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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/tsacct_kern.h>
24 #include <linux/cpumask.h>
25 #include <linux/percpu.h>
26 #include <net/genetlink.h>
27 #include <asm/atomic.h>
28
29 /*
30 * Maximum length of a cpumask that can be specified in
31 * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
32 */
33 #define TASKSTATS_CPUMASK_MAXLEN (100+6*NR_CPUS)
34
35 static DEFINE_PER_CPU(__u32, taskstats_seqnum) = { 0 };
36 static int family_registered;
37 kmem_cache_t *taskstats_cache;
38
39 static struct genl_family family = {
40 .id = GENL_ID_GENERATE,
41 .name = TASKSTATS_GENL_NAME,
42 .version = TASKSTATS_GENL_VERSION,
43 .maxattr = TASKSTATS_CMD_ATTR_MAX,
44 };
45
46 static struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1]
47 __read_mostly = {
48 [TASKSTATS_CMD_ATTR_PID] = { .type = NLA_U32 },
49 [TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
50 [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
51 [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
52
53 struct listener {
54 struct list_head list;
55 pid_t pid;
56 char valid;
57 };
58
59 struct listener_list {
60 struct rw_semaphore sem;
61 struct list_head list;
62 };
63 static DEFINE_PER_CPU(struct listener_list, listener_array);
64
65 enum actions {
66 REGISTER,
67 DEREGISTER,
68 CPU_DONT_CARE
69 };
70
71 static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
72 void **replyp, size_t size)
73 {
74 struct sk_buff *skb;
75 void *reply;
76
77 /*
78 * If new attributes are added, please revisit this allocation
79 */
80 skb = genlmsg_new(size, GFP_KERNEL);
81 if (!skb)
82 return -ENOMEM;
83
84 if (!info) {
85 int seq = get_cpu_var(taskstats_seqnum)++;
86 put_cpu_var(taskstats_seqnum);
87
88 reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
89 } else
90 reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
91 if (reply == NULL) {
92 nlmsg_free(skb);
93 return -EINVAL;
94 }
95
96 *skbp = skb;
97 *replyp = reply;
98 return 0;
99 }
100
101 /*
102 * Send taskstats data in @skb to listener with nl_pid @pid
103 */
104 static int send_reply(struct sk_buff *skb, pid_t pid)
105 {
106 struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
107 void *reply = genlmsg_data(genlhdr);
108 int rc;
109
110 rc = genlmsg_end(skb, reply);
111 if (rc < 0) {
112 nlmsg_free(skb);
113 return rc;
114 }
115
116 return genlmsg_unicast(skb, pid);
117 }
118
119 /*
120 * Send taskstats data in @skb to listeners registered for @cpu's exit data
121 */
122 static void send_cpu_listeners(struct sk_buff *skb, unsigned int cpu)
123 {
124 struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
125 struct listener_list *listeners;
126 struct listener *s, *tmp;
127 struct sk_buff *skb_next, *skb_cur = skb;
128 void *reply = genlmsg_data(genlhdr);
129 int rc, delcount = 0;
130
131 rc = genlmsg_end(skb, reply);
132 if (rc < 0) {
133 nlmsg_free(skb);
134 return;
135 }
136
137 rc = 0;
138 listeners = &per_cpu(listener_array, cpu);
139 down_read(&listeners->sem);
140 list_for_each_entry(s, &listeners->list, list) {
141 skb_next = NULL;
142 if (!list_is_last(&s->list, &listeners->list)) {
143 skb_next = skb_clone(skb_cur, GFP_KERNEL);
144 if (!skb_next)
145 break;
146 }
147 rc = genlmsg_unicast(skb_cur, s->pid);
148 if (rc == -ECONNREFUSED) {
149 s->valid = 0;
150 delcount++;
151 }
152 skb_cur = skb_next;
153 }
154 up_read(&listeners->sem);
155
156 if (skb_cur)
157 nlmsg_free(skb_cur);
158
159 if (!delcount)
160 return;
161
162 /* Delete invalidated entries */
163 down_write(&listeners->sem);
164 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
165 if (!s->valid) {
166 list_del(&s->list);
167 kfree(s);
168 }
169 }
170 up_write(&listeners->sem);
171 }
172
173 static int fill_pid(pid_t pid, struct task_struct *tsk,
174 struct taskstats *stats)
175 {
176 int rc = 0;
177
178 if (!tsk) {
179 rcu_read_lock();
180 tsk = find_task_by_pid(pid);
181 if (tsk)
182 get_task_struct(tsk);
183 rcu_read_unlock();
184 if (!tsk)
185 return -ESRCH;
186 } else
187 get_task_struct(tsk);
188
189 /*
190 * Each accounting subsystem adds calls to its functions to
191 * fill in relevant parts of struct taskstsats as follows
192 *
193 * per-task-foo(stats, tsk);
194 */
195
196 delayacct_add_tsk(stats, tsk);
197
198 /* fill in basic acct fields */
199 stats->version = TASKSTATS_VERSION;
200 bacct_add_tsk(stats, tsk);
201
202 /* fill in extended acct fields */
203 xacct_add_tsk(stats, tsk);
204
205 /* Define err: label here if needed */
206 put_task_struct(tsk);
207 return rc;
208
209 }
210
211 static int fill_tgid(pid_t tgid, struct task_struct *first,
212 struct taskstats *stats)
213 {
214 struct task_struct *tsk;
215 unsigned long flags;
216 int rc = -ESRCH;
217
218 /*
219 * Add additional stats from live tasks except zombie thread group
220 * leaders who are already counted with the dead tasks
221 */
222 rcu_read_lock();
223 if (!first)
