Root/kernel/posix-cpu-timers.c

1/*
2 * Implement CPU time clocks for the POSIX clock interface.
3 */
4
5#include <linux/sched.h>
6#include <linux/posix-timers.h>
7#include <linux/errno.h>
8#include <linux/math64.h>
9#include <asm/uaccess.h>
10#include <linux/kernel_stat.h>
11#include <trace/events/timer.h>
12
13/*
14 * Called after updating RLIMIT_CPU to run cpu timer and update
15 * tsk->signal->cputime_expires expiration cache if necessary. Needs
16 * siglock protection since other code may update expiration cache as
17 * well.
18 */
19void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
20{
21    cputime_t cputime = secs_to_cputime(rlim_new);
22
23    spin_lock_irq(&task->sighand->siglock);
24    set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
25    spin_unlock_irq(&task->sighand->siglock);
26}
27
28static int check_clock(const clockid_t which_clock)
29{
30    int error = 0;
31    struct task_struct *p;
32    const pid_t pid = CPUCLOCK_PID(which_clock);
33
34    if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
35        return -EINVAL;
36
37    if (pid == 0)
38        return 0;
39
40    rcu_read_lock();
41    p = find_task_by_vpid(pid);
42    if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
43           same_thread_group(p, current) : has_group_leader_pid(p))) {
44        error = -EINVAL;
45    }
46    rcu_read_unlock();
47
48    return error;
49}
50
51static inline union cpu_time_count
52timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
53{
54    union cpu_time_count ret;
55    ret.sched = 0; /* high half always zero when .cpu used */
56    if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
57        ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
58    } else {
59        ret.cpu = timespec_to_cputime(tp);
60    }
61    return ret;
62}
63
64static void sample_to_timespec(const clockid_t which_clock,
65                   union cpu_time_count cpu,
66                   struct timespec *tp)
67{
68    if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
69        *tp = ns_to_timespec(cpu.sched);
70    else
71        cputime_to_timespec(cpu.cpu, tp);
72}
73
74static inline int cpu_time_before(const clockid_t which_clock,
75                  union cpu_time_count now,
76                  union cpu_time_count then)
77{
78    if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
79        return now.sched < then.sched;
80    } else {
81        return now.cpu < then.cpu;
82    }
83}
84static inline void cpu_time_add(const clockid_t which_clock,
85                union cpu_time_count *acc,
86                    union cpu_time_count val)
87{
88    if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
89        acc->sched += val.sched;
90    } else {
91        acc->cpu += val.cpu;
92    }
93}
94static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
95                        union cpu_time_count a,
96                        union cpu_time_count b)
97{
98    if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
99        a.sched -= b.sched;
100    } else {
101        a.cpu -= b.cpu;
102    }
103    return a;
104}
105
106/*
107 * Update expiry time from increment, and increase overrun count,
108 * given the current clock sample.
109 */
110static void bump_cpu_timer(struct k_itimer *timer,
111                  union cpu_time_count now)
112{
113    int i;
114
115    if (timer->it.cpu.incr.sched == 0)
116        return;
117
118    if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
119        unsigned long long delta, incr;
120
121        if (now.sched < timer->it.cpu.expires.sched)
122            return;
123        incr = timer->it.cpu.incr.sched;
124        delta = now.sched + incr - timer->it.cpu.expires.sched;
125        /* Don't use (incr*2 < delta), incr*2 might overflow. */
126        for (i = 0; incr < delta - incr; i++)
127            incr = incr << 1;
128        for (; i >= 0; incr >>= 1, i--) {
129            if (delta < incr)
130                continue;
131            timer->it.cpu.expires.sched += incr;
132            timer->it_overrun += 1 << i;
133            delta -= incr;
134        }
135    } else {
136        cputime_t delta, incr;
137
138        if (now.cpu < timer->it.cpu.expires.cpu)
139            return;
140        incr = timer->it.cpu.incr.cpu;
141        delta = now.cpu + incr - timer->it.cpu.expires.cpu;
142        /* Don't use (incr*2 < delta), incr*2 might overflow. */
143        for (i = 0; incr < delta - incr; i++)
144                 incr += incr;
145        for (; i >= 0; incr = incr >> 1, i--) {
146            if (delta < incr)
147                continue;
148            timer->it.cpu.expires.cpu += incr;
149            timer->it_overrun += 1 << i;
150            delta -= incr;
151        }
152    }
153}
154
155static inline cputime_t prof_ticks(struct task_struct *p)
156{
157    return p->utime + p->stime;
158}
159static inline cputime_t virt_ticks(struct task_struct *p)
160{
161    return p->utime;
162}
163
164static int
165posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
166{
167    int error = check_clock(which_clock);
168    if (!error) {
169        tp->tv_sec = 0;
170        tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
171        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
172            /*
173             * If sched_clock is using a cycle counter, we
174             * don't have any idea of its true resolution
175             * exported, but it is much more than 1s/HZ.
176             */
177            tp->tv_nsec = 1;
178        }
179    }
180    return error;
181}
182
183static int
184posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
185{
186    /*
187     * You can never reset a CPU clock, but we check for other errors
188     * in the call before failing with EPERM.
189     */
190    int error = check_clock(which_clock);
191    if (error == 0) {
192        error = -EPERM;
193    }
194    return error;
195}
196
197
198/*
199 * Sample a per-thread clock for the given task.
