kernel/sched/topology.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Scheduler topology setup/handling methods
 */
#include "sched.h"

DEFINE_MUTEX(sched_domains_mutex);
#ifdef CONFIG_LOCKDEP
EXPORT_SYMBOL_GPL(sched_domains_mutex);
#endif

/* Protected by sched_domains_mutex: */
static cpumask_var_t sched_domains_tmpmask;
static cpumask_var_t sched_domains_tmpmask2;

#define IMBALANCE_SD_SHARE_CPUCAPACITY 110
#define IMBALANCE_SD_SHARE_PKG 117
#define IMBALANCE_SD_NUMA 2
#define IMBALANCE_SD_NUMA_DIRECT 2

#ifdef CONFIG_SCHED_DEBUG

static int __init sched_debug_setup(char *str)
{
    sched_debug_enabled = true;

    return 0;
}
early_param("sched_debug", sched_debug_setup);

static inline bool sched_debug(void)
{
    return sched_debug_enabled;
}

#define SD_FLAG(_name, mflags) [__##_name] = {.meta_flags = mflags, .name = #_name},
const struct sd_flag_debug sd_flag_debug[] = {
#include <linux/sched/sd_flags.h>
};
#undef SD_FLAG

static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, struct cpumask *groupmask)
{
    struct sched_group *group = sd->groups;
    unsigned long flags = sd->flags;
    unsigned int idx;

    cpumask_clear(groupmask);

    printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
    printk(KERN_CONT "span=%*pbl level=%s\n", cpumask_pr_args(sched_domain_span(sd)), sd->name);

    if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
        printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
    }
    if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) {
        printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
    }

    for_each_set_bit(idx, &flags, __SD_FLAG_CNT)
    {
        unsigned int flag = BIT(idx);
        unsigned int meta_flags = sd_flag_debug[idx].meta_flags;

        if ((meta_flags & SDF_SHARED_CHILD) && sd->child && !(sd->child->flags & flag)) {
            printk(KERN_ERR "ERROR: flag %s set here but not in child\n", sd_flag_debug[idx].name);
        }

        if ((meta_flags & SDF_SHARED_PARENT) && sd->parent && !(sd->parent->flags & flag)) {
            printk(KERN_ERR "ERROR: flag %s set here but not in parent\n", sd_flag_debug[idx].name);
        }
    }

    printk(KERN_DEBUG "%*s groups:", level + 1, "");
    do {
        if (!group) {
            printk("\n");
            printk(KERN_ERR "ERROR: group is NULL\n");
            break;
        }

        if (!cpumask_weight(sched_group_span(group))) {
            printk(KERN_CONT "\n");
            printk(KERN_ERR "ERROR: empty group\n");
            break;
        }

        if (!(sd->flags & SD_OVERLAP) && cpumask_intersects(groupmask, sched_group_span(group))) {
            printk(KERN_CONT "\n");
            printk(KERN_ERR "ERROR: repeated CPUs\n");
            break;
        }

        cpumask_or(groupmask, groupmask, sched_group_span(group));

        printk(KERN_CONT " %d:{ span=%*pbl", group->sgc->id, cpumask_pr_args(sched_group_span(group)));

        if ((sd->flags & SD_OVERLAP) && !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
            printk(KERN_CONT " mask=%*pbl", cpumask_pr_args(group_balance_mask(group)));
        }

        if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
            printk(KERN_CONT " cap=%lu", group->sgc->capacity);
        }

        if (group == sd->groups && sd->child && !cpumask_equal(sched_domain_span(sd->child), sched_group_span(group))) {
            printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
        }

        printk(KERN_CONT " }");

        group = group->next;

        if (group != sd->groups) {
            printk(KERN_CONT ",");
        }
    } while (group != sd->groups);
    printk(KERN_CONT "\n");

    if (!cpumask_equal(sched_domain_span(sd), groupmask)) {
        printk(KERN_ERR "ERROR: groups don't span domain->span\n");
    }

    if (sd->parent && !cpumask_subset(groupmask, sched_domain_span(sd->parent))) {
        printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
    }
    return 0;
}

static void sched_domain_debug(struct sched_domain *sd, int cpu)
{
    int level = 0;

    if (!sched_debug_enabled) {
        return;
    }

    if (!sd) {
        printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
        return;
    }

    printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);

    for (;;) {
        if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) {
            break;
        }
        level++;
        sd = sd->parent;
        if (!sd) {
            break;
        }
    }
}
#else /* !CONFIG_SCHED_DEBUG */

#define sched_debug_enabled 0
#define sched_domain_debug(sd, cpu)                                                                                    \
    do {                                                                                                               \
    } while (0)
static inline bool sched_debug(void)
{
    return false;
}
#endif /* CONFIG_SCHED_DEBUG */

/* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */
#define SD_FLAG(name, mflags) ((name) * !!((mflags)&SDF_NEEDS_GROUPS)) |
static const unsigned int SD_DEGENERATE_GROUPS_MASK =
#include <linux/sched/sd_flags.h>
    0;
#undef SD_FLAG

static int sd_degenerate(struct sched_domain *sd)
{
    if (cpumask_weight(sched_domain_span(sd)) == 1) {
        return 1;
    }

    /* Following flags need at least 2 groups */
    if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) && (sd->groups != sd->groups->next)) {
        return 0;
    }

    /* Following flags don't use groups */
    if (sd->flags & (SD_WAKE_AFFINE)) {
        return 0;
    }

    return 1;
}

static int sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
{
    unsigned long cflags = sd->flags, pflags = parent->flags;

    if (sd_degenerate(parent)) {
        return 1;
    }

    if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) {
        return 0;
    }

    /* Flags needing groups don't count if only 1 group in parent */
    if (parent->groups == parent->groups->next) {
        pflags &= ~SD_DEGENERATE_GROUPS_MASK;
    }

    if (~cflags & pflags) {
        return 0;
    }

    return 1;
}

#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
DEFINE_STATIC_KEY_FALSE(sched_energy_present);
unsigned int sysctl_sched_energy_aware = 1;
DEFINE_MUTEX(sched_energy_mutex);
bool sched_energy_update;

#ifdef CONFIG_PROC_SYSCTL
int sched_energy_aware_handler(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos)
{
    int ret, state;

    if (write && !capable(CAP_SYS_ADMIN)) {
        return -EPERM;
    }

    ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
    if (!ret && write) {
        state = static_branch_unlikely(&sched_energy_present);
        if (state != sysctl_sched_energy_aware) {
            mutex_lock(&sched_energy_mutex);
            sched_energy_update = 1;
            rebuild_sched_domains();
            sched_energy_update = 0;
            mutex_unlock(&sched_energy_mutex);
        }
    }

    return ret;
}
#endif

static void free_pd(struct perf_domain *pd)
{
    struct perf_domain *tmp;

    while (pd) {
        tmp = pd->next;
        kfree(pd);
        pd = tmp;
    }
}

static struct perf_domain *find_pd(struct perf_domain *pd, int cpu)
{
    while (pd) {
        if (cpumask_test_cpu(cpu, perf_domain_span(pd))) {
            return pd;
        }
        pd = pd->next;
    }

    return NULL;
}

static struct perf_domain *pd_init(int cpu)
{
    struct em_perf_domain *obj = em_cpu_get(cpu);
    struct perf_domain *pd;

    if (!obj) {
        if (sched_debug()) {
            pr_info("%s: no EM found for CPU%d\n", __func__, cpu);
        }
        return NULL;
    }

    pd = kzalloc(sizeof(*pd), GFP_KERNEL);
    if (!pd) {
        return NULL;
    }
    pd->em_pd = obj;

    return pd;
}

static void perf_domain_debug(const struct cpumask *cpu_map, struct perf_domain *pd)
{
    if (!sched_debug() || !pd) {
        return;
    }

    printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map));

    while (pd) {
        printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }", cpumask_first(perf_domain_span(pd)),
               cpumask_pr_args(perf_domain_span(pd)), em_pd_nr_perf_states(pd->em_pd));
        pd = pd->next;
    }

    printk(KERN_CONT "\n");
}

static void destroy_perf_domain_rcu(struct rcu_head *rp)
{
    struct perf_domain *pd;

    pd = container_of(rp, struct perf_domain, rcu);
    free_pd(pd);
}

static void sched_energy_set(bool has_eas)
{
    if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
        if (sched_debug()) {
            pr_info("%s: stopping EAS\n", __func__);
        }
        static_branch_disable_cpuslocked(&sched_energy_present);
    } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
        if (sched_debug()) {
            pr_info("%s: starting EAS\n", __func__);
        }
        static_branch_enable_cpuslocked(&sched_energy_present);
    }
}

