xref: /linux/kernel/taskstats.c (revision d642ef71) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * taskstats.c - Export per-task statistics to userland
4  *
5  * Copyright (C) Shailabh Nagar, IBM Corp. 2006
6  *           (C) Balbir Singh,   IBM Corp. 2006
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/taskstats_kern.h>
11 #include <linux/tsacct_kern.h>
12 #include <linux/acct.h>
13 #include <linux/delayacct.h>
14 #include <linux/cpumask.h>
15 #include <linux/percpu.h>
16 #include <linux/slab.h>
17 #include <linux/cgroupstats.h>
18 #include <linux/cgroup.h>
19 #include <linux/fs.h>
20 #include <linux/file.h>
21 #include <linux/pid_namespace.h>
22 #include <net/genetlink.h>
23 #include <linux/atomic.h>
24 #include <linux/sched/cputime.h>
25 
26 /*
27  * Maximum length of a cpumask that can be specified in
28  * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
29  */
30 #define TASKSTATS_CPUMASK_MAXLEN	(100+6*NR_CPUS)
31 
32 static DEFINE_PER_CPU(__u32, taskstats_seqnum);
33 static int family_registered;
34 struct kmem_cache *taskstats_cache;
35 
36 static struct genl_family family;
37 
38 static const struct nla_policy taskstats_cmd_get_policy[] = {
39 	[TASKSTATS_CMD_ATTR_PID]  = { .type = NLA_U32 },
40 	[TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
41 	[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
42 	[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
43 
44 static const struct nla_policy cgroupstats_cmd_get_policy[] = {
45 	[CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
46 };
47 
48 struct listener {
49 	struct list_head list;
50 	pid_t pid;
51 	char valid;
52 };
53 
54 struct listener_list {
55 	struct rw_semaphore sem;
56 	struct list_head list;
57 };
58 static DEFINE_PER_CPU(struct listener_list, listener_array);
59 
60 enum actions {
61 	REGISTER,
62 	DEREGISTER,
63 	CPU_DONT_CARE
64 };
65 
66 static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
67 				size_t size)
68 {
69 	struct sk_buff *skb;
70 	void *reply;
71 
72 	/*
73 	 * If new attributes are added, please revisit this allocation
74 	 */
75 	skb = genlmsg_new(size, GFP_KERNEL);
76 	if (!skb)
77 		return -ENOMEM;
78 
79 	if (!info) {
80 		int seq = this_cpu_inc_return(taskstats_seqnum) - 1;
81 
82 		reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
83 	} else
84 		reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
85 	if (reply == NULL) {
86 		nlmsg_free(skb);
87 		return -EINVAL;
88 	}
89 
90 	*skbp = skb;
91 	return 0;
92 }
93 
94 /*
95  * Send taskstats data in @skb to listener with nl_pid @pid
96  */
97 static int send_reply(struct sk_buff *skb, struct genl_info *info)
98 {
99 	struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
100 	void *reply = genlmsg_data(genlhdr);
101 
102 	genlmsg_end(skb, reply);
103 
104 	return genlmsg_reply(skb, info);
105 }
106 
107 /*
108  * Send taskstats data in @skb to listeners registered for @cpu's exit data
109  */
110 static void send_cpu_listeners(struct sk_buff *skb,
111 					struct listener_list *listeners)
112 {
113 	struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
114 	struct listener *s, *tmp;
115 	struct sk_buff *skb_next, *skb_cur = skb;
116 	void *reply = genlmsg_data(genlhdr);
117 	int delcount = 0;
118 
119 	genlmsg_end(skb, reply);
120 
121 	down_read(&listeners->sem);
122 	list_for_each_entry(s, &listeners->list, list) {
123 		int rc;
124 
125 		skb_next = NULL;
126 		if (!list_is_last(&s->list, &listeners->list)) {
127 			skb_next = skb_clone(skb_cur, GFP_KERNEL);
128 			if (!skb_next)
129 				break;
130 		}
131 		rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
132 		if (rc == -ECONNREFUSED) {
133 			s->valid = 0;
134 			delcount++;