200 */
201static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
202                union cpu_time_count *cpu)
203{
204    switch (CPUCLOCK_WHICH(which_clock)) {
205    default:
206        return -EINVAL;
207    case CPUCLOCK_PROF:
208        cpu->cpu = prof_ticks(p);
209        break;
210    case CPUCLOCK_VIRT:
211        cpu->cpu = virt_ticks(p);
212        break;
213    case CPUCLOCK_SCHED:
214        cpu->sched = task_sched_runtime(p);
215        break;
216    }
217    return 0;
218}
219
220void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
221{
222    struct signal_struct *sig = tsk->signal;
223    struct task_struct *t;
224
225    times->utime = sig->utime;
226    times->stime = sig->stime;
227    times->sum_exec_runtime = sig->sum_sched_runtime;
228
229    rcu_read_lock();
230    /* make sure we can trust tsk->thread_group list */
231    if (!likely(pid_alive(tsk)))
232        goto out;
233
234    t = tsk;
235    do {
236        times->utime += t->utime;
237        times->stime += t->stime;
238        times->sum_exec_runtime += task_sched_runtime(t);
239    } while_each_thread(tsk, t);
240out:
241    rcu_read_unlock();
242}
243
244static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
245{
246    if (b->utime > a->utime)
247        a->utime = b->utime;
248
249    if (b->stime > a->stime)
250        a->stime = b->stime;
251
252    if (b->sum_exec_runtime > a->sum_exec_runtime)
253        a->sum_exec_runtime = b->sum_exec_runtime;
254}
255
256void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
257{
258    struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
259    struct task_cputime sum;
260    unsigned long flags;
261
262    if (!cputimer->running) {
263        /*
264         * The POSIX timer interface allows for absolute time expiry
265         * values through the TIMER_ABSTIME flag, therefore we have
266         * to synchronize the timer to the clock every time we start
267         * it.
268         */
269        thread_group_cputime(tsk, &sum);
270        raw_spin_lock_irqsave(&cputimer->lock, flags);
271        cputimer->running = 1;
272        update_gt_cputime(&cputimer->cputime, &sum);
273    } else
274        raw_spin_lock_irqsave(&cputimer->lock, flags);
275    *times = cputimer->cputime;
276    raw_spin_unlock_irqrestore(&cputimer->lock, flags);
277}
278
279/*
280 * Sample a process (thread group) clock for the given group_leader task.
281 * Must be called with tasklist_lock held for reading.
282 */
283static int cpu_clock_sample_group(const clockid_t which_clock,
284                  struct task_struct *p,
285                  union cpu_time_count *cpu)
286{
287    struct task_cputime cputime;
288
289    switch (CPUCLOCK_WHICH(which_clock)) {
290    default:
291        return -EINVAL;
292    case CPUCLOCK_PROF:
293        thread_group_cputime(p, &cputime);
294        cpu->cpu = cputime.utime + cputime.stime;
295        break;
296    case CPUCLOCK_VIRT:
297        thread_group_cputime(p, &cputime);
298        cpu->cpu = cputime.utime;
299        break;
300    case CPUCLOCK_SCHED:
301        thread_group_cputime(p, &cputime);
302        cpu->sched = cputime.sum_exec_runtime;
303        break;
304    }
305    return 0;
306}
307
308
309static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
310{
311    const pid_t pid = CPUCLOCK_PID(which_clock);
312    int error = -EINVAL;
313    union cpu_time_count rtn;
314
315    if (pid == 0) {
316        /*
317         * Special case constant value for our own clocks.
318         * We don't have to do any lookup to find ourselves.
319         */
320        if (CPUCLOCK_PERTHREAD(which_clock)) {
321            /*
322             * Sampling just ourselves we can do with no locking.
323             */
324            error = cpu_clock_sample(which_clock,
325                         current, &rtn);
326        } else {
327            read_lock(&tasklist_lock);
328            error = cpu_clock_sample_group(which_clock,
329                               current, &rtn);
330            read_unlock(&tasklist_lock);
331        }
332    } else {
333        /*
334         * Find the given PID, and validate that the caller
335         * should be able to see it.
336         */
337        struct task_struct *p;
338        rcu_read_lock();
339        p = find_task_by_vpid(pid);
340        if (p) {
341            if (CPUCLOCK_PERTHREAD(which_clock)) {
342                if (same_thread_group(p, current)) {
343                    error = cpu_clock_sample(which_clock,
344                                 p, &rtn);
345                }
346            } else {
347                read_lock(&tasklist_lock);
348                if (thread_group_leader(p) && p->sighand) {
349                    error =
350                        cpu_clock_sample_group(which_clock,
351                                       p, &rtn);
352                }
353                read_unlock(&tasklist_lock);
354            }
355        }
356        rcu_read_unlock();
357    }
358
359    if (error)
360        return error;
361    sample_to_timespec(which_clock, rtn, tp);
362    return 0;
363}
364
365
366/*
367 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
368 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
369 * new timer already all-zeros initialized.
370 */
371static int posix_cpu_timer_create(struct k_itimer *new_timer)
372{
373    int ret = 0;
374    const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
375    struct task_struct *p;
376
377    if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
378        return -EINVAL;
379
380    INIT_LIST_HEAD(&new_timer->it.cpu.entry);
381
382    rcu_read_lock();
383    if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
384        if (pid == 0) {
385            p = current;
386        } else {
387            p = find_task_by_vpid(pid);
388            if (p && !same_thread_group(p, current))
389                p = NULL;
390        }
391    } else {
392        if (pid == 0) {
393            p = current->group_leader;
394        } else {
395            p = find_task_by_vpid(pid);
396            if (p && !has_group_leader_pid(p))
397                p = NULL;
398        }
399    }
400    new_timer->it.cpu.task = p;
401    if (p) {
402        get_task_struct(p);
403    } else {
404        ret = -EINVAL;
405    }
406    rcu_read_unlock();
407
408    return ret;
409}
410
411/*
412 * Clean up a CPU-clock timer that is about to be destroyed.
413 * This is called from timer deletion with the timer already locked.
414 * If we return TIMER_RETRY, it's necessary to release the timer's lock
415 * and try again. (This happens when the timer is in the middle of firing.)
