xref: /openbmc/linux/kernel/taskstats.c (revision bc5aa3a0) 
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 <linux/pid_namespace.h>
31 #include <net/genetlink.h>
32 #include <linux/atomic.h>
33 
34 /*
35  * Maximum length of a cpumask that can be specified in
36  * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
37  */
38 #define TASKSTATS_CPUMASK_MAXLEN	(100+6*NR_CPUS)
39 
40 static DEFINE_PER_CPU(__u32, taskstats_seqnum);
41 static int family_registered;
42 struct kmem_cache *taskstats_cache;
43 
44 static struct genl_family family = {
45 	.id		= GENL_ID_GENERATE,
46 	.name		= TASKSTATS_GENL_NAME,
47 	.version	= TASKSTATS_GENL_VERSION,
48 	.maxattr	= TASKSTATS_CMD_ATTR_MAX,
49 };
50 
51 static const struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
52 	[TASKSTATS_CMD_ATTR_PID]  = { .type = NLA_U32 },
53 	[TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
54 	[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
55 	[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
56 
57 static const struct nla_policy cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] = {
58 	[CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
59 };
60 
61 struct listener {
62 	struct list_head list;
63 	pid_t pid;
64 	char valid;
65 };
66 
67 struct listener_list {
68 	struct rw_semaphore sem;
69 	struct list_head list;
70 };
71 static DEFINE_PER_CPU(struct listener_list, listener_array);
72 
73 enum actions {
74 	REGISTER,
75 	DEREGISTER,
76 	CPU_DONT_CARE
77 };
78 
79 static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
80 				size_t size)
81 {
82 	struct sk_buff *skb;
83 	void *reply;
84 
85 	/*
86 	 * If new attributes are added, please revisit this allocation
87 	 */
88 	skb = genlmsg_new(size, GFP_KERNEL);
89 	if (!skb)
90 		return -ENOMEM;
91 
92 	if (!info) {
93 		int seq = this_cpu_inc_return(taskstats_seqnum) - 1;
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 
115 	genlmsg_end(skb, reply);
116 
117 	return genlmsg_reply(skb, info);
118 }
119 
120 /*
121  * Send taskstats data in @skb to listeners registered for @cpu's exit data
122  */
123 static void send_cpu_listeners(struct sk_buff *skb,
124 					struct listener_list *listeners)
125 {
126 	struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
127 	struct listener *s, *tmp;
128 	struct sk_buff *skb_next, *skb_cur = skb;
129 	void *reply = genlmsg_data(genlhdr);
130 	int rc, delcount = 0;
131 
132 	genlmsg_end(skb, reply);
133 
134 	rc = 0;
135 	down_read(&listeners->sem);
136 	list_for_each_entry(s, &listeners->list, list) {
137 		skb_next = NULL;
138 		if (!list_is_last(&s->list, &listeners->list)) {
139 			skb_next = skb_clone(skb_cur, GFP_KERNEL);
140 			if (!skb_next)
141 				break;
142 		}
143 		rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
144 		if (rc == -ECONNREFUSED) {
145 			s->valid = 0;
146 			delcount++;
147 		}
148 		skb_cur = skb_next;
149 	}
150 	up_read(&listeners->sem);
151 
152 	if (skb_cur)
153 		nlmsg_free(skb_cur);
154 
155 	if (!delcount)
156 		return;
157 
158 	/* Delete invalidated entries */
159 	down_write(&listeners->sem);
160 	list_for_each_entry_safe(s, tmp, &listeners->list, list) {
161 		if (!s->valid) {
162 			list_del(&s->list);
163 			kfree(s);
164 		}
165 	}
166 	up_write(&listeners->sem);
167 }
168 
169 static void fill_stats(struct user_namespace *user_ns,
170 		       struct pid_namespace *pid_ns,
171 		       struct task_struct *tsk, struct taskstats *stats)
172 {
173 	memset(stats, 0, sizeof(*stats));
174 	/*
175 	 * Each accounting subsystem adds calls to its functions to
176 	 * fill in relevant parts of struct taskstsats as follows
177 	 *
178 	 *	per-task-foo(stats, tsk);
179 	 */
180 
181 	delayacct_add_tsk(stats, tsk);
182 
183 	/* fill in basic acct fields */
184 	stats->version = TASKSTATS_VERSION;
185 	stats->nvcsw = tsk->nvcsw;
186 	stats->nivcsw = tsk->nivcsw;
187 	bacct_add_tsk(user_ns, pid_ns, stats, tsk);
188 
189 	/* fill in extended acct fields */
190 	xacct_add_tsk(stats, tsk);
191 }
192 
