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 <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
  39 static DEFINE_PER_CPU(__u32, taskstats_seqnum);
  40 static int family_registered;
  41 struct kmem_cache *taskstats_cache;
  42
  43 static 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
  50 static 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
  56 static const struct nla_policy cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] = {
  57         [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
  58 };
  59
  60 struct listener {
  61         struct list_head list;
  62         pid_t pid;
  63         char valid;
  64 };
  65
  66 struct listener_list {
  67         struct rw_semaphore sem;
  68         struct list_head list;
  69 };
  70 static DEFINE_PER_CPU(struct listener_list, listener_array);
  71
  72 enum actions {
  73         REGISTER,
  74         DEREGISTER,
  75         CPU_DONT_CARE
  76 };
  77
  78 static 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  */
 109 static 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  */
 127 static 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
 177 static 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
 199 static 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
 215 static 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;
 254 out:
 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
 265 static 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);
 280 ret:
 281         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 282         return;
 283 }
 284
 285 static 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         s = NULL;
 295         if (isadd == REGISTER) {
 296                 for_each_cpu(cpu, mask) {
 297                         if (!s)
 298                                 s = kmalloc_node(sizeof(struct listener),
 299                                                  GFP_KERNEL, cpu_to_node(cpu));
 300                         if (!s)
 301                                 goto cleanup;
 302                         s->pid = pid;
 303                         INIT_LIST_HEAD(&s->list);
 304                         s->valid = 1;
 305
 306                         listeners = &per_cpu(listener_array, cpu);
 307                         down_write(&listeners->sem);
 308                         list_for_each_entry_safe(s2, tmp, &listeners->list, list) {
 309                                 if (s2->pid == pid)
 310                                         goto next_cpu;
 311                         }
 312                         list_add(&s->list, &listeners->list);
 313                         s = NULL;
 314 next_cpu:
 315                         up_write(&listeners->sem);
 316                 }
 317                 kfree(s);
 318                 return 0;
 319         }
 320
 321         /* Deregister or cleanup */
 322 cleanup:
 323         for_each_cpu(cpu, mask) {
 324                 listeners = &per_cpu(listener_array, cpu);
 325                 down_write(&listeners->sem);
 326                 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 327                         if (s->pid == pid) {
 328                                 list_del(&s->list);
 329                                 kfree(s);
 330                                 break;
 331                         }
 332                 }
 333                 up_write(&listeners->sem);
 334         }
 335         return 0;
 336 }
 337
 338 static int parse(struct nlattr *na, struct cpumask *mask)
 339 {
 340         char *data;
 341         int len;
 342         int ret;
 343
 344         if (na == NULL)
 345                 return 1;
 346         len = nla_len(na);
 347         if (len > TASKSTATS_CPUMASK_MAXLEN)
 348                 return -E2BIG;
 349         if (len < 1)
 350                 return -EINVAL;
 351         data = kmalloc(len, GFP_KERNEL);
 352         if (!data)
 353                 return -ENOMEM;
 354         nla_strlcpy(data, na, len);
 355         ret = cpulist_parse(data, mask);
 356         kfree(data);
 357         return ret;
 358 }
 359
 360 #if defined(CONFIG_64BIT) && !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 361 #define TASKSTATS_NEEDS_PADDING 1
 362 #endif
 363
 364 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
 365 {
 366         struct nlattr *na, *ret;
 367         int aggr;
 368
 369         aggr = (type == TASKSTATS_TYPE_PID)
 370                         ? TASKSTATS_TYPE_AGGR_PID
 371                         : TASKSTATS_TYPE_AGGR_TGID;
 372
 373         /*
 374          * The taskstats structure is internally aligned on 8 byte
 375          * boundaries but the layout of the aggregrate reply, with
 376          * two NLA headers and the pid (each 4 bytes), actually
 377          * force the entire structure to be unaligned. This causes
 378          * the kernel to issue unaligned access warnings on some
 379          * architectures like ia64. Unfortunately, some software out there
 380          * doesn't properly unroll the NLA packet and assumes that the start
 381          * of the taskstats structure will always be 20 bytes from the start
 382          * of the netlink payload. Aligning the start of the taskstats
 383          * structure breaks this software, which we don't want. So, for now
 384          * the alignment only happens on architectures that require it
 385          * and those users will have to update to fixed versions of those
 386          * packages. Space is reserved in the packet only when needed.