135 		}
136 		skb_cur = skb_next;
137 	}
138 	up_read(&listeners->sem);
139 
140 	if (skb_cur)
141 		nlmsg_free(skb_cur);
142 
143 	if (!delcount)
144 		return;
145 
146 	/* Delete invalidated entries */
147 	down_write(&listeners->sem);
148 	list_for_each_entry_safe(s, tmp, &listeners->list, list) {
149 		if (!s->valid) {
150 			list_del(&s->list);
151 			kfree(s);
152 		}
153 	}
154 	up_write(&listeners->sem);
155 }
156 
157 static void exe_add_tsk(struct taskstats *stats, struct task_struct *tsk)
158 {
159 	/* No idea if I'm allowed to access that here, now. */
160 	struct file *exe_file = get_task_exe_file(tsk);
161 
162 	if (exe_file) {
163 		/* Following cp_new_stat64() in stat.c . */
164 		stats->ac_exe_dev =
165 			huge_encode_dev(exe_file->f_inode->i_sb->s_dev);
166 		stats->ac_exe_inode = exe_file->f_inode->i_ino;
167 		fput(exe_file);
168 	} else {
169 		stats->ac_exe_dev = 0;
170 		stats->ac_exe_inode = 0;
171 	}
172 }
173 
174 static void fill_stats(struct user_namespace *user_ns,
175 		       struct pid_namespace *pid_ns,
176 		       struct task_struct *tsk, struct taskstats *stats)
177 {
178 	memset(stats, 0, sizeof(*stats));
179 	/*
180 	 * Each accounting subsystem adds calls to its functions to
181 	 * fill in relevant parts of struct taskstsats as follows
182 	 *
183 	 *	per-task-foo(stats, tsk);
184 	 */
185 
186 	delayacct_add_tsk(stats, tsk);
187 
188 	/* fill in basic acct fields */
189 	stats->version = TASKSTATS_VERSION;
190 	stats->nvcsw = tsk->nvcsw;
191 	stats->nivcsw = tsk->nivcsw;
192 	bacct_add_tsk(user_ns, pid_ns, stats, tsk);
193 
194 	/* fill in extended acct fields */
195 	xacct_add_tsk(stats, tsk);
196 
197 	/* add executable info */
198 	exe_add_tsk(stats, tsk);
199 }
200 
201 static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
202 {
203 	struct task_struct *tsk;
204 
205 	tsk = find_get_task_by_vpid(pid);
206 	if (!tsk)
207 		return -ESRCH;
208 	fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
209 	put_task_struct(tsk);
210 	return 0;
211 }
212 
213 static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
214 {
215 	struct task_struct *tsk, *first;
216 	unsigned long flags;
217 	int rc = -ESRCH;
218 	u64 delta, utime, stime;
219 	u64 start_time;
220 
221 	/*
222 	 * Add additional stats from live tasks except zombie thread group
223 	 * leaders who are already counted with the dead tasks
224 	 */
225 	rcu_read_lock();
226 	first = find_task_by_vpid(tgid);
227 
228 	if (!first || !lock_task_sighand(first, &flags))
229 		goto out;
230 
231 	if (first->signal->stats)
232 		memcpy(stats, first->signal->stats, sizeof(*stats));
233 	else
234 		memset(stats, 0, sizeof(*stats));
235 
236 	start_time = ktime_get_ns();
237 	for_each_thread(first, tsk) {
238 		if (tsk->exit_state)
239 			continue;
240 		/*
241 		 * Accounting subsystem can call its functions here to
242 		 * fill in relevant parts of struct taskstsats as follows
243 		 *
244 		 *	per-task-foo(stats, tsk);
245 		 */
246 		delayacct_add_tsk(stats, tsk);
247 
248 		/* calculate task elapsed time in nsec */
249 		delta = start_time - tsk->start_time;
250 		/* Convert to micro seconds */
251 		do_div(delta, NSEC_PER_USEC);
252 		stats->ac_etime += delta;
253 
254 		task_cputime(tsk, &utime, &stime);
255 		stats->ac_utime += div_u64(utime, NSEC_PER_USEC);
256 		stats->ac_stime += div_u64(stime, NSEC_PER_USEC);
257 
258 		stats->nvcsw += tsk->nvcsw;
259 		stats->nivcsw += tsk->nivcsw;
260 	}
261 
262 	unlock_task_sighand(first, &flags);
263 	rc = 0;
264 out:
265 	rcu_read_unlock();
266 
267 	stats->version = TASKSTATS_VERSION;
268 	/*
269 	 * Accounting subsystems can also add calls here to modify
270 	 * fields of taskstats.
