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 struct kmem_cache *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                                 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 = genlmsg_new(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, &family, 0, cmd);
  89         } else
  90                 reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
  91         if (reply == NULL) {
  92                 nlmsg_free(skb);
  93                 return -EINVAL;
  94         }
  95
  96         *skbp = skb;
  97         return 0;
  98 }
  99
 100 /*
 101  * Send taskstats data in @skb to listener with nl_pid @pid
 102  */
 103 static int send_reply(struct sk_buff *skb, pid_t pid)
 104 {
 105         struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
 106         void *reply = genlmsg_data(genlhdr);
 107         int rc;
 108
 109         rc = genlmsg_end(skb, reply);
 110         if (rc < 0) {
 111                 nlmsg_free(skb);
 112                 return rc;
 113         }
 114
 115         return genlmsg_unicast(skb, pid);
 116 }
 117
 118 /*
 119  * Send taskstats data in @skb to listeners registered for @cpu's exit data
 120  */
 121 static void send_cpu_listeners(struct sk_buff *skb,
 122                                         struct listener_list *listeners)
 123 {
 124         struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
 125         struct listener *s, *tmp;
 126         struct sk_buff *skb_next, *skb_cur = skb;
 127         void *reply = genlmsg_data(genlhdr);
 128         int rc, delcount = 0;
 129
 130         rc = genlmsg_end(skb, reply);
 131         if (rc < 0) {
 132                 nlmsg_free(skb);
 133                 return;
 134         }
 135
 136         rc = 0;
 137         down_read(&listeners->sem);
 138         list_for_each_entry(s, &listeners->list, list) {
 139                 skb_next = NULL;
 140                 if (!list_is_last(&s->list, &listeners->list)) {
 141                         skb_next = skb_clone(skb_cur, GFP_KERNEL);
 142                         if (!skb_next)
 143                                 break;
 144                 }
 145                 rc = genlmsg_unicast(skb_cur, s->pid);
 146                 if (rc == -ECONNREFUSED) {
 147                         s->valid = 0;
 148                         delcount++;
 149                 }
 150                 skb_cur = skb_next;
 151         }
 152         up_read(&listeners->sem);
 153
 154         if (skb_cur)
 155                 nlmsg_free(skb_cur);
 156
 157         if (!delcount)
 158                 return;
 159
 160         /* Delete invalidated entries */
 161         down_write(&listeners->sem);
 162         list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 163                 if (!s->valid) {
 164                         list_del(&s->list);
 165                         kfree(s);
 166                 }
 167         }
 168         up_write(&listeners->sem);
 169 }
 170
 171 static int fill_pid(pid_t pid, struct task_struct *tsk,
 172                 struct taskstats *stats)
 173 {
 174         int rc = 0;
 175
 176         if (!tsk) {
 177                 rcu_read_lock();
 178                 tsk = find_task_by_pid(pid);
 179                 if (tsk)
 180                         get_task_struct(tsk);
 181                 rcu_read_unlock();
 182                 if (!tsk)
 183                         return -ESRCH;
 184         } else
 185                 get_task_struct(tsk);
 186
 187         memset(stats, 0, sizeof(*stats));
 188         /*
 189          * Each accounting subsystem adds calls to its functions to
 190          * fill in relevant parts of struct taskstsats as follows
 191          *
 192          *      per-task-foo(stats, tsk);
 193          */
 194
 195         delayacct_add_tsk(stats, tsk);
 196
 197         /* fill in basic acct fields */
 198         stats->version = TASKSTATS_VERSION;
 199         bacct_add_tsk(stats, tsk);
 200
 201         /* fill in extended acct fields */
 202         xacct_add_tsk(stats, tsk);
 203
 204         /* Define err: label here if needed */
 205         put_task_struct(tsk);
 206         return rc;
 207
 208 }
 209
 210 static int fill_tgid(pid_t tgid, struct task_struct *first,
 211                 struct taskstats *stats)
 212 {
 213         struct task_struct *tsk;
 214         unsigned long flags;
 215         int rc = -ESRCH;
 216
 217         /*
 218          * Add additional stats from live tasks except zombie thread group
 219          * leaders who are already counted with the dead tasks
 220          */
 221         rcu_read_lock();
 222         if (!first)
 223                 first = find_task_by_pid(tgid);
 224
 225         if (!first || !lock_task_sighand(first, &flags))
 226                 goto out;
 227
 228         if (first->signal->stats)
 229                 memcpy(stats, first->signal->stats, sizeof(*stats));
 230         else
 231                 memset(stats, 0, sizeof(*stats));
 232
 233         tsk = first;
 234         do {
 235                 if (tsk->exit_state)
 236                         continue;
 237                 /*
 238                  * Accounting subsystem can call its functions here to
 239                  * fill in relevant parts of struct taskstsats as follows
 240                  *
 241                  *      per-task-foo(stats, tsk);
 242                  */
 243                 delayacct_add_tsk(stats, tsk);
 244
 245         } while_each_thread(first, tsk);
 246
 247         unlock_task_sighand(first, &flags);
 248         rc = 0;
 249 out:
 250         rcu_read_unlock();
 251
 252         stats->version = TASKSTATS_VERSION;
 253         /*
 254          * Accounting subsytems can also add calls here to modify
 255          * fields of taskstats.