/*
 * EAS can be used on a root domain if it meets all the following conditions:
 *    1. an Energy Model (EM) is available;
 *    2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
 *    3. no SMT is detected.
 *    4. the EM complexity is low enough to keep scheduling overheads low;
 *    5. schedutil is driving the frequency of all CPUs of the rd;
 *
 * The complexity of the Energy Model is defined as:
 *
 *              C = nr_pd * (nr_cpus + nr_ps)
 *
 * with parameters defined as:
 *  - nr_pd:    the number of performance domains
 *  - nr_cpus:  the number of CPUs
 *  - nr_ps:    the sum of the number of performance states of all performance
 *              domains (for example, on a system with 2 performance domains,
 *              with 10 performance states each, nr_ps = 2 * 10 = 20).
 *
 * It is generally not a good idea to use such a model in the wake-up path on
 * very complex platforms because of the associated scheduling overheads. The
 * arbitrary constraint below prevents that. It makes EAS usable up to 16 CPUs
 * with per-CPU DVFS and less than 8 performance states each, for example.
 */
#define EM_MAX_COMPLEXITY 2048

static bool build_perf_domains(const struct cpumask *cpu_map)
{
    int i, nr_pd = 0, nr_ps = 0, nr_cpus = cpumask_weight(cpu_map);
    struct perf_domain *pd = NULL, *tmp;
    int cpu = cpumask_first(cpu_map);
    struct root_domain *rd = cpu_rq(cpu)->rd;
    struct cpufreq_policy *policy;
    struct cpufreq_governor *gov;

    if (!sysctl_sched_energy_aware) {
        goto free;
    }

    /* EAS is enabled for asymmetric CPU capacity topologies. */
    if (!per_cpu(sd_asym_cpucapacity, cpu)) {
        if (sched_debug()) {
            pr_info("rd %*pbl: CPUs do not have asymmetric capacities\n", cpumask_pr_args(cpu_map));
        }
        goto free;
    }

    /* EAS definitely does *not* handle SMT */
    if (sched_smt_active()) {
        pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n", cpumask_pr_args(cpu_map));
        goto free;
    }

    for_each_cpu(i, cpu_map)
    {
        /* Skip already covered CPUs. */
        if (find_pd(pd, i)) {
            continue;
        }

        /* Do not attempt EAS if schedutil is not being used. */
        policy = cpufreq_cpu_get(i);
        if (!policy) {
            goto free;
        }
        gov = policy->governor;
        cpufreq_cpu_put(policy);
        if (gov != &schedutil_gov) {
            if (rd->pd) {
                pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n", cpumask_pr_args(cpu_map));
            }
            goto free;
        }

        /* Create the new pd and add it to the local list. */
        tmp = pd_init(i);
        if (!tmp) {
            goto free;
        }
        tmp->next = pd;
        pd = tmp;

        /*
         * Count performance domains and performance states for the
         * complexity check.
         */
        nr_pd++;
        nr_ps += em_pd_nr_perf_states(pd->em_pd);
    }

    /* Bail out if the Energy Model complexity is too high. */
    if (nr_pd * (nr_ps + nr_cpus) > EM_MAX_COMPLEXITY) {
        WARN(1, "rd %*pbl: Failed to start EAS, EM complexity is too high\n", cpumask_pr_args(cpu_map));
        goto free;
    }

    perf_domain_debug(cpu_map, pd);

    /* Attach the new list of performance domains to the root domain. */
    tmp = rd->pd;
    rcu_assign_pointer(rd->pd, pd);
    if (tmp) {
        call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
    }

    return !!pd;

free:
    free_pd(pd);
    tmp = rd->pd;
    rcu_assign_pointer(rd->pd, NULL);
    if (tmp) {
        call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
    }

    return false;
}
#else
static void free_pd(struct perf_domain *pd)
{
}
#endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL */

static void free_rootdomain(struct rcu_head *rcu)
{
    struct root_domain *rd = container_of(rcu, struct root_domain, rcu);

    cpupri_cleanup(&rd->cpupri);
    cpudl_cleanup(&rd->cpudl);
    free_cpumask_var(rd->dlo_mask);
    free_cpumask_var(rd->rto_mask);
    free_cpumask_var(rd->online);
    free_cpumask_var(rd->span);
    free_pd(rd->pd);
    kfree(rd);
}

void rq_attach_root(struct rq *rq, struct root_domain *rd)
{
    struct root_domain *old_rd = NULL;
    unsigned long flags;

    raw_spin_lock_irqsave(&rq->lock, flags);

    if (rq->rd) {
        old_rd = rq->rd;

        if (cpumask_test_cpu(rq->cpu, old_rd->online)) {
            set_rq_offline(rq);
        }

        cpumask_clear_cpu(rq->cpu, old_rd->span);

        /*
         * If we dont want to free the old_rd yet then
         * set old_rd to NULL to skip the freeing later
         * in this function:
         */
        if (!atomic_dec_and_test(&old_rd->refcount)) {
            old_rd = NULL;
        }
    }

    atomic_inc(&rd->refcount);
    rq->rd = rd;

    cpumask_set_cpu(rq->cpu, rd->span);
    if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) {
        set_rq_online(rq);
    }

    raw_spin_unlock_irqrestore(&rq->lock, flags);

    if (old_rd) {
        call_rcu(&old_rd->rcu, free_rootdomain);
    }
}

void sched_get_rd(struct root_domain *rd)
{
    atomic_inc(&rd->refcount);
}

void sched_put_rd(struct root_domain *rd)
{
    if (!atomic_dec_and_test(&rd->refcount)) {
        return;
    }

    call_rcu(&rd->rcu, free_rootdomain);
}

static int init_rootdomain(struct root_domain *rd)
{
    if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL)) {
        goto out;
    }
    if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL)) {
        goto free_span;
    }
    if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL)) {
        goto free_online;
    }
    if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) {
        goto free_dlo_mask;
    }

#ifdef HAVE_RT_PUSH_IPI
    rd->rto_cpu = -1;
    raw_spin_lock_init(&rd->rto_lock);
    init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
#endif

    init_dl_bw(&rd->dl_bw);
    if (cpudl_init(&rd->cpudl) != 0) {
        goto free_rto_mask;
    }

    if (cpupri_init(&rd->cpupri) != 0) {
        goto free_cpudl;
    }

#ifdef CONFIG_SCHED_RT_CAS
    rd->max_cap_orig_cpu = -1;
#endif
    return 0;

free_cpudl:
    cpudl_cleanup(&rd->cpudl);
free_rto_mask:
    free_cpumask_var(rd->rto_mask);
free_dlo_mask:
    free_cpumask_var(rd->dlo_mask);
free_online:
    free_cpumask_var(rd->online);
free_span:
    free_cpumask_var(rd->span);
out:
    return -ENOMEM;
}

/*
 * By default the system creates a single root-domain with all CPUs as
 * members (mimicking the global state we have today).
 */
struct root_domain def_root_domain;

void init_defrootdomain(void)
{
    init_rootdomain(&def_root_domain);

    atomic_set(&def_root_domain.refcount, 1);
}

static struct root_domain *alloc_rootdomain(void)
{
    struct root_domain *rd;

    rd = kzalloc(sizeof(*rd), GFP_KERNEL);
    if (!rd) {
        return NULL;
    }

    if (init_rootdomain(rd) != 0) {
        kfree(rd);
        return NULL;
    }

    return rd;
}

static void free_sched_groups(struct sched_group *sg, int free_sgc)
{
    struct sched_group *tmp, *first;

    if (!sg) {
        return;
    }

    first = sg;
    do {
        tmp = sg->next;

        if (free_sgc && atomic_dec_and_test(&sg->sgc->ref)) {
            kfree(sg->sgc);
        }

        if (atomic_dec_and_test(&sg->ref)) {
            kfree(sg);
        }
        sg = tmp;
    } while (sg != first);
}

static void destroy_sched_domain(struct sched_domain *sd)
{
    /*
     * A normal sched domain may have multiple group references, an
     * overlapping domain, having private groups, only one.  Iterate,
     * dropping group/capacity references, freeing where none remain.
     */
    free_sched_groups(sd->groups, 1);

    if (sd->shared && atomic_dec_and_test(&sd->shared->ref)) {
        kfree(sd->shared);
    }
    kfree(sd);
}

static void destroy_sched_domains_rcu(struct rcu_head *rcu)
{
    struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);

    while (sd) {
        struct sched_domain *parent = sd->parent;
        destroy_sched_domain(sd);
        sd = parent;
    }
}

static void destroy_sched_domains(struct sched_domain *sd)
{
    if (sd) {
        call_rcu(&sd->rcu, destroy_sched_domains_rcu);
    }
}