224 first = find_task_by_pid(tgid);
225
226 if (!first || !lock_task_sighand(first, &flags))
227 goto out;
228
229 if (first->signal->stats)
230 memcpy(stats, first->signal->stats, sizeof(*stats));
231
232 tsk = first;
233 do {
234 if (tsk->exit_state)
235 continue;
236 /*
237 * Accounting subsystem can call its functions here to
238 * fill in relevant parts of struct taskstsats as follows
239 *
240 * per-task-foo(stats, tsk);
241 */
242 delayacct_add_tsk(stats, tsk);
243
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 subsytems can also add calls here to modify
254 * fields of taskstats.
255 */
256 return rc;
257 }
258
259
260 static void fill_tgid_exit(struct task_struct *tsk)
261 {
262 unsigned long flags;
263
264 spin_lock_irqsave(&tsk->sighand->siglock, flags);
265 if (!tsk->signal->stats)
266 goto ret;
267
268 /*
269 * Each accounting subsystem calls its functions here to
270 * accumalate its per-task stats for tsk, into the per-tgid structure
271 *
272 * per-task-foo(tsk->signal->stats, tsk);
273 */
274 delayacct_add_tsk(tsk->signal->stats, tsk);
275 ret:
276 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
277 return;
278 }
279
280 static int add_del_listener(pid_t pid, cpumask_t *maskp, int isadd)
281 {
282 struct listener_list *listeners;
283 struct listener *s, *tmp;
284 unsigned int cpu;
285 cpumask_t mask = *maskp;
286
287 if (!cpus_subset(mask, cpu_possible_map))
288 return -EINVAL;
289
290 if (isadd == REGISTER) {
291 for_each_cpu_mask(cpu, mask) {
292 s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
293 cpu_to_node(cpu));
294 if (!s)
295 goto cleanup;
296 s->pid = pid;
297 INIT_LIST_HEAD(&s->list);
298 s->valid = 1;
299
300 listeners = &per_cpu(listener_array, cpu);
301 down_write(&listeners->sem);
302 list_add(&s->list, &listeners->list);
303 up_write(&listeners->sem);
304 }
305 return 0;
306 }
307
308 /* Deregister or cleanup */
309 cleanup:
310 for_each_cpu_mask(cpu, mask) {
311 listeners = &per_cpu(listener_array, cpu);
312 down_write(&listeners->sem);
313 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
314 if (s->pid == pid) {
315 list_del(&s->list);
316 kfree(s);
317 break;
318 }
319 }
320 up_write(&listeners->sem);
321 }
322 return 0;
323 }
324
325 static int parse(struct nlattr *na, cpumask_t *mask)
326 {
327 char *data;
328 int len;
329 int ret;
330
331 if (na == NULL)
332 return 1;
333 len = nla_len(na);
334 if (len > TASKSTATS_CPUMASK_MAXLEN)
335 return -E2BIG;
336 if (len < 1)
337 return -EINVAL;
338 data = kmalloc(len, GFP_KERNEL);
339 if (!data)
340 return -ENOMEM;
341 nla_strlcpy(data, na, len);
342 ret = cpulist_parse(data, *mask);
343 kfree(data);
344 return ret;
345 }
346
347 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
348 {
349 int rc = 0;
350 struct sk_buff *rep_skb;
351 struct taskstats stats;
352 void *reply;
353 size_t size;
354 struct nlattr *na;
355 cpumask_t mask;
356
357 rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], &mask);
358 if (rc < 0)
359 return rc;
360 if (rc == 0)
361 return add_del_listener(info->snd_pid, &mask, REGISTER);
362
363 rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], &mask);
364 if (rc < 0)
365 return rc;
366 if (rc == 0)
367 return add_del_listener(info->snd_pid, &mask, DEREGISTER);
368
369 /*
370 * Size includes space for nested attributes
371 */
372 size = nla_total_size(sizeof(u32)) +
373 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
374
375 memset(&stats, 0, sizeof(stats));
376 rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
377 if (rc < 0)
378 return rc;
379
380 if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
381 u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
382 rc = fill_pid(pid, NULL, &stats);
383 if (rc < 0)
384 goto err;
385
386 na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
387 NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, pid);
388 NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
389 stats);
390 } else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
391 u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
392 rc = fill_tgid(tgid, NULL, &stats);
393 if (rc < 0)
394 goto err;
395
396 na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
397 NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, tgid);
398 NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
399 stats);
400 } else {
401 rc = -EINVAL;
402 goto err;
403 }
404
405 nla_nest_end(rep_skb, na);
406
407 return send_reply(rep_skb, info->snd_pid);
408
409 nla_put_failure:
410 rc = genlmsg_cancel(rep_skb, reply);
411 err:
412 nlmsg_free(rep_skb);
413 return rc;
414 }
415
416 void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu)
417 {
418 struct listener_list *listeners;
419 struct taskstats *tmp;
420 /*
421 * This is the cpu on which the task is exiting currently and will
422 * be the one for which the exit event is sent, even if the cpu
423 * on which this function is running changes later.