 256          */
 257         return rc;
 258 }
 259
 260
 261 static void fill_tgid_exit(struct task_struct *tsk)
 262 {
 263         unsigned long flags;
 264
 265         spin_lock_irqsave(&tsk->sighand->siglock, flags);
 266         if (!tsk->signal->stats)
 267                 goto ret;
 268
 269         /*
 270          * Each accounting subsystem calls its functions here to
 271          * accumalate its per-task stats for tsk, into the per-tgid structure
 272          *
 273          *      per-task-foo(tsk->signal->stats, tsk);
 274          */
 275         delayacct_add_tsk(tsk->signal->stats, tsk);
 276 ret:
 277         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 278         return;
 279 }
 280
 281 static int add_del_listener(pid_t pid, cpumask_t *maskp, int isadd)
 282 {
 283         struct listener_list *listeners;
 284         struct listener *s, *tmp;
 285         unsigned int cpu;
 286         cpumask_t mask = *maskp;
 287
 288         if (!cpus_subset(mask, cpu_possible_map))
 289                 return -EINVAL;
 290
 291         if (isadd == REGISTER) {
 292                 for_each_cpu_mask(cpu, mask) {
 293                         s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
 294                                          cpu_to_node(cpu));
 295                         if (!s)
 296                                 goto cleanup;
 297                         s->pid = pid;
 298                         INIT_LIST_HEAD(&s->list);
 299                         s->valid = 1;
 300
 301                         listeners = &per_cpu(listener_array, cpu);
 302                         down_write(&listeners->sem);
 303                         list_add(&s->list, &listeners->list);
 304                         up_write(&listeners->sem);
 305                 }
 306                 return 0;
 307         }
 308
 309         /* Deregister or cleanup */
 310 cleanup:
 311         for_each_cpu_mask(cpu, mask) {
 312                 listeners = &per_cpu(listener_array, cpu);
 313                 down_write(&listeners->sem);
 314                 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 315                         if (s->pid == pid) {
 316                                 list_del(&s->list);
 317                                 kfree(s);
 318                                 break;
 319                         }
 320                 }
 321                 up_write(&listeners->sem);
 322         }
 323         return 0;
 324 }
 325
 326 static int parse(struct nlattr *na, cpumask_t *mask)
 327 {
 328         char *data;
 329         int len;
 330         int ret;
 331
 332         if (na == NULL)
 333                 return 1;
 334         len = nla_len(na);
 335         if (len > TASKSTATS_CPUMASK_MAXLEN)
 336                 return -E2BIG;
 337         if (len < 1)
 338                 return -EINVAL;
 339         data = kmalloc(len, GFP_KERNEL);
 340         if (!data)
 341                 return -ENOMEM;
 342         nla_strlcpy(data, na, len);
 343         ret = cpulist_parse(data, *mask);
 344         kfree(data);
 345         return ret;
 346 }
 347
 348 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
 349 {
 350         struct nlattr *na, *ret;
 351         int aggr;
 352
 353         aggr = (type == TASKSTATS_TYPE_PID)
 354                         ? TASKSTATS_TYPE_AGGR_PID
 355                         : TASKSTATS_TYPE_AGGR_TGID;
 356
 357         na = nla_nest_start(skb, aggr);
 358         if (!na)
 359                 goto err;
 360         if (nla_put(skb, type, sizeof(pid), &pid) < 0)
 361                 goto err;
 362         ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
 363         if (!ret)
 364                 goto err;
 365         nla_nest_end(skb, na);
 366
 367         return nla_data(ret);
 368 err:
 369         return NULL;
 370 }
 371
 372 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 373 {
 374         int rc = 0;
 375         struct sk_buff *rep_skb;
 376         struct taskstats *stats;
 377         size_t size;
 378         cpumask_t mask;
 379
 380         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], &mask);
 381         if (rc < 0)
 382                 return rc;
 383         if (rc == 0)
 384                 return add_del_listener(info->snd_pid, &mask, REGISTER);
 385
 386         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], &mask);
 387         if (rc < 0)
 388                 return rc;
 389         if (rc == 0)
 390                 return add_del_listener(info->snd_pid, &mask, DEREGISTER);
 391
 392         /*
 393          * Size includes space for nested attributes
 394          */
 395         size = nla_total_size(sizeof(u32)) +
 396                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 397
 398         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
 399         if (rc < 0)
 400                 return rc;
 401
 402         rc = -EINVAL;
 403         if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
