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/tsacct_kern.h>
  24 #include <linux/cpumask.h>
  25 #include <linux/percpu.h>
  26 #include <net/genetlink.h>
  27 #include <asm/atomic.h>
  28
  29 /*
  30  * Maximum length of a cpumask that can be specified in
  31  * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
  32  */
  33 #define TASKSTATS_CPUMASK_MAXLEN        (100+6*NR_CPUS)
  34
  35 static DEFINE_PER_CPU(__u32, taskstats_seqnum) = { 0 };
  36 static int family_registered;
  37 kmem_cache_t *taskstats_cache;
  38
  39 static struct genl_family family = {
  40         .id             = GENL_ID_GENERATE,
  41         .name           = TASKSTATS_GENL_NAME,
  42         .version        = TASKSTATS_GENL_VERSION,
  43         .maxattr        = TASKSTATS_CMD_ATTR_MAX,
  44 };
  45
  46 static struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1]
  47 __read_mostly = {
  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 struct listener {
  54         struct list_head list;
  55         pid_t pid;
  56         char valid;
  57 };
  58
  59 struct listener_list {
  60         struct rw_semaphore sem;
  61         struct list_head list;
  62 };
  63 static DEFINE_PER_CPU(struct listener_list, listener_array);
  64
  65 enum actions {
  66         REGISTER,
  67         DEREGISTER,
  68         CPU_DONT_CARE
  69 };
  70
  71 static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
  72                         void **replyp, size_t size)
  73 {
  74         struct sk_buff *skb;
  75         void *reply;
  76
  77         /*
  78          * If new attributes are added, please revisit this allocation
  79          */
  80         skb = nlmsg_new(genlmsg_total_size(size), GFP_KERNEL);
  81         if (!skb)
  82                 return -ENOMEM;
  83
  84         if (!info) {
  85                 int seq = get_cpu_var(taskstats_seqnum)++;
  86                 put_cpu_var(taskstats_seqnum);
  87
  88                 reply = genlmsg_put(skb, 0, seq,
  89                                 family.id, 0, 0,
  90                                 cmd, family.version);
  91         } else
  92                 reply = genlmsg_put(skb, info->snd_pid, info->snd_seq,
  93                                 family.id, 0, 0,
  94                                 cmd, family.version);
  95         if (reply == NULL) {
  96                 nlmsg_free(skb);
  97                 return -EINVAL;
  98         }
  99
 100         *skbp = skb;
 101         *replyp = reply;
 102         return 0;
 103 }
 104
 105 /*
 106  * Send taskstats data in @skb to listener with nl_pid @pid
 107  */
 108 static int send_reply(struct sk_buff *skb, pid_t pid)
 109 {
 110         struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
 111         void *reply = genlmsg_data(genlhdr);
 112         int rc;
 113
 114         rc = genlmsg_end(skb, reply);
 115         if (rc < 0) {
 116                 nlmsg_free(skb);
 117                 return rc;
 118         }
 119
 120         return genlmsg_unicast(skb, pid);
 121 }
 122
 123 /*
 124  * Send taskstats data in @skb to listeners registered for @cpu's exit data
 125  */
 126 static void send_cpu_listeners(struct sk_buff *skb, unsigned int cpu)
 127 {
 128         struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
 129         struct listener_list *listeners;
 130         struct listener *s, *tmp;
 131         struct sk_buff *skb_next, *skb_cur = skb;
 132         void *reply = genlmsg_data(genlhdr);
 133         int rc, delcount = 0;
 134
 135         rc = genlmsg_end(skb, reply);
 136         if (rc < 0) {
 137                 nlmsg_free(skb);
 138                 return;
 139         }
 140
 141         rc = 0;
 142         listeners = &per_cpu(listener_array, cpu);
 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(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 int fill_pid(pid_t pid, struct task_struct *pidtsk,
 178                 struct taskstats *stats)
 179 {
 180         int rc = 0;
 181         struct task_struct *tsk = pidtsk;
 182
 183         if (!pidtsk) {
 184                 read_lock(&tasklist_lock);
 185                 tsk = find_task_by_pid(pid);
 186                 if (!tsk) {
 187                         read_unlock(&tasklist_lock);
 188                         return -ESRCH;
 189                 }
 190                 get_task_struct(tsk);
 191                 read_unlock(&tasklist_lock);
 192         } else
 193                 get_task_struct(tsk);
 194
 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         bacct_add_tsk(stats, tsk);
 207
 208         /* fill in extended acct fields */
 209         xacct_add_tsk(stats, tsk);
 210
 211         /* Define err: label here if needed */
 212         put_task_struct(tsk);
 213         return rc;
 214
 215 }
 216
 217 static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk,
 218                 struct taskstats *stats)
 219 {
 220         struct task_struct *tsk, *first;
 221         unsigned long flags;
 222
 223         /*
 224          * Add additional stats from live tasks except zombie thread group
 225          * leaders who are already counted with the dead tasks
 226          */
 227         first = tgidtsk;
 228         if (!first) {
 229                 read_lock(&tasklist_lock);
 230                 first = find_task_by_pid(tgid);
 231                 if (!first) {
 232                         read_unlock(&tasklist_lock);
 233                         return -ESRCH;
 234                 }
 235                 get_task_struct(first);
 236                 read_unlock(&tasklist_lock);
 237         } else
 238                 get_task_struct(first);
 239
 240         /* Start with stats from dead tasks */
 241         spin_lock_irqsave(&first->signal->stats_lock, flags);
 242         if (first->signal->stats)
 243                 memcpy(stats, first->signal->stats, sizeof(*stats));
 244         spin_unlock_irqrestore(&first->signal->stats_lock, flags);
 245
 246         tsk = first;
 247         read_lock(&tasklist_lock);
 248         do {
 249                 if (tsk->exit_state == EXIT_ZOMBIE && thread_group_leader(tsk))
 250                         continue;
 251                 /*
 252                  * Accounting subsystem can call its functions here to
 253                  * fill in relevant parts of struct taskstsats as follows
 254                  *
 255                  *      per-task-foo(stats, tsk);
 256                  */
 257                 delayacct_add_tsk(stats, tsk);
 258
 259         } while_each_thread(first, tsk);
 260         read_unlock(&tasklist_lock);
 261         stats->version = TASKSTATS_VERSION;
 262
 263         /*
 264          * Accounting subsytems can also add calls here to modify
 265          * fields of taskstats.
