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
  34 /*
  35  * Maximum length of a cpumask that can be specified in
  36  * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
  37  */
  38 #define TASKSTATS_CPUMASK_MAXLEN        (100+6*NR_CPUS)
  39
  40 static DEFINE_PER_CPU(__u32, taskstats_seqnum);
  41 static int family_registered;
  42 struct kmem_cache *taskstats_cache;
  43
  44 static struct genl_family family = {
  45         .id             = GENL_ID_GENERATE,
  46         .name           = TASKSTATS_GENL_NAME,
  47         .version        = TASKSTATS_GENL_VERSION,
  48         .maxattr        = TASKSTATS_CMD_ATTR_MAX,
  49 };
  50
  51 static const struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
  52         [TASKSTATS_CMD_ATTR_PID]  = { .type = NLA_U32 },
  53         [TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
  54         [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
  55         [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
  56
  57 static const struct nla_policy cgroupstats_cmd_get_policy[CGROUPSTATS_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         int rc;
 115
 116         rc = genlmsg_end(skb, reply);
 117         if (rc < 0) {
 118                 nlmsg_free(skb);
 119                 return rc;
 120         }
 121
 122         return genlmsg_reply(skb, info);
 123 }
 124
 125 /*
 126  * Send taskstats data in @skb to listeners registered for @cpu's exit data
 127  */
 128 static void send_cpu_listeners(struct sk_buff *skb,
 129                                         struct listener_list *listeners)
 130 {
 131         struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
 132         struct listener *s, *tmp;
 133         struct sk_buff *skb_next, *skb_cur = skb;
 134         void *reply = genlmsg_data(genlhdr);
 135         int rc, delcount = 0;
 136
 137         rc = genlmsg_end(skb, reply);
 138         if (rc < 0) {
 139                 nlmsg_free(skb);
 140                 return;
 141         }
 142
 143         rc = 0;
 144         down_read(&listeners->sem);
 145         list_for_each_entry(s, &listeners->list, list) {
 146                 skb_next = NULL;
 147                 if (!list_is_last(&s->list, &listeners->list)) {
 148                         skb_next = skb_clone(skb_cur, GFP_KERNEL);
 149                         if (!skb_next)
 150                                 break;
 151                 }
 152                 rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
 153                 if (rc == -ECONNREFUSED) {
 154                         s->valid = 0;
 155                         delcount++;
 156                 }
 157                 skb_cur = skb_next;
 158         }
 159         up_read(&listeners->sem);
 160
 161         if (skb_cur)
 162                 nlmsg_free(skb_cur);
 163
 164         if (!delcount)
 165                 return;
 166
 167         /* Delete invalidated entries */
 168         down_write(&listeners->sem);
 169         list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 170                 if (!s->valid) {
 171                         list_del(&s->list);
 172                         kfree(s);
 173                 }
 174         }
 175         up_write(&listeners->sem);
 176 }
 177
 178 static void fill_stats(struct user_namespace *user_ns,
 179                        struct pid_namespace *pid_ns,
 180                        struct task_struct *tsk, struct taskstats *stats)
 181 {
 182         memset(stats, 0, sizeof(*stats));
 183         /*
 184          * Each accounting subsystem adds calls to its functions to
 185          * fill in relevant parts of struct taskstsats as follows
 186          *
 187          *      per-task-foo(stats, tsk);
 188          */
 189
 190         delayacct_add_tsk(stats, tsk);
 191
 192         /* fill in basic acct fields */
 193         stats->version = TASKSTATS_VERSION;
 194         stats->nvcsw = tsk->nvcsw;
 195         stats->nivcsw = tsk->nivcsw;
 196         bacct_add_tsk(user_ns, pid_ns, stats, tsk);
 197
 198         /* fill in extended acct fields */
 199         xacct_add_tsk(stats, tsk);
 200 }
 201
 202 static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
 203 {
 204         struct task_struct *tsk;
 205
 206         rcu_read_lock();
 207         tsk = find_task_by_vpid(pid);
 208         if (tsk)
 209                 get_task_struct(tsk);
 210         rcu_read_unlock();
 211         if (!tsk)
 212                 return -ESRCH;
 213         fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
 214         put_task_struct(tsk);
 215         return 0;
 216 }
 217
 218 static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
 219 {
 220         struct task_struct *tsk, *first;
 221         unsigned long flags;
 222         int rc = -ESRCH;
 223
 224         /*
 225          * Add additional stats from live tasks except zombie thread group
 226          * leaders who are already counted with the dead tasks
 227          */
 228         rcu_read_lock();
 229         first = find_task_by_vpid(tgid);
 230
 231         if (!first || !lock_task_sighand(first, &flags))