416 */
417static int posix_cpu_timer_del(struct k_itimer *timer)
418{
419    struct task_struct *p = timer->it.cpu.task;
420    int ret = 0;
421
422    if (likely(p != NULL)) {
423        read_lock(&tasklist_lock);
424        if (unlikely(p->sighand == NULL)) {
425            /*
426             * We raced with the reaping of the task.
427             * The deletion should have cleared us off the list.
428             */
429            BUG_ON(!list_empty(&timer->it.cpu.entry));
430        } else {
431            spin_lock(&p->sighand->siglock);
432            if (timer->it.cpu.firing)
433                ret = TIMER_RETRY;
434            else
435                list_del(&timer->it.cpu.entry);
436            spin_unlock(&p->sighand->siglock);
437        }
438        read_unlock(&tasklist_lock);
439
440        if (!ret)
441            put_task_struct(p);
442    }
443
444    return ret;
445}
446
447/*
448 * Clean out CPU timers still ticking when a thread exited. The task
449 * pointer is cleared, and the expiry time is replaced with the residual
450 * time for later timer_gettime calls to return.
451 * This must be called with the siglock held.
452 */
453static void cleanup_timers(struct list_head *head,
454               cputime_t utime, cputime_t stime,
455               unsigned long long sum_exec_runtime)
456{
457    struct cpu_timer_list *timer, *next;
458    cputime_t ptime = utime + stime;
459
460    list_for_each_entry_safe(timer, next, head, entry) {
461        list_del_init(&timer->entry);
462        if (timer->expires.cpu < ptime) {
463            timer->expires.cpu = 0;
464        } else {
465            timer->expires.cpu -= ptime;
466        }
467    }
468
469    ++head;
470    list_for_each_entry_safe(timer, next, head, entry) {
471        list_del_init(&timer->entry);
472        if (timer->expires.cpu < utime) {
473            timer->expires.cpu = 0;
474        } else {
475            timer->expires.cpu -= utime;
476        }
477    }
478
479    ++head;
480    list_for_each_entry_safe(timer, next, head, entry) {
481        list_del_init(&timer->entry);
482        if (timer->expires.sched < sum_exec_runtime) {
483            timer->expires.sched = 0;
484        } else {
485            timer->expires.sched -= sum_exec_runtime;
486        }
487    }
488}
489
490/*
491 * These are both called with the siglock held, when the current thread
492 * is being reaped. When the final (leader) thread in the group is reaped,
493 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
494 */
495void posix_cpu_timers_exit(struct task_struct *tsk)
496{
497    cleanup_timers(tsk->cpu_timers,
498               tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
499
500}
501void posix_cpu_timers_exit_group(struct task_struct *tsk)
502{
503    struct signal_struct *const sig = tsk->signal;
504
505    cleanup_timers(tsk->signal->cpu_timers,
506               tsk->utime + sig->utime, tsk->stime + sig->stime,
507               tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
508}
509
510static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
511{
512    /*
513     * That's all for this thread or process.
514     * We leave our residual in expires to be reported.
515     */
516    put_task_struct(timer->it.cpu.task);
517    timer->it.cpu.task = NULL;
518    timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
519                         timer->it.cpu.expires,
520                         now);
521}
522
523static inline int expires_gt(cputime_t expires, cputime_t new_exp)
524{
525    return expires == 0 || expires > new_exp;
526}
527
528/*
529 * Insert the timer on the appropriate list before any timers that
530 * expire later. This must be called with the tasklist_lock held
531 * for reading, interrupts disabled and p->sighand->siglock taken.
532 */
533static void arm_timer(struct k_itimer *timer)
534{
535    struct task_struct *p = timer->it.cpu.task;
536    struct list_head *head, *listpos;
537    struct task_cputime *cputime_expires;
538    struct cpu_timer_list *const nt = &timer->it.cpu;
539    struct cpu_timer_list *next;
540
541    if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
542        head = p->cpu_timers;
543        cputime_expires = &p->cputime_expires;
544    } else {
545        head = p->signal->cpu_timers;
546        cputime_expires = &p->signal->cputime_expires;
547    }
548    head += CPUCLOCK_WHICH(timer->it_clock);
549
550    listpos = head;
551    list_for_each_entry(next, head, entry) {
552        if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
553            break;
554        listpos = &next->entry;
555    }
556    list_add(&nt->entry, listpos);
557
558    if (listpos == head) {
559        union cpu_time_count *exp = &nt->expires;
560
561        /*
562         * We are the new earliest-expiring POSIX 1.b timer, hence
563         * need to update expiration cache. Take into account that
564         * for process timers we share expiration cache with itimers
565         * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
566         */
567
568        switch (CPUCLOCK_WHICH(timer->it_clock)) {
569        case CPUCLOCK_PROF:
570            if (expires_gt(cputime_expires->prof_exp, exp->cpu))
571                cputime_expires->prof_exp = exp->cpu;
572            break;
573        case CPUCLOCK_VIRT:
574            if (expires_gt(cputime_expires->virt_exp, exp->cpu))
575                cputime_expires->virt_exp = exp->cpu;
576            break;
577        case CPUCLOCK_SCHED:
578            if (cputime_expires->sched_exp == 0 ||
579                cputime_expires->sched_exp > exp->sched)
580                cputime_expires->sched_exp = exp->sched;
581            break;
582        }
583    }
584}
585
586/*
587 * The timer is locked, fire it and arrange for its reload.
588 */
589static void cpu_timer_fire(struct k_itimer *timer)
590{
591    if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
592        /*
593         * User don't want any signal.
594         */
595        timer->it.cpu.expires.sched = 0;
596    } else if (unlikely(timer->sigq == NULL)) {
597        /*
598         * This a special case for clock_nanosleep,
599         * not a normal timer from sys_timer_create.
600         */
601        wake_up_process(timer->it_process);
602        timer->it.cpu.expires.sched = 0;
603    } else if (timer->it.cpu.incr.sched == 0) {
604        /*
605         * One-shot timer. Clear it as soon as it's fired.
