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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 void fill_stats(struct task_struct *tsk, struct taskstats *stats)
179 {
180 memset(stats, 0, sizeof(*stats));
181 /*
182 * Each accounting subsystem adds calls to its functions to
183 * fill in relevant parts of struct taskstsats as follows
184 *
185 * per-task-foo(stats, tsk);
186 */
187
188 delayacct_add_tsk(stats, tsk);
189
190 /* fill in basic acct fields */
191 stats->version = TASKSTATS_VERSION;
192 stats->nvcsw = tsk->nvcsw;
193 stats->nivcsw = tsk->nivcsw;
194 bacct_add_tsk(stats, tsk);
195
196 /* fill in extended acct fields */
197 xacct_add_tsk(stats, tsk);
198 }
199
200 static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
201 {
202 struct task_struct *tsk;
203
204 rcu_read_lock();
205 tsk = find_task_by_vpid(pid);
206 if (tsk)
207 get_task_struct(tsk);
208 rcu_read_unlock();
209 if (!tsk)
210 return -ESRCH;
211 fill_stats(tsk, stats);
212 put_task_struct(tsk);
213 return 0;
214 }
215
216 static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
217 {
218 struct task_struct *tsk, *first;
219 unsigned long flags;
220 int rc = -ESRCH;
221
222 /*
223 * Add additional stats from live tasks except zombie thread group
224 * leaders who are already counted with the dead tasks
225 */
226 rcu_read_lock();
227 first = find_task_by_vpid(tgid);
228
229 if (!first || !lock_task_sighand(first, &flags))
230 goto out;
231
232 if (first->signal->stats)
233 memcpy(stats, first->signal->stats, sizeof(*stats));
234 else
235 memset(stats, 0, 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 stats->nvcsw += tsk->nvcsw;
250 stats->nivcsw += tsk->nivcsw;
251 } while_each_thread(first, tsk);
252
253 unlock_task_sighand(first, &flags);
254 rc = 0;
255 out:
256 rcu_read_unlock();
257
258 stats->version = TASKSTATS_VERSION;
259 /*
260 * Accounting subsystems can also add calls here to modify
261 * fields of taskstats.
262 */
263 return rc;
264 }
265
266 static void fill_tgid_exit(struct task_struct *tsk)
267 {
268 unsigned long flags;
269
270 spin_lock_irqsave(&tsk->sighand->siglock, flags);
271 if (!tsk->signal->stats)
272 goto ret;
273
274 /*
275 * Each accounting subsystem calls its functions here to
276 * accumalate its per-task stats for tsk, into the per-tgid structure
277 *
278 * per-task-foo(tsk->signal->stats, tsk);
279 */
280 delayacct_add_tsk(tsk->signal->stats, tsk);
281 ret:
282 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
283 return;
284 }
285
286 static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
287 {
288 struct listener_list *listeners;
289 struct listener *s, *tmp;
290 unsigned int cpu;
291
292 if (!cpumask_subset(mask, cpu_possible_mask))
293 return -EINVAL;
294
295 if (isadd == REGISTER) {
296 for_each_cpu(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(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, struct cpumask *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 struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
353 {
354 struct nlattr *na, *ret;
355 int aggr;
356
357 /* If we don't pad, we end up with alignment on a 4 byte boundary.
358 * This causes lots of runtime warnings on systems requiring 8 byte
359 * alignment */
360 u32 pids[2] = { pid, 0 };
361 int pid_size = ALIGN(sizeof(pid), sizeof(long));
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, pid_size, pids) < 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 cmd_attr_register_cpumask(struct genl_info *info)
428 {
429 cpumask_var_t mask;
430 int rc;
431
432 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
433 return -ENOMEM;
434 rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
435 if (rc < 0)
436 goto out;
437 rc = add_del_listener(info->snd_pid, mask, REGISTER);
438 out:
439 free_cpumask_var(mask);
440 return rc;
441 }
442
443 static int cmd_attr_deregister_cpumask(struct genl_info *info)
444 {
445 cpumask_var_t mask;
446 int rc;
447
448 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
449 return -ENOMEM;
450 rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
451 if (rc < 0)
452 goto out;
453 rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
454 out:
455 free_cpumask_var(mask);
456 return rc;
457 }
458
459 static int cmd_attr_pid(struct genl_info *info)
460 {
461 struct taskstats *stats;
462 struct sk_buff *rep_skb;
463 size_t size;
464 u32 pid;
465 int rc;
466
467 size = nla_total_size(sizeof(u32)) +
468 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
469
470 rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
471 if (rc < 0)
472 return rc;
473
474 rc = -EINVAL;
475 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
476 stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
477 if (!stats)
478 goto err;
479
