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 <linux/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    if (isadd == REGISTER) {
295        for_each_cpu(cpu, mask) {
296            s = kmalloc_node(sizeof(struct listener),
297                    GFP_KERNEL, cpu_to_node(cpu));
298            if (!s)
299                goto cleanup;
300
301            s->pid = pid;
302            s->valid = 1;
303
304            listeners = &per_cpu(listener_array, cpu);
305            down_write(&listeners->sem);
306            list_for_each_entry(s2, &listeners->list, list) {
307                if (s2->pid == pid && s2->valid)
308                    goto exists;
309            }
310            list_add(&s->list, &listeners->list);
311            s = NULL;
312exists:
313            up_write(&listeners->sem);
314            kfree(s); /* nop if NULL */
315        }
316        return 0;
317    }
318
319    /* Deregister or cleanup */
320cleanup:
321    for_each_cpu(cpu, mask) {
322        listeners = &per_cpu(listener_array, cpu);
323        down_write(&listeners->sem);
324        list_for_each_entry_safe(s, tmp, &listeners->list, list) {
325            if (s->pid == pid) {
326                list_del(&s->list);
327                kfree(s);
328                break;
329            }
330        }
331        up_write(&listeners->sem);
332    }
333    return 0;
334}
335
336static int parse(struct nlattr *na, struct cpumask *mask)
337{
338    char *data;
339    int len;
340    int ret;
341
342    if (na == NULL)
343        return 1;
344    len = nla_len(na);
345    if (len > TASKSTATS_CPUMASK_MAXLEN)
346        return -E2BIG;
347    if (len < 1)
348        return -EINVAL;
349    data = kmalloc(len, GFP_KERNEL);
350    if (!data)
351        return -ENOMEM;
352    nla_strlcpy(data, na, len);
353    ret = cpulist_parse(data, mask);
354    kfree(data);
355    return ret;
356}
357
358#if defined(CONFIG_64BIT) && !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
359#define TASKSTATS_NEEDS_PADDING 1
360#endif
361
362static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
363{
364    struct nlattr *na, *ret;
365    int aggr;
366
367    aggr = (type == TASKSTATS_TYPE_PID)
368            ? TASKSTATS_TYPE_AGGR_PID
369            : TASKSTATS_TYPE_AGGR_TGID;
370
371    /*
372     * The taskstats structure is internally aligned on 8 byte
373     * boundaries but the layout of the aggregrate reply, with
374     * two NLA headers and the pid (each 4 bytes), actually
375     * force the entire structure to be unaligned. This causes
376     * the kernel to issue unaligned access warnings on some
377     * architectures like ia64. Unfortunately, some software out there
378     * doesn't properly unroll the NLA packet and assumes that the start
379     * of the taskstats structure will always be 20 bytes from the start
380     * of the netlink payload. Aligning the start of the taskstats
381     * structure breaks this software, which we don't want. So, for now
382     * the alignment only happens on architectures that require it
383     * and those users will have to update to fixed versions of those
384     * packages. Space is reserved in the packet only when needed.
385     * This ifdef should be removed in several years e.g. 2012 once
386     * we can be confident that fixed versions are installed on most
387     * systems. We add the padding before the aggregate since the
388     * aggregate is already a defined type.
389     */
390#ifdef TASKSTATS_NEEDS_PADDING
391    if (nla_put(skb, TASKSTATS_TYPE_NULL, 0, NULL) < 0)
392        goto err;
393#endif
394    na = nla_nest_start(skb, aggr);
395    if (!na)
396        goto err;
397
398    if (nla_put(skb, type, sizeof(pid), &pid) < 0)
399        goto err;
400    ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
401    if (!ret)
402        goto err;
403    nla_nest_end(skb, na);
404
405    return nla_data(ret);
406err:
407    return NULL;
408}
409
410static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
411{
412    int rc = 0;
413    struct sk_buff *rep_skb;
414    struct cgroupstats *stats;
415    struct nlattr *na;
416    size_t size;
417    u32 fd;
418    struct file *file;
419    int fput_needed;
420
421    na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
422    if (!na)
423        return -EINVAL;
424
425    fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
426    file = fget_light(fd, &fput_needed);
427    if (!file)
428        return 0;
429
430    size = nla_total_size(sizeof(struct cgroupstats));
431
432    rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
433                size);
434    if (rc < 0)
435        goto err;
436
437    na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
438                sizeof(struct cgroupstats));
439    stats = nla_data(na);
440    memset(stats, 0, sizeof(*stats));
441
442    rc = cgroupstats_build(stats, file->f_dentry);
443    if (rc < 0) {
444        nlmsg_free(rep_skb);
445        goto err;
446    }
447
448    rc = send_reply(rep_skb, info);
449
450err:
451    fput_light(file, fput_needed);
452    return rc;
453}
454
455static int cmd_attr_register_cpumask(struct genl_info *info)
456{
457    cpumask_var_t mask;
458    int rc;
459
460    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
461        return -ENOMEM;
462    rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
463    if (rc < 0)
464        goto out;
465    rc = add_del_listener(info->snd_pid, mask, REGISTER);
466out:
467    free_cpumask_var(mask);
468    return rc;
469}
470
471static int cmd_attr_deregister_cpumask(struct genl_info *info)
472{
473    cpumask_var_t mask;
474    int rc;
475
476    if (!alloc_cpumask_var(&mask, GFP_KERNEL))
477        return -ENOMEM;
478    rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
479    if (rc < 0)
480        goto out;
481    rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
482out:
483    free_cpumask_var(mask);
484    return rc;
485}
486
487static size_t taskstats_packet_size(void)
