linux/kernel/taskstats.c
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   1/*
   2 * taskstats.c - Export per-task statistics to userland
   3 *
   4 * Copyright (C) Shailabh Nagar, IBM Corp. 2006
   5 *           (C) Balbir Singh,   IBM Corp. 2006
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License as published by
   9 * the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 */
  18
  19#include <linux/kernel.h>
  20#include <linux/taskstats_kern.h>
  21#include <linux/tsacct_kern.h>
  22#include <linux/delayacct.h>
  23#include <linux/cpumask.h>
  24#include <linux/percpu.h>
  25#include <linux/slab.h>
  26#include <linux/cgroupstats.h>
  27#include <linux/cgroup.h>
  28#include <linux/fs.h>
  29#include <linux/file.h>
  30#include <net/genetlink.h>
  31#include <linux/atomic.h>
  32
  33/*
  34 * Maximum length of a cpumask that can be specified in
  35 * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
  36 */
  37#define TASKSTATS_CPUMASK_MAXLEN        (100+6*NR_CPUS)
  38
  39static DEFINE_PER_CPU(__u32, taskstats_seqnum);
  40static int family_registered;
  41struct kmem_cache *taskstats_cache;
  42
  43static struct genl_family family = {
  44        .id             = GENL_ID_GENERATE,
  45        .name           = TASKSTATS_GENL_NAME,
  46        .version        = TASKSTATS_GENL_VERSION,
  47        .maxattr        = TASKSTATS_CMD_ATTR_MAX,
  48};
  49
  50static const struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
  51        [TASKSTATS_CMD_ATTR_PID]  = { .type = NLA_U32 },
  52        [TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
  53        [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
  54        [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
  55
  56static const struct nla_policy cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] = {
  57        [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
  58};
  59
  60struct listener {
  61        struct list_head list;
  62        pid_t pid;
  63        char valid;
  64};
  65
  66struct listener_list {
  67        struct rw_semaphore sem;
  68        struct list_head list;
  69};
  70static DEFINE_PER_CPU(struct listener_list, listener_array);
  71
  72enum actions {
  73        REGISTER,
  74        DEREGISTER,
  75        CPU_DONT_CARE
  76};
  77
  78static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
  79                                size_t size)
  80{
  81        struct sk_buff *skb;
  82        void *reply;
  83
  84        /*
  85         * If new attributes are added, please revisit this allocation
  86         */
  87        skb = genlmsg_new(size, GFP_KERNEL);
  88        if (!skb)
  89                return -ENOMEM;
  90
  91        if (!info) {
  92                int seq = this_cpu_inc_return(taskstats_seqnum) - 1;
  93
  94                reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
  95        } else
  96                reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
  97        if (reply == NULL) {
  98                nlmsg_free(skb);
  99                return -EINVAL;
 100        }
 101
 102        *skbp = skb;
 103        return 0;
 104}
 105
 106/*
 107 * Send taskstats data in @skb to listener with nl_pid @pid
 108 */
 109static int send_reply(struct sk_buff *skb, struct genl_info *info)
 110{
 111        struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
 112        void *reply = genlmsg_data(genlhdr);
 113        int rc;
 114
 115        rc = genlmsg_end(skb, reply);
 116        if (rc < 0) {
 117                nlmsg_free(skb);
 118                return rc;
 119        }
 120
 121        return genlmsg_reply(skb, info);
 122}
 123
 124/*
 125 * Send taskstats data in @skb to listeners registered for @cpu's exit data
 126 */
 127static void send_cpu_listeners(struct sk_buff *skb,
 128                                        struct listener_list *listeners)
 129{
 130        struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
 131        struct listener *s, *tmp;
 132        struct sk_buff *skb_next, *skb_cur = skb;
 133        void *reply = genlmsg_data(genlhdr);
 134        int rc, delcount = 0;
