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         size = nlmsg_total_size(genlmsg_total_size(size));
  81         skb = nlmsg_new(size, GFP_KERNEL);
  82         if (!skb)
  83                 return -ENOMEM;
  84
  85         if (!info) {
  86                 int seq = get_cpu_var(taskstats_seqnum)++;
  87                 put_cpu_var(taskstats_seqnum);
  88
  89                 reply = genlmsg_put(skb, 0, seq,
  90                                 family.id, 0, 0,
  91                                 cmd, family.version);
  92         } else
  93                 reply = genlmsg_put(skb, info->snd_pid, info->snd_seq,
  94                                 family.id, 0, 0,
  95                                 cmd, family.version);
  96         if (reply == NULL) {
  97                 nlmsg_free(skb);
  98                 return -EINVAL;
  99         }
 100
 101         *skbp = skb;
 102         *replyp = reply;
 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, pid_t pid)
 110 {
 111         struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
 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_unicast(skb, pid);
 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, unsigned int cpu)
 128 {
 129         struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
 130         struct listener_list *listeners;
 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         listeners = &per_cpu(listener_array, cpu);
 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(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_pid(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         /*
 195          * Each accounting subsystem adds calls to its functions to
 196          * fill in relevant parts of struct taskstsats as follows
 197          *
 198          *      per-task-foo(stats, tsk);
 199          */
 200
 201         delayacct_add_tsk(stats, tsk);
 202
 203         /* fill in basic acct fields */
 204         stats->version = TASKSTATS_VERSION;
 205         bacct_add_tsk(stats, tsk);
 206
 207         /* fill in extended acct fields */
 208         xacct_add_tsk(stats, tsk);
 209
 210         /* Define err: label here if needed */
 211         put_task_struct(tsk);
 212         return rc;
 213
 214 }
 215
 216 static int fill_tgid(pid_t tgid, struct task_struct *first,
 217                 struct taskstats *stats)
 218 {
 219         struct task_struct *tsk;
 220         unsigned long flags;
 221         int rc = -ESRCH;
 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         rcu_read_lock();
 228         if (!first)
 229                 first = find_task_by_pid(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
 237         tsk = first;
 238         do {
 239                 if (tsk->exit_state)
 240                         continue;
 241                 /*
 242                  * Accounting subsystem can call its functions here to
 243                  * fill in relevant parts of struct taskstsats as follows
 244                  *
 245                  *      per-task-foo(stats, tsk);
 246                  */
 247                 delayacct_add_tsk(stats, tsk);
 248
 249         } while_each_thread(first, tsk);
 250
 251         unlock_task_sighand(first, &flags);
 252         rc = 0;
 253 out:
 254         rcu_read_unlock();
 255
 256         stats->version = TASKSTATS_VERSION;
 257         /*
 258          * Accounting subsytems can also add calls here to modify
 259          * fields of taskstats.
 260          */
 261         return rc;
 262 }
 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, cpumask_t *maskp, int isadd)
 286 {
 287         struct listener_list *listeners;
 288         struct listener *s, *tmp;
 289         unsigned int cpu;
 290         cpumask_t mask = *maskp;
 291
 292         if (!cpus_subset(mask, cpu_possible_map))
 293                 return -EINVAL;
 294
 295         if (isadd == REGISTER) {
 296                 for_each_cpu_mask(cpu, mask) {
 297                         s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
 298                                          cpu_to_node(cpu));
 299                         if (!s)
 300                                 goto cleanup;
 301                         s->pid = pid;
 302                         INIT_LIST_HEAD(&s->list);
 303                         s->valid = 1;
 304
 305                         listeners = &per_cpu(listener_array, cpu);
 306                         down_write(&listeners->sem);
 307                         list_add(&s->list, &listeners->list);
 308                         up_write(&listeners->sem);
 309                 }
 310                 return 0;
 311         }
 312
 313         /* Deregister or cleanup */
 314 cleanup:
 315         for_each_cpu_mask(cpu, mask) {
 316                 listeners = &per_cpu(listener_array, cpu);
 317                 down_write(&listeners->sem);
 318                 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
 319                         if (s->pid == pid) {
 320                                 list_del(&s->list);
 321                                 kfree(s);
 322                                 break;
 323                         }
 324                 }
 325                 up_write(&listeners->sem);
 326         }
 327         return 0;
 328 }
 329
 330 static int parse(struct nlattr *na, cpumask_t *mask)
 331 {
 332         char *data;
 333         int len;
 334         int ret;
 335
 336         if (na == NULL)
 337                 return 1;
 338         len = nla_len(na);
 339         if (len > TASKSTATS_CPUMASK_MAXLEN)
 340                 return -E2BIG;
 341         if (len < 1)
 342                 return -EINVAL;
 343         data = kmalloc(len, GFP_KERNEL);
 344         if (!data)
 345                 return -ENOMEM;
 346         nla_strlcpy(data, na, len);
 347         ret = cpulist_parse(data, *mask);
 348         kfree(data);
 349         return ret;
 350 }
 351
 352 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 353 {
 354         int rc = 0;
 355         struct sk_buff *rep_skb;
 356         struct taskstats stats;
 357         void *reply;
 358         size_t size;
 359         struct nlattr *na;
 360         cpumask_t mask;
 361
 362         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], &mask);
 363         if (rc < 0)
 364                 return rc;
 365         if (rc == 0)
 366                 return add_del_listener(info->snd_pid, &mask, REGISTER);
 367
 368         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], &mask);
 369         if (rc < 0)
 370                 return rc;
 371         if (rc == 0)
 372                 return add_del_listener(info->snd_pid, &mask, DEREGISTER);
 373
 374         /*
 375          * Size includes space for nested attributes
 376          */
 377         size = nla_total_size(sizeof(u32)) +
 378                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 379
 380         memset(&stats, 0, sizeof(stats));
 381         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
 382         if (rc < 0)
 383                 return rc;
 384
 385         if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
 386                 u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
 387                 rc = fill_pid(pid, NULL, &stats);
 388                 if (rc < 0)
 389                         goto err;
 390
 391                 na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
 392                 NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, pid);
 393                 NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 394                                 stats);
 395         } else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
 396                 u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
 397                 rc = fill_tgid(tgid, NULL, &stats);
 398                 if (rc < 0)
 399                         goto err;
 400
 401                 na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
 402                 NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, tgid);
 403                 NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 404                                 stats);
 405         } else {
 406                 rc = -EINVAL;
 407                 goto err;
 408         }
 409
 410         nla_nest_end(rep_skb, na);
 411
 412         return send_reply(rep_skb, info->snd_pid);
 413
 414 nla_put_failure:
 415         rc = genlmsg_cancel(rep_skb, reply);
 416 err:
 417         nlmsg_free(rep_skb);
 418         return rc;
 419 }
 420
 421 void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu)
 422 {
 423         struct listener_list *listeners;
 424         struct taskstats *tmp;
 425         /*
 426          * This is the cpu on which the task is exiting currently and will
 427          * be the one for which the exit event is sent, even if the cpu
 428          * on which this function is running changes later.
