kernel/taskstats.c

   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 <linux/pid_namespace.h>
  31 #include <net/genetlink.h>
  32 #include <linux/atomic.h>
  33 #include <linux/sched/cputime.h>
  34
  35 /*
  36  * Maximum length of a cpumask that can be specified in
  37  * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
  38  */
  39 #define TASKSTATS_CPUMASK_MAXLEN        (100+6*NR_CPUS)
  40
  41 static DEFINE_PER_CPU(__u32, taskstats_seqnum);
  42 static int family_registered;
  43 struct kmem_cache *taskstats_cache;
  44
  45 static struct genl_family family;
  46
  47 static const struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
  48         [TASKSTATS_CMD_ATTR_PID]  = { .type = NLA_U32 },
  49         [TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
  50         [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
  51         [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
  52
  53 /*
  54  * We have to use TASKSTATS_CMD_ATTR_MAX here, it is the maxattr in the family.
  55  * Make sure they are always aligned.
  56  */
  57 static const struct nla_policy cgroupstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
  58         [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
  59 };
  60
  61 struct listener {
  62         struct list_head list;
  63         pid_t pid;
  64         char valid;
  65 };
  66
  67 struct listener_list {
  68         struct rw_semaphore sem;
  69         struct list_head list;
  70 };
  71 static DEFINE_PER_CPU(struct listener_list, listener_array);
  72
  73 enum actions {
  74         REGISTER,
  75         DEREGISTER,
  76         CPU_DONT_CARE
  77 };
  78
  79 static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
  80                                 size_t size)
  81 {
  82         struct sk_buff *skb;
  83         void *reply;
  84
  85         /*
  86          * If new attributes are added, please revisit this allocation
  87          */
  88         skb = genlmsg_new(size, GFP_KERNEL);
  89         if (!skb)
  90                 return -ENOMEM;
  91
  92         if (!info) {
  93                 int seq = this_cpu_inc_return(taskstats_seqnum) - 1;
  94
  95                 reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
  96         } else
  97                 reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
  98         if (reply == NULL) {
  99                 nlmsg_free(skb);
 100                 return -EINVAL;
 101         }
 102
 103         *skbp = skb;
 104         return 0;
 105 }
 106
 107 /*
 108  * Send taskstats data in @skb to listener with nl_pid @pid
 109  */
 110 static int send_reply(struct sk_buff *skb, struct genl_info *info)
 111 {
 112         struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
 113         void *reply = genlmsg_data(genlhdr);
 114
 115         genlmsg_end(skb, reply);
 116
 117         return genlmsg_reply(skb, info);
 118 }
 119
 120 /*
 121  * Send taskstats data in @skb to listeners registered for @cpu's exit data
 122  */
 123 static void send_cpu_listeners(struct sk_buff *skb,
 124                                         struct listener_list *listeners)
 125 {
 126         struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
 127         struct listener *s, *tmp;
 128         struct sk_buff *skb_next, *skb_cur = skb;
 129         void *reply = genlmsg_data(genlhdr);
 130         int rc, delcount = 0;
 131
 132         genlmsg_end(skb, reply);
 133
 134         rc = 0;
 135         down_read(&listeners->sem);
 136         list_for_each_entry(s, &listeners->list, list) {
 137                 skb_next = NULL;
 138                 if (!list_is_last(&s->list, &listeners->list)) {
 139                         skb_next = skb_clone(skb_cur, GFP_KERNEL);
 140                         if (!skb_next)
 141                                 break;
 142                 }
 143                 rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
 144                 if (rc == -ECONNREFUSED) {
 145                         s->valid = 0;
 146                         delcount++;