606         */
607        posix_timer_event(timer, 0);
608        timer->it.cpu.expires.sched = 0;
609    } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
610        /*
611         * The signal did not get queued because the signal
612         * was ignored, so we won't get any callback to
613         * reload the timer. But we need to keep it
614         * ticking in case the signal is deliverable next time.
615         */
616        posix_cpu_timer_schedule(timer);
617    }
618}
619
620/*
621 * Sample a process (thread group) timer for the given group_leader task.
622 * Must be called with tasklist_lock held for reading.
623 */
624static int cpu_timer_sample_group(const clockid_t which_clock,
625                  struct task_struct *p,
626                  union cpu_time_count *cpu)
627{
628    struct task_cputime cputime;
629
630    thread_group_cputimer(p, &cputime);
631    switch (CPUCLOCK_WHICH(which_clock)) {
632    default:
633        return -EINVAL;
634    case CPUCLOCK_PROF:
635        cpu->cpu = cputime.utime + cputime.stime;
636        break;
637    case CPUCLOCK_VIRT:
638        cpu->cpu = cputime.utime;
639        break;
640    case CPUCLOCK_SCHED:
641        cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
642        break;
643    }
644    return 0;
645}
646
647/*
648 * Guts of sys_timer_settime for CPU timers.
649 * This is called with the timer locked and interrupts disabled.
650 * If we return TIMER_RETRY, it's necessary to release the timer's lock
651 * and try again. (This happens when the timer is in the middle of firing.)
652 */
653static int posix_cpu_timer_set(struct k_itimer *timer, int flags,
654                   struct itimerspec *new, struct itimerspec *old)
655{
656    struct task_struct *p = timer->it.cpu.task;
657    union cpu_time_count old_expires, new_expires, old_incr, val;
658    int ret;
659
660    if (unlikely(p == NULL)) {
661        /*
662         * Timer refers to a dead task's clock.
663         */
664        return -ESRCH;
665    }
666
667    new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
668
669    read_lock(&tasklist_lock);
670    /*
671     * We need the tasklist_lock to protect against reaping that
672     * clears p->sighand. If p has just been reaped, we can no
673     * longer get any information about it at all.
674     */
675    if (unlikely(p->sighand == NULL)) {
676        read_unlock(&tasklist_lock);
677        put_task_struct(p);
678        timer->it.cpu.task = NULL;
679        return -ESRCH;
680    }
681
682    /*
683     * Disarm any old timer after extracting its expiry time.
684     */
685    BUG_ON(!irqs_disabled());
686
687    ret = 0;
688    old_incr = timer->it.cpu.incr;
689    spin_lock(&p->sighand->siglock);
690    old_expires = timer->it.cpu.expires;
691    if (unlikely(timer->it.cpu.firing)) {
692        timer->it.cpu.firing = -1;
693        ret = TIMER_RETRY;
694    } else
695        list_del_init(&timer->it.cpu.entry);
696
697    /*
698     * We need to sample the current value to convert the new
699     * value from to relative and absolute, and to convert the
700     * old value from absolute to relative. To set a process
701     * timer, we need a sample to balance the thread expiry
702     * times (in arm_timer). With an absolute time, we must
703     * check if it's already passed. In short, we need a sample.
704     */
705    if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
706        cpu_clock_sample(timer->it_clock, p, &val);
707    } else {
708        cpu_timer_sample_group(timer->it_clock, p, &val);
709    }
710
711    if (old) {
712        if (old_expires.sched == 0) {
713            old->it_value.tv_sec = 0;
714            old->it_value.tv_nsec = 0;
715        } else {
716            /*
717             * Update the timer in case it has
718             * overrun already. If it has,
719             * we'll report it as having overrun
720             * and with the next reloaded timer
721             * already ticking, though we are
722             * swallowing that pending
723             * notification here to install the
724             * new setting.
725             */
726            bump_cpu_timer(timer, val);
727            if (cpu_time_before(timer->it_clock, val,
728                        timer->it.cpu.expires)) {
729                old_expires = cpu_time_sub(
730                    timer->it_clock,
731                    timer->it.cpu.expires, val);
732                sample_to_timespec(timer->it_clock,
733                           old_expires,
734                           &old->it_value);
735            } else {
736                old->it_value.tv_nsec = 1;
737                old->it_value.tv_sec = 0;
738            }
739        }
740    }
741
742    if (unlikely(ret)) {
743        /*
744         * We are colliding with the timer actually firing.
745         * Punt after filling in the timer's old value, and
746         * disable this firing since we are already reporting
747         * it as an overrun (thanks to bump_cpu_timer above).
748         */
749        spin_unlock(&p->sighand->siglock);
750        read_unlock(&tasklist_lock);
751        goto out;
752    }
753
754    if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
755        cpu_time_add(timer->it_clock, &new_expires, val);
756    }
757
758    /*
759     * Install the new expiry time (or zero).
760     * For a timer with no notification action, we don't actually
761     * arm the timer (we'll just fake it for timer_gettime).
762     */
763    timer->it.cpu.expires = new_expires;
764    if (new_expires.sched != 0 &&
765        cpu_time_before(timer->it_clock, val, new_expires)) {
766        arm_timer(timer);
767    }
768
769    spin_unlock(&p->sighand->siglock);
770    read_unlock(&tasklist_lock);
771
772    /*
773     * Install the new reload setting, and
774     * set up the signal and overrun bookkeeping.
775     */
776    timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
777                        &new->it_interval);
778
779    /*
780     * This acts as a modification timestamp for the timer,
781     * so any automatic reload attempt will punt on seeing
782     * that we have reset the timer manually.