 232                 goto out;
 233
 234         if (first->signal->stats)
 235                 memcpy(stats, first->signal->stats, sizeof(*stats));
 236         else
 237                 memset(stats, 0, sizeof(*stats));
 238
 239         tsk = first;
 240         do {
 241                 if (tsk->exit_state)
 242                         continue;
 243                 /*
 244                  * Accounting subsystem can call its functions here to
 245                  * fill in relevant parts of struct taskstsats as follows
 246                  *
 247                  *      per-task-foo(stats, tsk);
 248                  */
 249                 delayacct_add_tsk(stats, tsk);
 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
 294         if (!cpumask_subset(mask, cpu_possible_mask))
 295                 return -EINVAL;
 296
 297         if (current_user_ns() != &init_user_ns)
 298                 return -EINVAL;
 299
 300         if (task_active_pid_ns(current) != &init_pid_ns)
 301                 return -EINVAL;
 302
 303         if (isadd == REGISTER) {
 304                 for_each_cpu(cpu, mask) {
 305                         s = kmalloc_node(sizeof(struct listener),
 306                                         GFP_KERNEL, cpu_to_node(cpu));
 307                         if (!s)
 308                                 goto cleanup;
 309
 310                         s->pid = pid;
 311                         s->valid = 1;
 312
 313                         listeners = &per_cpu(listener_array, cpu);
 314                         down_write(&listeners->sem);
 315                         list_for_each_entry(s2, &listeners->list, list) {
 316                                 if (s2->pid == pid && s2->valid)
 317                                         goto exists;
 318                         }
 319                         list_add(&s->list, &listeners->list);
 320                         s = NULL;
 321 exists:
 322                         up_write(&listeners->sem);
 323                         kfree(s); /* nop if NULL */
 324                 }
 325                 return 0;
 326         }
 327
 328         /* Deregister or cleanup */
 329 cleanup:
 330         for_each_cpu(cpu, mask) {
 331                 listeners = &per_cpu(listener_array, cpu);
 332                 down_write(&listeners->sem);
 333                 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 334                         if (s->pid == pid) {
 335                                 list_del(&s->list);
 336                                 kfree(s);
 337                                 break;
 338                         }
 339                 }
 340                 up_write(&listeners->sem);
 341         }
 342         return 0;
 343 }
 344
 345 static int parse(struct nlattr *na, struct cpumask *mask)
 346 {
 347         char *data;
 348         int len;
 349         int ret;
 350
 351         if (na == NULL)
 352                 return 1;
 353         len = nla_len(na);
 354         if (len > TASKSTATS_CPUMASK_MAXLEN)
 355                 return -E2BIG;
 356         if (len < 1)
 357                 return -EINVAL;
 358         data = kmalloc(len, GFP_KERNEL);
 359         if (!data)
 360                 return -ENOMEM;
 361         nla_strlcpy(data, na, len);
 362         ret = cpulist_parse(data, mask);
 363         kfree(data);
 364         return ret;
 365 }
 366
 367 #if defined(CONFIG_64BIT) && !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 368 #define TASKSTATS_NEEDS_PADDING 1
 369 #endif
 370
 371 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
 372 {
 373         struct nlattr *na, *ret;
 374         int aggr;
 375
 376         aggr = (type == TASKSTATS_TYPE_PID)
 377                         ? TASKSTATS_TYPE_AGGR_PID
 378                         : TASKSTATS_TYPE_AGGR_TGID;
 379
 380         /*
 381          * The taskstats structure is internally aligned on 8 byte
 382          * boundaries but the layout of the aggregrate reply, with
 383          * two NLA headers and the pid (each 4 bytes), actually
 384          * force the entire structure to be unaligned. This causes
 385          * the kernel to issue unaligned access warnings on some
 386          * architectures like ia64. Unfortunately, some software out there
 387          * doesn't properly unroll the NLA packet and assumes that the start
 388          * of the taskstats structure will always be 20 bytes from the start
 389          * of the netlink payload. Aligning the start of the taskstats
 390          * structure breaks this software, which we don't want. So, for now
 391          * the alignment only happens on architectures that require it
 392          * and those users will have to update to fixed versions of those
 393          * packages. Space is reserved in the packet only when needed.
 394          * This ifdef should be removed in several years e.g. 2012 once
 395          * we can be confident that fixed versions are installed on most
 396          * systems. We add the padding before the aggregate since the
 397          * aggregate is already a defined type.