 147                 }
 148                 skb_cur = skb_next;
 149         }
 150         up_read(&listeners->sem);
 151
 152         if (skb_cur)
 153                 nlmsg_free(skb_cur);
 154
 155         if (!delcount)
 156                 return;
 157
 158         /* Delete invalidated entries */
 159         down_write(&listeners->sem);
 160         list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 161                 if (!s->valid) {
 162                         list_del(&s->list);
 163                         kfree(s);
 164                 }
 165         }
 166         up_write(&listeners->sem);
 167 }
 168
 169 static void fill_stats(struct user_namespace *user_ns,
 170                        struct pid_namespace *pid_ns,
 171                        struct task_struct *tsk, struct taskstats *stats)
 172 {
 173         memset(stats, 0, sizeof(*stats));
 174         /*
 175          * Each accounting subsystem adds calls to its functions to
 176          * fill in relevant parts of struct taskstsats as follows
 177          *
 178          *      per-task-foo(stats, tsk);
 179          */
 180
 181         delayacct_add_tsk(stats, tsk);
 182
 183         /* fill in basic acct fields */
 184         stats->version = TASKSTATS_VERSION;
 185         stats->nvcsw = tsk->nvcsw;
 186         stats->nivcsw = tsk->nivcsw;
 187         bacct_add_tsk(user_ns, pid_ns, stats, tsk);
 188
 189         /* fill in extended acct fields */
 190         xacct_add_tsk(stats, tsk);
 191 }
 192
 193 static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
 194 {
 195         struct task_struct *tsk;
 196
 197         tsk = find_get_task_by_vpid(pid);
 198         if (!tsk)
 199                 return -ESRCH;
 200         fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
 201         put_task_struct(tsk);
 202         return 0;
 203 }
 204
 205 static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
 206 {
 207         struct task_struct *tsk, *first;
 208         unsigned long flags;
 209         int rc = -ESRCH;
 210         u64 delta, utime, stime;
 211         u64 start_time;
 212
 213         /*
 214          * Add additional stats from live tasks except zombie thread group
 215          * leaders who are already counted with the dead tasks
 216          */
 217         rcu_read_lock();
 218         first = find_task_by_vpid(tgid);
 219
 220         if (!first || !lock_task_sighand(first, &flags))
 221                 goto out;
 222
 223         if (first->signal->stats)
 224                 memcpy(stats, first->signal->stats, sizeof(*stats));
 225         else
 226                 memset(stats, 0, sizeof(*stats));
 227
 228         tsk = first;
 229         start_time = ktime_get_ns();
 230         do {
 231                 if (tsk->exit_state)
 232                         continue;
 233                 /*
 234                  * Accounting subsystem can call its functions here to
 235                  * fill in relevant parts of struct taskstsats as follows
 236                  *
 237                  *      per-task-foo(stats, tsk);
 238                  */
 239                 delayacct_add_tsk(stats, tsk);
 240
 241                 /* calculate task elapsed time in nsec */
 242                 delta = start_time - tsk->start_time;
 243                 /* Convert to micro seconds */
 244                 do_div(delta, NSEC_PER_USEC);
 245                 stats->ac_etime += delta;
 246
 247                 task_cputime(tsk, &utime, &stime);
 248                 stats->ac_utime += div_u64(utime, NSEC_PER_USEC);
 249                 stats->ac_stime += div_u64(stime, NSEC_PER_USEC);
 250
 251                 stats->nvcsw += tsk->nvcsw;
 252                 stats->nivcsw += tsk->nivcsw;
 253         } while_each_thread(first, tsk);
 254
 255         unlock_task_sighand(first, &flags);
 256         rc = 0;
 257 out:
 258         rcu_read_unlock();
 259
 260         stats->version = TASKSTATS_VERSION;
 261         /*
 262          * Accounting subsystems can also add calls here to modify
 263          * fields of taskstats.