 135
 136        rc = genlmsg_end(skb, reply);
 137        if (rc < 0) {
 138                nlmsg_free(skb);
 139                return;
 140        }
 141
 142        rc = 0;
 143        down_read(&listeners->sem);
 144        list_for_each_entry(s, &listeners->list, list) {
 145                skb_next = NULL;
 146                if (!list_is_last(&s->list, &listeners->list)) {
 147                        skb_next = skb_clone(skb_cur, GFP_KERNEL);
 148                        if (!skb_next)
 149                                break;
 150                }
 151                rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
 152                if (rc == -ECONNREFUSED) {
 153                        s->valid = 0;
 154                        delcount++;
 155                }
 156                skb_cur = skb_next;
 157        }
 158        up_read(&listeners->sem);
 159
 160        if (skb_cur)
 161                nlmsg_free(skb_cur);
 162
 163        if (!delcount)
 164                return;
 165
 166        /* Delete invalidated entries */
 167        down_write(&listeners->sem);
 168        list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 169                if (!s->valid) {
 170                        list_del(&s->list);
 171                        kfree(s);
 172                }
 173        }
 174        up_write(&listeners->sem);
 175}
 176
 177static void fill_stats(struct task_struct *tsk, struct taskstats *stats)
 178{
 179        memset(stats, 0, sizeof(*stats));
 180        /*
 181         * Each accounting subsystem adds calls to its functions to
 182         * fill in relevant parts of struct taskstsats as follows
 183         *
 184         *      per-task-foo(stats, tsk);
 185         */
 186
 187        delayacct_add_tsk(stats, tsk);
 188
 189        /* fill in basic acct fields */
 190        stats->version = TASKSTATS_VERSION;
 191        stats->nvcsw = tsk->nvcsw;
 192        stats->nivcsw = tsk->nivcsw;
 193        bacct_add_tsk(stats, tsk);
 194
 195        /* fill in extended acct fields */
 196        xacct_add_tsk(stats, tsk);
 197}
 198
 199static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
 200{
 201        struct task_struct *tsk;
 202
 203        rcu_read_lock();
 204        tsk = find_task_by_vpid(pid);
 205        if (tsk)
 206                get_task_struct(tsk);
 207        rcu_read_unlock();
 208        if (!tsk)
 209                return -ESRCH;
 210        fill_stats(tsk, stats);
 211        put_task_struct(tsk);
 212        return 0;
 213}
 214
 215static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
 216{
 217        struct task_struct *tsk, *first;
 218        unsigned long flags;
 219        int rc = -ESRCH;
 220
 221        /*
 222         * Add additional stats from live tasks except zombie thread group
 223         * leaders who are already counted with the dead tasks
 224         */
 225        rcu_read_lock();
 226        first = find_task_by_vpid(tgid);
 227
 228        if (!first || !lock_task_sighand(first, &flags))
 229                goto out;
 230
 231        if (first->signal->stats)
 232                memcpy(stats, first->signal->stats, sizeof(*stats));
 233        else
 234                memset(stats, 0, sizeof(*stats));
 235
 236        tsk = first;
 237        do {
 238                if (tsk->exit_state)
 239                        continue;
 240                /*
 241                 * Accounting subsystem can call its functions here to
 242                 * fill in relevant parts of struct taskstsats as follows
 243                 *
 244                 *      per-task-foo(stats, tsk);
 245                 */
 246                delayacct_add_tsk(stats, tsk);
 247
 248                stats->nvcsw += tsk->nvcsw;
 249                stats->nivcsw += tsk->nivcsw;
 250        } while_each_thread(first, tsk);
 251
 252        unlock_task_sighand(first, &flags);
 253        rc = 0;
 254out:
 255        rcu_read_unlock();
 256
 257        stats->version = TASKSTATS_VERSION;
 258        /*
 259         * Accounting subsystems can also add calls here to modify
 260         * fields of taskstats.