/*
 * Keep a special pointer to the highest sched_domain that has
 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
 * allows us to avoid some pointer chasing select_idle_sibling().
 *
 * Also keep a unique ID per domain (we use the first CPU number in
 * the cpumask of the domain), this allows us to quickly tell if
 * two CPUs are in the same cache domain, see cpus_share_cache().
 */
DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
DEFINE_PER_CPU(int, sd_llc_size);
DEFINE_PER_CPU(int, sd_llc_id);
DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);

static void update_top_cache_domain(int cpu)
{
    struct sched_domain_shared *sds = NULL;
    struct sched_domain *sd;
    int id = cpu;
    int size = 1;

    sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
    if (sd) {
        id = cpumask_first(sched_domain_span(sd));
        size = cpumask_weight(sched_domain_span(sd));
        sds = sd->shared;
    }

    rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
    per_cpu(sd_llc_size, cpu) = size;
    per_cpu(sd_llc_id, cpu) = id;
    rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);

    sd = lowest_flag_domain(cpu, SD_NUMA);
    rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);

    sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
    rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);

    sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY);
    rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
}

/*
 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
 * hold the hotplug lock.
 */
static void cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
{
    struct rq *rq = cpu_rq(cpu);
    struct sched_domain *tmp;
    int numa_distance = 0;

    /* Remove the sched domains which do not contribute to scheduling. */
    for (tmp = sd; tmp;) {
        struct sched_domain *parent = tmp->parent;
        if (!parent) {
            break;
        }

        if (sd_parent_degenerate(tmp, parent)) {
            tmp->parent = parent->parent;
            if (parent->parent) {
                parent->parent->child = tmp;
            }
            /*
             * Transfer SD_PREFER_SIBLING down in case of a
             * degenerate parent; the spans match for this
             * so the property transfers.
             */
            if (parent->flags & SD_PREFER_SIBLING) {
                tmp->flags |= SD_PREFER_SIBLING;
            }
            destroy_sched_domain(parent);
        } else {
            tmp = tmp->parent;
        }
    }

    if (sd && sd_degenerate(sd)) {
        tmp = sd;
        sd = sd->parent;
        destroy_sched_domain(tmp);
        if (sd) {
            sd->child = NULL;
        }
    }

    for (tmp = sd; tmp; tmp = tmp->parent) {
        numa_distance += !!(tmp->flags & SD_NUMA);
    }

    sched_domain_debug(sd, cpu);

    rq_attach_root(rq, rd);
    tmp = rq->sd;
    rcu_assign_pointer(rq->sd, sd);
    dirty_sched_domain_sysctl(cpu);
    destroy_sched_domains(tmp);

    update_top_cache_domain(cpu);
}

struct s_data {
    struct sched_domain *__percpu *sd;
    struct root_domain *rd;
};

enum s_alloc {
    sa_rootdomain,
    sa_sd,
    sa_sd_storage,
    sa_none,
};

/*
 * Return the canonical balance CPU for this group, this is the first CPU
 * of this group that's also in the balance mask.
 *
 * The balance mask are all those CPUs that could actually end up at this
 * group. See build_balance_mask().
 *
 * Also see should_we_balance().
 */
int group_balance_cpu(struct sched_group *sg)
{
    return cpumask_first(group_balance_mask(sg));
}

/*
 * NUMA topology (first read the regular topology blurb below)
 *
 * Given a node-distance table, for example:
 *
 *   node   0   1   2   3
 *     0:  10  20  30  20
 *     1:  20  10  20  30
 *     2:  30  20  10  20
 *     3:  20  30  20  10
 *
 * which represents a 4 node ring topology like:
 *
 *   0 ----- 1
 *   |       |
 *   |       |
 *   |       |
 *   3 ----- 2
 *
 * We want to construct domains and groups to represent this. The way we go
 * about doing this is to build the domains on 'hops'. For each NUMA level we
 * construct the mask of all nodes reachable in @level hops.
 *
 * For the above NUMA topology that gives 3 levels:
 *
 * NUMA-2    0-3        0-3        0-3        0-3
 *  groups:    {0-1,3},{1-3}    {0-2},{0,2-3}    {1-3},{0-1,3}    {0,2-3},{0-2}
 *
 * NUMA-1    0-1,3        0-2        1-3        0,2-3
 *  groups:    {0},{1},{3}    {0},{1},{2}    {1},{2},{3}    {0},{2},{3}
 *
 * NUMA-0    0        1        2        3
 *
 *
 * As can be seen; things don't nicely line up as with the regular topology.
 * When we iterate a domain in child domain chunks some nodes can be
 * represented multiple times -- hence the "overlap" naming for this part of
 * the topology.
 *
 * In order to minimize this overlap, we only build enough groups to cover the
 * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
 *
 * Because
 *
 *  - the first group of each domain is its child domain; this
 *    gets us the first 0-1,3
 *  - the only uncovered node is 2, who's child domain is 1-3.
 *
 * However, because of the overlap, computing a unique CPU for each group is
 * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
 * groups include the CPUs of Node-0, while those CPUs would not in fact ever
 * end up at those groups (they would end up in group: 0-1,3).
 *
 * To correct this we have to introduce the group balance mask. This mask
 * will contain those CPUs in the group that can reach this group given the
 * (child) domain tree.
 *
 * With this we can once again compute balance_cpu and sched_group_capacity
 * relations.
 *
 * XXX include words on how balance_cpu is unique and therefore can be
 * used for sched_group_capacity links.
 *
 *
 * Another 'interesting' topology is
 *
 *   node   0   1   2   3
 *     0:  10  20  20  30
 *     1:  20  10  20  20
 *     2:  20  20  10  20
 *     3:  30  20  20  10
 *
 * Which looks a little like
 *
 *   0 ----- 1
 *   |     / |
 *   |   /   |
 *   | /     |
 *   2 ----- 3
 *
 * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
 * are not.
 *
 * This leads to a few particularly weird cases where the sched_domain's are
 * not of the same number for each CPU. Consider:
 *
 * NUMA-2    0-3                        0-3
 *  groups:    {0-2},{1-3}                    {1-3},{0-2}
 *
 * NUMA-1    0-2        0-3        0-3        1-3
 *
 * NUMA-0    0        1        2        3
 *
 */

/*
 * Build the balance mask; it contains only those CPUs that can arrive at this
 * group and should be considered to continue balancing.
 *
 * We do this during the group creation pass, therefore the group information
 * isn't complete yet, however since each group represents a (child) domain we
 * can fully construct this using the sched_domain bits (which are already
 * complete).
 */
static void build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
{
    const struct cpumask *sg_span = sched_group_span(sg);
    struct sd_data *sdd = sd->private;
    struct sched_domain *sibling;
    int i;

    cpumask_clear(mask);

    for_each_cpu(i, sg_span)
    {
        sibling = *per_cpu_ptr(sdd->sd, i);
        /*
         * Can happen in the asymmetric case, where these siblings are
         * unused. The mask will not be empty because those CPUs that
         * do have the top domain _should_ span the domain.
         */
        if (!sibling->child) {
            continue;
        }

        /* If we would not end up here, we can't continue from here */
        if (!cpumask_equal(sg_span, sched_domain_span(sibling->child))) {
            continue;
        }

        cpumask_set_cpu(i, mask);
    }

    /* We must not have empty masks here */
    WARN_ON_ONCE(cpumask_empty(mask));
}

/*
 * XXX: This creates per-node group entries; since the load-balancer will
 * immediately access remote memory to construct this group's load-balance
 * statistics having the groups node local is of dubious benefit.
 */
static struct sched_group *build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
{
    struct sched_group *sg;
    struct cpumask *sg_span;

    sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), GFP_KERNEL, cpu_to_node(cpu));
    if (!sg) {
        return NULL;
    }

    sg_span = sched_group_span(sg);
    if (sd->child) {
        cpumask_copy(sg_span, sched_domain_span(sd->child));
    } else {
        cpumask_copy(sg_span, sched_domain_span(sd));
    }

    atomic_inc(&sg->ref);
    return sg;
}

static void init_overlap_sched_group(struct sched_domain *sd, struct sched_group *sg)
{
    struct cpumask *mask = sched_domains_tmpmask2;
    struct sd_data *sdd = sd->private;
    struct cpumask *sg_span;
    int cpu;

    build_balance_mask(sd, sg, mask);
    cpu = cpumask_first_and(sched_group_span(sg), mask);

    sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
    if (atomic_inc_return(&sg->sgc->ref) == 1) {
        cpumask_copy(group_balance_mask(sg), mask);
    } else {
        WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
    }

