Root/kernel/taskstats.c

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
40static DEFINE_PER_CPU(__u32, taskstats_seqnum);
41static int family_registered;
42struct kmem_cache *taskstats_cache;
43
44static 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
51static 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
57static const struct nla_policy cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] = {
58    [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
59};
60
61struct listener {
62    struct list_head list;
63    pid_t pid;
64    char valid;
65};
66
67struct listener_list {
68    struct rw_semaphore sem;
69    struct list_head list;
70};
71static DEFINE_PER_CPU(struct listener_list, listener_array);
72
73enum actions {
74    REGISTER,
75    DEREGISTER,
76    CPU_DONT_CARE
77};
78
79static 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 */
110static 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    int rc;
115
116    rc = genlmsg_end(skb, reply);
117    if (rc < 0) {
118        nlmsg_free(skb);
119        return rc;
120    }
121
122    return genlmsg_reply(skb, info);
123}
124
125/*
126 * Send taskstats data in @skb to listeners registered for @cpu's exit data
127 */
128static void send_cpu_listeners(struct sk_buff *skb,
129                    struct listener_list *listeners)
130{
131    struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
132    struct listener *s, *tmp;
133    struct sk_buff *skb_next, *skb_cur = skb;
134    void *reply = genlmsg_data(genlhdr);
135    int rc, delcount = 0;
136
137    rc = genlmsg_end(skb, reply);
138    if (rc < 0) {
139        nlmsg_free(skb);
140        return;
141    }
142
143    rc = 0;
144    down_read(&listeners->sem);
145    list_for_each_entry(s, &listeners->list, list) {
146        skb_next = NULL;
147        if (!list_is_last(&s->list, &listeners->list)) {
148            skb_next = skb_clone(skb_cur, GFP_KERNEL);
149            if (!skb_next)
150                break;
151        }
152        rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
153        if (rc == -ECONNREFUSED) {
154            s->valid = 0;
155            delcount++;
156        }
157        skb_cur = skb_next;
158    }
159    up_read(&listeners->sem);
160
161    if (skb_cur)
162        nlmsg_free(skb_cur);
163
164    if (!delcount)
165        return;
166
167    /* Delete invalidated entries */
168    down_write(&listeners->sem);
169    list_for_each_entry_safe(s, tmp, &listeners->list, list) {
170        if (!s->valid) {
171            list_del(&s->list);
172            kfree(s);
173        }
174    }
175    up_write(&listeners->sem);
176}
177
178static void fill_stats(struct user_namespace *user_ns,
179               struct pid_namespace *pid_ns,
180               struct task_struct *tsk, struct taskstats *stats)
181{
182    memset(stats, 0, sizeof(*stats));
183    /*
184     * Each accounting subsystem adds calls to its functions to
185     * fill in relevant parts of struct taskstsats as follows
186     *
187     * per-task-foo(stats, tsk);
188     */
189
190    delayacct_add_tsk(stats, tsk);
191
192    /* fill in basic acct fields */
193    stats->version = TASKSTATS_VERSION;
194    stats->nvcsw = tsk->nvcsw;
195    stats->nivcsw = tsk->nivcsw;
196    bacct_add_tsk(user_ns, pid_ns, stats, tsk);
197
198    /* fill in extended acct fields */
199    xacct_add_tsk(stats, tsk);
200}
201
202static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
203{
204    struct task_struct *tsk;
205
206    rcu_read_lock();
207    tsk = find_task_by_vpid(pid);
208    if (tsk)
209        get_task_struct(tsk);
210    rcu_read_unlock();
211    if (!tsk)
212        return -ESRCH;
213    fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
214    put_task_struct(tsk);
215    return 0;
216}
217
218static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
219{
220    struct task_struct *tsk, *first;
221    unsigned long flags;
222    int rc = -ESRCH;
223
224    /*
225     * Add additional stats from live tasks except zombie thread group
226     * leaders who are already counted with the dead tasks
227     */
228    rcu_read_lock();
229    first = find_task_by_vpid(tgid);
230
231    if (!first || !lock_task_sighand(first, &flags))
232        goto out;
233
234    if (first->signal->stats)
235        memcpy(stats, first->signal->stats, sizeof(*stats));
236    else
237        memset(stats, 0, sizeof(*stats));
238
239    tsk = first;
240    do {
241        if (tsk->exit_state)
242            continue;
243        /*
244         * Accounting subsystem can call its functions here to
245         * fill in relevant parts of struct taskstsats as follows
246         *
247         * per-task-foo(stats, tsk);
248         */
249        delayacct_add_tsk(stats, tsk);
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;
257out:
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
268static 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);
283ret:
284    spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
285    return;
286}
287
288static 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;
323exists:
324            up_write(&listeners->sem);
325            kfree(s); /* nop if NULL */
326        }
327        return 0;
328    }
329
330    /* Deregister or cleanup */
331cleanup:
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
347static 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#if defined(CONFIG_64BIT) && !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
370#define TASKSTATS_NEEDS_PADDING 1
371#endif
372
373static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
374{
375    struct nlattr *na, *ret;
376    int aggr;
377
378    aggr = (type == TASKSTATS_TYPE_PID)
379            ? TASKSTATS_TYPE_AGGR_PID
380            : TASKSTATS_TYPE_AGGR_TGID;
381
382    /*
383     * The taskstats structure is internally aligned on 8 byte
384     * boundaries but the layout of the aggregrate reply, with
385     * two NLA headers and the pid (each 4 bytes), actually
386     * force the entire structure to be unaligned. This causes
387     * the kernel to issue unaligned access warnings on some
388     * architectures like ia64. Unfortunately, some software out there
389     * doesn't properly unroll the NLA packet and assumes that the start
390     * of the taskstats structure will always be 20 bytes from the start
391     * of the netlink payload. Aligning the start of the taskstats
392     * structure breaks this software, which we don't want. So, for now
393     * the alignment only happens on architectures that require it
394     * and those users will have to update to fixed versions of those
395     * packages. Space is reserved in the packet only when needed.