783     */
784    timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
785        ~REQUEUE_PENDING;
786    timer->it_overrun_last = 0;
787    timer->it_overrun = -1;
788
789    if (new_expires.sched != 0 &&
790        !cpu_time_before(timer->it_clock, val, new_expires)) {
791        /*
792         * The designated time already passed, so we notify
793         * immediately, even if the thread never runs to
794         * accumulate more time on this clock.
795         */
796        cpu_timer_fire(timer);
797    }
798
799    ret = 0;
800 out:
801    if (old) {
802        sample_to_timespec(timer->it_clock,
803                   old_incr, &old->it_interval);
804    }
805    return ret;
806}
807
808static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
809{
810    union cpu_time_count now;
811    struct task_struct *p = timer->it.cpu.task;
812    int clear_dead;
813
814    /*
815     * Easy part: convert the reload time.
816     */
817    sample_to_timespec(timer->it_clock,
818               timer->it.cpu.incr, &itp->it_interval);
819
820    if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all. */
821        itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
822        return;
823    }
824
825    if (unlikely(p == NULL)) {
826        /*
827         * This task already died and the timer will never fire.
828         * In this case, expires is actually the dead value.
829         */
830    dead:
831        sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
832                   &itp->it_value);
833        return;
834    }
835
836    /*
837     * Sample the clock to take the difference with the expiry time.
838     */
839    if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
840        cpu_clock_sample(timer->it_clock, p, &now);
841        clear_dead = p->exit_state;
842    } else {
843        read_lock(&tasklist_lock);
844        if (unlikely(p->sighand == NULL)) {
845            /*
846             * The process has been reaped.
847             * We can't even collect a sample any more.
848             * Call the timer disarmed, nothing else to do.
849             */
850            put_task_struct(p);
851            timer->it.cpu.task = NULL;
852            timer->it.cpu.expires.sched = 0;
853            read_unlock(&tasklist_lock);
854            goto dead;
855        } else {
856            cpu_timer_sample_group(timer->it_clock, p, &now);
857            clear_dead = (unlikely(p->exit_state) &&
858                      thread_group_empty(p));
859        }
860        read_unlock(&tasklist_lock);
861    }
862
863    if (unlikely(clear_dead)) {
864        /*
865         * We've noticed that the thread is dead, but
866         * not yet reaped. Take this opportunity to
867         * drop our task ref.
868         */
869        clear_dead_task(timer, now);
870        goto dead;
871    }
872
873    if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
874        sample_to_timespec(timer->it_clock,
875                   cpu_time_sub(timer->it_clock,
876                        timer->it.cpu.expires, now),
877                   &itp->it_value);
878    } else {
879        /*
880         * The timer should have expired already, but the firing
881         * hasn't taken place yet. Say it's just about to expire.
882         */
883        itp->it_value.tv_nsec = 1;
884        itp->it_value.tv_sec = 0;
885    }
886}
887
888/*
889 * Check for any per-thread CPU timers that have fired and move them off
890 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
891 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
892 */
893static void check_thread_timers(struct task_struct *tsk,
894                struct list_head *firing)
895{
896    int maxfire;
897    struct list_head *timers = tsk->cpu_timers;
898    struct signal_struct *const sig = tsk->signal;
899    unsigned long soft;
900
901    maxfire = 20;
902    tsk->cputime_expires.prof_exp = 0;
903    while (!list_empty(timers)) {
904        struct cpu_timer_list *t = list_first_entry(timers,
905                              struct cpu_timer_list,
906                              entry);
907        if (!--maxfire || prof_ticks(tsk) < t->expires.cpu) {
908            tsk->cputime_expires.prof_exp = t->expires.cpu;
909            break;
910        }
911        t->firing = 1;
912        list_move_tail(&t->entry, firing);
913    }
914
915    ++timers;
916    maxfire = 20;
917    tsk->cputime_expires.virt_exp = 0;
918    while (!list_empty(timers)) {
919        struct cpu_timer_list *t = list_first_entry(timers,
920                              struct cpu_timer_list,
921                              entry);
922        if (!--maxfire || virt_ticks(tsk) < t->expires.cpu) {
923            tsk->cputime_expires.virt_exp = t->expires.cpu;
924            break;
925        }
926        t->firing = 1;
927        list_move_tail(&t->entry, firing);
928    }
929
930    ++timers;
931    maxfire = 20;
932    tsk->cputime_expires.sched_exp = 0;
933    while (!list_empty(timers)) {
934        struct cpu_timer_list *t = list_first_entry(timers,
935                              struct cpu_timer_list,
936                              entry);
937        if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
938            tsk->cputime_expires.sched_exp = t->expires.sched;
939            break;
940        }
941        t->firing = 1;
942        list_move_tail(&t->entry, firing);
943    }
944
945    /*
946     * Check for the special case thread timers.
947     */
948    soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
949    if (soft != RLIM_INFINITY) {
950        unsigned long hard =
951            ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
952
953        if (hard != RLIM_INFINITY &&
954            tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
955            /*
956             * At the hard limit, we just die.
957             * No need to calculate anything else now.
958             */
959            __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
960            return;
961        }
962        if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
963            /*
964             * At the soft limit, send a SIGXCPU every second.
965             */
966            if (soft < hard) {
967                soft += USEC_PER_SEC;
968                sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
969            }
970            printk(KERN_INFO
971                "RT Watchdog Timeout: %s[%d]\n",
972                tsk->comm, task_pid_nr(tsk));
973            __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
974        }
975    }
976}
977
978static void stop_process_timers(struct signal_struct *sig)
979{
980    struct thread_group_cputimer *cputimer = &sig->cputimer;
981    unsigned long flags;
982
983    raw_spin_lock_irqsave(&cputimer->lock, flags);
984    cputimer->running = 0;
985    raw_spin_unlock_irqrestore(&cputimer->lock, flags);
986}
987
988static u32 onecputick;
989
990static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
991                 cputime_t *expires, cputime_t cur_time, int signo)
992{
993    if (!it->expires)
994        return;
995
996    if (cur_time >= it->expires) {
997        if (it->incr) {
998            it->expires += it->incr;
999            it->error += it->incr_error;
1000            if (it->error >= onecputick) {
1001                it->expires -= cputime_one_jiffy;
1002                it->error -= onecputick;
1003            }
1004        } else {
1005            it->expires = 0;
1006        }
1007
1008        trace_itimer_expire(signo == SIGPROF ?