 264          */
 265         return rc;
 266 }
 267
 268 static void fill_tgid_exit(struct task_struct *tsk)
 269 {
 270         unsigned long flags;
 271
 272         spin_lock_irqsave(&tsk->sighand->siglock, flags);
 273         if (!tsk->signal->stats)
 274                 goto ret;
 275
 276         /*
 277          * Each accounting subsystem calls its functions here to
 278          * accumalate its per-task stats for tsk, into the per-tgid structure
 279          *
 280          *      per-task-foo(tsk->signal->stats, tsk);
 281          */
 282         delayacct_add_tsk(tsk->signal->stats, tsk);
 283 ret:
 284         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 285         return;
 286 }
 287
 288 static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
 289 {
 290         struct listener_list *listeners;
 291         struct listener *s, *tmp, *s2;
 292         unsigned int cpu;
 293         int ret = 0;
 294
 295         if (!cpumask_subset(mask, cpu_possible_mask))
 296                 return -EINVAL;
 297
 298         if (current_user_ns() != &init_user_ns)
 299                 return -EINVAL;
 300
 301         if (task_active_pid_ns(current) != &init_pid_ns)
 302                 return -EINVAL;
 303
 304         if (isadd == REGISTER) {
 305                 for_each_cpu(cpu, mask) {
 306                         s = kmalloc_node(sizeof(struct listener),
 307                                         GFP_KERNEL, cpu_to_node(cpu));
 308                         if (!s) {
 309                                 ret = -ENOMEM;
 310                                 goto cleanup;
 311                         }
 312                         s->pid = pid;
 313                         s->valid = 1;
 314
 315                         listeners = &per_cpu(listener_array, cpu);
 316                         down_write(&listeners->sem);
 317                         list_for_each_entry(s2, &listeners->list, list) {
 318                                 if (s2->pid == pid && s2->valid)
 319                                         goto exists;
 320                         }
 321                         list_add(&s->list, &listeners->list);
 322                         s = NULL;
 323 exists:
 324                         up_write(&listeners->sem);
 325                         kfree(s); /* nop if NULL */
 326                 }
 327                 return 0;
 328         }
 329
 330         /* Deregister or cleanup */
 331 cleanup:
 332         for_each_cpu(cpu, mask) {
 333                 listeners = &per_cpu(listener_array, cpu);
 334                 down_write(&listeners->sem);
 335                 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 336                         if (s->pid == pid) {
 337                                 list_del(&s->list);
 338                                 kfree(s);
 339                                 break;
 340                         }
 341                 }
 342                 up_write(&listeners->sem);
 343         }
 344         return ret;
 345 }
 346
 347 static int parse(struct nlattr *na, struct cpumask *mask)
 348 {
 349         char *data;
 350         int len;
 351         int ret;
 352
 353         if (na == NULL)
 354                 return 1;
 355         len = nla_len(na);
 356         if (len > TASKSTATS_CPUMASK_MAXLEN)
 357                 return -E2BIG;
 358         if (len < 1)
 359                 return -EINVAL;
 360         data = kmalloc(len, GFP_KERNEL);
 361         if (!data)
 362                 return -ENOMEM;
 363         nla_strlcpy(data, na, len);
 364         ret = cpulist_parse(data, mask);
 365         kfree(data);
 366         return ret;
 367 }
 368
 369 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
 370 {
 371         struct nlattr *na, *ret;
 372         int aggr;
 373
 374         aggr = (type == TASKSTATS_TYPE_PID)
 375                         ? TASKSTATS_TYPE_AGGR_PID
 376                         : TASKSTATS_TYPE_AGGR_TGID;
 377
 378         na = nla_nest_start_noflag(skb, aggr);
 379         if (!na)
 380                 goto err;
 381
 382         if (nla_put(skb, type, sizeof(pid), &pid) < 0) {
 383                 nla_nest_cancel(skb, na);
 384                 goto err;
 385         }
 386         ret = nla_reserve_64bit(skb, TASKSTATS_TYPE_STATS,
 387                                 sizeof(struct taskstats), TASKSTATS_TYPE_NULL);
 388         if (!ret) {
 389                 nla_nest_cancel(skb, na);
 390                 goto err;
 391         }
 392         nla_nest_end(skb, na);
 393
 394         return nla_data(ret);
 395 err:
 396         return NULL;
 397 }
 398
 399 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 400 {
 401         int rc = 0;
 402         struct sk_buff *rep_skb;
 403         struct cgroupstats *stats;
 404         struct nlattr *na;
 405         size_t size;
 406         u32 fd;
 407         struct fd f;
 408
 409         na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
 410         if (!na)
 411                 return -EINVAL;
 412
 413         fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
 414         f = fdget(fd);