    /*
     * Initialize sgc->capacity such that even if we mess up the
     * domains and no possible iteration will get us here, we won't
     * die on a /0 trap.
     */
    sg_span = sched_group_span(sg);
    sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
    sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
    sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
}

static struct sched_domain *find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling)
{
    /*
     * The proper descendant would be the one whose child won't span out
     * of sd
     */
    while (sibling->child && !cpumask_subset(sched_domain_span(sibling->child), sched_domain_span(sd))) {
        sibling = sibling->child;
    }

    /*
     * As we are referencing sgc across different topology level, we need
     * to go down to skip those sched_domains which don't contribute to
     * scheduling because they will be degenerated in cpu_attach_domain
     */
    while (sibling->child && cpumask_equal(sched_domain_span(sibling->child), sched_domain_span(sibling))) {
        sibling = sibling->child;
    }

    return sibling;
}

static int build_overlap_sched_groups(struct sched_domain *sd, int cpu)
{
    struct sched_group *first = NULL, *last = NULL, *sg;
    const struct cpumask *span = sched_domain_span(sd);
    struct cpumask *covered = sched_domains_tmpmask;
    struct sd_data *sdd = sd->private;
    struct sched_domain *sibling;
    int i;

    cpumask_clear(covered);

    for_each_cpu_wrap(i, span, cpu)
    {
        struct cpumask *sg_span;

        if (cpumask_test_cpu(i, covered)) {
            continue;
        }

        sibling = *per_cpu_ptr(sdd->sd, i);
        /*
         * Asymmetric node setups can result in situations where the
         * domain tree is of unequal depth, make sure to skip domains
         * that already cover the entire range.
         *
         * In that case build_sched_domains() will have terminated the
         * iteration early and our sibling sd spans will be empty.
         * Domains should always include the CPU they're built on, so
         * check that.
         */
        if (!cpumask_test_cpu(i, sched_domain_span(sibling))) {
            continue;
        }

        /*
         * Usually we build sched_group by sibling's child sched_domain
         * But for machines whose NUMA diameter are 3 or above, we move
         * to build sched_group by sibling's proper descendant's child
         * domain because sibling's child sched_domain will span out of
         * the sched_domain being built as below.
         *
         * Smallest diameter=3 topology is:
         *
         *   node   0   1   2   3
         *     0:  10  20  30  40
         *     1:  20  10  20  30
         *     2:  30  20  10  20
         *     3:  40  30  20  10
         *
         *   0 --- 1 --- 2 --- 3
         *
         * NUMA-3       0-3             N/A             N/A             0-3
         *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
         *
         * NUMA-2       0-2             0-3             0-3             1-3
         *  groups:     {0-1},{1-3}     {0-2},{2-3}     {1-3},{0-1}     {2-3},{0-2}
         *
         * NUMA-1       0-1             0-2             1-3             2-3
         *  groups:     {0},{1}         {1},{2},{0}     {2},{3},{1}     {3},{2}
         *
         * NUMA-0       0               1               2               3
         *
         * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the
         * group span isn't a subset of the domain span.
         */
        if (sibling->child && !cpumask_subset(sched_domain_span(sibling->child), span)) {
            sibling = find_descended_sibling(sd, sibling);
        }

        sg = build_group_from_child_sched_domain(sibling, cpu);
        if (!sg) {
            goto fail;
        }

        sg_span = sched_group_span(sg);
        cpumask_or(covered, covered, sg_span);

        init_overlap_sched_group(sibling, sg);

        if (!first) {
            first = sg;
        }
        if (last) {
            last->next = sg;
        }
        last = sg;
        last->next = first;
    }
    sd->groups = first;

    return 0;

fail:
    free_sched_groups(first, 0);

    return -ENOMEM;
}

/*
 * Package topology (also see the load-balance blurb in fair.c)
 *
 * The scheduler builds a tree structure to represent a number of important
 * topology features. By default (default_topology[]) these include:
 *
 *  - Simultaneous multithreading (SMT)
 *  - Multi-Core Cache (MC)
 *  - Package (DIE)
 *
 * Where the last one more or less denotes everything up to a NUMA node.
 *
 * The tree consists of 3 primary data structures:
 *
 *    sched_domain -> sched_group -> sched_group_capacity
 *        ^ ^             ^ ^
 *          `-'             `-'
 *
 * The sched_domains are per-CPU and have a two way link (parent & child) and
 * denote the ever growing mask of CPUs belonging to that level of topology.
 *
 * Each sched_domain has a circular (double) linked list of sched_group's, each
 * denoting the domains of the level below (or individual CPUs in case of the
 * first domain level). The sched_group linked by a sched_domain includes the
 * CPU of that sched_domain [*].
 *
 * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
 *
 * CPU   0   1   2   3   4   5   6   7
 *
 * DIE  [                             ]
 * MC   [             ] [             ]
 * SMT  [     ] [     ] [     ] [     ]
 *
 *  - or -
 *
 * DIE  0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
 * MC    0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
 * SMT  0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
 *
 * CPU   0   1   2   3   4   5   6   7
 *
 * One way to think about it is: sched_domain moves you up and down among these
 * topology levels, while sched_group moves you sideways through it, at child
 * domain granularity.
 *
 * sched_group_capacity ensures each unique sched_group has shared storage.
 *
 * There are two related construction problems, both require a CPU that
 * uniquely identify each group (for a given domain):
 *
 *  - The first is the balance_cpu (see should_we_balance() and the
 *    load-balance blub in fair.c); for each group we only want 1 CPU to
 *    continue balancing at a higher domain.
 *
 *  - The second is the sched_group_capacity; we want all identical groups
 *    to share a single sched_group_capacity.
 *
 * Since these topologies are exclusive by construction. That is, its
 * impossible for an SMT thread to belong to multiple cores, and cores to
 * be part of multiple caches. There is a very clear and unique location
 * for each CPU in the hierarchy.
 *
 * Therefore computing a unique CPU for each group is trivial (the iteration
 * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
 * group), we can simply pick the first CPU in each group.
 *
 *
 * [*] in other words, the first group of each domain is its child domain.
 */

static struct sched_group *get_group(int cpu, struct sd_data *sdd)
{
    struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
    struct sched_domain *child = sd->child;
    struct sched_group *sg;
    bool already_visited;

    if (child) {
        cpu = cpumask_first(sched_domain_span(child));
    }

    sg = *per_cpu_ptr(sdd->sg, cpu);
    sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);

    /* Increase refcounts for claim_allocations: */
    already_visited = atomic_inc_return(&sg->ref) > 1;
    /* sgc visits should follow a similar trend as sg */
    WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1));

    /* If we have already visited that group, it's already initialized. */
    if (already_visited) {
        return sg;
    }

    if (child) {
        cpumask_copy(sched_group_span(sg), sched_domain_span(child));
        cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
    } else {
        cpumask_set_cpu(cpu, sched_group_span(sg));
        cpumask_set_cpu(cpu, group_balance_mask(sg));
    }

    sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
    sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
    sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;

    return sg;
}

/*
 * build_sched_groups will build a circular linked list of the groups
 * covered by the given span, will set each group's ->cpumask correctly,
 * and will initialize their ->sgc.
 *
 * Assumes the sched_domain tree is fully constructed
 */
static int build_sched_groups(struct sched_domain *sd, int cpu)
{
    struct sched_group *first = NULL, *last = NULL;
    struct sd_data *sdd = sd->private;
    const struct cpumask *span = sched_domain_span(sd);
    struct cpumask *covered;
    int i;

    lockdep_assert_held(&sched_domains_mutex);
    covered = sched_domains_tmpmask;

    cpumask_clear(covered);

    for_each_cpu_wrap(i, span, cpu)
    {
        struct sched_group *sg;

        if (cpumask_test_cpu(i, covered)) {
            continue;
        }

        sg = get_group(i, sdd);

        cpumask_or(covered, covered, sched_group_span(sg));

        if (!first) {
            first = sg;
        }
        if (last) {
            last->next = sg;
        }
        last = sg;
    }
    last->next = first;
    sd->groups = first;

    return 0;
}

/*
 * Initialize sched groups cpu_capacity.
 *
 * cpu_capacity indicates the capacity of sched group, which is used while
 * distributing the load between different sched groups in a sched domain.
 * Typically cpu_capacity for all the groups in a sched domain will be same
 * unless there are asymmetries in the topology. If there are asymmetries,
 * group having more cpu_capacity will pickup more load compared to the
 * group having less cpu_capacity.
 */
void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
{
    struct sched_group *sg = sd->groups;
#ifdef CONFIG_CPU_ISOLATION_OPT
    cpumask_t avail_mask;
#endif