 404                 u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 405                 stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
 406                 if (!stats)
 407                         goto err;
 408
 409                 rc = fill_pid(pid, NULL, stats);
 410                 if (rc < 0)
 411                         goto err;
 412         } else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
 413                 u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 414                 stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 415                 if (!stats)
 416                         goto err;
 417
 418                 rc = fill_tgid(tgid, NULL, stats);
 419                 if (rc < 0)
 420                         goto err;
 421         } else
 422                 goto err;
 423
 424         return send_reply(rep_skb, info->snd_pid);
 425 err:
 426         nlmsg_free(rep_skb);
 427         return rc;
 428 }
 429
 430 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
 431 {
 432         struct signal_struct *sig = tsk->signal;
 433         struct taskstats *stats;
 434
 435         if (sig->stats || thread_group_empty(tsk))
 436                 goto ret;
 437
 438         /* No problem if kmem_cache_zalloc() fails */
 439         stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
 440
 441         spin_lock_irq(&tsk->sighand->siglock);
 442         if (!sig->stats) {
 443                 sig->stats = stats;
 444                 stats = NULL;
 445         }
 446         spin_unlock_irq(&tsk->sighand->siglock);
 447
 448         if (stats)
 449                 kmem_cache_free(taskstats_cache, stats);
 450 ret:
 451         return sig->stats;
 452 }
 453
 454 /* Send pid data out on exit */
 455 void taskstats_exit(struct task_struct *tsk, int group_dead)
 456 {
 457         int rc;
 458         struct listener_list *listeners;
 459         struct taskstats *stats;
 460         struct sk_buff *rep_skb;
 461         size_t size;
 462         int is_thread_group;
 463
 464         if (!family_registered)
 465                 return;
 466
 467         /*
 468          * Size includes space for nested attributes
 469          */
 470         size = nla_total_size(sizeof(u32)) +
 471                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 472
 473         is_thread_group = !!taskstats_tgid_alloc(tsk);
 474         if (is_thread_group) {
 475                 /* PID + STATS + TGID + STATS */
 476                 size = 2 * size;
 477                 /* fill the tsk->signal->stats structure */
 478                 fill_tgid_exit(tsk);
 479         }
 480
 481         listeners = &__raw_get_cpu_var(listener_array);
 482         if (list_empty(&listeners->list))
 483                 return;
 484
 485         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
 486         if (rc < 0)
 487                 return;
 488
 489         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
 490         if (!stats)
 491                 goto err;
 492
 493         rc = fill_pid(tsk->pid, tsk, stats);
 494         if (rc < 0)
 495                 goto err;
 496
 497         /*
 498          * Doesn't matter if tsk is the leader or the last group member leaving
 499          */
 500         if (!is_thread_group || !group_dead)
 501                 goto send;
 502
 503         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
 504         if (!stats)
 505                 goto err;
 506
 507         memcpy(stats, tsk->signal->stats, sizeof(*stats));
 508
 509 send:
 510         send_cpu_listeners(rep_skb, listeners);
 511         return;
 512 err:
 513         nlmsg_free(rep_skb);
 514 }
 515
 516 static struct genl_ops taskstats_ops = {
 517         .cmd            = TASKSTATS_CMD_GET,
 518         .doit           = taskstats_user_cmd,
 519         .policy         = taskstats_cmd_get_policy,
 520 };
 521
 522 /* Needed early in initialization */
 523 void __init taskstats_init_early(void)
 524 {
 525         unsigned int i;
 526
 527         taskstats_cache = kmem_cache_create("taskstats_cache",
 528                                                 sizeof(struct taskstats),
 529                                                 0, SLAB_PANIC, NULL, NULL);
 530         for_each_possible_cpu(i) {
 531                 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 532                 init_rwsem(&(per_cpu(listener_array, i).sem));
 533         }
 534 }
 535
 536 static int __init taskstats_init(void)
 537 {
 538         int rc;
 539
 540         rc = genl_register_family(&family);
 541         if (rc)
 542                 return rc;
 543
 544         rc = genl_register_ops(&family, &taskstats_ops);
 545         if (rc < 0)
 546                 goto err;
 547
 548         family_registered = 1;
 549         return 0;
 550 err:
 551         genl_unregister_family(&family);
 552         return rc;
 553 }
 554
 555 /*
 556  * late initcall ensures initialization of statistics collection
 557  * mechanisms precedes initialization of the taskstats interface
 558  */
 559 late_initcall(taskstats_init);