
1686                         init_sched_groups_capacity(i, sd);
1687                 }
1688         }
1689
1690         /* Attach the domains */
1691         rcu_read_lock();
1692         for_each_cpu(i, cpu_map) {
1693                 rq = cpu_rq(i);
1694                 sd = *per_cpu_ptr(d.sd, i);
1695
1696                 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
1697                 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
1698                         WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
1699
1700                 cpu_attach_domain(sd, d.rd, i);
1701         }
1702         rcu_read_unlock();
1703
1704         if (rq && sched_debug_enabled) {
1705                 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
1706                         cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
1707         }
1708
1709         ret = 0;
1710 error:
1711         __free_domain_allocs(&d, alloc_state, cpu_map);
1712
1713         return ret;
1714 }
1715
1716 /* Current sched domains: */
1717 static cpumask_var_t                    *doms_cur;
1718
1719 /* Number of sched domains in 'doms_cur': */
1720 static int                              ndoms_cur;
1721
1722 /* Attribues of custom domains in 'doms_cur' */
1723 static struct sched_domain_attr         *dattr_cur;
1724
1725 /*
1726  * Special case: If a kmalloc() of a doms_cur partition (array of
1727  * cpumask) fails, then fallback to a single sched domain,
1728  * as determined by the single cpumask fallback_doms.
1729  */
1730 static cpumask_var_t                    fallback_doms;
1731
1732 /*
1733  * arch_update_cpu_topology lets virtualized architectures update the
1734  * CPU core maps. It is supposed to return 1 if the topology changed
1735  * or 0 if it stayed the same.
1736  */
1737 int __weak arch_update_cpu_topology(void)
1738 {
1739         return 0;
1740 }
1741
1742 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
1743 {
1744         int i;
1745         cpumask_var_t *doms;
1746
1747         doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
1748         if (!doms)
1749                 return NULL;
1750         for (i = 0; i < ndoms; i++) {
1751                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
1752                         free_sched_domains(doms, i);
1753                         return NULL;
1754                 }
1755         }
1756         return doms;
1757 }
1758
1759 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
1760 {
1761         unsigned int i;
1762         for (i = 0; i < ndoms; i++)
1763                 free_cpumask_var(doms[i]);
1764         kfree(doms);
1765 }
1766
1767 /*
1768  * Set up scheduler domains and groups. Callers must hold the hotplug lock.
1769  * For now this just excludes isolated CPUs, but could be used to
1770  * exclude other special cases in the future.
1771  */
1772 int sched_init_domains(const struct cpumask *cpu_map)
1773 {
1774         int err;
1775
1776         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
1777         zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
1778         zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
1779
1780         arch_update_cpu_topology();
1781         ndoms_cur = 1;
1782         doms_cur = alloc_sched_domains(ndoms_cur);
1783         if (!doms_cur)
1784                 doms_cur = &fallback_doms;
1785         cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
1786         err = build_sched_domains(doms_cur[0], NULL);
1787         register_sched_domain_sysctl();
1788
1789         return err;
1790 }
1791
1792 /*
1793  * Detach sched domains from a group of CPUs specified in cpu_map
1794  * These CPUs will now be attached to the NULL domain
1795  */
1796 static void detach_destroy_domains(const struct cpumask *cpu_map)
1797 {
1798         int i;
1799
1800         rcu_read_lock();
1801         for_each_cpu(i, cpu_map)
1802                 cpu_attach_domain(NULL, &def_root_domain, i);
1803         rcu_read_unlock();
1804 }
1805
1806 /* handle null as "default" */
1807 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
1808                         struct sched_domain_attr *new, int idx_new)
1809 {
1810         struct sched_domain_attr tmp;
1811
1812         /* Fast path: */
1813         if (!new && !cur)
1814                 return 1;
1815
1816         tmp = SD_ATTR_INIT;
1817
1818         return !memcmp(cur ? (cur + idx_cur) : &tmp,
1819                         new ? (new + idx_new) : &tmp,
1820                         sizeof(struct sched_domain_attr));
1821 }
1822
1823 /*
1824  * Partition sched domains as specified by the 'ndoms_new'
1825  * cpumasks in the array doms_new[] of cpumasks. This compares
1826  * doms_new[] to the current sched domain partitioning, doms_cur[].
