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/cgroupstats.h>
26 #include <linux/cgroup.h>
27 #include <linux/fs.h>
28 #include <linux/file.h>
29 #include <net/genetlink.h>
30 #include <asm/atomic.h>
31
32 /*
33 * Maximum length of a cpumask that can be specified in
34 * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
35 */
36 #define TASKSTATS_CPUMASK_MAXLEN (100+6*NR_CPUS)
37
38 static DEFINE_PER_CPU(__u32, taskstats_seqnum);
39 static int family_registered;
40 struct kmem_cache *taskstats_cache;
41
42 static struct genl_family family = {
43 .id = GENL_ID_GENERATE,
44 .name = TASKSTATS_GENL_NAME,
45 .version = TASKSTATS_GENL_VERSION,
46 .maxattr = TASKSTATS_CMD_ATTR_MAX,
47 };
48
49 static struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1]
50 __read_mostly = {
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 struct nla_policy
57 cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] __read_mostly = {
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
prepare_reply(struct genl_info * info,u8 cmd,struct sk_buff ** skbp,size_t size)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 = get_cpu_var(taskstats_seqnum)++;
94 put_cpu_var(taskstats_seqnum);
95
96 reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
97 } else
98 reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
99 if (reply == NULL) {
100 nlmsg_free(skb);
101 return -EINVAL;
102 }
103
104 *skbp = skb;
105 return 0;
106 }
107
108 /*
109 * Send taskstats data in @skb to listener with nl_pid @pid
110 */
send_reply(struct sk_buff * skb,pid_t pid)111 static int send_reply(struct sk_buff *skb, pid_t pid)
112 {
113 struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
114 void *reply = genlmsg_data(genlhdr);
115 int rc;
116
117 rc = genlmsg_end(skb, reply);
118 if (rc < 0) {
119 nlmsg_free(skb);
120 return rc;
121 }
122
123 return genlmsg_unicast(skb, pid);
124 }
125
126 /*
127 * Send taskstats data in @skb to listeners registered for @cpu's exit data
128 */
send_cpu_listeners(struct sk_buff * skb,struct listener_list * listeners)129 static void send_cpu_listeners(struct sk_buff *skb,
130 struct listener_list *listeners)
131 {
132 struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
133 struct listener *s, *tmp;
134 struct sk_buff *skb_next, *skb_cur = skb;
135 void *reply = genlmsg_data(genlhdr);
136 int rc, delcount = 0;
137
138 rc = genlmsg_end(skb, reply);
139 if (rc < 0) {
140 nlmsg_free(skb);
141 return;
142 }
143
144 rc = 0;
145 down_read(&listeners->sem);
146 list_for_each_entry(s, &listeners->list, list) {
147 skb_next = NULL;
148 if (!list_is_last(&s->list, &listeners->list)) {
149 skb_next = skb_clone(skb_cur, GFP_KERNEL);
150 if (!skb_next)
151 break;
152 }
153 rc = genlmsg_unicast(skb_cur, s->pid);
154 if (rc == -ECONNREFUSED) {
155 s->valid = 0;
156 delcount++;
157 }
158 skb_cur = skb_next;
159 }
160 up_read(&listeners->sem);
161
162 if (skb_cur)
163 nlmsg_free(skb_cur);
164
165 if (!delcount)
166 return;
167
168 /* Delete invalidated entries */
169 down_write(&listeners->sem);
170 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
171 if (!s->valid) {
172 list_del(&s->list);
173 kfree(s);
174 }
175 }
176 up_write(&listeners->sem);
177 }
178
fill_pid(pid_t pid,struct task_struct * tsk,struct taskstats * stats)179 static int fill_pid(pid_t pid, struct task_struct *tsk,
180 struct taskstats *stats)
181 {
182 int rc = 0;
183
184 if (!tsk) {
185 rcu_read_lock();
186 tsk = find_task_by_vpid(pid);
187 if (tsk)
188 get_task_struct(tsk);
189 rcu_read_unlock();
190 if (!tsk)
191 return -ESRCH;
192 } else
193 get_task_struct(tsk);
194
195 memset(stats, 0, sizeof(*stats));
196 /*
197 * Each accounting subsystem adds calls to its functions to