 261         */
 262        return rc;
 263}
 264
 265static void fill_tgid_exit(struct task_struct *tsk)
 266{
 267        unsigned long flags;
 268
 269        spin_lock_irqsave(&tsk->sighand->siglock, flags);
 270        if (!tsk->signal->stats)
 271                goto ret;
 272
 273        /*
 274         * Each accounting subsystem calls its functions here to
 275         * accumalate its per-task stats for tsk, into the per-tgid structure
 276         *
 277         *      per-task-foo(tsk->signal->stats, tsk);
 278         */
 279        delayacct_add_tsk(tsk->signal->stats, tsk);
 280ret:
 281        spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 282        return;
 283}
 284
 285static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
 286{
 287        struct listener_list *listeners;
 288        struct listener *s, *tmp, *s2;
 289        unsigned int cpu;
 290
 291        if (!cpumask_subset(mask, cpu_possible_mask))
 292                return -EINVAL;
 293
 294        if (isadd == REGISTER) {
 295                for_each_cpu(cpu, mask) {
 296                        s = kmalloc_node(sizeof(struct listener),
 297                                        GFP_KERNEL, cpu_to_node(cpu));
 298                        if (!s)
 299                                goto cleanup;
 300
 301                        s->pid = pid;
 302                        s->valid = 1;
 303
 304                        listeners = &per_cpu(listener_array, cpu);
 305                        down_write(&listeners->sem);
 306                        list_for_each_entry(s2, &listeners->list, list) {
 307                                if (s2->pid == pid && s2->valid)
 308                                        goto exists;
 309                        }
 310                        list_add(&s->list, &listeners->list);
 311                        s = NULL;
 312exists:
 313                        up_write(&listeners->sem);
 314                        kfree(s); /* nop if NULL */
 315                }
 316                return 0;
 317        }
 318
 319        /* Deregister or cleanup */
 320cleanup:
 321        for_each_cpu(cpu, mask) {
 322                listeners = &per_cpu(listener_array, cpu);
 323                down_write(&listeners->sem);
 324                list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 325                        if (s->pid == pid) {
 326                                list_del(&s->list);
 327                                kfree(s);
 328                                break;
 329                        }
 330                }
 331                up_write(&listeners->sem);
 332        }
 333        return 0;
 334}
 335
 336static int parse(struct nlattr *na, struct cpumask *mask)
 337{
 338        char *data;
 339        int len;
 340        int ret;
 341
 342        if (na == NULL)
 343                return 1;
 344        len = nla_len(na);
 345        if (len > TASKSTATS_CPUMASK_MAXLEN)
 346                return -E2BIG;
 347        if (len < 1)
 348                return -EINVAL;
 349        data = kmalloc(len, GFP_KERNEL);
 350        if (!data)
 351                return -ENOMEM;
 352        nla_strlcpy(data, na, len);
 353        ret = cpulist_parse(data, mask);
 354        kfree(data);
 355        return ret;
 356}
 357
 358#if defined(CONFIG_64BIT) && !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 359#define TASKSTATS_NEEDS_PADDING 1
 360#endif
 361
 362static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
 363{
 364        struct nlattr *na, *ret;
 365        int aggr;
 366
 367        aggr = (type == TASKSTATS_TYPE_PID)
 368                        ? TASKSTATS_TYPE_AGGR_PID
 369                        : TASKSTATS_TYPE_AGGR_TGID;
 370
 371        /*
 372         * The taskstats structure is internally aligned on 8 byte
 373         * boundaries but the layout of the aggregrate reply, with
 374         * two NLA headers and the pid (each 4 bytes), actually
 375         * force the entire structure to be unaligned. This causes
 376         * the kernel to issue unaligned access warnings on some
 377         * architectures like ia64. Unfortunately, some software out there
 378         * doesn't properly unroll the NLA packet and assumes that the start
 379         * of the taskstats structure will always be 20 bytes from the start
 380         * of the netlink payload. Aligning the start of the taskstats
 381         * structure breaks this software, which we don't want. So, for now
 382         * the alignment only happens on architectures that require it
 383         * and those users will have to update to fixed versions of those
 384         * packages. Space is reserved in the packet only when needed.
 385         * This ifdef should be removed in several years e.g. 2012 once
 386         * we can be confident that fixed versions are installed on most
 387         * systems. We add the padding before the aggregate since the
 388         * aggregate is already a defined type.