271 	 */
272 	return rc;
273 }
274 
275 static void fill_tgid_exit(struct task_struct *tsk)
276 {
277 	unsigned long flags;
278 
279 	spin_lock_irqsave(&tsk->sighand->siglock, flags);
280 	if (!tsk->signal->stats)
281 		goto ret;
282 
283 	/*
284 	 * Each accounting subsystem calls its functions here to
285 	 * accumalate its per-task stats for tsk, into the per-tgid structure
286 	 *
287 	 *	per-task-foo(tsk->signal->stats, tsk);
288 	 */
289 	delayacct_add_tsk(tsk->signal->stats, tsk);
290 ret:
291 	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
292 	return;
293 }
294 
295 static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
296 {
297 	struct listener_list *listeners;
298 	struct listener *s, *tmp, *s2;
299 	unsigned int cpu;
300 	int ret = 0;
301 
302 	if (!cpumask_subset(mask, cpu_possible_mask))
303 		return -EINVAL;
304 
305 	if (current_user_ns() != &init_user_ns)
306 		return -EINVAL;
307 
308 	if (task_active_pid_ns(current) != &init_pid_ns)
309 		return -EINVAL;
310 
311 	if (isadd == REGISTER) {
312 		for_each_cpu(cpu, mask) {
313 			s = kmalloc_node(sizeof(struct listener),
314 					GFP_KERNEL, cpu_to_node(cpu));
315 			if (!s) {
316 				ret = -ENOMEM;
317 				goto cleanup;
318 			}
319 			s->pid = pid;
320 			s->valid = 1;
321 
322 			listeners = &per_cpu(listener_array, cpu);
323 			down_write(&listeners->sem);
324 			list_for_each_entry(s2, &listeners->list, list) {
325 				if (s2->pid == pid && s2->valid)
326 					goto exists;
327 			}
328 			list_add(&s->list, &listeners->list);
329 			s = NULL;
330 exists:
331 			up_write(&listeners->sem);
332 			kfree(s); /* nop if NULL */
333 		}
334 		return 0;
335 	}
336 
337 	/* Deregister or cleanup */
338 cleanup:
339 	for_each_cpu(cpu, mask) {
340 		listeners = &per_cpu(listener_array, cpu);
341 		down_write(&listeners->sem);
342 		list_for_each_entry_safe(s, tmp, &listeners->list, list) {
343 			if (s->pid == pid) {
344 				list_del(&s->list);
345 				kfree(s);
346 				break;
347 			}
348 		}
349 		up_write(&listeners->sem);
350 	}
351 	return ret;
352 }
353 
354 static int parse(struct nlattr *na, struct cpumask *mask)
355 {
356 	char *data;
357 	int len;
358 	int ret;
359 
360 	if (na == NULL)
361 		return 1;
362 	len = nla_len(na);
363 	if (len > TASKSTATS_CPUMASK_MAXLEN)
364 		return -E2BIG;
365 	if (len < 1)
366 		return -EINVAL;
367 	data = kmalloc(len, GFP_KERNEL);
368 	if (!data)
369 		return -ENOMEM;
370 	nla_strscpy(data, na, len);
371 	ret = cpulist_parse(data, mask);
372 	kfree(data);
373 	return ret;
374 }
375 
376 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
377 {
378 	struct nlattr *na, *ret;
379 	int aggr;
380 
381 	aggr = (type == TASKSTATS_TYPE_PID)
382 			? TASKSTATS_TYPE_AGGR_PID
383 			: TASKSTATS_TYPE_AGGR_TGID;
384 
385 	na = nla_nest_start_noflag(skb, aggr);
386 	if (!na)
387 		goto err;
388 
389 	if (nla_put(skb, type, sizeof(pid), &pid) < 0) {
390 		nla_nest_cancel(skb, na);
391 		goto err;
392 	}
393 	ret = nla_reserve_64bit(skb, TASKSTATS_TYPE_STATS,
394 				sizeof(struct taskstats), TASKSTATS_TYPE_NULL);
395 	if (!ret) {
396 		nla_nest_cancel(skb, na);
397 		goto err;
398 	}
399 	nla_nest_end(skb, na);
400 
401 	return nla_data(ret);
402 err:
403 	return NULL;
404 }
405 
406 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
407 {
408 	int rc = 0;
409 	struct sk_buff *rep_skb;
410 	struct cgroupstats *stats;
411 	struct nlattr *na;
412 	size_t size;
413 	u32 fd;
414 	struct fd f;
415 
416 	na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
417 	if (!na)
418 		return -EINVAL;
419 
420 	fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
421 	f = fdget(fd);
422 	if (!f.file)
423 		return 0;
424 
425 	size = nla_total_size(sizeof(struct cgroupstats));
426 
427 	rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
428 				size);
429 	if (rc < 0)
430 		goto err;
431 
432 	na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
433 				sizeof(struct cgroupstats));