    WARN_ON(!sg);

    do {
        int cpu, max_cpu = -1;

#ifdef CONFIG_CPU_ISOLATION_OPT
        cpumask_andnot(&avail_mask, sched_group_span(sg), cpu_isolated_mask);
        sg->group_weight = cpumask_weight(&avail_mask);
#else
        sg->group_weight = cpumask_weight(sched_group_span(sg));
#endif

        if (!(sd->flags & SD_ASYM_PACKING)) {
            goto next;
        }

        for_each_cpu(cpu, sched_group_span(sg))
        {
            if (max_cpu < 0) {
                max_cpu = cpu;
            } else if (sched_asym_prefer(cpu, max_cpu)) {
                max_cpu = cpu;
            }
        }
        sg->asym_prefer_cpu = max_cpu;

    next:
        sg = sg->next;
    } while (sg != sd->groups);

    if (cpu != group_balance_cpu(sg)) {
        return;
    }

    update_group_capacity(sd, cpu);
}

/*
 * Initializers for schedule domains
 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
 */

static int default_relax_domain_level = -1;
int sched_domain_level_max;

static int __init setup_relax_domain_level(char *str)
{
    if (kstrtoint(str, 0, &default_relax_domain_level)) {
        pr_warn("Unable to set relax_domain_level\n");
    }

    return 1;
}
__setup("relax_domain_level=", setup_relax_domain_level);

static void set_domain_attribute(struct sched_domain *sd, struct sched_domain_attr *attr)
{
    int request;

    if (!attr || attr->relax_domain_level < 0) {
        if (default_relax_domain_level < 0) {
            return;
        }
        request = default_relax_domain_level;
    } else {
        request = attr->relax_domain_level;
    }

    if (sd->level > request) {
        /* Turn off idle balance on this domain: */
        sd->flags &= ~(SD_BALANCE_WAKE | SD_BALANCE_NEWIDLE);
    }
}

static void __sdt_free(const struct cpumask *cpu_map);
static int __sdt_alloc(const struct cpumask *cpu_map);

static void __free_domain_allocs(struct s_data *d, enum s_alloc what, const struct cpumask *cpu_map)
{
    switch (what) {
        case sa_rootdomain:
            if (!atomic_read(&d->rd->refcount)) {
                free_rootdomain(&d->rd->rcu);
            }
            fallthrough;
        case sa_sd:
            free_percpu(d->sd);
            fallthrough;
        case sa_sd_storage:
            __sdt_free(cpu_map);
            fallthrough;
        case sa_none:
            break;
    }
}

static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
{
    memset(d, 0, sizeof(*d));

    if (__sdt_alloc(cpu_map)) {
        return sa_sd_storage;
    }
    d->sd = alloc_percpu(struct sched_domain *);
    if (!d->sd) {
        return sa_sd_storage;
    }
    d->rd = alloc_rootdomain();
    if (!d->rd) {
        return sa_sd;
    }

    return sa_rootdomain;
}

/*
 * NULL the sd_data elements we've used to build the sched_domain and
 * sched_group structure so that the subsequent __free_domain_allocs()
 * will not free the data we're using.
 */
static void claim_allocations(int cpu, struct sched_domain *sd)
{
    struct sd_data *sdd = sd->private;

    WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
    *per_cpu_ptr(sdd->sd, cpu) = NULL;

    if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref)) {
        *per_cpu_ptr(sdd->sds, cpu) = NULL;
    }

    if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) {
        *per_cpu_ptr(sdd->sg, cpu) = NULL;
    }

    if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref)) {
        *per_cpu_ptr(sdd->sgc, cpu) = NULL;
    }
}

#ifdef CONFIG_NUMA
enum numa_topology_type sched_numa_topology_type;

static int sched_domains_numa_levels;
static int sched_domains_curr_level;

int sched_max_numa_distance;
static int *sched_domains_numa_distance;
static struct cpumask ***sched_domains_numa_masks;
int __read_mostly node_reclaim_distance = RECLAIM_DISTANCE;
#endif

/*
 * SD_flags allowed in topology descriptions.
 *
 * These flags are purely descriptive of the topology and do not prescribe
 * behaviour. Behaviour is artificial and mapped in the below sd_init()
 * function:
 *
 *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
 *   SD_SHARE_PKG_RESOURCES - describes shared caches
 *   SD_NUMA                - describes NUMA topologies
 *
 * Odd one out, which beside describing the topology has a quirk also
 * prescribes the desired behaviour that goes along with it:
 *
 *   SD_ASYM_PACKING        - describes SMT quirks
 */
#define TOPOLOGY_SD_FLAGS (SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES | SD_NUMA | SD_ASYM_PACKING)

static struct sched_domain *sd_init(struct sched_domain_topology_level *tl, const struct cpumask *cpu_map,
                                    struct sched_domain *child, int dflags, int cpu)
{
    struct sd_data *sdd = &tl->data;
    struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
    int sd_id, sd_weight, sd_flags = 0;

#ifdef CONFIG_NUMA
    /*
     * Ugly hack to pass state to sd_numa_mask()...
     */
    sched_domains_curr_level = tl->numa_level;
#endif

    sd_weight = cpumask_weight(tl->mask(cpu));

    if (tl->sd_flags) {
        sd_flags = (*tl->sd_flags)();
    }
    if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS, "wrong sd_flags in topology description\n")) {
        sd_flags &= TOPOLOGY_SD_FLAGS;
    }

    /* Apply detected topology flags */
    sd_flags |= dflags;

    *sd = (struct sched_domain) {
        .min_interval = sd_weight,
        .max_interval = 2 * sd_weight,
        .busy_factor = 16,
        .imbalance_pct = 117,

        .cache_nice_tries = 0,

        .flags = 1 * SD_BALANCE_NEWIDLE | 1 * SD_BALANCE_EXEC | 1 * SD_BALANCE_FORK | 0 * SD_BALANCE_WAKE |
                 1 * SD_WAKE_AFFINE | 0 * SD_SHARE_CPUCAPACITY | 0 * SD_SHARE_PKG_RESOURCES | 0 * SD_SERIALIZE |
                 1 * SD_PREFER_SIBLING | 0 * SD_NUMA | sd_flags,

        .last_balance = jiffies,
        .balance_interval = sd_weight,
        .max_newidle_lb_cost = 0,
        .next_decay_max_lb_cost = jiffies,
        .child = child,
#ifdef CONFIG_SCHED_DEBUG
        .name = tl->name,
#endif
    };

    cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
    sd_id = cpumask_first(sched_domain_span(sd));

    /*
     * Convert topological properties into behaviour.
     */

    /* Don't attempt to spread across CPUs of different capacities. */
    if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child) {
        sd->child->flags &= ~SD_PREFER_SIBLING;
    }

    if (sd->flags & SD_SHARE_CPUCAPACITY) {
        sd->imbalance_pct = IMBALANCE_SD_SHARE_CPUCAPACITY;
    } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
        sd->imbalance_pct = IMBALANCE_SD_SHARE_PKG;
        sd->cache_nice_tries = 1;

#ifdef CONFIG_NUMA
    } else if (sd->flags & SD_NUMA) {
        sd->cache_nice_tries = IMBALANCE_SD_NUMA;

        sd->flags &= ~SD_PREFER_SIBLING;
        sd->flags |= SD_SERIALIZE;
        if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) {
            sd->flags &= ~(SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE);
        }

