projects/linux·blob v5.18-rc4 · refs

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