193 static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
194 {
195 	struct task_struct *tsk;
196 
197 	rcu_read_lock();
198 	tsk = find_task_by_vpid(pid);
199 	if (tsk)
200 		get_task_struct(tsk);
201 	rcu_read_unlock();
202 	if (!tsk)
203 		return -ESRCH;
204 	fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
205 	put_task_struct(tsk);
206 	return 0;
207 }
208 
209 static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
210 {
211 	struct task_struct *tsk, *first;
212 	unsigned long flags;
213 	int rc = -ESRCH;
214 
215 	/*
216 	 * Add additional stats from live tasks except zombie thread group
217 	 * leaders who are already counted with the dead tasks
218 	 */
219 	rcu_read_lock();
220 	first = find_task_by_vpid(tgid);
221 
222 	if (!first || !lock_task_sighand(first, &flags))
223 		goto out;
224 
225 	if (first->signal->stats)
226 		memcpy(stats, first->signal->stats, sizeof(*stats));
227 	else
228 		memset(stats, 0, sizeof(*stats));
229 
230 	tsk = first;
231 	do {
232 		if (tsk->exit_state)
233 			continue;
234 		/*
235 		 * Accounting subsystem can call its functions here to
236 		 * fill in relevant parts of struct taskstsats as follows
237 		 *
238 		 *	per-task-foo(stats, tsk);
239 		 */
240 		delayacct_add_tsk(stats, tsk);
241 
242 		stats->nvcsw += tsk->nvcsw;
243 		stats->nivcsw += tsk->nivcsw;
244 	} while_each_thread(first, tsk);
245 
246 	unlock_task_sighand(first, &flags);
247 	rc = 0;
248 out:
249 	rcu_read_unlock();
250 
251 	stats->version = TASKSTATS_VERSION;
252 	/*
253 	 * Accounting subsystems can also add calls here to modify
254 	 * fields of taskstats.
255 	 */
256 	return rc;
257 }
258 
259 static void fill_tgid_exit(struct task_struct *tsk)
260 {
261 	unsigned long flags;
262 
263 	spin_lock_irqsave(&tsk->sighand->siglock, flags);
264 	if (!tsk->signal->stats)
265 		goto ret;
266 
267 	/*
268 	 * Each accounting subsystem calls its functions here to
269 	 * accumalate its per-task stats for tsk, into the per-tgid structure
270 	 *
271 	 *	per-task-foo(tsk->signal->stats, tsk);
272 	 */
273 	delayacct_add_tsk(tsk->signal->stats, tsk);
274 ret:
275 	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
276 	return;
277 }
278 
279 static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
280 {
281 	struct listener_list *listeners;
282 	struct listener *s, *tmp, *s2;
283 	unsigned int cpu;
284 	int ret = 0;
285 
286 	if (!cpumask_subset(mask, cpu_possible_mask))
287 		return -EINVAL;
288 
289 	if (current_user_ns() != &init_user_ns)
290 		return -EINVAL;
291 
292 	if (task_active_pid_ns(current) != &init_pid_ns)
293 		return -EINVAL;
294 
295 	if (isadd == REGISTER) {
296 		for_each_cpu(cpu, mask) {
297 			s = kmalloc_node(sizeof(struct listener),
298 					GFP_KERNEL, cpu_to_node(cpu));
299 			if (!s) {
300 				ret = -ENOMEM;
301 				goto cleanup;
302 			}
303 			s->pid = pid;
304 			s->valid = 1;
305 
306 			listeners = &per_cpu(listener_array, cpu);
307 			down_write(&listeners->sem);
308 			list_for_each_entry(s2, &listeners->list, list) {
309 				if (s2->pid == pid && s2->valid)
310 					goto exists;
311 			}
312 			list_add(&s->list, &listeners->list);
313 			s = NULL;
314 exists:
315 			up_write(&listeners->sem);
316 			kfree(s); /* nop if NULL */
317 		}
318 		return 0;
319 	}
320 
321 	/* Deregister or cleanup */
322 cleanup:
323 	for_each_cpu(cpu, mask) {
324 		listeners = &per_cpu(listener_array, cpu);
325 		down_write(&listeners->sem);
326 		list_for_each_entry_safe(s, tmp, &listeners->list, list) {
327 			if (s->pid == pid) {
328 				list_del(&s->list);
329 				kfree(s);
330 				break;
331 			}
332 		}
333 		up_write(&listeners->sem);
334 	}
335 	return ret;
336 }
337 
338 static int parse(struct nlattr *na, struct cpumask *mask)
339 {
340 	char *data;
341 	int len;
342 	int ret;
343 
344 	if (na == NULL)
345 		return 1;
346 	len = nla_len(na);
347 	if (len > TASKSTATS_CPUMASK_MAXLEN)
348 		return -E2BIG;
349 	if (len < 1)
350 		return -EINVAL;
351 	data = kmalloc(len, GFP_KERNEL);
352 	if (!data)
