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 <net/genetlink.h>
31#include <asm/atomic.h>
32
33/*
34 * Maximum length of a cpumask that can be specified in
35 * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
36 */
37#define TASKSTATS_CPUMASK_MAXLEN (100+6*NR_CPUS)
38
39static DEFINE_PER_CPU(__u32, taskstats_seqnum);
40static int family_registered;
41struct kmem_cache *taskstats_cache;
42
43static struct genl_family family = {
44    .id = GENL_ID_GENERATE,
45    .name = TASKSTATS_GENL_NAME,
46    .version = TASKSTATS_GENL_VERSION,
47    .maxattr = TASKSTATS_CMD_ATTR_MAX,
48};
49
50static const struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
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
56static const struct nla_policy cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] = {
57    [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
58};
59
60struct listener {
61    struct list_head list;
62    pid_t pid;
63    char valid;
64};
65
66struct listener_list {
67    struct rw_semaphore sem;
68    struct list_head list;
69};
70static DEFINE_PER_CPU(struct listener_list, listener_array);
71
72enum actions {
73    REGISTER,
74    DEREGISTER,
75    CPU_DONT_CARE
76};
77
78static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
79                size_t size)
80{
81    struct sk_buff *skb;
82    void *reply;
83
84    /*
85     * If new attributes are added, please revisit this allocation
86     */
87    skb = genlmsg_new(size, GFP_KERNEL);
88    if (!skb)
89        return -ENOMEM;
90
91    if (!info) {
92        int seq = this_cpu_inc_return(taskstats_seqnum) - 1;
93
94        reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
95    } else
96        reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
97    if (reply == NULL) {
98        nlmsg_free(skb);
99        return -EINVAL;
100    }
101
102    *skbp = skb;
103    return 0;
104}
105
106/*
107 * Send taskstats data in @skb to listener with nl_pid @pid
108 */
109static int send_reply(struct sk_buff *skb, struct genl_info *info)
110{
111    struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
112    void *reply = genlmsg_data(genlhdr);
113    int rc;
114
115    rc = genlmsg_end(skb, reply);
116    if (rc < 0) {
117        nlmsg_free(skb);
118        return rc;
119    }
120
121    return genlmsg_reply(skb, info);
122}
123
124/*
125 * Send taskstats data in @skb to listeners registered for @cpu's exit data
126 */
127static void send_cpu_listeners(struct sk_buff *skb,
128                    struct listener_list *listeners)
129{
130    struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
131    struct listener *s, *tmp;
132    struct sk_buff *skb_next, *skb_cur = skb;
133    void *reply = genlmsg_data(genlhdr);
134    int rc, delcount = 0;
135
136    rc = genlmsg_end(skb, reply);
137    if (rc < 0) {
138        nlmsg_free(skb);
139        return;
140    }
141
142    rc = 0;
143    down_read(&listeners->sem);
144    list_for_each_entry(s, &listeners->list, list) {
145        skb_next = NULL;
146        if (!list_is_last(&s->list, &listeners->list)) {
147            skb_next = skb_clone(skb_cur, GFP_KERNEL);
148            if (!skb_next)
149                break;
150        }
151        rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
152        if (rc == -ECONNREFUSED) {
153            s->valid = 0;
154            delcount++;
155        }
156        skb_cur = skb_next;
157    }
158    up_read(&listeners->sem);
159
160    if (skb_cur)
161        nlmsg_free(skb_cur);
162
163    if (!delcount)
164        return;
165
166    /* Delete invalidated entries */
167    down_write(&listeners->sem);
168    list_for_each_entry_safe(s, tmp, &listeners->list, list) {
169        if (!s->valid) {
170            list_del(&s->list);
171            kfree(s);
172        }
173    }
174    up_write(&listeners->sem);
175}
176
177static void fill_stats(struct task_struct *tsk, struct taskstats *stats)
178{
179    memset(stats, 0, sizeof(*stats));
180    /*
181     * Each accounting subsystem adds calls to its functions to
182     * fill in relevant parts of struct taskstsats as follows
183     *
184     * per-task-foo(stats, tsk);
185     */
186
187    delayacct_add_tsk(stats, tsk);
188
189    /* fill in basic acct fields */
190    stats->version = TASKSTATS_VERSION;
191    stats->nvcsw = tsk->nvcsw;
192    stats->nivcsw = tsk->nivcsw;
193    bacct_add_tsk(stats, tsk);
194
195    /* fill in extended acct fields */
196    xacct_add_tsk(stats, tsk);
197}
198
199static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
200{
201    struct task_struct *tsk;
202
203    rcu_read_lock();
204    tsk = find_task_by_vpid(pid);
205    if (tsk)
206        get_task_struct(tsk);
207    rcu_read_unlock();
208    if (!tsk)
209        return -ESRCH;
210    fill_stats(tsk, stats);
211    put_task_struct(tsk);
212    return 0;
213}
214
215static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
216{
217    struct task_struct *tsk, *first;
218    unsigned long flags;
219    int rc = -ESRCH;
220
221    /*
222     * Add additional stats from live tasks except zombie thread group