#endif
    } else {
        sd->cache_nice_tries = 1;
    }

    /*
     * For all levels sharing cache; connect a sched_domain_shared
     * instance.
     */
    if (sd->flags & SD_SHARE_PKG_RESOURCES) {
        sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
        atomic_inc(&sd->shared->ref);
        atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
    }

    sd->private = sdd;

    return sd;
}

/*
 * Topology list, bottom-up.
 */
static struct sched_domain_topology_level default_topology[] = {
#ifdef CONFIG_SCHED_SMT
    {cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT)},
#endif
#ifdef CONFIG_SCHED_MC
    {cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC)},
#endif
    {cpu_cpu_mask, SD_INIT_NAME(DIE)},
    {
        NULL,
    },
};

static struct sched_domain_topology_level *sched_domain_topology = default_topology;

#define for_each_sd_topology(tl) for (tl = sched_domain_topology; (tl)->mask; (tl)++)

void set_sched_topology(struct sched_domain_topology_level *tl)
{
    if (WARN_ON_ONCE(sched_smp_initialized)) {
        return;
    }

    sched_domain_topology = tl;
}

#ifdef CONFIG_NUMA

static const struct cpumask *sd_numa_mask(int cpu)
{
    return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
}

static void sched_numa_warn(const char *str)
{
    static int done = false;
    int i, j;

    if (done) {
        return;
    }

    done = true;

    printk(KERN_WARNING "ERROR: %s\n\n", str);

    for (i = 0; i < nr_node_ids; i++) {
        printk(KERN_WARNING "  ");
        for (j = 0; j < nr_node_ids; j++) {
            printk(KERN_CONT "%02d ", node_distance(i, j));
        }
        printk(KERN_CONT "\n");
    }
    printk(KERN_WARNING "\n");
}

bool find_numa_distance(int distance)
{
    int i;

    if (distance == node_distance(0, 0)) {
        return true;
    }

    for (i = 0; i < sched_domains_numa_levels; i++) {
        if (sched_domains_numa_distance[i] == distance) {
            return true;
        }
    }

    return false;
}

/*
 * A system can have three types of NUMA topology:
 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
 *
 * The difference between a glueless mesh topology and a backplane
 * topology lies in whether communication between not directly
 * connected nodes goes through intermediary nodes (where programs
 * could run), or through backplane controllers. This affects
 * placement of programs.
 *
 * The type of topology can be discerned with the following tests:
 * - If the maximum distance between any nodes is 1 hop, the system
 *   is directly connected.
 * - If for two nodes A and B, located N > 1 hops away from each other,
 *   there is an intermediary node C, which is < N hops away from both
 *   nodes A and B, the system is a glueless mesh.
 */
static void init_numa_topology_type(void)
{
    int a, b, c, n;

    n = sched_max_numa_distance;

    if (sched_domains_numa_levels <= IMBALANCE_SD_NUMA_DIRECT) {
        sched_numa_topology_type = NUMA_DIRECT;
        return;
    }

    for_each_online_node(a)
    {
        for_each_online_node(b)
        {
            /* Find two nodes furthest removed from each other. */
            if (node_distance(a, b) < n) {
                continue;
            }

            /* Is there an intermediary node between a and b? */
            for_each_online_node(c)
            {
                if (node_distance(a, c) < n && node_distance(b, c) < n) {
                    sched_numa_topology_type = NUMA_GLUELESS_MESH;
                    return;
                }
            }

            sched_numa_topology_type = NUMA_BACKPLANE;
            return;
        }
    }
}

#define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)

void sched_init_numa(void)
{
    struct sched_domain_topology_level *tl;
    unsigned long *distance_map;
    int nr_levels = 0;
    int i, j;

    /*
     * O(nr_nodes^2) deduplicating selection sort -- in order to find the
     * unique distances in the node_distance() table.
     */
    distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL);
    if (!distance_map) {
        return;
    }

    bitmap_zero(distance_map, NR_DISTANCE_VALUES);
    for (i = 0; i < nr_node_ids; i++) {
        for (j = 0; j < nr_node_ids; j++) {
            int distance = node_distance(i, j);
            if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
                sched_numa_warn("Invalid distance value range");
                return;
            }

            bitmap_set(distance_map, distance, 1);
        }
    }
    /*
     * We can now figure out how many unique distance values there are and
     * allocate memory accordingly.
     */
    nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES);

    sched_domains_numa_distance = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
    if (!sched_domains_numa_distance) {
        bitmap_free(distance_map);
        return;
    }

    for (i = 0, j = 0; i < nr_levels; i++, j++) {
        j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
        sched_domains_numa_distance[i] = j;
    }

    bitmap_free(distance_map);

    /*
     * 'nr_levels' contains the number of unique distances
     *
     * The sched_domains_numa_distance[] array includes the actual distance
     * numbers.
     */

    /*
     * Here, we should temporarily reset sched_domains_numa_levels to 0.
     * If it fails to allocate memory for array sched_domains_numa_masks[][],
     * the array will contain less then 'nr_levels' members. This could be
     * dangerous when we use it to iterate array sched_domains_numa_masks[][]
     * in other functions.
     *
     * We reset it to 'nr_levels' at the end of this function.
     */
    sched_domains_numa_levels = 0;

    sched_domains_numa_masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
    if (!sched_domains_numa_masks) {
        return;
    }

    /*
     * Now for each level, construct a mask per node which contains all
     * CPUs of nodes that are that many hops away from us.
     */
    for (i = 0; i < nr_levels; i++) {
        sched_domains_numa_masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
        if (!sched_domains_numa_masks[i]) {
            return;
        }

        for (j = 0; j < nr_node_ids; j++) {
            struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
            int k;

            if (!mask) {
                return;
            }

            sched_domains_numa_masks[i][j] = mask;

            for_each_node(k)
            {
                if (sched_debug() && (node_distance(j, k) != node_distance(k, j))) {
                    sched_numa_warn("Node-distance not symmetric");
                }

                if (node_distance(j, k) > sched_domains_numa_distance[i]) {
                    continue;
                }

                cpumask_or(mask, mask, cpumask_of_node(k));
            }
        }
    }

    /* Compute default topology size */
    for (i = 0; sched_domain_topology[i].mask; i++) {
        ;
    }

    tl = kzalloc((i + nr_levels + 1) * sizeof(struct sched_domain_topology_level), GFP_KERNEL);
    if (!tl) {
        return;
    }

    /*
     * Copy the default topology bits..
     */
    for (i = 0; sched_domain_topology[i].mask; i++) {
        tl[i] = sched_domain_topology[i];
    }

    /*
     * Add the NUMA identity distance, aka single NODE.
     */
    tl[i++] = (struct sched_domain_topology_level) {.mask = sd_numa_mask, .numa_level = 0, SD_INIT_NAME(NODE)};

    /*
     * .. and append 'j' levels of NUMA goodness.
     */
    for (j = 1; j < nr_levels; i++, j++) {
        tl[i] = (struct sched_domain_topology_level) {
            .mask = sd_numa_mask,
            .sd_flags = cpu_numa_flags,
            .flags = SDTL_OVERLAP,
            .numa_level = j,
            SD_INIT_NAME(NUMA)};
    }

    sched_domain_topology = tl;

    sched_domains_numa_levels = nr_levels;
    sched_max_numa_distance = sched_domains_numa_distance[nr_levels - 1];

    init_numa_topology_type();
}

void sched_domains_numa_masks_set(unsigned int cpu)
{
    int node = cpu_to_node(cpu);
    int i, j;

    for (i = 0; i < sched_domains_numa_levels; i++) {
        for (j = 0; j < nr_node_ids; j++) {
            if (node_distance(j, node) <= sched_domains_numa_distance[i]) {
                cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
            }
        }
    }
}

void sched_domains_numa_masks_clear(unsigned int cpu)
{
    int i, j;

    for (i = 0; i < sched_domains_numa_levels; i++) {
        for (j = 0; j < nr_node_ids; j++) {
            cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
        }
    }
}

/*
 * sched_numa_find_closest() - given the NUMA topology, find the cpu
 *                             closest to @cpu from @cpumask.
 * cpumask: cpumask to find a cpu from
 * cpu: cpu to be close to
 *
 * returns: cpu, or nr_cpu_ids when nothing found.
 */
int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
{
    int i, j = cpu_to_node(cpu);

    for (i = 0; i < sched_domains_numa_levels; i++) {
        cpu = cpumask_any_and(cpus, sched_domains_numa_masks[i][j]);
        if (cpu < nr_cpu_ids) {
            return cpu;
        }
    }
    return nr_cpu_ids;
}

