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 <asm/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 = get_cpu_var(taskstats_seqnum)++;
  93                 put_cpu_var(taskstats_seqnum);
  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 int fill_pid(pid_t pid, struct task_struct *tsk,
 179                 struct taskstats *stats)
 180 {
 181         int rc = 0;
 182
 183         if (!tsk) {
 184                 rcu_read_lock();
 185                 tsk = find_task_by_vpid(pid);
 186                 if (tsk)
 187                         get_task_struct(tsk);
 188                 rcu_read_unlock();
 189                 if (!tsk)
 190                         return -ESRCH;
 191         } else
 192                 get_task_struct(tsk);
 193
 194         memset(stats, 0, sizeof(*stats));
 195         /*
 196          * Each accounting subsystem adds calls to its functions to
 197          * fill in relevant parts of struct taskstsats as follows
 198          *
 199          *      per-task-foo(stats, tsk);
 200          */
 201
 202         delayacct_add_tsk(stats, tsk);
 203
 204         /* fill in basic acct fields */
 205         stats->version = TASKSTATS_VERSION;
 206         stats->nvcsw = tsk->nvcsw;
 207         stats->nivcsw = tsk->nivcsw;
 208         bacct_add_tsk(stats, tsk);
 209
 210         /* fill in extended acct fields */
 211         xacct_add_tsk(stats, tsk);
 212
 213         /* Define err: label here if needed */
 214         put_task_struct(tsk);
 215         return rc;
 216
 217 }
 218
 219 static int fill_tgid(pid_t tgid, struct task_struct *first,
 220                 struct taskstats *stats)
 221 {
 222         struct task_struct *tsk;
 223         unsigned long flags;
 224         int rc = -ESRCH;
 225
 226         /*
 227          * Add additional stats from live tasks except zombie thread group
 228          * leaders who are already counted with the dead tasks
 229          */
 230         rcu_read_lock();
 231         if (!first)
 232                 first = find_task_by_vpid(tgid);
 233
 234         if (!first || !lock_task_sighand(first, &flags))
 235                 goto out;
 236
 237         if (first->signal->stats)
 238                 memcpy(stats, first->signal->stats, sizeof(*stats));
 239         else
 240                 memset(stats, 0, sizeof(*stats));
 241
 242         tsk = first;
 243         do {
 244                 if (tsk->exit_state)
 245                         continue;
 246                 /*
 247                  * Accounting subsystem can call its functions here to
 248                  * fill in relevant parts of struct taskstsats as follows
 249                  *
 250                  *      per-task-foo(stats, tsk);
 251                  */
 252                 delayacct_add_tsk(stats, tsk);
 253
 254                 stats->nvcsw += tsk->nvcsw;
 255                 stats->nivcsw += tsk->nivcsw;
 256         } while_each_thread(first, tsk);
 257
 258         unlock_task_sighand(first, &flags);
 259         rc = 0;
 260 out:
 261         rcu_read_unlock();
 262
 263         stats->version = TASKSTATS_VERSION;
 264         /*
 265          * Accounting subsystems can also add calls here to modify
 266          * fields of taskstats.