434 	if (na == NULL) {
435 		nlmsg_free(rep_skb);
436 		rc = -EMSGSIZE;
437 		goto err;
438 	}
439 
440 	stats = nla_data(na);
441 	memset(stats, 0, sizeof(*stats));
442 
443 	rc = cgroupstats_build(stats, f.file->f_path.dentry);
444 	if (rc < 0) {
445 		nlmsg_free(rep_skb);
446 		goto err;
447 	}
448 
449 	rc = send_reply(rep_skb, info);
450 
451 err:
452 	fdput(f);
453 	return rc;
454 }
455 
456 static int cmd_attr_register_cpumask(struct genl_info *info)
457 {
458 	cpumask_var_t mask;
459 	int rc;
460 
461 	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
462 		return -ENOMEM;
463 	rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
464 	if (rc < 0)
465 		goto out;
466 	rc = add_del_listener(info->snd_portid, mask, REGISTER);
467 out:
468 	free_cpumask_var(mask);
469 	return rc;
470 }
471 
472 static int cmd_attr_deregister_cpumask(struct genl_info *info)
473 {
474 	cpumask_var_t mask;
475 	int rc;
476 
477 	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
478 		return -ENOMEM;
479 	rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
480 	if (rc < 0)
481 		goto out;
482 	rc = add_del_listener(info->snd_portid, mask, DEREGISTER);
483 out:
484 	free_cpumask_var(mask);
485 	return rc;
486 }
487 
488 static size_t taskstats_packet_size(void)
489 {
490 	size_t size;
491 
492 	size = nla_total_size(sizeof(u32)) +
493 		nla_total_size_64bit(sizeof(struct taskstats)) +
494 		nla_total_size(0);
495 
496 	return size;
497 }
498 
499 static int cmd_attr_pid(struct genl_info *info)
500 {
501 	struct taskstats *stats;
502 	struct sk_buff *rep_skb;
503 	size_t size;
504 	u32 pid;
505 	int rc;
506 
507 	size = taskstats_packet_size();
508 
509 	rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
510 	if (rc < 0)
511 		return rc;
512 
513 	rc = -EINVAL;
514 	pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
515 	stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
516 	if (!stats)
517 		goto err;
518 
519 	rc = fill_stats_for_pid(pid, stats);
520 	if (rc < 0)
521 		goto err;
522 	return send_reply(rep_skb, info);
523 err:
524 	nlmsg_free(rep_skb);
525 	return rc;
526 }
527 
528 static int cmd_attr_tgid(struct genl_info *info)
529 {
530 	struct taskstats *stats;
531 	struct sk_buff *rep_skb;
532 	size_t size;
533 	u32 tgid;
534 	int rc;
535 
536 	size = taskstats_packet_size();
537 
538 	rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
539 	if (rc < 0)
540 		return rc;
541 
542 	rc = -EINVAL;
543 	tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
544 	stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
545 	if (!stats)
546 		goto err;
547 
548 	rc = fill_stats_for_tgid(tgid, stats);
549 	if (rc < 0)
550 		goto err;
551 	return send_reply(rep_skb, info);
552 err:
553 	nlmsg_free(rep_skb);
554 	return rc;
555 }
556 
557 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
558 {
559 	if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
560 		return cmd_attr_register_cpumask(info);
561 	else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
562 		return cmd_attr_deregister_cpumask(info);
563 	else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
564 		return cmd_attr_pid(info);
565 	else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
566 		return cmd_attr_tgid(info);
567 	else
568 		return -EINVAL;
569 }
570 
571 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
572 {
573 	struct signal_struct *sig = tsk->signal;
574 	struct taskstats *stats_new, *stats;
575 
576 	/* Pairs with smp_store_release() below. */
577 	stats = smp_load_acquire(&sig->stats);
578 	if (stats || thread_group_empty(tsk))
579 		return stats;
580 
581 	/* No problem if kmem_cache_zalloc() fails */
582 	stats_new = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
583 
584 	spin_lock_irq(&tsk->sighand->siglock);
585 	stats = sig->stats;
586 	if (!stats) {
587 		/*
588 		 * Pairs with smp_store_release() above and order the
589 		 * kmem_cache_zalloc().
