// SPDX-License-Identifier: GPL-2.0
/*
 * /proc/schedstat implementation
 */

void __update_stats_wait_start(struct rq *rq, struct task_struct *p,
                               struct sched_statistics *stats)
{
        u64 wait_start, prev_wait_start;

        wait_start = rq_clock(rq);
        prev_wait_start = schedstat_val(stats->wait_start);

        if (p && likely(wait_start > prev_wait_start))
                wait_start -= prev_wait_start;

        __schedstat_set(stats->wait_start, wait_start);
}

void __update_stats_wait_end(struct rq *rq, struct task_struct *p,
                             struct sched_statistics *stats)
{
        u64 delta = rq_clock(rq) - schedstat_val(stats->wait_start);

        if (p) {
                if (task_on_rq_migrating(p)) {
                        /*
                         * Preserve migrating task's wait time so wait_start
                         * time stamp can be adjusted to accumulate wait time
                         * prior to migration.
                         */
                        __schedstat_set(stats->wait_start, delta);

                        return;
                }

                trace_sched_stat_wait(p, delta);
        }

        __schedstat_set(stats->wait_max,
                        max(schedstat_val(stats->wait_max), delta));
        __schedstat_inc(stats->wait_count);
        __schedstat_add(stats->wait_sum, delta);
        __schedstat_set(stats->wait_start, 0);
}

void __update_stats_enqueue_sleeper(struct rq *rq, struct task_struct *p,
                                    struct sched_statistics *stats)
{
        u64 sleep_start, block_start;

        sleep_start = schedstat_val(stats->sleep_start);
        block_start = schedstat_val(stats->block_start);

        if (sleep_start) {
                u64 delta = rq_clock(rq) - sleep_start;

                if ((s64)delta < 0)
                        delta = 0;

                if (unlikely(delta > schedstat_val(stats->sleep_max)))
                        __schedstat_set(stats->sleep_max, delta);

                __schedstat_set(stats->sleep_start, 0);
                __schedstat_add(stats->sum_sleep_runtime, delta);

                if (p) {
                        account_scheduler_latency(p, delta >> 10, 1);
                        trace_sched_stat_sleep(p, delta);
                }
        }

        if (block_start) {
                u64 delta = rq_clock(rq) - block_start;

                if ((s64)delta < 0)
                        delta = 0;

                if (unlikely(delta > schedstat_val(stats->block_max)))
                        __schedstat_set(stats->block_max, delta);

                __schedstat_set(stats->block_start, 0);
                __schedstat_add(stats->sum_sleep_runtime, delta);
                __schedstat_add(stats->sum_block_runtime, delta);

                if (p) {
                        if (p->in_iowait) {
                                __schedstat_add(stats->iowait_sum, delta);
                                __schedstat_inc(stats->iowait_count);
                                trace_sched_stat_iowait(p, delta);
                        }

                        trace_sched_stat_blocked(p, delta);

                        /*
                         * Blocking time is in units of nanosecs, so shift by
                         * 20 to get a milliseconds-range estimation of the
                         * amount of time that the task spent sleeping:
                         */
                        if (unlikely(prof_on == SLEEP_PROFILING)) {
                                profile_hits(SLEEP_PROFILING,
                                             (void *)get_wchan(p),
                                             delta >> 20);
                        }
                        account_scheduler_latency(p, delta >> 10, 0);
                }
        }
}

/*
 * Current schedstat API version.
 *
 * Bump this up when changing the output format or the meaning of an existing
 * format, so that tools can adapt (or abort)
 */
#define SCHEDSTAT_VERSION 15

static int show_schedstat(struct seq_file *seq, void *v)
{
        int cpu;

        if (v == (void *)1) {
                seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
                seq_printf(seq, "timestamp %lu\n", jiffies);
        } else {
                struct rq *rq;
#ifdef CONFIG_SMP
                struct sched_domain *sd;
                int dcount = 0;
#endif
                cpu = (unsigned long)(v - 2);
                rq = cpu_rq(cpu);

                /* runqueue-specific stats */
                seq_printf(seq,
                    "cpu%d %u 0 %u %u %u %u %llu %llu %lu",
                    cpu, rq->yld_count,
                    rq->sched_count, rq->sched_goidle,
                    rq->ttwu_count, rq->ttwu_local,
                    rq->rq_cpu_time,
                    rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);

                seq_printf(seq, "\n");

#ifdef CONFIG_SMP
                /* domain-specific stats */
                rcu_read_lock();
                for_each_domain(cpu, sd) {
                        enum cpu_idle_type itype;

                        seq_printf(seq, "domain%d %*pb", dcount++,
                                   cpumask_pr_args(sched_domain_span(sd)));
                        for (itype = CPU_IDLE; itype < CPU_MAX_IDLE_TYPES;
                                        itype++) {
                                seq_printf(seq, " %u %u %u %u %u %u %u %u",
                                    sd->lb_count[itype],
                                    sd->lb_balanced[itype],
                                    sd->lb_failed[itype],
                                    sd->lb_imbalance[itype],
                                    sd->lb_gained[itype],
                                    sd->lb_hot_gained[itype],
                                    sd->lb_nobusyq[itype],
                                    sd->lb_nobusyg[itype]);
                        }
                        seq_printf(seq,
                                   " %u %u %u %u %u %u %u %u %u %u %u %u\n",
                            sd->alb_count, sd->alb_failed, sd->alb_pushed,
                            sd->sbe_count, sd->sbe_balanced, sd->sbe_pushed,
                            sd->sbf_count, sd->sbf_balanced, sd->sbf_pushed,
                            sd->ttwu_wake_remote, sd->ttwu_move_affine,
                            sd->ttwu_move_balance);
                }
                rcu_read_unlock();
#endif
        }
        return 0;
}

/*
 * This iterator needs some explanation.
 * It returns 1 for the header position.
 * This means 2 is cpu 0.
 * In a hotplugged system some CPUs, including cpu 0, may be missing so we have
 * to use cpumask_* to iterate over the CPUs.
 */
static void *schedstat_start(struct seq_file *file, loff_t *offset)
{
        unsigned long n = *offset;

        if (n == 0)
                return (void *) 1;

        n--;

        if (n > 0)
                n = cpumask_next(n - 1, cpu_online_mask);
        else
                n = cpumask_first(cpu_online_mask);

        *offset = n + 1;

        if (n < nr_cpu_ids)
                return (void *)(unsigned long)(n + 2);

        return NULL;
}

static void *schedstat_next(struct seq_file *file, void *data, loff_t *offset)
{
        (*offset)++;

        return schedstat_start(file, offset);
}

static void schedstat_stop(struct seq_file *file, void *data)
{
}

static const struct seq_operations schedstat_sops = {
        .start = schedstat_start,
        .next  = schedstat_next,
        .stop  = schedstat_stop,
        .show  = show_schedstat,
};

static int __init proc_schedstat_init(void)
{
        proc_create_seq("schedstat", 0, NULL, &schedstat_sops);
        return 0;
}
subsys_initcall(proc_schedstat_init);