424 */
425 *mycpu = raw_smp_processor_id();
426
427 *ptidstats = NULL;
428 tmp = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
429 if (!tmp)
430 return;
431
432 listeners = &per_cpu(listener_array, *mycpu);
433 down_read(&listeners->sem);
434 if (!list_empty(&listeners->list)) {
435 *ptidstats = tmp;
436 tmp = NULL;
437 }
438 up_read(&listeners->sem);
439 kfree(tmp);
440 }
441
442 /* Send pid data out on exit */
443 void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
444 int group_dead, unsigned int mycpu)
445 {
446 int rc;
447 struct sk_buff *rep_skb;
448 void *reply;
449 size_t size;
450 int is_thread_group;
451 struct nlattr *na;
452
453 if (!family_registered)
454 return;
455
456 /*
457 * Size includes space for nested attributes
458 */
459 size = nla_total_size(sizeof(u32)) +
460 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
461
462 is_thread_group = (tsk->signal->stats != NULL);
463 if (is_thread_group) {
464 /* PID + STATS + TGID + STATS */
465 size = 2 * size;
466 /* fill the tsk->signal->stats structure */
467 fill_tgid_exit(tsk);
468 }
469
470 if (!tidstats)
471 return;
472
473 rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
474 if (rc < 0)
475 goto ret;
476
477 rc = fill_pid(tsk->pid, tsk, tidstats);
478 if (rc < 0)
479 goto err_skb;
480
481 na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_PID);
482 NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_PID, (u32)tsk->pid);
483 NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
484 *tidstats);
485 nla_nest_end(rep_skb, na);
486
487 if (!is_thread_group)
488 goto send;
489
490 /*
491 * Doesn't matter if tsk is the leader or the last group member leaving
492 */
493 if (!group_dead)
494 goto send;
495
496 na = nla_nest_start(rep_skb, TASKSTATS_TYPE_AGGR_TGID);
497 NLA_PUT_U32(rep_skb, TASKSTATS_TYPE_TGID, (u32)tsk->tgid);
498 /* No locking needed for tsk->signal->stats since group is dead */
499 NLA_PUT_TYPE(rep_skb, struct taskstats, TASKSTATS_TYPE_STATS,
500 *tsk->signal->stats);
501 nla_nest_end(rep_skb, na);
502
503 send:
504 send_cpu_listeners(rep_skb, mycpu);
505 return;
506
507 nla_put_failure:
508 genlmsg_cancel(rep_skb, reply);
509 err_skb:
510 nlmsg_free(rep_skb);
511 ret:
512 return;
513 }
514
515 static struct genl_ops taskstats_ops = {
516 .cmd = TASKSTATS_CMD_GET,
517 .doit = taskstats_user_cmd,
518 .policy = taskstats_cmd_get_policy,
519 };
520
521 /* Needed early in initialization */
522 void __init taskstats_init_early(void)
523 {
524 unsigned int i;
525
526 taskstats_cache = kmem_cache_create("taskstats_cache",
527 sizeof(struct taskstats),
528 0, SLAB_PANIC, NULL, NULL);
529 for_each_possible_cpu(i) {
530 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
531 init_rwsem(&(per_cpu(listener_array, i).sem));
532 }
533 }
534
535 static int __init taskstats_init(void)
536 {
537 int rc;
538
539 rc = genl_register_family(&family);
540 if (rc)
541 return rc;
542
543 rc = genl_register_ops(&family, &taskstats_ops);
544 if (rc < 0)
545 goto err;
546
547 family_registered = 1;
548 return 0;
549 err:
550 genl_unregister_family(&family);
551 return rc;
552 }
553
554 /*
555 * late initcall ensures initialization of statistics collection
556 * mechanisms precedes initialization of the taskstats interface
557 */
558 late_initcall(taskstats_init);