590 		 */
591 		smp_store_release(&sig->stats, stats_new);
592 		stats = stats_new;
593 		stats_new = NULL;
594 	}
595 	spin_unlock_irq(&tsk->sighand->siglock);
596 
597 	if (stats_new)
598 		kmem_cache_free(taskstats_cache, stats_new);
599 
600 	return stats;
601 }
602 
603 /* Send pid data out on exit */
604 void taskstats_exit(struct task_struct *tsk, int group_dead)
605 {
606 	int rc;
607 	struct listener_list *listeners;
608 	struct taskstats *stats;
609 	struct sk_buff *rep_skb;
610 	size_t size;
611 	int is_thread_group;
612 
613 	if (!family_registered)
614 		return;
615 
616 	/*
617 	 * Size includes space for nested attributes
618 	 */
619 	size = taskstats_packet_size();
620 
621 	is_thread_group = !!taskstats_tgid_alloc(tsk);
622 	if (is_thread_group) {
623 		/* PID + STATS + TGID + STATS */
624 		size = 2 * size;
625 		/* fill the tsk->signal->stats structure */
626 		fill_tgid_exit(tsk);
627 	}
628 
629 	listeners = raw_cpu_ptr(&listener_array);
630 	if (list_empty(&listeners->list))
631 		return;
632 
633 	rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
634 	if (rc < 0)
635 		return;
636 
637 	stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID,
638 			 task_pid_nr_ns(tsk, &init_pid_ns));
639 	if (!stats)
640 		goto err;
641 
642 	fill_stats(&init_user_ns, &init_pid_ns, tsk, stats);
643 	if (group_dead)
644 		stats->ac_flag |= AGROUP;
645 
646 	/*
647 	 * Doesn't matter if tsk is the leader or the last group member leaving
648 	 */
649 	if (!is_thread_group || !group_dead)
650 		goto send;
651 
652 	stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID,
653 			 task_tgid_nr_ns(tsk, &init_pid_ns));
654 	if (!stats)
655 		goto err;
656 
657 	memcpy(stats, tsk->signal->stats, sizeof(*stats));
658 
659 send:
660 	send_cpu_listeners(rep_skb, listeners);
661 	return;
662 err:
663 	nlmsg_free(rep_skb);
664 }
665 
666 static const struct genl_ops taskstats_ops[] = {
667 	{
668 		.cmd		= TASKSTATS_CMD_GET,
669 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
670 		.doit		= taskstats_user_cmd,
671 		.policy		= taskstats_cmd_get_policy,
672 		.maxattr	= ARRAY_SIZE(taskstats_cmd_get_policy) - 1,
673 		.flags		= GENL_ADMIN_PERM,
674 	},
675 	{
676 		.cmd		= CGROUPSTATS_CMD_GET,
677 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
678 		.doit		= cgroupstats_user_cmd,
679 		.policy		= cgroupstats_cmd_get_policy,
680 		.maxattr	= ARRAY_SIZE(cgroupstats_cmd_get_policy) - 1,
681 	},
682 };
683 
684 static struct genl_family family __ro_after_init = {
685 	.name		= TASKSTATS_GENL_NAME,
686 	.version	= TASKSTATS_GENL_VERSION,
687 	.module		= THIS_MODULE,
688 	.ops		= taskstats_ops,
689 	.n_ops		= ARRAY_SIZE(taskstats_ops),
690 	.resv_start_op	= CGROUPSTATS_CMD_GET + 1,
691 	.netnsok	= true,
692 };
693 
694 /* Needed early in initialization */
695 void __init taskstats_init_early(void)
696 {
697 	unsigned int i;
698 
699 	taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
700 	for_each_possible_cpu(i) {
701 		INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
702 		init_rwsem(&(per_cpu(listener_array, i).sem));
703 	}
704 }
705 
706 static int __init taskstats_init(void)
707 {
708 	int rc;
709 
710 	rc = genl_register_family(&family);
711 	if (rc)
712 		return rc;
713 
714 	family_registered = 1;
715 	pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
716 	return 0;
717 }
718 
719 /*
720  * late initcall ensures initialization of statistics collection
721  * mechanisms precedes initialization of the taskstats interface
722  */
723 late_initcall(taskstats_init);
724