1009                    ITIMER_PROF : ITIMER_VIRTUAL,
1010                    tsk->signal->leader_pid, cur_time);
1011        __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1012    }
1013
1014    if (it->expires && (!*expires || it->expires < *expires)) {
1015        *expires = it->expires;
1016    }
1017}
1018
1019/**
1020 * task_cputime_zero - Check a task_cputime struct for all zero fields.
1021 *
1022 * @cputime: The struct to compare.
1023 *
1024 * Checks @cputime to see if all fields are zero. Returns true if all fields
1025 * are zero, false if any field is nonzero.
1026 */
1027static inline int task_cputime_zero(const struct task_cputime *cputime)
1028{
1029    if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
1030        return 1;
1031    return 0;
1032}
1033
1034/*
1035 * Check for any per-thread CPU timers that have fired and move them
1036 * off the tsk->*_timers list onto the firing list. Per-thread timers
1037 * have already been taken off.
1038 */
1039static void check_process_timers(struct task_struct *tsk,
1040                 struct list_head *firing)
1041{
1042    int maxfire;
1043    struct signal_struct *const sig = tsk->signal;
1044    cputime_t utime, ptime, virt_expires, prof_expires;
1045    unsigned long long sum_sched_runtime, sched_expires;
1046    struct list_head *timers = sig->cpu_timers;
1047    struct task_cputime cputime;
1048    unsigned long soft;
1049
1050    /*
1051     * Collect the current process totals.
1052     */
1053    thread_group_cputimer(tsk, &cputime);
1054    utime = cputime.utime;
1055    ptime = utime + cputime.stime;
1056    sum_sched_runtime = cputime.sum_exec_runtime;
1057    maxfire = 20;
1058    prof_expires = 0;
1059    while (!list_empty(timers)) {
1060        struct cpu_timer_list *tl = list_first_entry(timers,
1061                              struct cpu_timer_list,
1062                              entry);
1063        if (!--maxfire || ptime < tl->expires.cpu) {
1064            prof_expires = tl->expires.cpu;
1065            break;
1066        }
1067        tl->firing = 1;
1068        list_move_tail(&tl->entry, firing);
1069    }
1070
1071    ++timers;
1072    maxfire = 20;
1073    virt_expires = 0;
1074    while (!list_empty(timers)) {
1075        struct cpu_timer_list *tl = list_first_entry(timers,
1076                              struct cpu_timer_list,
1077                              entry);
1078        if (!--maxfire || utime < tl->expires.cpu) {
1079            virt_expires = tl->expires.cpu;
1080            break;
1081        }
1082        tl->firing = 1;
1083        list_move_tail(&tl->entry, firing);
1084    }
1085
1086    ++timers;
1087    maxfire = 20;
1088    sched_expires = 0;
1089    while (!list_empty(timers)) {
1090        struct cpu_timer_list *tl = list_first_entry(timers,
1091                              struct cpu_timer_list,
1092                              entry);
1093        if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1094            sched_expires = tl->expires.sched;
1095            break;
1096        }
1097        tl->firing = 1;
1098        list_move_tail(&tl->entry, firing);
1099    }
1100
1101    /*
1102     * Check for the special case process timers.
1103     */
1104    check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1105             SIGPROF);
1106    check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1107             SIGVTALRM);
1108    soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1109    if (soft != RLIM_INFINITY) {
1110        unsigned long psecs = cputime_to_secs(ptime);
1111        unsigned long hard =
1112            ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1113        cputime_t x;
1114        if (psecs >= hard) {
1115            /*
1116             * At the hard limit, we just die.
1117             * No need to calculate anything else now.
1118             */
1119            __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1120            return;
1121        }
1122        if (psecs >= soft) {
1123            /*
1124             * At the soft limit, send a SIGXCPU every second.
1125             */
1126            __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1127            if (soft < hard) {
1128                soft++;
1129                sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1130            }
1131        }
1132        x = secs_to_cputime(soft);
1133        if (!prof_expires || x < prof_expires) {
1134            prof_expires = x;
1135        }
1136    }
1137
1138    sig->cputime_expires.prof_exp = prof_expires;
1139    sig->cputime_expires.virt_exp = virt_expires;
1140    sig->cputime_expires.sched_exp = sched_expires;
1141    if (task_cputime_zero(&sig->cputime_expires))
1142        stop_process_timers(sig);
1143}
1144
1145/*
1146 * This is called from the signal code (via do_schedule_next_timer)
1147 * when the last timer signal was delivered and we have to reload the timer.
1148 */
1149void posix_cpu_timer_schedule(struct k_itimer *timer)
1150{
1151    struct task_struct *p = timer->it.cpu.task;
1152    union cpu_time_count now;
1153
1154    if (unlikely(p == NULL))
1155        /*
1156         * The task was cleaned up already, no future firings.
1157         */
1158        goto out;
1159
1160    /*
1161     * Fetch the current sample and update the timer's expiry time.
1162     */
1163    if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1164        cpu_clock_sample(timer->it_clock, p, &now);
1165        bump_cpu_timer(timer, now);
1166        if (unlikely(p->exit_state)) {
1167            clear_dead_task(timer, now);
1168            goto out;
1169        }
1170        read_lock(&tasklist_lock); /* arm_timer needs it. */
1171        spin_lock(&p->sighand->siglock);
1172    } else {
1173        read_lock(&tasklist_lock);
1174        if (unlikely(p->sighand == NULL)) {
1175            /*
1176             * The process has been reaped.