396     * This ifdef should be removed in several years e.g. 2012 once
397     * we can be confident that fixed versions are installed on most
398     * systems. We add the padding before the aggregate since the
399     * aggregate is already a defined type.
400     */
401#ifdef TASKSTATS_NEEDS_PADDING
402    if (nla_put(skb, TASKSTATS_TYPE_NULL, 0, NULL) < 0)
403        goto err;
404#endif
405    na = nla_nest_start(skb, aggr);
406    if (!na)
407        goto err;
408
409    if (nla_put(skb, type, sizeof(pid), &pid) < 0) {
410        nla_nest_cancel(skb, na);
411        goto err;
412    }
413    ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
414    if (!ret) {
415        nla_nest_cancel(skb, na);
416        goto err;
417    }
418    nla_nest_end(skb, na);
419
420    return nla_data(ret);
421err:
422    return NULL;
423}
424
425static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
426{
427    int rc = 0;
428    struct sk_buff *rep_skb;
429    struct cgroupstats *stats;
430    struct nlattr *na;
431    size_t size;
432    u32 fd;
433    struct fd f;
434
435    na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
436    if (!na)
437        return -EINVAL;
438
439    fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
440    f = fdget(fd);
441    if (!f.file)
442        return 0;
443
444    size = nla_total_size(sizeof(struct cgroupstats));
445
446    rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
447                size);
448    if (rc < 0)
449        goto err;
450
451    na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
452                sizeof(struct cgroupstats));
453    if (na == NULL) {
454        nlmsg_free(rep_skb);
455        rc = -EMSGSIZE;
456        goto err;
457    }
458
459    stats = nla_data(na);
460    memset(stats, 0, sizeof(*stats));
461
462    rc = cgroupstats_build(stats, f.file->f_dentry);
463    if (rc < 0) {
464        nlmsg_free(rep_skb);
465        goto err;
466    }
467
468    rc = send_reply(rep_skb, info);
469
470err:
471    fdput(f);
472    return rc;
473}
474
475static int cmd_attr_register_cpumask(struct genl_info *info)
476{
477    cpumask_var_t mask;
478    int rc;
479
480    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
481        return -ENOMEM;
482    rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
483    if (rc < 0)
484        goto out;
485    rc = add_del_listener(info->snd_portid, mask, REGISTER);
486out:
487    free_cpumask_var(mask);
488    return rc;
489}
490
491static int cmd_attr_deregister_cpumask(struct genl_info *info)
492{
493    cpumask_var_t mask;
494    int rc;
495
496    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
497        return -ENOMEM;
498    rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
499    if (rc < 0)
500        goto out;
501    rc = add_del_listener(info->snd_portid, mask, DEREGISTER);
502out:
503    free_cpumask_var(mask);
504    return rc;
505}
506
507static size_t taskstats_packet_size(void)
508{
509    size_t size;
510
511    size = nla_total_size(sizeof(u32)) +
512        nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
513#ifdef TASKSTATS_NEEDS_PADDING
514    size += nla_total_size(0); /* Padding for alignment */
515#endif
516    return size;
517}
518
519static int cmd_attr_pid(struct genl_info *info)
520{
521    struct taskstats *stats;
522    struct sk_buff *rep_skb;
523    size_t size;
524    u32 pid;
525    int rc;
526
527    size = taskstats_packet_size();
528
529    rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
530    if (rc < 0)
531        return rc;
532
533    rc = -EINVAL;
534    pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
535    stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
536    if (!stats)
537        goto err;
538
539    rc = fill_stats_for_pid(pid, stats);
540    if (rc < 0)
541        goto err;
542    return send_reply(rep_skb, info);
543err:
544    nlmsg_free(rep_skb);
545    return rc;
546}
547
548static int cmd_attr_tgid(struct genl_info *info)
549{
550    struct taskstats *stats;
551    struct sk_buff *rep_skb;
552    size_t size;
553    u32 tgid;
554    int rc;
555
556    size = taskstats_packet_size();
557
558    rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
559    if (rc < 0)
560        return rc;
561
562    rc = -EINVAL;
563    tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
564    stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