 387          * This ifdef should be removed in several years e.g. 2012 once
 388          * we can be confident that fixed versions are installed on most
 389          * systems. We add the padding before the aggregate since the
 390          * aggregate is already a defined type.
 391          */
 392 #ifdef TASKSTATS_NEEDS_PADDING
 393         if (nla_put(skb, TASKSTATS_TYPE_NULL, 0, NULL) < 0)
 394                 goto err;
 395 #endif
 396         na = nla_nest_start(skb, aggr);
 397         if (!na)
 398                 goto err;
 399
 400         if (nla_put(skb, type, sizeof(pid), &pid) < 0)
 401                 goto err;
 402         ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
 403         if (!ret)
 404                 goto err;
 405         nla_nest_end(skb, na);
 406
 407         return nla_data(ret);
 408 err:
 409         return NULL;
 410 }
 411
 412 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 413 {
 414         int rc = 0;
 415         struct sk_buff *rep_skb;
 416         struct cgroupstats *stats;
 417         struct nlattr *na;
 418         size_t size;
 419         u32 fd;
 420         struct file *file;
 421         int fput_needed;
 422
 423         na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
 424         if (!na)
 425                 return -EINVAL;
 426
 427         fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
 428         file = fget_light(fd, &fput_needed);
 429         if (!file)
 430                 return 0;
 431
 432         size = nla_total_size(sizeof(struct cgroupstats));
 433
 434         rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
 435                                 size);
 436         if (rc < 0)
 437                 goto err;
 438
 439         na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
 440                                 sizeof(struct cgroupstats));
 441         stats = nla_data(na);
 442         memset(stats, 0, sizeof(*stats));
 443
 444         rc = cgroupstats_build(stats, file->f_dentry);
 445         if (rc < 0) {
 446                 nlmsg_free(rep_skb);
 447                 goto err;
 448         }
 449
 450         rc = send_reply(rep_skb, info);
 451
 452 err:
 453         fput_light(file, fput_needed);
 454         return rc;
 455 }
 456
 457 static int cmd_attr_register_cpumask(struct genl_info *info)
 458 {
 459         cpumask_var_t mask;
 460         int rc;
 461
 462         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 463                 return -ENOMEM;
 464         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
 465         if (rc < 0)
 466                 goto out;
 467         rc = add_del_listener(info->snd_pid, mask, REGISTER);
 468 out:
 469         free_cpumask_var(mask);
 470         return rc;
 471 }
 472
 473 static int cmd_attr_deregister_cpumask(struct genl_info *info)
 474 {
 475         cpumask_var_t mask;
 476         int rc;
 477
 478         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 479                 return -ENOMEM;
 480         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
 481         if (rc < 0)
 482                 goto out;
 483         rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
 484 out:
 485         free_cpumask_var(mask);
 486         return rc;
 487 }
 488
 489 static size_t taskstats_packet_size(void)
 490 {
 491         size_t size;
 492
 493         size = nla_total_size(sizeof(u32)) +
 494                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 495 #ifdef TASKSTATS_NEEDS_PADDING
 496         size += nla_total_size(0); /* Padding for alignment */
 497 #endif
 498         return size;
 499 }
 500
 501 static int cmd_attr_pid(struct genl_info *info)
 502 {
 503         struct taskstats *stats;
 504         struct sk_buff *rep_skb;
 505         size_t size;
 506         u32 pid;
 507         int rc;
 508
 509         size = taskstats_packet_size();
 510
 511         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 512         if (rc < 0)
 513                 return rc;
 514
 515         rc = -EINVAL;
 516         pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 517         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
 518         if (!stats)
 519                 goto err;
 520
 521         rc = fill_stats_for_pid(pid, stats);
 522         if (rc < 0)
 523                 goto err;
 524         return send_reply(rep_skb, info);
 525 err:
 526         nlmsg_free(rep_skb);
 527         return rc;
 528 }
 529
 530 static int cmd_attr_tgid(struct genl_info *info)
 531 {
 532         struct taskstats *stats;
 533         struct sk_buff *rep_skb;
 534         size_t size;
 535         u32 tgid;
 536         int rc;
 537
 538         size = taskstats_packet_size();
 539
 540         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 541         if (rc < 0)
 542                 return rc;
 543
 544         rc = -EINVAL;
 545         tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 546         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 547         if (!stats)
 548                 goto err;
 549
 550         rc = fill_stats_for_tgid(tgid, stats);