1827  * It destroys each deleted domain and builds each new domain.
1828  *
1829  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
1830  * The masks don't intersect (don't overlap.) We should setup one
1831  * sched domain for each mask. CPUs not in any of the cpumasks will
1832  * not be load balanced. If the same cpumask appears both in the
1833  * current 'doms_cur' domains and in the new 'doms_new', we can leave
1834  * it as it is.
1835  *
1836  * The passed in 'doms_new' should be allocated using
1837  * alloc_sched_domains.  This routine takes ownership of it and will
1838  * free_sched_domains it when done with it. If the caller failed the
1839  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
1840  * and partition_sched_domains() will fallback to the single partition
1841  * 'fallback_doms', it also forces the domains to be rebuilt.
1842  *
1843  * If doms_new == NULL it will be replaced with cpu_online_mask.
1844  * ndoms_new == 0 is a special case for destroying existing domains,
1845  * and it will not create the default domain.
1846  *
1847  * Call with hotplug lock held
1848  */
1849 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
1850                              struct sched_domain_attr *dattr_new)
1851 {
1852         int i, j, n;
1853         int new_topology;
1854
1855         mutex_lock(&sched_domains_mutex);
1856
1857         /* Always unregister in case we don't destroy any domains: */
1858         unregister_sched_domain_sysctl();
1859
1860         /* Let the architecture update CPU core mappings: */
1861         new_topology = arch_update_cpu_topology();
1862
1863         if (!doms_new) {
1864                 WARN_ON_ONCE(dattr_new);
1865                 n = 0;
1866                 doms_new = alloc_sched_domains(1);
1867                 if (doms_new) {
1868                         n = 1;
1869                         cpumask_and(doms_new[0], cpu_active_mask,
1870                                     housekeeping_cpumask(HK_FLAG_DOMAIN));
1871                 }
1872         } else {
1873                 n = ndoms_new;
1874         }
1875
1876         /* Destroy deleted domains: */
1877         for (i = 0; i < ndoms_cur; i++) {
1878                 for (j = 0; j < n && !new_topology; j++) {
1879                         if (cpumask_equal(doms_cur[i], doms_new[j])
1880                             && dattrs_equal(dattr_cur, i, dattr_new, j))
1881                                 goto match1;
1882                 }
1883                 /* No match - a current sched domain not in new doms_new[] */
1884                 detach_destroy_domains(doms_cur[i]);
1885 match1:
1886                 ;
1887         }
1888
1889         n = ndoms_cur;
1890         if (!doms_new) {
1891                 n = 0;
1892                 doms_new = &fallback_doms;
1893                 cpumask_and(doms_new[0], cpu_active_mask,
1894                             housekeeping_cpumask(HK_FLAG_DOMAIN));
1895         }
1896
1897         /* Build new domains: */
1898         for (i = 0; i < ndoms_new; i++) {
1899                 for (j = 0; j < n && !new_topology; j++) {
1900                         if (cpumask_equal(doms_new[i], doms_cur[j])
1901                             && dattrs_equal(dattr_new, i, dattr_cur, j))
1902                                 goto match2;
1903                 }
1904                 /* No match - add a new doms_new */
1905                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
1906 match2:
1907                 ;
1908         }
1909
1910         /* Remember the new sched domains: */
1911         if (doms_cur != &fallback_doms)
1912                 free_sched_domains(doms_cur, ndoms_cur);
1913
1914         kfree(dattr_cur);
1915         doms_cur = doms_new;
1916         dattr_cur = dattr_new;
1917         ndoms_cur = ndoms_new;
1918
1919         register_sched_domain_sysctl();
1920
1921         mutex_unlock(&sched_domains_mutex);
1922 }