 266          */
 267
 268         return 0;
 269 }
 270
 271
 272 static void fill_tgid_exit(struct task_struct *tsk)
 273 {
 274         unsigned long flags;
 275
 276         spin_lock_irqsave(&tsk->signal->stats_lock, 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->signal->stats_lock, flags);
 289         return;
 290 }
 291
 292 static int add_del_listener(pid_t pid, cpumask_t *maskp, int isadd)
 293 {
 294         struct listener_list *listeners;
 295         struct listener *s, *tmp;
 296         unsigned int cpu;
 297         cpumask_t mask = *maskp;
 298
 299         if (!cpus_subset(mask, cpu_possible_map))
 300                 return -EINVAL;
 301
 302         if (isadd == REGISTER) {
 303                 for_each_cpu_mask(cpu, mask) {
 304                         s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
 305                                          cpu_to_node(cpu));
 306                         if (!s)
 307                                 goto cleanup;
 308                         s->pid = pid;
 309                         INIT_LIST_HEAD(&s->list);
 310                         s->valid = 1;
 311
 312                         listeners = &per_cpu(listener_array, cpu);
 313                         down_write(&listeners->sem);
 314                         list_add(&s->list, &listeners->list);
 315                         up_write(&listeners->sem);
 316                 }
 317                 return 0;
 318         }
 319
 320         /* Deregister or cleanup */
 321 cleanup:
 322         for_each_cpu_mask(cpu, mask) {
 323                 listeners = &per_cpu(listener_array, cpu);
 324                 down_write(&listeners->sem);
 325                 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 326                         if (s->pid == pid) {
 327                                 list_del(&s->list);
 328                                 kfree(s);
 329                                 break;
 330                         }
 331                 }
 332                 up_write(&listeners->sem);
 333         }
 334         return 0;
 335 }
 336
 337 static int parse(struct nlattr *na, cpumask_t *mask)
 338 {
 339         char *data;
 340         int len;
 341         int ret;
 342
 343         if (na == NULL)
 344                 return 1;
 345         len = nla_len(na);
 346         if (len > TASKSTATS_CPUMASK_MAXLEN)
 347                 return -E2BIG;
 348         if (len < 1)
 349                 return -EINVAL;
 350         data = kmalloc(len, GFP_KERNEL);
 351         if (!data)
 352                 return -ENOMEM;
 353         nla_strlcpy(data, na, len);
 354         ret = cpulist_parse(data, *mask);
 355         kfree(data);
 356         return ret;
 357 }
 358
 359 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 360 {
 361         int rc = 0;
 362         struct sk_buff *rep_skb;
 363         struct taskstats stats;
 364         void *reply;
 365         size_t size;
 366         struct nlattr *na;
 367         cpumask_t mask;
 368
 369         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], &mask);
 370         if (rc < 0)
 371                 return rc;
 372         if (rc == 0)
 373                 return add_del_listener(info->snd_pid, &mask, REGISTER);
 374
 375         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], &mask);
 376         if (rc < 0)
 377                 return rc;
 378         if (rc == 0)
 379                 return add_del_listener(info->snd_pid, &mask, DEREGISTER);
 380
 381         /*
 382          * Size includes space for nested attributes
 383          */
 384         size = nla_total_size(sizeof(u32)) +
 385                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 386
 387         memset(&stats, 0, sizeof(stats));
 388         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
 389         if (rc < 0)
 390                 return rc;
 391
 392         if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
 393                 u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 394                 rc = fill_pid(pid, NULL, &stats);
 395                 if (rc < 0)
 396                         goto err;
 397
 398                 na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
 399                 NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, pid);
 400                 NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 401                                 stats);
 402         } else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
 403                 u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 404                 rc = fill_tgid(tgid, NULL, &stats);
 405                 if (rc < 0)
 406                         goto err;
 407
 408                 na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
 409                 NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 410                 NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 411                                 stats);
 412         } else {
 413                 rc = -EINVAL;
 414                 goto err;
 415         }
 416
 417         nla_nest_end(rep_skb, na);
 418
 419         return send_reply(rep_skb, info->snd_pid);
 420
 421 nla_put_failure:
 422         return genlmsg_cancel(rep_skb, reply);
 423 err:
 424         nlmsg_free(rep_skb);
 425         return rc;
 426 }
 427
 428 void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu)
 429 {
 430         struct listener_list *listeners;
 431         struct taskstats *tmp;
 432         /*
 433          * This is the cpu on which the task is exiting currently and will
 434          * be the one for which the exit event is sent, even if the cpu
 435          * on which this function is running changes later.