565    if (!stats)
566        goto err;
567
568    rc = fill_stats_for_tgid(tgid, stats);
569    if (rc < 0)
570        goto err;
571    return send_reply(rep_skb, info);
572err:
573    nlmsg_free(rep_skb);
574    return rc;
575}
576
577static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
578{
579    if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
580        return cmd_attr_register_cpumask(info);
581    else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
582        return cmd_attr_deregister_cpumask(info);
583    else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
584        return cmd_attr_pid(info);
585    else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
586        return cmd_attr_tgid(info);
587    else
588        return -EINVAL;
589}
590
591static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
592{
593    struct signal_struct *sig = tsk->signal;
594    struct taskstats *stats;
595
596    if (sig->stats || thread_group_empty(tsk))
597        goto ret;
598
599    /* No problem if kmem_cache_zalloc() fails */
600    stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
601
602    spin_lock_irq(&tsk->sighand->siglock);
603    if (!sig->stats) {
604        sig->stats = stats;
605        stats = NULL;
606    }
607    spin_unlock_irq(&tsk->sighand->siglock);
608
609    if (stats)
610        kmem_cache_free(taskstats_cache, stats);
611ret:
612    return sig->stats;
613}
614
615/* Send pid data out on exit */
616void taskstats_exit(struct task_struct *tsk, int group_dead)
617{
618    int rc;
619    struct listener_list *listeners;
620    struct taskstats *stats;
621    struct sk_buff *rep_skb;
622    size_t size;
623    int is_thread_group;
624
625    if (!family_registered)
626        return;
627
628    /*
629     * Size includes space for nested attributes
630     */
631    size = taskstats_packet_size();
632
633    is_thread_group = !!taskstats_tgid_alloc(tsk);
634    if (is_thread_group) {
635        /* PID + STATS + TGID + STATS */
636        size = 2 * size;
637        /* fill the tsk->signal->stats structure */
638        fill_tgid_exit(tsk);
639    }
640
641    listeners = __this_cpu_ptr(&listener_array);
642    if (list_empty(&listeners->list))
643        return;
644
645    rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
646    if (rc < 0)
647        return;
648
649    stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID,
650             task_pid_nr_ns(tsk, &init_pid_ns));
651    if (!stats)
652        goto err;
653
654    fill_stats(&init_user_ns, &init_pid_ns, tsk, stats);
655
656    /*
657     * Doesn't matter if tsk is the leader or the last group member leaving
658     */
659    if (!is_thread_group || !group_dead)
660        goto send;
661
662    stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID,
663             task_tgid_nr_ns(tsk, &init_pid_ns));
664    if (!stats)
665        goto err;
666
667    memcpy(stats, tsk->signal->stats, sizeof(*stats));
668
669send:
670    send_cpu_listeners(rep_skb, listeners);
671    return;
672err:
673    nlmsg_free(rep_skb);
674}
675
676static const struct genl_ops taskstats_ops[] = {
677    {
678        .cmd = TASKSTATS_CMD_GET,
679        .doit = taskstats_user_cmd,
680        .policy = taskstats_cmd_get_policy,
681        .flags = GENL_ADMIN_PERM,
682    },
683    {
684        .cmd = CGROUPSTATS_CMD_GET,
685        .doit = cgroupstats_user_cmd,
686        .policy = cgroupstats_cmd_get_policy,
687    },
688};
689
690/* Needed early in initialization */
691void __init taskstats_init_early(void)
692{
693    unsigned int i;
694
695    taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
696    for_each_possible_cpu(i) {
697        INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
698        init_rwsem(&(per_cpu(listener_array, i).sem));
699    }
700}
701
702static int __init taskstats_init(void)
703{
704    int rc;
705
706    rc = genl_register_family_with_ops(&family, taskstats_ops);
707    if (rc)
708        return rc;
709
710    family_registered = 1;
711    pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
712    return 0;
713}
714
715/*
716 * late initcall ensures initialization of statistics collection
717 * mechanisms precedes initialization of the taskstats interface
718 */
719late_initcall(taskstats_init);
720

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