1177             * We can't even collect a sample any more.
1178             */
1179            put_task_struct(p);
1180            timer->it.cpu.task = p = NULL;
1181            timer->it.cpu.expires.sched = 0;
1182            goto out_unlock;
1183        } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1184            /*
1185             * We've noticed that the thread is dead, but
1186             * not yet reaped. Take this opportunity to
1187             * drop our task ref.
1188             */
1189            clear_dead_task(timer, now);
1190            goto out_unlock;
1191        }
1192        spin_lock(&p->sighand->siglock);
1193        cpu_timer_sample_group(timer->it_clock, p, &now);
1194        bump_cpu_timer(timer, now);
1195        /* Leave the tasklist_lock locked for the call below. */
1196    }
1197
1198    /*
1199     * Now re-arm for the new expiry time.
1200     */
1201    BUG_ON(!irqs_disabled());
1202    arm_timer(timer);
1203    spin_unlock(&p->sighand->siglock);
1204
1205out_unlock:
1206    read_unlock(&tasklist_lock);
1207
1208out:
1209    timer->it_overrun_last = timer->it_overrun;
1210    timer->it_overrun = -1;
1211    ++timer->it_requeue_pending;
1212}
1213
1214/**
1215 * task_cputime_expired - Compare two task_cputime entities.
1216 *
1217 * @sample: The task_cputime structure to be checked for expiration.
1218 * @expires: Expiration times, against which @sample will be checked.
1219 *
1220 * Checks @sample against @expires to see if any field of @sample has expired.
1221 * Returns true if any field of the former is greater than the corresponding
1222 * field of the latter if the latter field is set. Otherwise returns false.
1223 */
1224static inline int task_cputime_expired(const struct task_cputime *sample,
1225                    const struct task_cputime *expires)
1226{
1227    if (expires->utime && sample->utime >= expires->utime)
1228        return 1;
1229    if (expires->stime && sample->utime + sample->stime >= expires->stime)
1230        return 1;
1231    if (expires->sum_exec_runtime != 0 &&
1232        sample->sum_exec_runtime >= expires->sum_exec_runtime)
1233        return 1;
1234    return 0;
1235}
1236
1237/**
1238 * fastpath_timer_check - POSIX CPU timers fast path.
1239 *
1240 * @tsk: The task (thread) being checked.
1241 *
1242 * Check the task and thread group timers. If both are zero (there are no
1243 * timers set) return false. Otherwise snapshot the task and thread group
1244 * timers and compare them with the corresponding expiration times. Return
1245 * true if a timer has expired, else return false.
1246 */
1247static inline int fastpath_timer_check(struct task_struct *tsk)
1248{
1249    struct signal_struct *sig;
1250
1251    if (!task_cputime_zero(&tsk->cputime_expires)) {
1252        struct task_cputime task_sample = {
1253            .utime = tsk->utime,
1254            .stime = tsk->stime,
1255            .sum_exec_runtime = tsk->se.sum_exec_runtime
1256        };
1257
1258        if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1259            return 1;
1260    }
1261
1262    sig = tsk->signal;
1263    if (sig->cputimer.running) {
1264        struct task_cputime group_sample;
1265
1266        raw_spin_lock(&sig->cputimer.lock);
1267        group_sample = sig->cputimer.cputime;
1268        raw_spin_unlock(&sig->cputimer.lock);
1269
1270        if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1271            return 1;
1272    }
1273
1274    return 0;
1275}
1276
1277/*
1278 * This is called from the timer interrupt handler. The irq handler has
1279 * already updated our counts. We need to check if any timers fire now.
1280 * Interrupts are disabled.
1281 */
1282void run_posix_cpu_timers(struct task_struct *tsk)
1283{
1284    LIST_HEAD(firing);
1285    struct k_itimer *timer, *next;
1286    unsigned long flags;
1287
1288    BUG_ON(!irqs_disabled());
1289
1290    /*
1291     * The fast path checks that there are no expired thread or thread
1292     * group timers. If that's so, just return.
1293     */
1294    if (!fastpath_timer_check(tsk))
1295        return;
1296
1297    if (!lock_task_sighand(tsk, &flags))
1298        return;
1299    /*
1300     * Here we take off tsk->signal->cpu_timers[N] and
1301     * tsk->cpu_timers[N] all the timers that are firing, and
1302     * put them on the firing list.
1303     */
1304    check_thread_timers(tsk, &firing);
1305    /*
1306     * If there are any active process wide timers (POSIX 1.b, itimers,
1307     * RLIMIT_CPU) cputimer must be running.
1308     */
1309    if (tsk->signal->cputimer.running)
1310        check_process_timers(tsk, &firing);
1311
1312    /*
1313     * We must release these locks before taking any timer's lock.
1314     * There is a potential race with timer deletion here, as the
1315     * siglock now protects our private firing list. We have set
1316     * the firing flag in each timer, so that a deletion attempt
1317     * that gets the timer lock before we do will give it up and
1318     * spin until we've taken care of that timer below.
1319     */
1320    unlock_task_sighand(tsk, &flags);
1321
1322    /*
1323     * Now that all the timers on our list have the firing flag,
1324     * no one will touch their list entries but us. We'll take
1325     * each timer's lock before clearing its firing flag, so no
1326     * timer call will interfere.
1327     */
1328    list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1329        int cpu_firing;
1330
1331        spin_lock(&timer->it_lock);
1332        list_del_init(&timer->it.cpu.entry);
1333        cpu_firing = timer->it.cpu.firing;
1334        timer->it.cpu.firing = 0;
1335        /*
1336         * The firing flag is -1 if we collided with a reset
1337         * of the timer, which already reported this
1338         * almost-firing as an overrun. So don't generate an event.