 398          */
 399 #ifdef TASKSTATS_NEEDS_PADDING
 400         if (nla_put(skb, TASKSTATS_TYPE_NULL, 0, NULL) < 0)
 401                 goto err;
 402 #endif
 403         na = nla_nest_start(skb, aggr);
 404         if (!na)
 405                 goto err;
 406
 407         if (nla_put(skb, type, sizeof(pid), &pid) < 0)
 408                 goto err;
 409         ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
 410         if (!ret)
 411                 goto err;
 412         nla_nest_end(skb, na);
 413
 414         return nla_data(ret);
 415 err:
 416         return NULL;
 417 }
 418
 419 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 420 {
 421         int rc = 0;
 422         struct sk_buff *rep_skb;
 423         struct cgroupstats *stats;
 424         struct nlattr *na;
 425         size_t size;
 426         u32 fd;
 427         struct fd f;
 428
 429         na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
 430         if (!na)
 431                 return -EINVAL;
 432
 433         fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
 434         f = fdget(fd);
 435         if (!f.file)
 436                 return 0;
 437
 438         size = nla_total_size(sizeof(struct cgroupstats));
 439
 440         rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
 441                                 size);
 442         if (rc < 0)
 443                 goto err;
 444
 445         na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
 446                                 sizeof(struct cgroupstats));
 447         if (na == NULL) {
 448                 nlmsg_free(rep_skb);
 449                 rc = -EMSGSIZE;
 450                 goto err;
 451         }
 452
 453         stats = nla_data(na);
 454         memset(stats, 0, sizeof(*stats));
 455
 456         rc = cgroupstats_build(stats, f.file->f_dentry);
 457         if (rc < 0) {
 458                 nlmsg_free(rep_skb);
 459                 goto err;
 460         }
 461
 462         rc = send_reply(rep_skb, info);
 463
 464 err:
 465         fdput(f);
 466         return rc;
 467 }
 468
 469 static int cmd_attr_register_cpumask(struct genl_info *info)
 470 {
 471         cpumask_var_t mask;
 472         int rc;
 473
 474         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 475                 return -ENOMEM;
 476         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
 477         if (rc < 0)
 478                 goto out;
 479         rc = add_del_listener(info->snd_portid, mask, REGISTER);
 480 out:
 481         free_cpumask_var(mask);
 482         return rc;
 483 }
 484
 485 static int cmd_attr_deregister_cpumask(struct genl_info *info)
 486 {
 487         cpumask_var_t mask;
 488         int rc;
 489
 490         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 491                 return -ENOMEM;
 492         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
 493         if (rc < 0)
 494                 goto out;
 495         rc = add_del_listener(info->snd_portid, mask, DEREGISTER);
 496 out:
 497         free_cpumask_var(mask);
 498         return rc;
 499 }
 500
 501 static size_t taskstats_packet_size(void)
 502 {
 503         size_t size;
 504
 505         size = nla_total_size(sizeof(u32)) +
 506                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 507 #ifdef TASKSTATS_NEEDS_PADDING
 508         size += nla_total_size(0); /* Padding for alignment */
 509 #endif
 510         return size;
 511 }
 512
 513 static int cmd_attr_pid(struct genl_info *info)
 514 {
 515         struct taskstats *stats;
 516         struct sk_buff *rep_skb;
 517         size_t size;
 518         u32 pid;
 519         int rc;
 520
 521         size = taskstats_packet_size();
 522
 523         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 524         if (rc < 0)
 525                 return rc;
 526
 527         rc = -EINVAL;
 528         pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 529         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
 530         if (!stats)
 531                 goto err;
 532
 533         rc = fill_stats_for_pid(pid, stats);
 534         if (rc < 0)
 535                 goto err;
 536         return send_reply(rep_skb, info);
 537 err:
 538         nlmsg_free(rep_skb);
 539         return rc;
 540 }
 541
 542 static int cmd_attr_tgid(struct genl_info *info)
 543 {
 544         struct taskstats *stats;
 545         struct sk_buff *rep_skb;
 546         size_t size;
 547         u32 tgid;
 548         int rc;
 549
 550         size = taskstats_packet_size();
 551
 552         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 553         if (rc < 0)
 554                 return rc;
 555
 556         rc = -EINVAL;
 557         tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 558         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 559         if (!stats)
 560                 goto err;
 561
 562         rc = fill_stats_for_tgid(tgid, stats);
 563         if (rc < 0)
 564                 goto err;
 565         return send_reply(rep_skb, info);
 566 err:
 567         nlmsg_free(rep_skb);
 568         return rc;
 569 }
 570