 415         if (!f.file)
 416                 return 0;
 417
 418         size = nla_total_size(sizeof(struct cgroupstats));
 419
 420         rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
 421                                 size);
 422         if (rc < 0)
 423                 goto err;
 424
 425         na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
 426                                 sizeof(struct cgroupstats));
 427         if (na == NULL) {
 428                 nlmsg_free(rep_skb);
 429                 rc = -EMSGSIZE;
 430                 goto err;
 431         }
 432
 433         stats = nla_data(na);
 434         memset(stats, 0, sizeof(*stats));
 435
 436         rc = cgroupstats_build(stats, f.file->f_path.dentry);
 437         if (rc < 0) {
 438                 nlmsg_free(rep_skb);
 439                 goto err;
 440         }
 441
 442         rc = send_reply(rep_skb, info);
 443
 444 err:
 445         fdput(f);
 446         return rc;
 447 }
 448
 449 static int cmd_attr_register_cpumask(struct genl_info *info)
 450 {
 451         cpumask_var_t mask;
 452         int rc;
 453
 454         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 455                 return -ENOMEM;
 456         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
 457         if (rc < 0)
 458                 goto out;
 459         rc = add_del_listener(info->snd_portid, mask, REGISTER);
 460 out:
 461         free_cpumask_var(mask);
 462         return rc;
 463 }
 464
 465 static int cmd_attr_deregister_cpumask(struct genl_info *info)
 466 {
 467         cpumask_var_t mask;
 468         int rc;
 469
 470         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 471                 return -ENOMEM;
 472         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
 473         if (rc < 0)
 474                 goto out;
 475         rc = add_del_listener(info->snd_portid, mask, DEREGISTER);
 476 out:
 477         free_cpumask_var(mask);
 478         return rc;
 479 }
 480
 481 static size_t taskstats_packet_size(void)
 482 {
 483         size_t size;
 484
 485         size = nla_total_size(sizeof(u32)) +
 486                 nla_total_size_64bit(sizeof(struct taskstats)) +
 487                 nla_total_size(0);
 488
 489         return size;
 490 }
 491
 492 static int cmd_attr_pid(struct genl_info *info)
 493 {
 494         struct taskstats *stats;
 495         struct sk_buff *rep_skb;
 496         size_t size;
 497         u32 pid;
 498         int rc;
 499
 500         size = taskstats_packet_size();
 501
 502         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 503         if (rc < 0)
 504                 return rc;
 505
 506         rc = -EINVAL;
 507         pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 508         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
 509         if (!stats)
 510                 goto err;
 511
 512         rc = fill_stats_for_pid(pid, stats);
 513         if (rc < 0)
 514                 goto err;
 515         return send_reply(rep_skb, info);
 516 err:
 517         nlmsg_free(rep_skb);
 518         return rc;
 519 }
 520
 521 static int cmd_attr_tgid(struct genl_info *info)
 522 {
 523         struct taskstats *stats;
 524         struct sk_buff *rep_skb;
 525         size_t size;
 526         u32 tgid;
 527         int rc;
 528
 529         size = taskstats_packet_size();
 530
 531         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 532         if (rc < 0)
 533                 return rc;
 534
 535         rc = -EINVAL;
 536         tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 537         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 538         if (!stats)
 539                 goto err;
 540
 541         rc = fill_stats_for_tgid(tgid, stats);
 542         if (rc < 0)
 543                 goto err;
 544         return send_reply(rep_skb, info);
 545 err:
 546         nlmsg_free(rep_skb);
 547         return rc;
 548 }
 549
 550 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 551 {
 552         if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
 553                 return cmd_attr_register_cpumask(info);
 554         else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
 555                 return cmd_attr_deregister_cpumask(info);
 556         else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
 557                 return cmd_attr_pid(info);
 558         else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
 559                 return cmd_attr_tgid(info);
 560         else
 561                 return -EINVAL;
 562 }
 563
 564 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
 565 {
 566         struct signal_struct *sig = tsk->signal;
 567         struct taskstats *stats;
 568
 569         if (sig->stats || thread_group_empty(tsk))
 570                 goto ret;
 571
 572         /* No problem if kmem_cache_zalloc() fails */
 573         stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
 574
 575         spin_lock_irq(&tsk->sighand->siglock);
 576         if (!sig->stats) {
 577                 sig->stats = stats;