 389         */
 390#ifdef TASKSTATS_NEEDS_PADDING
 391        if (nla_put(skb, TASKSTATS_TYPE_NULL, 0, NULL) < 0)
 392                goto err;
 393#endif
 394        na = nla_nest_start(skb, aggr);
 395        if (!na)
 396                goto err;
 397
 398        if (nla_put(skb, type, sizeof(pid), &pid) < 0)
 399                goto err;
 400        ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
 401        if (!ret)
 402                goto err;
 403        nla_nest_end(skb, na);
 404
 405        return nla_data(ret);
 406err:
 407        return NULL;
 408}
 409
 410static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 411{
 412        int rc = 0;
 413        struct sk_buff *rep_skb;
 414        struct cgroupstats *stats;
 415        struct nlattr *na;
 416        size_t size;
 417        u32 fd;
 418        struct file *file;
 419        int fput_needed;
 420
 421        na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
 422        if (!na)
 423                return -EINVAL;
 424
 425        fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
 426        file = fget_light(fd, &fput_needed);
 427        if (!file)
 428                return 0;
 429
 430        size = nla_total_size(sizeof(struct cgroupstats));
 431
 432        rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
 433                                size);
 434        if (rc < 0)
 435                goto err;
 436
 437        na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
 438                                sizeof(struct cgroupstats));
 439        stats = nla_data(na);
 440        memset(stats, 0, sizeof(*stats));
 441
 442        rc = cgroupstats_build(stats, file->f_dentry);
 443        if (rc < 0) {
 444                nlmsg_free(rep_skb);
 445                goto err;
 446        }
 447
 448        rc = send_reply(rep_skb, info);
 449
 450err:
 451        fput_light(file, fput_needed);
 452        return rc;
 453}
 454
 455static int cmd_attr_register_cpumask(struct genl_info *info)
 456{
 457        cpumask_var_t mask;
 458        int rc;
 459
 460        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 461                return -ENOMEM;
 462        rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
 463        if (rc < 0)
 464                goto out;
 465        rc = add_del_listener(info->snd_pid, mask, REGISTER);
 466out:
 467        free_cpumask_var(mask);
 468        return rc;
 469}
 470
 471static int cmd_attr_deregister_cpumask(struct genl_info *info)
 472{
 473        cpumask_var_t mask;
 474        int rc;
 475
 476        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 477                return -ENOMEM;
 478        rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
 479        if (rc < 0)
 480                goto out;
 481        rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
 482out:
 483        free_cpumask_var(mask);
 484        return rc;
 485}
 486
 487static size_t taskstats_packet_size(void)
 488{
 489        size_t size;
 490
 491        size = nla_total_size(sizeof(u32)) +
 492                nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 493#ifdef TASKSTATS_NEEDS_PADDING
 494        size += nla_total_size(0); /* Padding for alignment */
 495#endif
 496        return size;
 497}
 498
 499static int cmd_attr_pid(struct genl_info *info)
 500{
 501        struct taskstats *stats;
 502        struct sk_buff *rep_skb;
 503        size_t size;
 504        u32 pid;
 505        int rc;
 506
 507        size = taskstats_packet_size();
 508
 509        rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 510        if (rc < 0)
 511                return rc;
 512
 513        rc = -EINVAL;
 514        pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 515        stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
 516        if (!stats)
 517                goto err;
 518
 519        rc = fill_stats_for_pid(pid, stats);
 520        if (rc < 0)
 521                goto err;
 522        return send_reply(rep_skb, info);
 523err:
 524        nlmsg_free(rep_skb);
 525        return rc;
 526}
 527
 528static int cmd_attr_tgid(struct genl_info *info)
 529{
 530        struct taskstats *stats;
 531        struct sk_buff *rep_skb;
 532        size_t size;
 533        u32 tgid;
 534        int rc;
 535
 536        size = taskstats_packet_size();
 537
 538        rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 539        if (rc < 0)
 540                return rc;
 541
 542        rc = -EINVAL;
 543        tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 544        stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 545        if (!stats)
 546                goto err;
 547
 548        rc = fill_stats_for_tgid(tgid, stats);
 549        if (rc < 0)
 550                goto err;
 551        return send_reply(rep_skb, info);
 552err:
 553        nlmsg_free(rep_skb);
 554        return rc;
 555}
 556