 436          */
 437         *mycpu = raw_smp_processor_id();
 438
 439         *ptidstats = NULL;
 440         tmp = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
 441         if (!tmp)
 442                 return;
 443
 444         listeners = &per_cpu(listener_array, *mycpu);
 445         down_read(&listeners->sem);
 446         if (!list_empty(&listeners->list)) {
 447                 *ptidstats = tmp;
 448                 tmp = NULL;
 449         }
 450         up_read(&listeners->sem);
 451         kfree(tmp);
 452 }
 453
 454 /* Send pid data out on exit */
 455 void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
 456                         int group_dead, unsigned int mycpu)
 457 {
 458         int rc;
 459         struct sk_buff *rep_skb;
 460         void *reply;
 461         size_t size;
 462         int is_thread_group;
 463         struct nlattr *na;
 464         unsigned long flags;
 465
 466         if (!family_registered || !tidstats)
 467                 return;
 468
 469         spin_lock_irqsave(&tsk->signal->stats_lock, flags);
 470         is_thread_group = tsk->signal->stats ? 1 : 0;
 471         spin_unlock_irqrestore(&tsk->signal->stats_lock, flags);
 472
 473         rc = 0;
 474         /*
 475          * Size includes space for nested attributes
 476          */
 477         size = nla_total_size(sizeof(u32)) +
 478                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 479
 480         if (is_thread_group)
 481                 size = 2 * size;        /* PID + STATS + TGID + STATS */
 482
 483         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
 484         if (rc < 0)
 485                 goto ret;
 486
 487         rc = fill_pid(tsk->pid, tsk, tidstats);
 488         if (rc < 0)
 489                 goto err_skb;
 490
 491         na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
 492         NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, (u32)tsk->pid);
 493         NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 494                         *tidstats);
 495         nla_nest_end(rep_skb, na);
 496
 497         if (!is_thread_group)
 498                 goto send;
 499
 500         /*
 501          * tsk has/had a thread group so fill the tsk->signal->stats structure
 502          * Doesn't matter if tsk is the leader or the last group member leaving
 503          */
 504
 505         fill_tgid_exit(tsk);
 506         if (!group_dead)
 507                 goto send;
 508
 509         na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
 510         NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, (u32)tsk->tgid);
 511         /* No locking needed for tsk->signal->stats since group is dead */
 512         NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 513                         *tsk->signal->stats);
 514         nla_nest_end(rep_skb, na);
 515
 516 send:
 517         send_cpu_listeners(rep_skb, mycpu);
 518         return;
 519
 520 nla_put_failure:
 521         genlmsg_cancel(rep_skb, reply);
 522         goto ret;
 523 err_skb:
 524         nlmsg_free(rep_skb);
 525 ret:
 526         return;
 527 }
 528
 529 static struct genl_ops taskstats_ops = {
 530         .cmd            = TASKSTATS_CMD_GET,
 531         .doit           = taskstats_user_cmd,
 532         .policy         = taskstats_cmd_get_policy,
 533 };
 534
 535 /* Needed early in initialization */
 536 void __init taskstats_init_early(void)
 537 {
 538         unsigned int i;
 539
 540         taskstats_cache = kmem_cache_create("taskstats_cache",
 541                                                 sizeof(struct taskstats),
 542                                                 0, SLAB_PANIC, NULL, NULL);
 543         for_each_possible_cpu(i) {
 544                 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 545                 init_rwsem(&(per_cpu(listener_array, i).sem));
 546         }
 547 }
 548
 549 static int __init taskstats_init(void)
 550 {
 551         int rc;
 552
 553         rc = genl_register_family(&family);
 554         if (rc)
 555                 return rc;
 556
 557         rc = genl_register_ops(&family, &taskstats_ops);
 558         if (rc < 0)
 559                 goto err;
 560
 561         family_registered = 1;
 562         return 0;
 563 err:
 564         genl_unregister_family(&family);
 565         return rc;
 566 }
 567
 568 /*
 569  * late initcall ensures initialization of statistics collection
 570  * mechanisms precedes initialization of the taskstats interface
 571  */
 572 late_initcall(taskstats_init);