353 		return -ENOMEM;
354 	nla_strlcpy(data, na, len);
355 	ret = cpulist_parse(data, mask);
356 	kfree(data);
357 	return ret;
358 }
359 
360 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
361 {
362 	struct nlattr *na, *ret;
363 	int aggr;
364 
365 	aggr = (type == TASKSTATS_TYPE_PID)
366 			? TASKSTATS_TYPE_AGGR_PID
367 			: TASKSTATS_TYPE_AGGR_TGID;
368 
369 	na = nla_nest_start(skb, aggr);
370 	if (!na)
371 		goto err;
372 
373 	if (nla_put(skb, type, sizeof(pid), &pid) < 0) {
374 		nla_nest_cancel(skb, na);
375 		goto err;
376 	}
377 	ret = nla_reserve_64bit(skb, TASKSTATS_TYPE_STATS,
378 				sizeof(struct taskstats), TASKSTATS_TYPE_NULL);
379 	if (!ret) {
380 		nla_nest_cancel(skb, na);
381 		goto err;
382 	}
383 	nla_nest_end(skb, na);
384 
385 	return nla_data(ret);
386 err:
387 	return NULL;
388 }
389 
390 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
391 {
392 	int rc = 0;
393 	struct sk_buff *rep_skb;
394 	struct cgroupstats *stats;
395 	struct nlattr *na;
396 	size_t size;
397 	u32 fd;
398 	struct fd f;
399 
400 	na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
401 	if (!na)
402 		return -EINVAL;
403 
404 	fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
405 	f = fdget(fd);
406 	if (!f.file)
407 		return 0;
408 
409 	size = nla_total_size(sizeof(struct cgroupstats));
410 
411 	rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
412 				size);
413 	if (rc < 0)
414 		goto err;
415 
416 	na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
417 				sizeof(struct cgroupstats));
418 	if (na == NULL) {
419 		nlmsg_free(rep_skb);
420 		rc = -EMSGSIZE;
421 		goto err;
422 	}
423 
424 	stats = nla_data(na);
425 	memset(stats, 0, sizeof(*stats));
426 
427 	rc = cgroupstats_build(stats, f.file->f_path.dentry);
428 	if (rc < 0) {
429 		nlmsg_free(rep_skb);
430 		goto err;
431 	}
432 
433 	rc = send_reply(rep_skb, info);
434 
435 err:
436 	fdput(f);
437 	return rc;
438 }
439 
440 static int cmd_attr_register_cpumask(struct genl_info *info)
441 {
442 	cpumask_var_t mask;
443 	int rc;
444 
445 	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
446 		return -ENOMEM;
447 	rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
448 	if (rc < 0)
449 		goto out;
450 	rc = add_del_listener(info->snd_portid, mask, REGISTER);
451 out:
452 	free_cpumask_var(mask);
453 	return rc;
454 }
455 
456 static int cmd_attr_deregister_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_DEREGISTER_CPUMASK], mask);
464 	if (rc < 0)
465 		goto out;
466 	rc = add_del_listener(info->snd_portid, mask, DEREGISTER);
467 out:
468 	free_cpumask_var(mask);
469 	return rc;
470 }
471 
472 static size_t taskstats_packet_size(void)
473 {
474 	size_t size;
475 
476 	size = nla_total_size(sizeof(u32)) +
477 		nla_total_size_64bit(sizeof(struct taskstats)) +
478 		nla_total_size(0);
479 
480 	return size;
481 }
482 
483 static int cmd_attr_pid(struct genl_info *info)
484 {
485 	struct taskstats *stats;
486 	struct sk_buff *rep_skb;
487 	size_t size;
488 	u32 pid;
489 	int rc;
490 
491 	size = taskstats_packet_size();
492 
493 	rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
494 	if (rc < 0)
495 		return rc;
496 
497 	rc = -EINVAL;
498 	pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
499 	stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
500 	if (!stats)
501 		goto err;
502 
503 	rc = fill_stats_for_pid(pid, stats);
504 	if (rc < 0)
505 		goto err;
506 	return send_reply(rep_skb, info);
507 err:
508 	nlmsg_free(rep_skb);
509 	return rc;
510 }
511 
512 static int cmd_attr_tgid(struct genl_info *info)
513 {
514 	struct taskstats *stats;
515 	struct sk_buff *rep_skb;
516 	size_t size;
517 	u32 tgid;
518 	int rc;
519 
520 	size = taskstats_packet_size();
521 
522 	rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
523 	if (rc < 0)
524 		return rc;
525 
526 	rc = -EINVAL;
527 	tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
528 	stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
529 	if (!stats)
530 		goto err;
531 