 571 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 572 {
 573         if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
 574                 return cmd_attr_register_cpumask(info);
 575         else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
 576                 return cmd_attr_deregister_cpumask(info);
 577         else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
 578                 return cmd_attr_pid(info);
 579         else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
 580                 return cmd_attr_tgid(info);
 581         else
 582                 return -EINVAL;
 583 }
 584
 585 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
 586 {
 587         struct signal_struct *sig = tsk->signal;
 588         struct taskstats *stats;
 589
 590         if (sig->stats || thread_group_empty(tsk))
 591                 goto ret;
 592
 593         /* No problem if kmem_cache_zalloc() fails */
 594         stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
 595
 596         spin_lock_irq(&tsk->sighand->siglock);
 597         if (!sig->stats) {
 598                 sig->stats = stats;
 599                 stats = NULL;
 600         }
 601         spin_unlock_irq(&tsk->sighand->siglock);
 602
 603         if (stats)
 604                 kmem_cache_free(taskstats_cache, stats);
 605 ret:
 606         return sig->stats;
 607 }
 608
 609 /* Send pid data out on exit */
 610 void taskstats_exit(struct task_struct *tsk, int group_dead)
 611 {
 612         int rc;
 613         struct listener_list *listeners;
 614         struct taskstats *stats;
 615         struct sk_buff *rep_skb;
 616         size_t size;
 617         int is_thread_group;
 618
 619         if (!family_registered)
 620                 return;
 621
 622         /*
 623          * Size includes space for nested attributes
 624          */
 625         size = taskstats_packet_size();
 626
 627         is_thread_group = !!taskstats_tgid_alloc(tsk);
 628         if (is_thread_group) {
 629                 /* PID + STATS + TGID + STATS */
 630                 size = 2 * size;
 631                 /* fill the tsk->signal->stats structure */
 632                 fill_tgid_exit(tsk);
 633         }
 634
 635         listeners = __this_cpu_ptr(&listener_array);
 636         if (list_empty(&listeners->list))
 637                 return;
 638
 639         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
 640         if (rc < 0)
 641                 return;
 642
 643         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID,
 644                          task_pid_nr_ns(tsk, &init_pid_ns));
 645         if (!stats)
 646                 goto err;
 647
 648         fill_stats(&init_user_ns, &init_pid_ns, tsk, stats);
 649
 650         /*
 651          * Doesn't matter if tsk is the leader or the last group member leaving
 652          */
 653         if (!is_thread_group || !group_dead)
 654                 goto send;
 655
 656         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID,
 657                          task_tgid_nr_ns(tsk, &init_pid_ns));
 658         if (!stats)
 659                 goto err;
 660
 661         memcpy(stats, tsk->signal->stats, sizeof(*stats));
 662
 663 send:
 664         send_cpu_listeners(rep_skb, listeners);
 665         return;
 666 err:
 667         nlmsg_free(rep_skb);
 668 }
 669
 670 static struct genl_ops taskstats_ops = {
 671         .cmd            = TASKSTATS_CMD_GET,
 672         .doit           = taskstats_user_cmd,
 673         .policy         = taskstats_cmd_get_policy,
 674         .flags          = GENL_ADMIN_PERM,
 675 };
 676
 677 static struct genl_ops cgroupstats_ops = {
 678         .cmd            = CGROUPSTATS_CMD_GET,
 679         .doit           = cgroupstats_user_cmd,
 680         .policy         = cgroupstats_cmd_get_policy,
 681 };
 682
 683 /* Needed early in initialization */
 684 void __init taskstats_init_early(void)
 685 {
 686         unsigned int i;
 687
 688         taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
 689         for_each_possible_cpu(i) {
 690                 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 691                 init_rwsem(&(per_cpu(listener_array, i).sem));
 692         }
 693 }
 694
 695 static int __init taskstats_init(void)
 696 {
 697         int rc;
 698
 699         rc = genl_register_family(&family);
 700         if (rc)
 701                 return rc;
 702
 703         rc = genl_register_ops(&family, &taskstats_ops);
 704         if (rc < 0)
 705                 goto err;
 706
 707         rc = genl_register_ops(&family, &cgroupstats_ops);
 708         if (rc < 0)
 709                 goto err_cgroup_ops;
 710
 711         family_registered = 1;
 712         pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
 713         return 0;
 714 err_cgroup_ops:
 715         genl_unregister_ops(&family, &taskstats_ops);
 716 err:
 717         genl_unregister_family(&family);
 718         return rc;
 719 }
 720
 721 /*
 722  * late initcall ensures initialization of statistics collection
 723  * mechanisms precedes initialization of the taskstats interface
 724  */
 725 late_initcall(taskstats_init);