223     * leaders who are already counted with the dead tasks
224     */
225    rcu_read_lock();
226    first = find_task_by_vpid(tgid);
227
228    if (!first || !lock_task_sighand(first, &flags))
229        goto out;
230
231    if (first->signal->stats)
232        memcpy(stats, first->signal->stats, sizeof(*stats));
233    else
234        memset(stats, 0, sizeof(*stats));
235
236    tsk = first;
237    do {
238        if (tsk->exit_state)
239            continue;
240        /*
241         * Accounting subsystem can call its functions here to
242         * fill in relevant parts of struct taskstsats as follows
243         *
244         * per-task-foo(stats, tsk);
245         */
246        delayacct_add_tsk(stats, tsk);
247
248        stats->nvcsw += tsk->nvcsw;
249        stats->nivcsw += tsk->nivcsw;
250    } while_each_thread(first, tsk);
251
252    unlock_task_sighand(first, &flags);
253    rc = 0;
254out:
255    rcu_read_unlock();
256
257    stats->version = TASKSTATS_VERSION;
258    /*
259     * Accounting subsystems can also add calls here to modify
260     * fields of taskstats.
261     */
262    return rc;
263}
264
265static void fill_tgid_exit(struct task_struct *tsk)
266{
267    unsigned long flags;
268
269    spin_lock_irqsave(&tsk->sighand->siglock, flags);
270    if (!tsk->signal->stats)
271        goto ret;
272
273    /*
274     * Each accounting subsystem calls its functions here to
275     * accumalate its per-task stats for tsk, into the per-tgid structure
276     *
277     * per-task-foo(tsk->signal->stats, tsk);
278     */
279    delayacct_add_tsk(tsk->signal->stats, tsk);
280ret:
281    spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
282    return;
283}
284
285static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
286{
287    struct listener_list *listeners;
288    struct listener *s, *tmp, *s2;
289    unsigned int cpu;
290
291    if (!cpumask_subset(mask, cpu_possible_mask))
292        return -EINVAL;
293
294    s = NULL;
295    if (isadd == REGISTER) {
296        for_each_cpu(cpu, mask) {
297            if (!s)
298                s = kmalloc_node(sizeof(struct listener),
299                         GFP_KERNEL, cpu_to_node(cpu));
300            if (!s)
301                goto cleanup;
302            s->pid = pid;
303            INIT_LIST_HEAD(&s->list);
304            s->valid = 1;
305
306            listeners = &per_cpu(listener_array, cpu);
307            down_write(&listeners->sem);
308            list_for_each_entry_safe(s2, tmp, &listeners->list, list) {
309                if (s2->pid == pid)
310                    goto next_cpu;
311            }
312            list_add(&s->list, &listeners->list);
313            s = NULL;
314next_cpu:
315            up_write(&listeners->sem);
316        }
317        kfree(s);
318        return 0;
319    }
320
321    /* Deregister or cleanup */
322cleanup:
323    for_each_cpu(cpu, mask) {
324        listeners = &per_cpu(listener_array, cpu);
325        down_write(&listeners->sem);
326        list_for_each_entry_safe(s, tmp, &listeners->list, list) {
327            if (s->pid == pid) {
328                list_del(&s->list);
329                kfree(s);
330                break;
331            }
332        }
333        up_write(&listeners->sem);
334    }
335    return 0;
336}
337
338static int parse(struct nlattr *na, struct cpumask *mask)
339{
340    char *data;
341    int len;
342    int ret;
343
344    if (na == NULL)
345        return 1;
346    len = nla_len(na);
347    if (len > TASKSTATS_CPUMASK_MAXLEN)
348        return -E2BIG;
349    if (len < 1)
350        return -EINVAL;
351    data = kmalloc(len, GFP_KERNEL);
352    if (!data)
353        return -ENOMEM;
354    nla_strlcpy(data, na, len);
355    ret = cpulist_parse(data, mask);
356    kfree(data);
357    return ret;
358}
359
360#if defined(CONFIG_64BIT) && !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
361#define TASKSTATS_NEEDS_PADDING 1
362#endif
363
364static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
365{
366    struct nlattr *na, *ret;
367    int aggr;
368
369    aggr = (type == TASKSTATS_TYPE_PID)
370            ? TASKSTATS_TYPE_AGGR_PID
371            : TASKSTATS_TYPE_AGGR_TGID;
372
373    /*
374     * The taskstats structure is internally aligned on 8 byte
375     * boundaries but the layout of the aggregrate reply, with
376     * two NLA headers and the pid (each 4 bytes), actually
377     * force the entire structure to be unaligned. This causes
378     * the kernel to issue unaligned access warnings on some
379     * architectures like ia64. Unfortunately, some software out there
380     * doesn't properly unroll the NLA packet and assumes that the start
381     * of the taskstats structure will always be 20 bytes from the start
382     * of the netlink payload. Aligning the start of the taskstats
383     * structure breaks this software, which we don't want. So, for now
384     * the alignment only happens on architectures that require it
385     * and those users will have to update to fixed versions of those
386     * packages. Space is reserved in the packet only when needed.