#endif /* CONFIG_NUMA */

static int __sdt_alloc(const struct cpumask *cpu_map)
{
    struct sched_domain_topology_level *tl;
    int j;

    for (tl = sched_domain_topology; (tl)->mask; (tl)++) {
        struct sd_data *sdd = &tl->data;

        sdd->sd = alloc_percpu(struct sched_domain *);
        if (!sdd->sd) {
            return -ENOMEM;
        }

        sdd->sds = alloc_percpu(struct sched_domain_shared *);
        if (!sdd->sds) {
            return -ENOMEM;
        }

        sdd->sg = alloc_percpu(struct sched_group *);
        if (!sdd->sg) {
            return -ENOMEM;
        }

        sdd->sgc = alloc_percpu(struct sched_group_capacity *);
        if (!sdd->sgc) {
            return -ENOMEM;
        }

        for_each_cpu(j, cpu_map)
        {
            struct sched_domain *sd;
            struct sched_domain_shared *sds;
            struct sched_group *sg;
            struct sched_group_capacity *sgc;

            sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), GFP_KERNEL, cpu_to_node(j));
            if (!sd) {
                return -ENOMEM;
            }

            *per_cpu_ptr(sdd->sd, j) = sd;

            sds = kzalloc_node(sizeof(struct sched_domain_shared), GFP_KERNEL, cpu_to_node(j));
            if (!sds) {
                return -ENOMEM;
            }

            *per_cpu_ptr(sdd->sds, j) = sds;

            sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), GFP_KERNEL, cpu_to_node(j));
            if (!sg) {
                return -ENOMEM;
            }

            sg->next = sg;

            *per_cpu_ptr(sdd->sg, j) = sg;

            sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(), GFP_KERNEL, cpu_to_node(j));
            if (!sgc) {
                return -ENOMEM;
            }

#ifdef CONFIG_SCHED_DEBUG
            sgc->id = j;
#endif

            *per_cpu_ptr(sdd->sgc, j) = sgc;
        }
    }

    return 0;
}

static void __sdt_free(const struct cpumask *cpu_map)
{
    struct sched_domain_topology_level *tl;
    int j;

    for (tl = sched_domain_topology; (tl)->mask; (tl)++) {
        struct sd_data *sdd = &tl->data;

        for_each_cpu(j, cpu_map) {
            struct sched_domain *sd;

            if (sdd->sd) {
                sd = *per_cpu_ptr(sdd->sd, j);
                if (sd && (sd->flags & SD_OVERLAP)) {
                    free_sched_groups(sd->groups, 0);
                }
                kfree(*per_cpu_ptr(sdd->sd, j));
            }

            if (sdd->sds) {
                kfree(*per_cpu_ptr(sdd->sds, j));
            }
            if (sdd->sg) {
                kfree(*per_cpu_ptr(sdd->sg, j));
            }
            if (sdd->sgc) {
                kfree(*per_cpu_ptr(sdd->sgc, j));
            }
        }
        free_percpu(sdd->sd);
        sdd->sd = NULL;
        free_percpu(sdd->sds);
        sdd->sds = NULL;
        free_percpu(sdd->sg);
        sdd->sg = NULL;
        free_percpu(sdd->sgc);
        sdd->sgc = NULL;
    }
}

static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, const struct cpumask *cpu_map,
                                               struct sched_domain_attr *attr, struct sched_domain *child, int dflags,
                                               int cpu)
{
    struct sched_domain *sd = sd_init(tl, cpu_map, child, dflags, cpu);

    if (child) {
        sd->level = child->level + 1;
        sched_domain_level_max = max(sched_domain_level_max, sd->level);
        child->parent = sd;

        if (!cpumask_subset(sched_domain_span(child), sched_domain_span(sd))) {
            pr_err("BUG: arch topology borken\n");
#ifdef CONFIG_SCHED_DEBUG
            pr_err("     the %s domain not a subset of the %s domain\n", child->name, sd->name);
#endif
            /* Fixup, ensure @sd has at least @child CPUs. */
            cpumask_or(sched_domain_span(sd), sched_domain_span(sd), sched_domain_span(child));
        }
    }
    set_domain_attribute(sd, attr);

    return sd;
}

/*
 * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
 * any two given CPUs at this (non-NUMA) topology level.
 */
static bool topology_span_sane(struct sched_domain_topology_level *tl, const struct cpumask *cpu_map, int cpu)
{
    int i;

    /* NUMA levels are allowed to overlap */
    if (tl->flags & SDTL_OVERLAP) {
        return true;
    }

    /*
     * Non-NUMA levels cannot partially overlap - they must be either
     * completely equal or completely disjoint. Otherwise we can end up
     * breaking the sched_group lists - i.e. a later get_group() pass
     * breaks the linking done for an earlier span.
     */
    for_each_cpu(i, cpu_map)
    {
        if (i == cpu) {
            continue;
        }
        /*
         * We should 'and' all those masks with 'cpu_map' to exactly
         * match the topology we're about to build, but that can only
         * remove CPUs, which only lessens our ability to detect
         * overlaps
         */
        if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) && cpumask_intersects(tl->mask(cpu), tl->mask(i))) {
            return false;
        }
    }

    return true;
}

/*
 * Find the sched_domain_topology_level where all CPU capacities are visible
 * for all CPUs.
 */
static struct sched_domain_topology_level *asym_cpu_capacity_level(const struct cpumask *cpu_map)
{
    int i, j, asym_level = 0;
    bool asym = false;
    struct sched_domain_topology_level *tl, *asym_tl = NULL;
    unsigned long cap;

    /* Is there any asymmetry? */
    cap = arch_scale_cpu_capacity(cpumask_first(cpu_map));

    for_each_cpu(i, cpu_map)
    {
        if (arch_scale_cpu_capacity(i) != cap) {
            asym = true;
            break;
        }
    }

    if (!asym) {
        return NULL;
    }

    /*
     * Examine topology from all CPU's point of views to detect the lowest
     * sched_domain_topology_level where a highest capacity CPU is visible
     * to everyone.
     */
    for_each_cpu(i, cpu_map)
    {
        unsigned long max_capacity = arch_scale_cpu_capacity(i);
        int tl_id = 0;

        for (tl = sched_domain_topology; (tl)->mask; (tl)++) {
            if (tl_id < asym_level) {
                goto next_level;
            }

            for_each_cpu_and(j, tl->mask(i), cpu_map) {
                unsigned long capacity;

                capacity = arch_scale_cpu_capacity(j);
                if (capacity <= max_capacity) {
                    continue;
                }

                max_capacity = capacity;
                asym_level = tl_id;
                asym_tl = tl;
            }
        next_level:
            tl_id++;
        }
    }

    return asym_tl;
}

/*
 * Build sched domains for a given set of CPUs and attach the sched domains
 * to the individual CPUs
 */
static int build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
{
    enum s_alloc alloc_state = sa_none;
    struct sched_domain *sd;
    struct s_data d;
    struct rq *rq = NULL;
    int i, ret = -ENOMEM;
    struct sched_domain_topology_level *tl_asym;
    bool has_asym = false;

    if (WARN_ON(cpumask_empty(cpu_map))) {
        goto error;
    }

    alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
    if (alloc_state != sa_rootdomain) {
        goto error;
    }

    tl_asym = asym_cpu_capacity_level(cpu_map);

    /* Set up domains for CPUs specified by the cpu_map: */
    for_each_cpu(i, cpu_map)
    {
        struct sched_domain_topology_level *tl;
        int dflags = 0;

        sd = NULL;
        for (tl = sched_domain_topology; (tl)->mask; (tl)++) {
            if (tl == tl_asym) {
                dflags |= SD_ASYM_CPUCAPACITY;
                has_asym = true;
            }

            if (WARN_ON(!topology_span_sane(tl, cpu_map, i))) {
                goto error;
            }

            sd = build_sched_domain(tl, cpu_map, attr, sd, dflags, i);

            if (tl == sched_domain_topology) {
                *per_cpu_ptr(d.sd, i) = sd;
            }
            if (tl->flags & SDTL_OVERLAP) {
                sd->flags |= SD_OVERLAP;
            }
            if (cpumask_equal(cpu_map, sched_domain_span(sd))) {
                break;
            }
        }
    }

    /* Build the groups for the domains */
    for_each_cpu(i, cpu_map)
    {
        for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
            sd->span_weight = cpumask_weight(sched_domain_span(sd));
            if (sd->flags & SD_OVERLAP) {
                if (build_overlap_sched_groups(sd, i)) {
                    goto error;
                }
            } else {
                if (build_sched_groups(sd, i)) {
                    goto error;
                }
            }
        }
    }