 429          */
 430         *mycpu = raw_smp_processor_id();
 431
 432         *ptidstats = NULL;
 433         tmp = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
 434         if (!tmp)
 435                 return;
 436
 437         listeners = &per_cpu(listener_array, *mycpu);
 438         down_read(&listeners->sem);
 439         if (!list_empty(&listeners->list)) {
 440                 *ptidstats = tmp;
 441                 tmp = NULL;
 442         }
 443         up_read(&listeners->sem);
 444         kfree(tmp);
 445 }
 446
 447 /* Send pid data out on exit */
 448 void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
 449                         int group_dead, unsigned int mycpu)
 450 {
 451         int rc;
 452         struct sk_buff *rep_skb;
 453         void *reply;
 454         size_t size;
 455         int is_thread_group;
 456         struct nlattr *na;
 457
 458         if (!family_registered)
 459                 return;
 460
 461         /*
 462          * Size includes space for nested attributes
 463          */
 464         size = nla_total_size(sizeof(u32)) +
 465                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 466
 467         is_thread_group = (tsk->signal->stats != NULL);
 468         if (is_thread_group) {
 469                 /* PID + STATS + TGID + STATS */
 470                 size = 2 * size;
 471                 /* fill the tsk->signal->stats structure */
 472                 fill_tgid_exit(tsk);
 473         }
 474
 475         if (!tidstats)
 476                 return;
 477
 478         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
 479         if (rc < 0)
 480                 goto ret;
 481
 482         rc = fill_pid(tsk->pid, tsk, tidstats);
 483         if (rc < 0)
 484                 goto err_skb;
 485
 486         na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
 487         NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, (u32)tsk->pid);
 488         NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 489                         *tidstats);
 490         nla_nest_end(rep_skb, na);
 491
 492         if (!is_thread_group)
 493                 goto send;
 494
 495         /*
 496          * Doesn't matter if tsk is the leader or the last group member leaving
 497          */
 498         if (!group_dead)
 499                 goto send;
 500
 501         na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
 502         NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, (u32)tsk->tgid);
 503         /* No locking needed for tsk->signal->stats since group is dead */
 504         NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
 505                         *tsk->signal->stats);
 506         nla_nest_end(rep_skb, na);
 507
 508 send:
 509         send_cpu_listeners(rep_skb, mycpu);
 510         return;
 511
 512 nla_put_failure:
 513         genlmsg_cancel(rep_skb, reply);
 514 err_skb:
 515         nlmsg_free(rep_skb);
 516 ret:
 517         return;
 518 }
 519
 520 static struct genl_ops taskstats_ops = {
 521         .cmd            = TASKSTATS_CMD_GET,
 522         .doit           = taskstats_user_cmd,
 523         .policy         = taskstats_cmd_get_policy,
 524 };
 525
 526 /* Needed early in initialization */
 527 void __init taskstats_init_early(void)
 528 {
 529         unsigned int i;
 530
 531         taskstats_cache = kmem_cache_create("taskstats_cache",
 532                                                 sizeof(struct taskstats),
 533                                                 0, SLAB_PANIC, NULL, NULL);
 534         for_each_possible_cpu(i) {
 535                 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
 536                 init_rwsem(&(per_cpu(listener_array, i).sem));
 537         }
 538 }
 539
 540 static int __init taskstats_init(void)
 541 {
 542         int rc;
 543
 544         rc = genl_register_family(&family);
 545         if (rc)
 546                 return rc;
 547
 548         rc = genl_register_ops(&family, &taskstats_ops);
 549         if (rc < 0)
 550                 goto err;
 551
 552         family_registered = 1;
 553         return 0;
 554 err:
 555         genl_unregister_family(&family);
 556         return rc;
 557 }
 558
 559 /*
 560  * late initcall ensures initialization of statistics collection
 561  * mechanisms precedes initialization of the taskstats interface
 562  */
 563 late_initcall(taskstats_init);