 557static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 558{
 559        if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
 560                return cmd_attr_register_cpumask(info);
 561        else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
 562                return cmd_attr_deregister_cpumask(info);
 563        else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
 564                return cmd_attr_pid(info);
 565        else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
 566                return cmd_attr_tgid(info);
 567        else
 568                return -EINVAL;
 569}
 570
 571static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
 572{
 573        struct signal_struct *sig = tsk->signal;
 574        struct taskstats *stats;
 575
 576        if (sig->stats || thread_group_empty(tsk))
 577                goto ret;
 578
 579        /* No problem if kmem_cache_zalloc() fails */
 580        stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
 581
 582        spin_lock_irq(&tsk->sighand->siglock);
 583        if (!sig->stats) {
 584                sig->stats = stats;
 585                stats = NULL;
 586        }
 587        spin_unlock_irq(&tsk->sighand->siglock);
 588
 589        if (stats)
 590                kmem_cache_free(taskstats_cache, stats);
 591ret:
 592        return sig->stats;
 593}
 594
 595/* Send pid data out on exit */
 596void taskstats_exit(struct task_struct *tsk, int group_dead)
 597{
 598        int rc;
 599        struct listener_list *listeners;
 600        struct taskstats *stats;
 601        struct sk_buff *rep_skb;
 602        size_t size;
 603        int is_thread_group;
 604
 605        if (!family_registered)
 606                return;
 607
 608        /*
 609         * Size includes space for nested attributes
 610         */
 611        size = taskstats_packet_size();
 612
 613        is_thread_group = !!taskstats_tgid_alloc(tsk);
 614        if (is_thread_group) {
 615                /* PID + STATS + TGID + STATS */
 616                size = 2 * size;
 617                /* fill the tsk->signal->stats structure */
 618                fill_tgid_exit(tsk);
 619        }
 620
 621        listeners = __this_cpu_ptr(&listener_array);
 622        if (list_empty(&listeners->list))
 623                return;
 624
 625        rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
 626        if (rc < 0)
 627                return;
 628
 629        stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
 630        if (!stats)
 631                goto err;
 632
 633        fill_stats(tsk, stats);
 634
 635        /*
 636         * Doesn't matter if tsk is the leader or the last group member leaving
 637         */
 638        if (!is_thread_group || !group_dead)
 639                goto send;
 640
 641        stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
 642        if (!stats)
 643                goto err;
 644
 645        memcpy(stats, tsk->signal->stats, sizeof(*stats));
 646
 647send:
 648        send_cpu_listeners(rep_skb, listeners);
 649        return;
 650err:
 651        nlmsg_free(rep_skb);
 652}
 653
 654static struct genl_ops taskstats_ops = {
 655        .cmd            = TASKSTATS_CMD_GET,
 656        .doit           = taskstats_user_cmd,
 657        .policy         = taskstats_cmd_get_policy,
 658        .flags          = GENL_ADMIN_PERM,
 659};
 660
 661static struct genl_ops cgroupstats_ops = {
 662        .cmd            = CGROUPSTATS_CMD_GET,
 663        .doit           = cgroupstats_user_cmd,
 664        .policy         = cgroupstats_cmd_get_policy,
 665};
 666
 667/* Needed early in initialization */
 668void __init taskstats_init_early(void)
 669{
 670        unsigned int i;
 671
 672        taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
 673        for_each_possible_cpu(i) {
 674                INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 675                init_rwsem(&(per_cpu(listener_array, i).sem));
 676        }
 677}
 678
 679static int __init taskstats_init(void)
 680{
 681        int rc;
 682
 683        rc = genl_register_family(&family);
 684        if (rc)
 685                return rc;
 686
 687        rc = genl_register_ops(&family, &taskstats_ops);
 688        if (rc < 0)
 689                goto err;
 690
 691        rc = genl_register_ops(&family, &cgroupstats_ops);
 692        if (rc < 0)
 693                goto err_cgroup_ops;
 694
 695        family_registered = 1;
 696        pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
 697        return 0;
 698err_cgroup_ops:
 699        genl_unregister_ops(&family, &taskstats_ops);
 700err:
 701        genl_unregister_family(&family);
 702        return rc;
 703}
 704
 705/*
 706 * late initcall ensures initialization of statistics collection
 707 * mechanisms precedes initialization of the taskstats interface
 708 */
 709late_initcall(taskstats_init);
 710
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