    /* Calculate CPU capacity for physical packages and nodes */
    for (i = nr_cpumask_bits - 1; i >= 0; i--) {
        if (!cpumask_test_cpu(i, cpu_map)) {
            continue;
        }

        for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
            claim_allocations(i, sd);
            init_sched_groups_capacity(i, sd);
        }
    }

    /* Attach the domains */
    rcu_read_lock();
    for_each_cpu(i, cpu_map)
    {
#ifdef CONFIG_SCHED_RT_CAS
        int max_cpu = READ_ONCE(d.rd->max_cap_orig_cpu);
#endif

        rq = cpu_rq(i);
        sd = *per_cpu_ptr(d.sd, i);

#ifdef CONFIG_SCHED_RT_CAS
        if (max_cpu < 0 || arch_scale_cpu_capacity(i) > arch_scale_cpu_capacity(max_cpu)) {
            WRITE_ONCE(d.rd->max_cap_orig_cpu, i);
        }
#endif

        /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
        if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity)) {
            WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
        }

        cpu_attach_domain(sd, d.rd, i);
    }
    rcu_read_unlock();

    if (has_asym) {
        static_branch_inc_cpuslocked(&sched_asym_cpucapacity);
    }

    if (rq && sched_debug_enabled) {
        pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n", cpumask_pr_args(cpu_map),
                rq->rd->max_cpu_capacity);
    }

    ret = 0;
error:
    __free_domain_allocs(&d, alloc_state, cpu_map);

    return ret;
}

/* Current sched domains: */
static cpumask_var_t *doms_cur;

/* Number of sched domains in 'doms_cur': */
static int ndoms_cur;

/* Attribues of custom domains in 'doms_cur' */
static struct sched_domain_attr *dattr_cur;

/*
 * Special case: If a kmalloc() of a doms_cur partition (array of
 * cpumask) fails, then fallback to a single sched domain,
 * as determined by the single cpumask fallback_doms.
 */
static cpumask_var_t fallback_doms;

/*
 * arch_update_cpu_topology lets virtualized architectures update the
 * CPU core maps. It is supposed to return 1 if the topology changed
 * or 0 if it stayed the same.
 */
int __weak arch_update_cpu_topology(void)
{
    return 0;
}

cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
{
    int i;
    cpumask_var_t *doms;

    doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
    if (!doms) {
        return NULL;
    }
    for (i = 0; i < ndoms; i++) {
        if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
            free_sched_domains(doms, i);
            return NULL;
        }
    }
    return doms;
}

void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
{
    unsigned int i;
    for (i = 0; i < ndoms; i++) {
        free_cpumask_var(doms[i]);
    }
    kfree(doms);
}

/*
 * Set up scheduler domains and groups.  For now this just excludes isolated
 * CPUs, but could be used to exclude other special cases in the future.
 */
int sched_init_domains(const struct cpumask *cpu_map)
{
    int err;

    zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
    zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
    zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);

    arch_update_cpu_topology();
    ndoms_cur = 1;
    doms_cur = alloc_sched_domains(ndoms_cur);
    if (!doms_cur) {
        doms_cur = &fallback_doms;
    }
    cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
    err = build_sched_domains(doms_cur[0], NULL);
    register_sched_domain_sysctl();

    return err;
}

/*
 * Detach sched domains from a group of CPUs specified in cpu_map
 * These CPUs will now be attached to the NULL domain
 */
static void detach_destroy_domains(const struct cpumask *cpu_map)
{
    unsigned int cpu = cpumask_any(cpu_map);
    int i;

    if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu))) {
        static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
    }

    rcu_read_lock();
    for_each_cpu(i, cpu_map) cpu_attach_domain(NULL, &def_root_domain, i);
    rcu_read_unlock();
}

/* handle null as "default" */
static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, struct sched_domain_attr *new, int idx_new)
{
    struct sched_domain_attr tmp;

    /* Fast path: */
    if (!new && !cur) {
        return 1;
    }

    tmp = SD_ATTR_INIT;

    return !memcmp(cur ? (cur + idx_cur) : &tmp, new ? (new + idx_new) : &tmp, sizeof(struct sched_domain_attr));
}

/*
 * Partition sched domains as specified by the 'ndoms_new'
 * cpumasks in the array doms_new[] of cpumasks. This compares
 * doms_new[] to the current sched domain partitioning, doms_cur[].
 * It destroys each deleted domain and builds each new domain.
 *
 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
 * The masks don't intersect (don't overlap.) We should setup one
 * sched domain for each mask. CPUs not in any of the cpumasks will
 * not be load balanced. If the same cpumask appears both in the
 * current 'doms_cur' domains and in the new 'doms_new', we can leave
 * it as it is.
 *
 * The passed in 'doms_new' should be allocated using
 * alloc_sched_domains.  This routine takes ownership of it and will
 * free_sched_domains it when done with it. If the caller failed the
 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
 * and partition_sched_domains() will fallback to the single partition
 * 'fallback_doms', it also forces the domains to be rebuilt.
 *
 * If doms_new == NULL it will be replaced with cpu_online_mask.
 * ndoms_new == 0 is a special case for destroying existing domains,
 * and it will not create the default domain.
 *
 * Call with hotplug lock and sched_domains_mutex held
 */
void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[], struct sched_domain_attr *dattr_new)
{
    bool __maybe_unused has_eas = false;
    int i, j, n;
    int new_topology;

    lockdep_assert_held(&sched_domains_mutex);

    /* Always unregister in case we don't destroy any domains: */
    unregister_sched_domain_sysctl();

    /* Let the architecture update CPU core mappings: */
    new_topology = arch_update_cpu_topology();

    if (!doms_new) {
        WARN_ON_ONCE(dattr_new);
        n = 0;
        doms_new = alloc_sched_domains(1);
        if (doms_new) {
            n = 1;
            cpumask_and(doms_new[0], cpu_active_mask, housekeeping_cpumask(HK_FLAG_DOMAIN));
        }
    } else {
        n = ndoms_new;
    }

    /* Destroy deleted domains: */
    for (i = 0; i < ndoms_cur; i++) {
        for (j = 0; j < n && !new_topology; j++) {
            if (cpumask_equal(doms_cur[i], doms_new[j]) && dattrs_equal(dattr_cur, i, dattr_new, j)) {
                struct root_domain *rd;

                /*
                 * This domain won't be destroyed and as such
                 * its dl_bw->total_bw needs to be cleared.  It
                 * will be recomputed in function
                 * update_tasks_root_domain().
                 */
                rd = cpu_rq(cpumask_any(doms_cur[i]))->rd;
                dl_clear_root_domain(rd);
                goto match1;
            }
        }
        /* No match - a current sched domain not in new doms_new[] */
        detach_destroy_domains(doms_cur[i]);
    match1:;
    }

    n = ndoms_cur;
    if (!doms_new) {
        n = 0;
        doms_new = &fallback_doms;
        cpumask_and(doms_new[0], cpu_active_mask, housekeeping_cpumask(HK_FLAG_DOMAIN));
    }

    /* Build new domains: */
    for (i = 0; i < ndoms_new; i++) {
        for (j = 0; j < n && !new_topology; j++) {
            if (cpumask_equal(doms_new[i], doms_cur[j]) && dattrs_equal(dattr_new, i, dattr_cur, j)) {
                goto match2;
            }
        }
        /* No match - add a new doms_new */
        build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
    match2:;
    }

#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
    /* Build perf. domains: */
    for (i = 0; i < ndoms_new; i++) {
        for (j = 0; j < n && !sched_energy_update; j++) {
            if (cpumask_equal(doms_new[i], doms_cur[j]) && cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) {
                has_eas = true;
                goto match3;
            }
        }
        /* No match - add perf. domains for a new rd */
        has_eas |= build_perf_domains(doms_new[i]);
    match3:;
    }
    sched_energy_set(has_eas);
#endif

    /* Remember the new sched domains: */
    if (doms_cur != &fallback_doms) {
        free_sched_domains(doms_cur, ndoms_cur);
    }

    kfree(dattr_cur);
    doms_cur = doms_new;
    dattr_cur = dattr_new;
    ndoms_cur = ndoms_new;

    register_sched_domain_sysctl();
}

/*
 * Call with hotplug lock held
 */
void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], struct sched_domain_attr *dattr_new)
{
    mutex_lock(&sched_domains_mutex);
    partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
    mutex_unlock(&sched_domains_mutex);
}