 267          */
 268         return rc;
 269 }
 270
 271
 272 static void fill_tgid_exit(struct task_struct *tsk)
 273 {
 274         unsigned long flags;
 275
 276         spin_lock_irqsave(&tsk->sighand->siglock, flags);
 277         if (!tsk->signal->stats)
 278                 goto ret;
 279
 280         /*
 281          * Each accounting subsystem calls its functions here to
 282          * accumalate its per-task stats for tsk, into the per-tgid structure
 283          *
 284          *      per-task-foo(tsk->signal->stats, tsk);
 285          */
 286         delayacct_add_tsk(tsk->signal->stats, tsk);
 287 ret:
 288         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 289         return;
 290 }
 291
 292 static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
 293 {
 294         struct listener_list *listeners;
 295         struct listener *s, *tmp;
 296         unsigned int cpu;
 297
 298         if (!cpumask_subset(mask, cpu_possible_mask))
 299                 return -EINVAL;
 300
 301         if (isadd == REGISTER) {
 302                 for_each_cpu(cpu, mask) {
 303                         s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
 304                                          cpu_to_node(cpu));
 305                         if (!s)
 306                                 goto cleanup;
 307                         s->pid = pid;
 308                         INIT_LIST_HEAD(&s->list);
 309                         s->valid = 1;
 310
 311                         listeners = &per_cpu(listener_array, cpu);
 312                         down_write(&listeners->sem);
 313                         list_add(&s->list, &listeners->list);
 314                         up_write(&listeners->sem);
 315                 }
 316                 return 0;
 317         }
 318
 319         /* Deregister or cleanup */
 320 cleanup:
 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
 336 static 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 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
 359 {
 360         struct nlattr *na, *ret;
 361         int aggr;
 362
 363         aggr = (type == TASKSTATS_TYPE_PID)
 364                         ? TASKSTATS_TYPE_AGGR_PID
 365                         : TASKSTATS_TYPE_AGGR_TGID;
 366
 367         na = nla_nest_start(skb, aggr);
 368         if (!na)
 369                 goto err;
 370         if (nla_put(skb, type, sizeof(pid), &pid) < 0)
 371                 goto err;
 372         ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
 373         if (!ret)
 374                 goto err;
 375         nla_nest_end(skb, na);
 376
 377         return nla_data(ret);
 378 err:
 379         return NULL;
 380 }
 381
 382 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 383 {
 384         int rc = 0;
 385         struct sk_buff *rep_skb;
 386         struct cgroupstats *stats;
 387         struct nlattr *na;
 388         size_t size;
 389         u32 fd;
 390         struct file *file;
 391         int fput_needed;
 392
 393         na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
 394         if (!na)
 395                 return -EINVAL;
 396
 397         fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
 398         file = fget_light(fd, &fput_needed);
 399         if (!file)
 400                 return 0;
 401
 402         size = nla_total_size(sizeof(struct cgroupstats));
 403
 404         rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
 405                                 size);
 406         if (rc < 0)
 407                 goto err;
 408
 409         na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
 410                                 sizeof(struct cgroupstats));
 411         stats = nla_data(na);
 412         memset(stats, 0, sizeof(*stats));
 413
 414         rc = cgroupstats_build(stats, file->f_dentry);
 415         if (rc < 0) {
 416                 nlmsg_free(rep_skb);
 417                 goto err;
 418         }
 419
 420         rc = send_reply(rep_skb, info);
 421
 422 err:
 423         fput_light(file, fput_needed);
 424         return rc;
 425 }
 426
 427 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 428 {
 429         int rc;
 430         struct sk_buff *rep_skb;
 431         struct taskstats *stats;
 432         size_t size;
 433         cpumask_var_t mask;
 434
 435         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 436                 return -ENOMEM;
 437
 438         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
 439         if (rc < 0)
 440                 goto free_return_rc;
 441         if (rc == 0) {
 442                 rc = add_del_listener(info->snd_pid, mask, REGISTER);
 443                 goto free_return_rc;
 444         }
 445
 446         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
 447         if (rc < 0)
 448                 goto free_return_rc;
 449         if (rc == 0) {
 450                 rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
 451 free_return_rc:
 452                 free_cpumask_var(mask);
 453                 return rc;
 454         }
 455         free_cpumask_var(mask);
 456
 457         /*
 458          * Size includes space for nested attributes
 459          */
 460         size = nla_total_size(sizeof(u32)) +
 461                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 462
 463         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 464         if (rc < 0)
 465                 return rc;
 466
 467         rc = -EINVAL;