488{
489    size_t size;
490
491    size = nla_total_size(sizeof(u32)) +
492        nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
493#ifdef TASKSTATS_NEEDS_PADDING
494    size += nla_total_size(0); /* Padding for alignment */
495#endif
496    return size;
497}
498
499static int cmd_attr_pid(struct genl_info *info)
500{
501    struct taskstats *stats;
502    struct sk_buff *rep_skb;
503    size_t size;
504    u32 pid;
505    int rc;
506
507    size = taskstats_packet_size();
508
509    rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
510    if (rc < 0)
511        return rc;
512
513    rc = -EINVAL;
514    pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
515    stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
516    if (!stats)
517        goto err;
518
519    rc = fill_stats_for_pid(pid, stats);
520    if (rc < 0)
521        goto err;
522    return send_reply(rep_skb, info);
523err:
524    nlmsg_free(rep_skb);
525    return rc;
526}
527
528static int cmd_attr_tgid(struct genl_info *info)
529{
530    struct taskstats *stats;
531    struct sk_buff *rep_skb;
532    size_t size;
533    u32 tgid;
534    int rc;
535
536    size = taskstats_packet_size();
537
538    rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
539    if (rc < 0)
540        return rc;
541
542    rc = -EINVAL;
543    tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
544    stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
545    if (!stats)
546        goto err;
547
548    rc = fill_stats_for_tgid(tgid, stats);
549    if (rc < 0)
550        goto err;
551    return send_reply(rep_skb, info);
552err:
553    nlmsg_free(rep_skb);
554    return rc;
555}
556
557static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
558{
559    if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
560        return cmd_attr_register_cpumask(info);
561    else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
562        return cmd_attr_deregister_cpumask(info);
563    else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
564        return cmd_attr_pid(info);
565    else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
566        return cmd_attr_tgid(info);
567    else
568        return -EINVAL;
569}
570
571static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
572{
573    struct signal_struct *sig = tsk->signal;
574    struct taskstats *stats;
575
576    if (sig->stats || thread_group_empty(tsk))
577        goto ret;
578
579    /* No problem if kmem_cache_zalloc() fails */
580    stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
581
582    spin_lock_irq(&tsk->sighand->siglock);
583    if (!sig->stats) {
584        sig->stats = stats;
585        stats = NULL;
586    }
587    spin_unlock_irq(&tsk->sighand->siglock);
588
589    if (stats)
590        kmem_cache_free(taskstats_cache, stats);
591ret:
592    return sig->stats;
593}
594
595/* Send pid data out on exit */
596void taskstats_exit(struct task_struct *tsk, int group_dead)
597{
598    int rc;
599    struct listener_list *listeners;
600    struct taskstats *stats;
601    struct sk_buff *rep_skb;
602    size_t size;
603    int is_thread_group;
604
605    if (!family_registered)
606        return;
607
608    /*
609     * Size includes space for nested attributes
610     */
611    size = taskstats_packet_size();
612
613    is_thread_group = !!taskstats_tgid_alloc(tsk);
614    if (is_thread_group) {
615        /* PID + STATS + TGID + STATS */
616        size = 2 * size;
617        /* fill the tsk->signal->stats structure */
618        fill_tgid_exit(tsk);
619    }
620
621    listeners = __this_cpu_ptr(&listener_array);
622    if (list_empty(&listeners->list))
623        return;
624
625    rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
626    if (rc < 0)
627        return;
628
629    stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
630    if (!stats)
631        goto err;
632
633    fill_stats(tsk, stats);
634
635    /*
636     * Doesn't matter if tsk is the leader or the last group member leaving
637     */
638    if (!is_thread_group || !group_dead)
639        goto send;
640
641    stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
642    if (!stats)
643        goto err;
644
645    memcpy(stats, tsk->signal->stats, sizeof(*stats));
646
647send:
648    send_cpu_listeners(rep_skb, listeners);
649    return;
650err:
651    nlmsg_free(rep_skb);
652}
653
654static struct genl_ops taskstats_ops = {
655    .cmd = TASKSTATS_CMD_GET,
656    .doit = taskstats_user_cmd,
657    .policy = taskstats_cmd_get_policy,
658    .flags = GENL_ADMIN_PERM,
659};
660
661static struct genl_ops cgroupstats_ops = {
662    .cmd = CGROUPSTATS_CMD_GET,
663    .doit = cgroupstats_user_cmd,
664    .policy = cgroupstats_cmd_get_policy,
665};
666
667/* Needed early in initialization */
668void __init taskstats_init_early(void)
669{
670    unsigned int i;
671
672    taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
673    for_each_possible_cpu(i) {
674        INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
675        init_rwsem(&(per_cpu(listener_array, i).sem));
676    }
677}
678
679static int __init taskstats_init(void)
680{
681    int rc;
682
683    rc = genl_register_family(&family);
684    if (rc)
685        return rc;
686
687    rc = genl_register_ops(&family, &taskstats_ops);
688    if (rc < 0)
689        goto err;
690
691    rc = genl_register_ops(&family, &cgroupstats_ops);
692    if (rc < 0)
693        goto err_cgroup_ops;
694
695    family_registered = 1;
696    pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
697    return 0;
698err_cgroup_ops:
699    genl_unregister_ops(&family, &taskstats_ops);
700err:
701    genl_unregister_family(&family);
702    return rc;
703}
704
705/*
706 * late initcall ensures initialization of statistics collection
707 * mechanisms precedes initialization of the taskstats interface
708 */
709late_initcall(taskstats_init);
710

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