480 rc = fill_stats_for_pid(pid, stats);
481 if (rc < 0)
482 goto err;
483 return send_reply(rep_skb, info);
484 err:
485 nlmsg_free(rep_skb);
486 return rc;
487 }
488
489 static int cmd_attr_tgid(struct genl_info *info)
490 {
491 struct taskstats *stats;
492 struct sk_buff *rep_skb;
493 size_t size;
494 u32 tgid;
495 int rc;
496
497 size = nla_total_size(sizeof(u32)) +
498 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
499
500 rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
501 if (rc < 0)
502 return rc;
503
504 rc = -EINVAL;
505 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
506 stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
507 if (!stats)
508 goto err;
509
510 rc = fill_stats_for_tgid(tgid, stats);
511 if (rc < 0)
512 goto err;
513 return send_reply(rep_skb, info);
514 err:
515 nlmsg_free(rep_skb);
516 return rc;
517 }
518
519 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
520 {
521 if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
522 return cmd_attr_register_cpumask(info);
523 else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
524 return cmd_attr_deregister_cpumask(info);
525 else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
526 return cmd_attr_pid(info);
527 else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
528 return cmd_attr_tgid(info);
529 else
530 return -EINVAL;
531 }
532
533 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
534 {
535 struct signal_struct *sig = tsk->signal;
536 struct taskstats *stats;
537
538 if (sig->stats || thread_group_empty(tsk))
539 goto ret;
540
541 /* No problem if kmem_cache_zalloc() fails */
542 stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
543
544 spin_lock_irq(&tsk->sighand->siglock);
545 if (!sig->stats) {
546 sig->stats = stats;
547 stats = NULL;
548 }
549 spin_unlock_irq(&tsk->sighand->siglock);
550
551 if (stats)
552 kmem_cache_free(taskstats_cache, stats);
553 ret:
554 return sig->stats;
555 }
556
557 /* Send pid data out on exit */
558 void taskstats_exit(struct task_struct *tsk, int group_dead)
559 {
560 int rc;
561 struct listener_list *listeners;
562 struct taskstats *stats;
563 struct sk_buff *rep_skb;
564 size_t size;
565 int is_thread_group;
566
567 if (!family_registered)
568 return;
569
570 /*
571 * Size includes space for nested attributes
572 */
573 size = nla_total_size(sizeof(u32)) +
574 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
575
576 is_thread_group = !!taskstats_tgid_alloc(tsk);
577 if (is_thread_group) {
578 /* PID + STATS + TGID + STATS */
579 size = 2 * size;
580 /* fill the tsk->signal->stats structure */
581 fill_tgid_exit(tsk);
582 }
583
584 listeners = &__raw_get_cpu_var(listener_array);
585 if (list_empty(&listeners->list))
586 return;
587
588 rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
589 if (rc < 0)
590 return;
591
592 stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
593 if (!stats)
594 goto err;
595
596 fill_stats(tsk, stats);
597
598 /*
599 * Doesn't matter if tsk is the leader or the last group member leaving
600 */
601 if (!is_thread_group || !group_dead)
602 goto send;
603
604 stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
605 if (!stats)
606 goto err;
607
608 memcpy(stats, tsk->signal->stats, sizeof(*stats));
609
610 send:
611 send_cpu_listeners(rep_skb, listeners);
612 return;
613 err:
614 nlmsg_free(rep_skb);
615 }
616
617 static struct genl_ops taskstats_ops = {
618 .cmd = TASKSTATS_CMD_GET,
619 .doit = taskstats_user_cmd,
620 .policy = taskstats_cmd_get_policy,
621 };
622
623 static struct genl_ops cgroupstats_ops = {
624 .cmd = CGROUPSTATS_CMD_GET,
625 .doit = cgroupstats_user_cmd,
626 .policy = cgroupstats_cmd_get_policy,
627 };
628
629 /* Needed early in initialization */
630 void __init taskstats_init_early(void)
631 {
632 unsigned int i;
633
634 taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
635 for_each_possible_cpu(i) {
636 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
637 init_rwsem(&(per_cpu(listener_array, i).sem));
638 }
639 }
640
641 static int __init taskstats_init(void)
642 {
643 int rc;
644
645 rc = genl_register_family(&family);
646 if (rc)
647 return rc;
648
649 rc = genl_register_ops(&family, &taskstats_ops);
650 if (rc < 0)
651 goto err;
652
653 rc = genl_register_ops(&family, &cgroupstats_ops);
654 if (rc < 0)
655 goto err_cgroup_ops;
656
657 family_registered = 1;
658 printk("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
659 return 0;
660 err_cgroup_ops:
661 genl_unregister_ops(&family, &taskstats_ops);
662 err:
663 genl_unregister_family(&family);
664 return rc;
665 }
666
667 /*
668 * late initcall ensures initialization of statistics collection
669 * mechanisms precedes initialization of the taskstats interface
670 */
671 late_initcall(taskstats_init);