387     * This ifdef should be removed in several years e.g. 2012 once
388     * we can be confident that fixed versions are installed on most
389     * systems. We add the padding before the aggregate since the
390     * aggregate is already a defined type.
391     */
392#ifdef TASKSTATS_NEEDS_PADDING
393    if (nla_put(skb, TASKSTATS_TYPE_NULL, 0, NULL) < 0)
394        goto err;
395#endif
396    na = nla_nest_start(skb, aggr);
397    if (!na)
398        goto err;
399
400    if (nla_put(skb, type, sizeof(pid), &pid) < 0)
401        goto err;
402    ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
403    if (!ret)
404        goto err;
405    nla_nest_end(skb, na);
406
407    return nla_data(ret);
408err:
409    return NULL;
410}
411
412static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
413{
414    int rc = 0;
415    struct sk_buff *rep_skb;
416    struct cgroupstats *stats;
417    struct nlattr *na;
418    size_t size;
419    u32 fd;
420    struct file *file;
421    int fput_needed;
422
423    na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
424    if (!na)
425        return -EINVAL;
426
427    fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
428    file = fget_light(fd, &fput_needed);
429    if (!file)
430        return 0;
431
432    size = nla_total_size(sizeof(struct cgroupstats));
433
434    rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
435                size);
436    if (rc < 0)
437        goto err;
438
439    na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
440                sizeof(struct cgroupstats));
441    stats = nla_data(na);
442    memset(stats, 0, sizeof(*stats));
443
444    rc = cgroupstats_build(stats, file->f_dentry);
445    if (rc < 0) {
446        nlmsg_free(rep_skb);
447        goto err;
448    }
449
450    rc = send_reply(rep_skb, info);
451
452err:
453    fput_light(file, fput_needed);
454    return rc;
455}
456
457static int cmd_attr_register_cpumask(struct genl_info *info)
458{
459    cpumask_var_t mask;
460    int rc;
461
462    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
463        return -ENOMEM;
464    rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
465    if (rc < 0)
466        goto out;
467    rc = add_del_listener(info->snd_pid, mask, REGISTER);
468out:
469    free_cpumask_var(mask);
470    return rc;
471}
472
473static int cmd_attr_deregister_cpumask(struct genl_info *info)
474{
475    cpumask_var_t mask;
476    int rc;
477
478    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
479        return -ENOMEM;
480    rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
481    if (rc < 0)
482        goto out;
483    rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
484out:
485    free_cpumask_var(mask);
486    return rc;
487}
488
489static size_t taskstats_packet_size(void)
490{
491    size_t size;
492
493    size = nla_total_size(sizeof(u32)) +
494        nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
495#ifdef TASKSTATS_NEEDS_PADDING
496    size += nla_total_size(0); /* Padding for alignment */
497#endif
498    return size;
499}
500
501static int cmd_attr_pid(struct genl_info *info)
502{
503    struct taskstats *stats;
504    struct sk_buff *rep_skb;
505    size_t size;
506    u32 pid;
507    int rc;
508
509    size = taskstats_packet_size();
510
511    rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
512    if (rc < 0)
513        return rc;
514
515    rc = -EINVAL;
516    pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
517    stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
518    if (!stats)
519        goto err;
520
521    rc = fill_stats_for_pid(pid, stats);
522    if (rc < 0)
523        goto err;
524    return send_reply(rep_skb, info);
525err:
526    nlmsg_free(rep_skb);
527    return rc;
528}
529
530static int cmd_attr_tgid(struct genl_info *info)
531{
532    struct taskstats *stats;
533    struct sk_buff *rep_skb;
534    size_t size;
535    u32 tgid;
536    int rc;
537
538    size = taskstats_packet_size();
539
540    rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
541    if (rc < 0)
542        return rc;
543
544    rc = -EINVAL;
545    tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
546    stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
547    if (!stats)
548        goto err;
549
550    rc = fill_stats_for_tgid(tgid, stats);
551    if (rc < 0)