 468         if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
 469                 u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 470                 stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
 471                 if (!stats)
 472                         goto err;
 473
 474                 rc = fill_pid(pid, NULL, stats);
 475                 if (rc < 0)
 476                         goto err;
 477         } else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
 478                 u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 479                 stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 480                 if (!stats)
 481                         goto err;
 482
 483                 rc = fill_tgid(tgid, NULL, stats);
 484                 if (rc < 0)
 485                         goto err;
 486         } else
 487                 goto err;
 488
 489         return send_reply(rep_skb, info);
 490 err:
 491         nlmsg_free(rep_skb);
 492         return rc;
 493 }
 494
 495 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
 496 {
 497         struct signal_struct *sig = tsk->signal;
 498         struct taskstats *stats;
 499
 500         if (sig->stats || thread_group_empty(tsk))
 501                 goto ret;
 502
 503         /* No problem if kmem_cache_zalloc() fails */
 504         stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
 505
 506         spin_lock_irq(&tsk->sighand->siglock);
 507         if (!sig->stats) {
 508                 sig->stats = stats;
 509                 stats = NULL;
 510         }
 511         spin_unlock_irq(&tsk->sighand->siglock);
 512
 513         if (stats)
 514                 kmem_cache_free(taskstats_cache, stats);
 515 ret:
 516         return sig->stats;
 517 }
 518
 519 /* Send pid data out on exit */
 520 void taskstats_exit(struct task_struct *tsk, int group_dead)
 521 {
 522         int rc;
 523         struct listener_list *listeners;
 524         struct taskstats *stats;
 525         struct sk_buff *rep_skb;
 526         size_t size;
 527         int is_thread_group;
 528
 529         if (!family_registered)
 530                 return;
 531
 532         /*
 533          * Size includes space for nested attributes
 534          */
 535         size = nla_total_size(sizeof(u32)) +
 536                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 537
 538         is_thread_group = !!taskstats_tgid_alloc(tsk);
 539         if (is_thread_group) {
 540                 /* PID + STATS + TGID + STATS */
 541                 size = 2 * size;
 542                 /* fill the tsk->signal->stats structure */
 543                 fill_tgid_exit(tsk);
 544         }
 545
 546         listeners = &__raw_get_cpu_var(listener_array);
 547         if (list_empty(&listeners->list))
 548                 return;
 549
 550         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
 551         if (rc < 0)
 552                 return;
 553
 554         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
 555         if (!stats)
 556                 goto err;
 557
 558         rc = fill_pid(-1, tsk, stats);
 559         if (rc < 0)
 560                 goto err;
 561
 562         /*
 563          * Doesn't matter if tsk is the leader or the last group member leaving
 564          */
 565         if (!is_thread_group || !group_dead)
 566                 goto send;
 567
 568         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
 569         if (!stats)
 570                 goto err;
 571
 572         memcpy(stats, tsk->signal->stats, sizeof(*stats));
 573
 574 send:
 575         send_cpu_listeners(rep_skb, listeners);
 576         return;
 577 err:
 578         nlmsg_free(rep_skb);
 579 }
 580
 581 static struct genl_ops taskstats_ops = {
 582         .cmd            = TASKSTATS_CMD_GET,
 583         .doit           = taskstats_user_cmd,
 584         .policy         = taskstats_cmd_get_policy,
 585 };
 586
 587 static struct genl_ops cgroupstats_ops = {
 588         .cmd            = CGROUPSTATS_CMD_GET,
 589         .doit           = cgroupstats_user_cmd,
 590         .policy         = cgroupstats_cmd_get_policy,
 591 };
 592
 593 /* Needed early in initialization */
 594 void __init taskstats_init_early(void)
 595 {
 596         unsigned int i;
 597
 598         taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
 599         for_each_possible_cpu(i) {
 600                 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 601                 init_rwsem(&(per_cpu(listener_array, i).sem));
 602         }
 603 }
 604
 605 static int __init taskstats_init(void)
 606 {
 607         int rc;
 608
 609         rc = genl_register_family(&family);
 610         if (rc)
 611                 return rc;
 612
 613         rc = genl_register_ops(&family, &taskstats_ops);
 614         if (rc < 0)
 615                 goto err;
 616
 617         rc = genl_register_ops(&family, &cgroupstats_ops);
 618         if (rc < 0)
 619                 goto err_cgroup_ops;
 620
 621         family_registered = 1;
 622         printk("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
 623         return 0;
 624 err_cgroup_ops:
 625         genl_unregister_ops(&family, &taskstats_ops);
 626 err:
 627         genl_unregister_family(&family);
 628         return rc;
 629 }
 630
 631 /*
 632  * late initcall ensures initialization of statistics collection
 633  * mechanisms precedes initialization of the taskstats interface
 634  */
 635 late_initcall(taskstats_init);