 578                 stats = NULL;
 579         }
 580         spin_unlock_irq(&tsk->sighand->siglock);
 581
 582         if (stats)
 583                 kmem_cache_free(taskstats_cache, stats);
 584 ret:
 585         return sig->stats;
 586 }
 587
 588 /* Send pid data out on exit */
 589 void taskstats_exit(struct task_struct *tsk, int group_dead)
 590 {
 591         int rc;
 592         struct listener_list *listeners;
 593         struct taskstats *stats;
 594         struct sk_buff *rep_skb;
 595         size_t size;
 596         int is_thread_group;
 597
 598         if (!family_registered)
 599                 return;
 600
 601         /*
 602          * Size includes space for nested attributes
 603          */
 604         size = taskstats_packet_size();
 605
 606         is_thread_group = !!taskstats_tgid_alloc(tsk);
 607         if (is_thread_group) {
 608                 /* PID + STATS + TGID + STATS */
 609                 size = 2 * size;
 610                 /* fill the tsk->signal->stats structure */
 611                 fill_tgid_exit(tsk);
 612         }
 613
 614         listeners = raw_cpu_ptr(&listener_array);
 615         if (list_empty(&listeners->list))
 616                 return;
 617
 618         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
 619         if (rc < 0)
 620                 return;
 621
 622         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID,
 623                          task_pid_nr_ns(tsk, &init_pid_ns));
 624         if (!stats)
 625                 goto err;
 626
 627         fill_stats(&init_user_ns, &init_pid_ns, tsk, stats);
 628
 629         /*
 630          * Doesn't matter if tsk is the leader or the last group member leaving
 631          */
 632         if (!is_thread_group || !group_dead)
 633                 goto send;
 634
 635         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID,
 636                          task_tgid_nr_ns(tsk, &init_pid_ns));
 637         if (!stats)
 638                 goto err;
 639
 640         memcpy(stats, tsk->signal->stats, sizeof(*stats));
 641
 642 send:
 643         send_cpu_listeners(rep_skb, listeners);
 644         return;
 645 err:
 646         nlmsg_free(rep_skb);
 647 }
 648
 649 static const struct genl_ops taskstats_ops[] = {
 650         {
 651                 .cmd            = TASKSTATS_CMD_GET,
 652                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 653                 .doit           = taskstats_user_cmd,
 654                 /* policy enforced later */
 655                 .flags          = GENL_ADMIN_PERM | GENL_CMD_CAP_HASPOL,
 656         },
 657         {
 658                 .cmd            = CGROUPSTATS_CMD_GET,
 659                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 660                 .doit           = cgroupstats_user_cmd,
 661                 /* policy enforced later */
 662                 .flags          = GENL_CMD_CAP_HASPOL,
 663         },
 664 };
 665
 666 static int taskstats_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
 667                               struct genl_info *info)
 668 {
 669         const struct nla_policy *policy = NULL;
 670
 671         switch (ops->cmd) {
 672         case TASKSTATS_CMD_GET:
 673                 policy = taskstats_cmd_get_policy;
 674                 break;
 675         case CGROUPSTATS_CMD_GET:
 676                 policy = cgroupstats_cmd_get_policy;
 677                 break;
 678         default:
 679                 return -EINVAL;
 680         }
 681
 682         return nlmsg_validate_deprecated(info->nlhdr, GENL_HDRLEN,
 683                                          TASKSTATS_CMD_ATTR_MAX, policy,
 684                                          info->extack);
 685 }
 686
 687 static struct genl_family family __ro_after_init = {
 688         .name           = TASKSTATS_GENL_NAME,
 689         .version        = TASKSTATS_GENL_VERSION,
 690         .maxattr        = TASKSTATS_CMD_ATTR_MAX,
 691         .module         = THIS_MODULE,
 692         .ops            = taskstats_ops,
 693         .n_ops          = ARRAY_SIZE(taskstats_ops),
 694         .pre_doit       = taskstats_pre_doit,
 695 };
 696
 697 /* Needed early in initialization */
 698 void __init taskstats_init_early(void)
 699 {
 700         unsigned int i;
 701
 702         taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
 703         for_each_possible_cpu(i) {
 704                 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 705                 init_rwsem(&(per_cpu(listener_array, i).sem));
 706         }
 707 }
 708
 709 static int __init taskstats_init(void)
 710 {
 711         int rc;
 712
 713         rc = genl_register_family(&family);
 714         if (rc)
 715                 return rc;
 716
 717         family_registered = 1;
 718         pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
 719         return 0;
 720 }
 721
 722 /*
 723  * late initcall ensures initialization of statistics collection
 724  * mechanisms precedes initialization of the taskstats interface
 725  */
 726 late_initcall(taskstats_init);