198 * fill in relevant parts of struct taskstsats as follows
199 *
200 * per-task-foo(stats, tsk);
201 */
202
203 delayacct_add_tsk(stats, tsk);
204
205 /* fill in basic acct fields */
206 stats->version = TASKSTATS_VERSION;
207 stats->nvcsw = tsk->nvcsw;
208 stats->nivcsw = tsk->nivcsw;
209 bacct_add_tsk(stats, tsk);
210
211 /* fill in extended acct fields */
212 xacct_add_tsk(stats, tsk);
213
214 /* Define err: label here if needed */
215 put_task_struct(tsk);
216 return rc;
217
218 }
219
fill_tgid(pid_t tgid,struct task_struct * first,struct taskstats * stats)220 static int fill_tgid(pid_t tgid, struct task_struct *first,
221 struct taskstats *stats)
222 {
223 struct task_struct *tsk;
224 unsigned long flags;
225 int rc = -ESRCH;
226
227 /*
228 * Add additional stats from live tasks except zombie thread group
229 * leaders who are already counted with the dead tasks
230 */
231 rcu_read_lock();
232 if (!first)
233 first = find_task_by_vpid(tgid);
234
235 if (!first || !lock_task_sighand(first, &flags))
236 goto out;
237
238 if (first->signal->stats)
239 memcpy(stats, first->signal->stats, sizeof(*stats));
240 else
241 memset(stats, 0, sizeof(*stats));
242
243 tsk = first;
244 do {
245 if (tsk->exit_state)
246 continue;
247 /*
248 * Accounting subsystem can call its functions here to
249 * fill in relevant parts of struct taskstsats as follows
250 *
251 * per-task-foo(stats, tsk);
252 */
253 delayacct_add_tsk(stats, tsk);
254
255 stats->nvcsw += tsk->nvcsw;
256 stats->nivcsw += tsk->nivcsw;
257 } while_each_thread(first, tsk);
258
259 unlock_task_sighand(first, &flags);
260 rc = 0;
261 out:
262 rcu_read_unlock();
263
264 stats->version = TASKSTATS_VERSION;
265 /*
266 * Accounting subsystems can also add calls here to modify
267 * fields of taskstats.
268 */
269 return rc;
270 }
271
272
fill_tgid_exit(struct task_struct * tsk)273 static void fill_tgid_exit(struct task_struct *tsk)
274 {
275 unsigned long flags;
276
277 spin_lock_irqsave(&tsk->sighand->siglock, flags);
278 if (!tsk->signal->stats)
279 goto ret;
280
281 /*
282 * Each accounting subsystem calls its functions here to
283 * accumalate its per-task stats for tsk, into the per-tgid structure
284 *
285 * per-task-foo(tsk->signal->stats, tsk);
286 */
287 delayacct_add_tsk(tsk->signal->stats, tsk);
288 ret:
289 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
290 return;
291 }
292
add_del_listener(pid_t pid,const struct cpumask * mask,int isadd)293 static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
294 {
295 struct listener_list *listeners;
296 struct listener *s, *tmp;
297 unsigned int cpu;
298
299 if (!cpumask_subset(mask, cpu_possible_mask))
300 return -EINVAL;
301
302 if (isadd == REGISTER) {
303 for_each_cpu(cpu, mask) {
304 s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
305 cpu_to_node(cpu));
306 if (!s)
307 goto cleanup;
308 s->pid = pid;
309 INIT_LIST_HEAD(&s->list);
310 s->valid = 1;
311
312 listeners = &per_cpu(listener_array, cpu);
313 down_write(&listeners->sem);
314 list_add(&s->list, &listeners->list);
315 up_write(&listeners->sem);
316 }
317 return 0;
318 }
319
320 /* Deregister or cleanup */
321 cleanup:
322 for_each_cpu(cpu, mask) {
323 listeners = &per_cpu(listener_array, cpu);
324 down_write(&listeners->sem);
325 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
326 if (s->pid == pid) {
327 list_del(&s->list);
328 kfree(s);
329 break;
330 }
331 }
332 up_write(&listeners->sem);
333 }
334 return 0;
335 }
336
parse(struct nlattr * na,struct cpumask * mask)337 static int parse(struct nlattr *na, struct cpumask *mask)
338 {
339 char *data;
340 int len;
341 int ret;
342
343 if (na == NULL)
344 return 1;
