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TOMOYO Linux Cross Reference
Linux/kernel/taskstats.c

Version: ~ [ linux-5.1-rc2 ] ~ [ linux-5.0.4 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.31 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.108 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.165 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.177 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.137 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.63 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 #include <linux/sched/cputime.h>
 34 
 35 /*
 36  * Maximum length of a cpumask that can be specified in
 37  * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
 38  */
 39 #define TASKSTATS_CPUMASK_MAXLEN        (100+6*NR_CPUS)
 40 
 41 static DEFINE_PER_CPU(__u32, taskstats_seqnum);
 42 static int family_registered;
 43 struct kmem_cache *taskstats_cache;
 44 
 45 static struct genl_family family;
 46 
 47 static const struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
 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 /*
 54  * We have to use TASKSTATS_CMD_ATTR_MAX here, it is the maxattr in the family.
 55  * Make sure they are always aligned.
 56  */
 57 static const struct nla_policy cgroupstats_cmd_get_policy[TASKSTATS_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         tsk = find_get_task_by_vpid(pid);
198         if (!tsk)
199                 return -ESRCH;
200         fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
201         put_task_struct(tsk);
202         return 0;
203 }
204 
205 static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
206 {
207         struct task_struct *tsk, *first;
208         unsigned long flags;
209         int rc = -ESRCH;
210         u64 delta, utime, stime;
211         u64 start_time;
212 
213         /*
214          * Add additional stats from live tasks except zombie thread group
215          * leaders who are already counted with the dead tasks
216          */
217         rcu_read_lock();
218         first = find_task_by_vpid(tgid);
219 
220         if (!first || !lock_task_sighand(first, &flags))
221                 goto out;
222 
223         if (first->signal->stats)
224                 memcpy(stats, first->signal->stats, sizeof(*stats));
225         else
226                 memset(stats, 0, sizeof(*stats));
227 
228         tsk = first;
229         start_time = ktime_get_ns();
230         do {
231                 if (tsk->exit_state)
232                         continue;
233                 /*
234                  * Accounting subsystem can call its functions here to
235                  * fill in relevant parts of struct taskstsats as follows
236                  *
237                  *      per-task-foo(stats, tsk);
238                  */
239                 delayacct_add_tsk(stats, tsk);
240 
241                 /* calculate task elapsed time in nsec */
242                 delta = start_time - tsk->start_time;
243                 /* Convert to micro seconds */
244                 do_div(delta, NSEC_PER_USEC);
245                 stats->ac_etime += delta;
246 
247                 task_cputime(tsk, &utime, &stime);
248                 stats->ac_utime += div_u64(utime, NSEC_PER_USEC);
249                 stats->ac_stime += div_u64(stime, NSEC_PER_USEC);
250 
251                 stats->nvcsw += tsk->nvcsw;
252                 stats->nivcsw += tsk->nivcsw;
253         } while_each_thread(first, tsk);
254 
255         unlock_task_sighand(first, &flags);
256         rc = 0;
257 out:
258         rcu_read_unlock();
259 
260         stats->version = TASKSTATS_VERSION;
261         /*
262          * Accounting subsystems can also add calls here to modify
263          * fields of taskstats.
264          */
265         return rc;
266 }
267 
268 static void fill_tgid_exit(struct task_struct *tsk)
269 {
270         unsigned long flags;
271 
272         spin_lock_irqsave(&tsk->sighand->siglock, flags);
273         if (!tsk->signal->stats)
274                 goto ret;
275 
276         /*
277          * Each accounting subsystem calls its functions here to
278          * accumalate its per-task stats for tsk, into the per-tgid structure
279          *
280          *      per-task-foo(tsk->signal->stats, tsk);
281          */
282         delayacct_add_tsk(tsk->signal->stats, tsk);
283 ret:
284         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
285         return;
286 }
287 
288 static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
289 {
290         struct listener_list *listeners;
291         struct listener *s, *tmp, *s2;
292         unsigned int cpu;
293         int ret = 0;
294 
295         if (!cpumask_subset(mask, cpu_possible_mask))
296                 return -EINVAL;
297 
298         if (current_user_ns() != &init_user_ns)
299                 return -EINVAL;
300 
301         if (task_active_pid_ns(current) != &init_pid_ns)
302                 return -EINVAL;
303 
304         if (isadd == REGISTER) {
305                 for_each_cpu(cpu, mask) {
306                         s = kmalloc_node(sizeof(struct listener),
307                                         GFP_KERNEL, cpu_to_node(cpu));
308                         if (!s) {
309                                 ret = -ENOMEM;
310                                 goto cleanup;
311                         }
312                         s->pid = pid;
313                         s->valid = 1;
314 
315                         listeners = &per_cpu(listener_array, cpu);
316                         down_write(&listeners->sem);
317                         list_for_each_entry(s2, &listeners->list, list) {
318                                 if (s2->pid == pid && s2->valid)
319                                         goto exists;
320                         }
321                         list_add(&s->list, &listeners->list);
322                         s = NULL;
323 exists:
324                         up_write(&listeners->sem);
325                         kfree(s); /* nop if NULL */
326                 }
327                 return 0;
328         }
329 
330         /* Deregister or cleanup */
331 cleanup:
332         for_each_cpu(cpu, mask) {
333                 listeners = &per_cpu(listener_array, cpu);
334                 down_write(&listeners->sem);
335                 list_for_each_entry_safe(s, tmp, &listeners->list, list) {
336                         if (s->pid == pid) {
337                                 list_del(&s->list);
338                                 kfree(s);
339                                 break;
340                         }
341                 }
342                 up_write(&listeners->sem);
343         }
344         return ret;
345 }
346 
347 static int parse(struct nlattr *na, struct cpumask *mask)
348 {
349         char *data;
350         int len;
351         int ret;
352 
353         if (na == NULL)
354                 return 1;
355         len = nla_len(na);
356         if (len > TASKSTATS_CPUMASK_MAXLEN)
357                 return -E2BIG;
358         if (len < 1)
359                 return -EINVAL;
360         data = kmalloc(len, GFP_KERNEL);
361         if (!data)
362                 return -ENOMEM;
363         nla_strlcpy(data, na, len);
364         ret = cpulist_parse(data, mask);
365         kfree(data);
366         return ret;
367 }
368 
369 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
370 {
371         struct nlattr *na, *ret;
372         int aggr;
373 
374         aggr = (type == TASKSTATS_TYPE_PID)
375                         ? TASKSTATS_TYPE_AGGR_PID
376                         : TASKSTATS_TYPE_AGGR_TGID;
377 
378         na = nla_nest_start(skb, aggr);
379         if (!na)
380                 goto err;
381 
382         if (nla_put(skb, type, sizeof(pid), &pid) < 0) {
383                 nla_nest_cancel(skb, na);
384                 goto err;
385         }
386         ret = nla_reserve_64bit(skb, TASKSTATS_TYPE_STATS,
387                                 sizeof(struct taskstats), TASKSTATS_TYPE_NULL);
388         if (!ret) {
389                 nla_nest_cancel(skb, na);
390                 goto err;
391         }
392         nla_nest_end(skb, na);
393 
394         return nla_data(ret);
395 err:
396         return NULL;
397 }
398 
399 static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
400 {
401         int rc = 0;
402         struct sk_buff *rep_skb;
403         struct cgroupstats *stats;
404         struct nlattr *na;
405         size_t size;
406         u32 fd;
407         struct fd f;
408 
409         na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
410         if (!na)
411                 return -EINVAL;
412 
413         fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
414         f = fdget(fd);
415         if (!f.file)
416                 return 0;
417 
418         size = nla_total_size(sizeof(struct cgroupstats));
419 
420         rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
421                                 size);
422         if (rc < 0)
423                 goto err;
424 
425         na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
426                                 sizeof(struct cgroupstats));
427         if (na == NULL) {
428                 nlmsg_free(rep_skb);
429                 rc = -EMSGSIZE;
430                 goto err;
431         }
432 
433         stats = nla_data(na);
434         memset(stats, 0, sizeof(*stats));
435 
436         rc = cgroupstats_build(stats, f.file->f_path.dentry);
437         if (rc < 0) {
438                 nlmsg_free(rep_skb);
439                 goto err;
440         }
441 
442         rc = send_reply(rep_skb, info);
443 
444 err:
445         fdput(f);
446         return rc;
447 }
448 
449 static int cmd_attr_register_cpumask(struct genl_info *info)
450 {
451         cpumask_var_t mask;
452         int rc;
453 
454         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
455                 return -ENOMEM;
456         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
457         if (rc < 0)
458                 goto out;
459         rc = add_del_listener(info->snd_portid, mask, REGISTER);
460 out:
461         free_cpumask_var(mask);
462         return rc;
463 }
464 
465 static int cmd_attr_deregister_cpumask(struct genl_info *info)
466 {
467         cpumask_var_t mask;
468         int rc;
469 
470         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
471                 return -ENOMEM;
472         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
473         if (rc < 0)
474                 goto out;
475         rc = add_del_listener(info->snd_portid, mask, DEREGISTER);
476 out:
477         free_cpumask_var(mask);
478         return rc;
479 }
480 
481 static size_t taskstats_packet_size(void)
482 {
483         size_t size;
484 
485         size = nla_total_size(sizeof(u32)) +
486                 nla_total_size_64bit(sizeof(struct taskstats)) +
487                 nla_total_size(0);
488 
489         return size;
490 }
491 
492 static int cmd_attr_pid(struct genl_info *info)
493 {
494         struct taskstats *stats;
495         struct sk_buff *rep_skb;
496         size_t size;
497         u32 pid;
498         int rc;
499 
500         size = taskstats_packet_size();
501 
502         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
503         if (rc < 0)
504                 return rc;
505 
506         rc = -EINVAL;
507         pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
508         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
509         if (!stats)
510                 goto err;
511 
512         rc = fill_stats_for_pid(pid, stats);
513         if (rc < 0)
514                 goto err;
515         return send_reply(rep_skb, info);
516 err:
517         nlmsg_free(rep_skb);
518         return rc;
519 }
520 
521 static int cmd_attr_tgid(struct genl_info *info)