552        goto err;
553    return send_reply(rep_skb, info);
554err:
555    nlmsg_free(rep_skb);
556    return rc;
557}
558
559static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
560{
561    if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
562        return cmd_attr_register_cpumask(info);
563    else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
564        return cmd_attr_deregister_cpumask(info);
565    else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
566        return cmd_attr_pid(info);
567    else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
568        return cmd_attr_tgid(info);
569    else
570        return -EINVAL;
571}
572
573static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
574{
575    struct signal_struct *sig = tsk->signal;
576    struct taskstats *stats;
577
578    if (sig->stats || thread_group_empty(tsk))
579        goto ret;
580
581    /* No problem if kmem_cache_zalloc() fails */
582    stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
583
584    spin_lock_irq(&tsk->sighand->siglock);
585    if (!sig->stats) {
586        sig->stats = stats;
587        stats = NULL;
588    }
589    spin_unlock_irq(&tsk->sighand->siglock);
590
591    if (stats)
592        kmem_cache_free(taskstats_cache, stats);
593ret:
594    return sig->stats;
595}
596
597/* Send pid data out on exit */
598void taskstats_exit(struct task_struct *tsk, int group_dead)
599{
600    int rc;
601    struct listener_list *listeners;
602    struct taskstats *stats;
603    struct sk_buff *rep_skb;
604    size_t size;
605    int is_thread_group;
606
607    if (!family_registered)
608        return;
609
610    /*
611     * Size includes space for nested attributes
612     */
613    size = taskstats_packet_size();
614
615    is_thread_group = !!taskstats_tgid_alloc(tsk);
616    if (is_thread_group) {
617        /* PID + STATS + TGID + STATS */
618        size = 2 * size;
619        /* fill the tsk->signal->stats structure */
620        fill_tgid_exit(tsk);
621    }
622
623    listeners = __this_cpu_ptr(&listener_array);
624    if (list_empty(&listeners->list))
625        return;
626
627    rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
628    if (rc < 0)
629        return;
630
631    stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
632    if (!stats)
633        goto err;
634
635    fill_stats(tsk, stats);
636
637    /*
638     * Doesn't matter if tsk is the leader or the last group member leaving
639     */
640    if (!is_thread_group || !group_dead)
641        goto send;
642
643    stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
644    if (!stats)
645        goto err;
646
647    memcpy(stats, tsk->signal->stats, sizeof(*stats));
648
649send:
650    send_cpu_listeners(rep_skb, listeners);
651    return;
652err:
653    nlmsg_free(rep_skb);
654}
655
656static struct genl_ops taskstats_ops = {
657    .cmd = TASKSTATS_CMD_GET,
658    .doit = taskstats_user_cmd,
659    .policy = taskstats_cmd_get_policy,
660};
661
662static struct genl_ops cgroupstats_ops = {
663    .cmd = CGROUPSTATS_CMD_GET,
664    .doit = cgroupstats_user_cmd,
665    .policy = cgroupstats_cmd_get_policy,
666};
667
668/* Needed early in initialization */
669void __init taskstats_init_early(void)
670{
671    unsigned int i;
672
673    taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
674    for_each_possible_cpu(i) {
675        INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
676        init_rwsem(&(per_cpu(listener_array, i).sem));
677    }
678}
679
680static int __init taskstats_init(void)
681{
682    int rc;
683
684    rc = genl_register_family(&family);
685    if (rc)
686        return rc;
687
688    rc = genl_register_ops(&family, &taskstats_ops);
689    if (rc < 0)
690        goto err;
691
692    rc = genl_register_ops(&family, &cgroupstats_ops);
693    if (rc < 0)
694        goto err_cgroup_ops;
695
696    family_registered = 1;
697    pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
698    return 0;
699err_cgroup_ops:
700    genl_unregister_ops(&family, &taskstats_ops);
701err:
702    genl_unregister_family(&family);
703    return rc;
704}
705
706/*
707 * late initcall ensures initialization of statistics collection
708 * mechanisms precedes initialization of the taskstats interface
709 */
710late_initcall(taskstats_init);
711

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