345 len = nla_len(na);
346 if (len > TASKSTATS_CPUMASK_MAXLEN)
347 return -E2BIG;
348 if (len < 1)
349 return -EINVAL;
350 data = kmalloc(len, GFP_KERNEL);
351 if (!data)
352 return -ENOMEM;
353 nla_strlcpy(data, na, len);
354 ret = cpulist_parse(data, mask);
355 kfree(data);
356 return ret;
357 }
358
mk_reply(struct sk_buff * skb,int type,u32 pid)359 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
360 {
361 struct nlattr *na, *ret;
362 int aggr;
363
364 aggr = (type == TASKSTATS_TYPE_PID)
365 ? TASKSTATS_TYPE_AGGR_PID
366 : TASKSTATS_TYPE_AGGR_TGID;
367
368 na = nla_nest_start(skb, aggr);
369 if (!na)
370 goto err;
371 if (nla_put(skb, type, sizeof(pid), &pid) < 0)
372 goto err;
373 ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
374 if (!ret)
375 goto err;
376 nla_nest_end(skb, na);
377
378 return nla_data(ret);
379 err:
380 return NULL;
381 }
382
cgroupstats_user_cmd(struct sk_buff * skb,struct genl_info * info)383 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
384 {
385 int rc = 0;
386 struct sk_buff *rep_skb;
387 struct cgroupstats *stats;
388 struct nlattr *na;
389 size_t size;
390 u32 fd;
391 struct file *file;
392 int fput_needed;
393
394 na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
395 if (!na)
396 return -EINVAL;
397
398 fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
399 file = fget_light(fd, &fput_needed);
400 if (!file)
401 return 0;
402
403 size = nla_total_size(sizeof(struct cgroupstats));
404
405 rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
406 size);
407 if (rc < 0)
408 goto err;
409
410 na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
411 sizeof(struct cgroupstats));
412 stats = nla_data(na);
413 memset(stats, 0, sizeof(*stats));
414
415 rc = cgroupstats_build(stats, file->f_dentry);
416 if (rc < 0) {
417 nlmsg_free(rep_skb);
418 goto err;
419 }
420
421 rc = send_reply(rep_skb, info->snd_pid);
422
423 err:
424 fput_light(file, fput_needed);
425 return rc;
426 }
427
taskstats_user_cmd(struct sk_buff * skb,struct genl_info * info)428 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
429 {
430 int rc;
431 struct sk_buff *rep_skb;
432 struct taskstats *stats;
433 size_t size;
434 cpumask_var_t mask;
435
436 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
437 return -ENOMEM;
438
439 rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
440 if (rc < 0)
441 goto free_return_rc;
442 if (rc == 0) {
443 rc = add_del_listener(info->snd_pid, mask, REGISTER);
444 goto free_return_rc;
445 }
446
447 rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
448 if (rc < 0)
449 goto free_return_rc;
450 if (rc == 0) {
451 rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
452 free_return_rc:
453 free_cpumask_var(mask);
454 return rc;
455 }
456 free_cpumask_var(mask);
457
458 /*
459 * Size includes space for nested attributes
460 */
461 size = nla_total_size(sizeof(u32)) +
462 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
463
464 rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
465 if (rc < 0)
466 return rc;
467
468 rc = -EINVAL;
469 if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
470 u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
471 stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
472 if (!stats)
473 goto err;
474
475 rc = fill_pid(pid, NULL, stats);
476 if (rc < 0)
477 goto err;
478 } else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
479 u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
480 stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
481 if (!stats)
482 goto err;
483
484 rc = fill_tgid(tgid, NULL, stats);
485 if (rc < 0)
486 goto err;
487 } else
488 goto err;
489
490 return send_reply(rep_skb, info->snd_pid);