532 	rc = fill_stats_for_tgid(tgid, stats);
533 	if (rc < 0)
534 		goto err;
535 	return send_reply(rep_skb, info);
536 err:
537 	nlmsg_free(rep_skb);
538 	return rc;
539 }
540 
541 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
542 {
543 	if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
544 		return cmd_attr_register_cpumask(info);
545 	else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
546 		return cmd_attr_deregister_cpumask(info);
547 	else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
548 		return cmd_attr_pid(info);
549 	else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
550 		return cmd_attr_tgid(info);
551 	else
552 		return -EINVAL;
553 }
554 
555 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
556 {
557 	struct signal_struct *sig = tsk->signal;
558 	struct taskstats *stats;
559 
560 	if (sig->stats || thread_group_empty(tsk))
561 		goto ret;
562 
563 	/* No problem if kmem_cache_zalloc() fails */
564 	stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
565 
566 	spin_lock_irq(&tsk->sighand->siglock);
567 	if (!sig->stats) {
568 		sig->stats = stats;
569 		stats = NULL;
570 	}
571 	spin_unlock_irq(&tsk->sighand->siglock);
572 
573 	if (stats)
574 		kmem_cache_free(taskstats_cache, stats);
575 ret:
576 	return sig->stats;
577 }
578 
579 /* Send pid data out on exit */
580 void taskstats_exit(struct task_struct *tsk, int group_dead)
581 {
582 	int rc;
583 	struct listener_list *listeners;
584 	struct taskstats *stats;
585 	struct sk_buff *rep_skb;
586 	size_t size;
587 	int is_thread_group;
588 
589 	if (!family_registered)
590 		return;
591 
592 	/*
593 	 * Size includes space for nested attributes
594 	 */
595 	size = taskstats_packet_size();
596 
597 	is_thread_group = !!taskstats_tgid_alloc(tsk);
598 	if (is_thread_group) {
599 		/* PID + STATS + TGID + STATS */
600 		size = 2 * size;
601 		/* fill the tsk->signal->stats structure */
602 		fill_tgid_exit(tsk);
603 	}
604 
605 	listeners = raw_cpu_ptr(&listener_array);
606 	if (list_empty(&listeners->list))
607 		return;
608 
609 	rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
610 	if (rc < 0)
611 		return;
612 
613 	stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID,
614 			 task_pid_nr_ns(tsk, &init_pid_ns));
615 	if (!stats)
616 		goto err;
617 
618 	fill_stats(&init_user_ns, &init_pid_ns, tsk, stats);
619 
620 	/*
621 	 * Doesn't matter if tsk is the leader or the last group member leaving
622 	 */
623 	if (!is_thread_group || !group_dead)
624 		goto send;
625 
626 	stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID,
627 			 task_tgid_nr_ns(tsk, &init_pid_ns));
628 	if (!stats)
629 		goto err;
630 
631 	memcpy(stats, tsk->signal->stats, sizeof(*stats));
632 
633 send:
634 	send_cpu_listeners(rep_skb, listeners);
635 	return;
636 err:
637 	nlmsg_free(rep_skb);
638 }
639 
640 static const struct genl_ops taskstats_ops[] = {
641 	{
642 		.cmd		= TASKSTATS_CMD_GET,
643 		.doit		= taskstats_user_cmd,
644 		.policy		= taskstats_cmd_get_policy,
645 		.flags		= GENL_ADMIN_PERM,
646 	},
647 	{
648 		.cmd		= CGROUPSTATS_CMD_GET,
649 		.doit		= cgroupstats_user_cmd,
650 		.policy		= cgroupstats_cmd_get_policy,
651 	},
652 };
653 
654 /* Needed early in initialization */
655 void __init taskstats_init_early(void)
656 {
657 	unsigned int i;
658 
659 	taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
660 	for_each_possible_cpu(i) {
661 		INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
662 		init_rwsem(&(per_cpu(listener_array, i).sem));
663 	}
664 }
665 
666 static int __init taskstats_init(void)
667 {
668 	int rc;
669 
670 	rc = genl_register_family_with_ops(&family, taskstats_ops);
671 	if (rc)
672 		return rc;
673 
674 	family_registered = 1;
675 	pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
676 	return 0;
677 }
678 
679 /*
680  * late initcall ensures initialization of statistics collection
681  * mechanisms precedes initialization of the taskstats interface
682  */
683 late_initcall(taskstats_init);
684