 551         if (rc < 0)
 552                 goto err;
 553         return send_reply(rep_skb, info);
 554 err:
 555         nlmsg_free(rep_skb);
 556         return rc;
 557 }
 558
 559 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 560 {
 561         if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
 562                 return cmd_attr_register_cpumask(info);
 563         else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
 564                 return cmd_attr_deregister_cpumask(info);
 565         else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
 566                 return cmd_attr_pid(info);
 567         else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
 568                 return cmd_attr_tgid(info);
 569         else
 570                 return -EINVAL;
 571 }
 572
 573 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
 574 {
 575         struct signal_struct *sig = tsk->signal;
 576         struct taskstats *stats;
 577
 578         if (sig->stats || thread_group_empty(tsk))
 579                 goto ret;
 580
 581         /* No problem if kmem_cache_zalloc() fails */
 582         stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
 583
 584         spin_lock_irq(&tsk->sighand->siglock);
 585         if (!sig->stats) {
 586                 sig->stats = stats;
 587                 stats = NULL;
 588         }
 589         spin_unlock_irq(&tsk->sighand->siglock);
 590
 591         if (stats)
 592                 kmem_cache_free(taskstats_cache, stats);
 593 ret:
 594         return sig->stats;
 595 }
 596
 597 /* Send pid data out on exit */
 598 void taskstats_exit(struct task_struct *tsk, int group_dead)
 599 {
 600         int rc;
 601         struct listener_list *listeners;
 602         struct taskstats *stats;
 603         struct sk_buff *rep_skb;
 604         size_t size;
 605         int is_thread_group;
 606
 607         if (!family_registered)
 608                 return;
 609
 610         /*
 611          * Size includes space for nested attributes
 612          */
 613         size = taskstats_packet_size();
 614
 615         is_thread_group = !!taskstats_tgid_alloc(tsk);
 616         if (is_thread_group) {
 617                 /* PID + STATS + TGID + STATS */
 618                 size = 2 * size;
 619                 /* fill the tsk->signal->stats structure */
 620                 fill_tgid_exit(tsk);
 621         }
 622
 623         listeners = __this_cpu_ptr(&listener_array);
 624         if (list_empty(&listeners->list))
 625                 return;
 626
 627         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
 628         if (rc < 0)
 629                 return;
 630
 631         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
 632         if (!stats)
 633                 goto err;
 634
 635         fill_stats(tsk, stats);
 636
 637         /*
 638          * Doesn't matter if tsk is the leader or the last group member leaving
 639          */
 640         if (!is_thread_group || !group_dead)
 641                 goto send;
 642
 643         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
 644         if (!stats)
 645                 goto err;
 646
 647         memcpy(stats, tsk->signal->stats, sizeof(*stats));
 648
 649 send:
 650         send_cpu_listeners(rep_skb, listeners);
 651         return;
 652 err:
 653         nlmsg_free(rep_skb);
 654 }
 655
 656 static struct genl_ops taskstats_ops = {
 657         .cmd            = TASKSTATS_CMD_GET,
 658         .doit           = taskstats_user_cmd,
 659         .policy         = taskstats_cmd_get_policy,
 660 };
 661
 662 static struct genl_ops cgroupstats_ops = {
 663         .cmd            = CGROUPSTATS_CMD_GET,
 664         .doit           = cgroupstats_user_cmd,
 665         .policy         = cgroupstats_cmd_get_policy,
 666 };
 667
 668 /* Needed early in initialization */
 669 void __init taskstats_init_early(void)
 670 {
 671         unsigned int i;
 672
 673         taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
 674         for_each_possible_cpu(i) {
 675                 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 676                 init_rwsem(&(per_cpu(listener_array, i).sem));
 677         }
 678 }
 679
 680 static int __init taskstats_init(void)
 681 {
 682         int rc;
 683
 684         rc = genl_register_family(&family);
 685         if (rc)
 686                 return rc;
 687
 688         rc = genl_register_ops(&family, &taskstats_ops);
 689         if (rc < 0)
 690                 goto err;
 691
 692         rc = genl_register_ops(&family, &cgroupstats_ops);
 693         if (rc < 0)
 694                 goto err_cgroup_ops;
 695
 696         family_registered = 1;
 697         pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
 698         return 0;
 699 err_cgroup_ops:
 700         genl_unregister_ops(&family, &taskstats_ops);
 701 err:
 702         genl_unregister_family(&family);
 703         return rc;
 704 }
 705
 706 /*
 707  * late initcall ensures initialization of statistics collection
 708  * mechanisms precedes initialization of the taskstats interface
 709  */
 710 late_initcall(taskstats_init);