491 err:
492 nlmsg_free(rep_skb);
493 return rc;
494 }
495
taskstats_tgid_alloc(struct task_struct * tsk)496 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
497 {
498 struct signal_struct *sig = tsk->signal;
499 struct taskstats *stats;
500
501 if (sig->stats || thread_group_empty(tsk))
502 goto ret;
503
504 /* No problem if kmem_cache_zalloc() fails */
505 stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
506
507 spin_lock_irq(&tsk->sighand->siglock);
508 if (!sig->stats) {
509 sig->stats = stats;
510 stats = NULL;
511 }
512 spin_unlock_irq(&tsk->sighand->siglock);
513
514 if (stats)
515 kmem_cache_free(taskstats_cache, stats);
516 ret:
517 return sig->stats;
518 }
519
520 /* Send pid data out on exit */
taskstats_exit(struct task_struct * tsk,int group_dead)521 void taskstats_exit(struct task_struct *tsk, int group_dead)
522 {
523 int rc;
524 struct listener_list *listeners;
525 struct taskstats *stats;
526 struct sk_buff *rep_skb;
527 size_t size;
528 int is_thread_group;
529
530 if (!family_registered)
531 return;
532
533 /*
534 * Size includes space for nested attributes
535 */
536 size = nla_total_size(sizeof(u32)) +
537 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
538
539 is_thread_group = !!taskstats_tgid_alloc(tsk);
540 if (is_thread_group) {
541 /* PID + STATS + TGID + STATS */
542 size = 2 * size;
543 /* fill the tsk->signal->stats structure */
544 fill_tgid_exit(tsk);
545 }
546
547 listeners = &__raw_get_cpu_var(listener_array);
548 if (list_empty(&listeners->list))
549 return;
550
551 rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
552 if (rc < 0)
553 return;
554
555 stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
556 if (!stats)
557 goto err;
558
559 rc = fill_pid(-1, tsk, stats);
560 if (rc < 0)
561 goto err;
562
563 /*
564 * Doesn't matter if tsk is the leader or the last group member leaving
565 */
566 if (!is_thread_group || !group_dead)
567 goto send;
568
569 stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
570 if (!stats)
571 goto err;
572
573 memcpy(stats, tsk->signal->stats, sizeof(*stats));
574
575 send:
576 send_cpu_listeners(rep_skb, listeners);
577 return;
578 err:
579 nlmsg_free(rep_skb);
580 }
581
582 static struct genl_ops taskstats_ops = {
583 .cmd = TASKSTATS_CMD_GET,
584 .doit = taskstats_user_cmd,
585 .policy = taskstats_cmd_get_policy,
586 };
587
588 static struct genl_ops cgroupstats_ops = {
589 .cmd = CGROUPSTATS_CMD_GET,
590 .doit = cgroupstats_user_cmd,
591 .policy = cgroupstats_cmd_get_policy,
592 };
593
594 /* Needed early in initialization */
taskstats_init_early(void)595 void __init taskstats_init_early(void)
596 {
597 unsigned int i;
598
599 taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
600 for_each_possible_cpu(i) {
601 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
602 init_rwsem(&(per_cpu(listener_array, i).sem));
603 }
604 }
605
taskstats_init(void)606 static int __init taskstats_init(void)
607 {
608 int rc;
609
610 rc = genl_register_family(&family);
611 if (rc)
612 return rc;
613
614 rc = genl_register_ops(&family, &taskstats_ops);
615 if (rc < 0)
616 goto err;
617
618 rc = genl_register_ops(&family, &cgroupstats_ops);
619 if (rc < 0)
620 goto err_cgroup_ops;
621
622 family_registered = 1;
623 printk("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
624 return 0;
625 err_cgroup_ops:
626 genl_unregister_ops(&family, &taskstats_ops);
627 err:
628 genl_unregister_family(&family);
629 return rc;
630 }
631
632 /*
633 * late initcall ensures initialization of statistics collection
634 * mechanisms precedes initialization of the taskstats interface
635 */
636 late_initcall(taskstats_init);
637