522 {
523         struct taskstats *stats;
524         struct sk_buff *rep_skb;
525         size_t size;
526         u32 tgid;
527         int rc;
528 
529         size = taskstats_packet_size();
530 
531         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
532         if (rc < 0)
533                 return rc;
534 
535         rc = -EINVAL;
536         tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
537         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
538         if (!stats)
539                 goto err;
540 
541         rc = fill_stats_for_tgid(tgid, stats);
542         if (rc < 0)
543                 goto err;
544         return send_reply(rep_skb, info);
545 err:
546         nlmsg_free(rep_skb);
547         return rc;
548 }
549 
550 static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
551 {
552         if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
553                 return cmd_attr_register_cpumask(info);
554         else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
555                 return cmd_attr_deregister_cpumask(info);
556         else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
557                 return cmd_attr_pid(info);
558         else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
559                 return cmd_attr_tgid(info);
560         else
561                 return -EINVAL;
562 }
563 
564 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
565 {
566         struct signal_struct *sig = tsk->signal;
567         struct taskstats *stats;
568 
569         if (sig->stats || thread_group_empty(tsk))
570                 goto ret;
571 
572         /* No problem if kmem_cache_zalloc() fails */
573         stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
574 
575         spin_lock_irq(&tsk->sighand->siglock);
576         if (!sig->stats) {
577                 sig->stats = stats;
578                 stats = NULL;
579         }
580         spin_unlock_irq(&tsk->sighand->siglock);
581 
582         if (stats)
583                 kmem_cache_free(taskstats_cache, stats);
584 ret:
585         return sig->stats;
586 }
587 
588 /* Send pid data out on exit */
589 void taskstats_exit(struct task_struct *tsk, int group_dead)
590 {
591         int rc;
592         struct listener_list *listeners;
593         struct taskstats *stats;
594         struct sk_buff *rep_skb;
595         size_t size;
596         int is_thread_group;
597 
598         if (!family_registered)
599                 return;
600 
601         /*
602          * Size includes space for nested attributes
603          */
604         size = taskstats_packet_size();
605 
606         is_thread_group = !!taskstats_tgid_alloc(tsk);
607         if (is_thread_group) {
608                 /* PID + STATS + TGID + STATS */
609                 size = 2 * size;
610                 /* fill the tsk->signal->stats structure */
611                 fill_tgid_exit(tsk);
612         }
613 
614         listeners = raw_cpu_ptr(&listener_array);
615         if (list_empty(&listeners->list))
616                 return;
617 
618         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
619         if (rc < 0)
620                 return;
621 
622         stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID,
623                          task_pid_nr_ns(tsk, &init_pid_ns));
624         if (!stats)
625                 goto err;
626 
627         fill_stats(&init_user_ns, &init_pid_ns, tsk, stats);
628 
629         /*
630          * Doesn't matter if tsk is the leader or the last group member leaving
631          */
632         if (!is_thread_group || !group_dead)
633                 goto send;
634 
635         stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID,
636                          task_tgid_nr_ns(tsk, &init_pid_ns));
637         if (!stats)
638                 goto err;
639 
640         memcpy(stats, tsk->signal->stats, sizeof(*stats));
641 
642 send:
643         send_cpu_listeners(rep_skb, listeners);
644         return;
645 err:
646         nlmsg_free(rep_skb);
647 }
648 
649 static const struct genl_ops taskstats_ops[] = {
650         {
651                 .cmd            = TASKSTATS_CMD_GET,
652                 .doit           = taskstats_user_cmd,
653                 .policy         = taskstats_cmd_get_policy,
654                 .flags          = GENL_ADMIN_PERM,
655         },
656         {
657                 .cmd            = CGROUPSTATS_CMD_GET,
658                 .doit           = cgroupstats_user_cmd,
659                 .policy         = cgroupstats_cmd_get_policy,
660         },
661 };
662 
663 static struct genl_family family __ro_after_init = {
664         .name           = TASKSTATS_GENL_NAME,
665         .version        = TASKSTATS_GENL_VERSION,
666         .maxattr        = TASKSTATS_CMD_ATTR_MAX,
667         .module         = THIS_MODULE,
668         .ops            = taskstats_ops,
669         .n_ops          = ARRAY_SIZE(taskstats_ops),
670 };
671 
672 /* Needed early in initialization */
673 void __init taskstats_init_early(void)
674 {
675         unsigned int i;
676 
677         taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
678         for_each_possible_cpu(i) {
679                 INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
680                 init_rwsem(&(per_cpu(listener_array, i).sem));
681         }
682 }
683 
684 static int __init taskstats_init(void)
685 {
686         int rc;
687 
688         rc = genl_register_family(&family);
689         if (rc)
690                 return rc;
691 
692         family_registered = 1;
693         pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
694         return 0;
695 }
696 
697 /*
698  * late initcall ensures initialization of statistics collection
699  * mechanisms precedes initialization of the taskstats interface
700  */
701 late_initcall(taskstats_init);
702 

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