1339         */
1340        if (likely(cpu_firing >= 0))
1341            cpu_timer_fire(timer);
1342        spin_unlock(&timer->it_lock);
1343    }
1344}
1345
1346/*
1347 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1348 * The tsk->sighand->siglock must be held by the caller.
1349 */
1350void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1351               cputime_t *newval, cputime_t *oldval)
1352{
1353    union cpu_time_count now;
1354
1355    BUG_ON(clock_idx == CPUCLOCK_SCHED);
1356    cpu_timer_sample_group(clock_idx, tsk, &now);
1357
1358    if (oldval) {
1359        /*
1360         * We are setting itimer. The *oldval is absolute and we update
1361         * it to be relative, *newval argument is relative and we update
1362         * it to be absolute.
1363         */
1364        if (*oldval) {
1365            if (*oldval <= now.cpu) {
1366                /* Just about to fire. */
1367                *oldval = cputime_one_jiffy;
1368            } else {
1369                *oldval -= now.cpu;
1370            }
1371        }
1372
1373        if (!*newval)
1374            return;
1375        *newval += now.cpu;
1376    }
1377
1378    /*
1379     * Update expiration cache if we are the earliest timer, or eventually
1380     * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1381     */
1382    switch (clock_idx) {
1383    case CPUCLOCK_PROF:
1384        if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1385            tsk->signal->cputime_expires.prof_exp = *newval;
1386        break;
1387    case CPUCLOCK_VIRT:
1388        if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1389            tsk->signal->cputime_expires.virt_exp = *newval;
1390        break;
1391    }
1392}
1393
1394static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1395                struct timespec *rqtp, struct itimerspec *it)
1396{
1397    struct k_itimer timer;
1398    int error;
1399
1400    /*
1401     * Set up a temporary timer and then wait for it to go off.
1402     */
1403    memset(&timer, 0, sizeof timer);
1404    spin_lock_init(&timer.it_lock);
1405    timer.it_clock = which_clock;
1406    timer.it_overrun = -1;
1407    error = posix_cpu_timer_create(&timer);
1408    timer.it_process = current;
1409    if (!error) {
1410        static struct itimerspec zero_it;
1411
1412        memset(it, 0, sizeof *it);
1413        it->it_value = *rqtp;
1414
1415        spin_lock_irq(&timer.it_lock);
1416        error = posix_cpu_timer_set(&timer, flags, it, NULL);
1417        if (error) {
1418            spin_unlock_irq(&timer.it_lock);
1419            return error;
1420        }
1421
1422        while (!signal_pending(current)) {
1423            if (timer.it.cpu.expires.sched == 0) {
1424                /*
1425                 * Our timer fired and was reset.
1426                 */
1427                spin_unlock_irq(&timer.it_lock);
1428                return 0;
1429            }
1430
1431            /*
1432             * Block until cpu_timer_fire (or a signal) wakes us.
1433             */
1434            __set_current_state(TASK_INTERRUPTIBLE);
1435            spin_unlock_irq(&timer.it_lock);
1436            schedule();
1437            spin_lock_irq(&timer.it_lock);
1438        }
1439
1440        /*
1441         * We were interrupted by a signal.
1442         */
1443        sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1444        posix_cpu_timer_set(&timer, 0, &zero_it, it);
1445        spin_unlock_irq(&timer.it_lock);
1446
1447        if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1448            /*
1449             * It actually did fire already.
1450             */
1451            return 0;
1452        }
1453
1454        error = -ERESTART_RESTARTBLOCK;
1455    }
1456
1457    return error;
1458}
1459
1460static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1461
1462static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1463                struct timespec *rqtp, struct timespec __user *rmtp)
1464{
1465    struct restart_block *restart_block =
1466        &current_thread_info()->restart_block;
1467    struct itimerspec it;
1468    int error;
1469
1470    /*
1471     * Diagnose required errors first.
1472     */
1473    if (CPUCLOCK_PERTHREAD(which_clock) &&
1474        (CPUCLOCK_PID(which_clock) == 0 ||
1475         CPUCLOCK_PID(which_clock) == current->pid))
1476        return -EINVAL;
1477
1478    error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1479
1480    if (error == -ERESTART_RESTARTBLOCK) {
1481
1482        if (flags & TIMER_ABSTIME)
1483            return -ERESTARTNOHAND;
1484        /*
1485         * Report back to the user the time still remaining.
1486         */
1487        if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1488            return -EFAULT;
1489
1490        restart_block->fn = posix_cpu_nsleep_restart;
1491        restart_block->nanosleep.clockid = which_clock;
1492        restart_block->nanosleep.rmtp = rmtp;
1493        restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1494    }
1495    return error;
1496}
1497
1498static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1499{
1500    clockid_t which_clock = restart_block->nanosleep.clockid;
1501    struct timespec t;
1502    struct itimerspec it;
1503    int error;
1504
1505    t = ns_to_timespec(restart_block->nanosleep.expires);
1506
1507    error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1508
1509    if (error == -ERESTART_RESTARTBLOCK) {
1510        struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1511        /*
1512         * Report back to the user the time still remaining.
1513         */
1514        if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1515            return -EFAULT;
1516
1517        restart_block->nanosleep.expires = timespec_to_ns(&t);
1518    }
1519    return error;
1520
1521}
1522
1523#define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1524#define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1525
1526static int process_cpu_clock_getres(const clockid_t which_clock,
1527                    struct timespec *tp)
1528{
1529    return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1530}
1531static int process_cpu_clock_get(const clockid_t which_clock,
1532                 struct timespec *tp)
1533{
1534    return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1535}
1536static int process_cpu_timer_create(struct k_itimer *timer)
1537{
1538    timer->it_clock = PROCESS_CLOCK;
1539    return posix_cpu_timer_create(timer);
1540}
1541static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1542                  struct timespec *rqtp,
1543                  struct timespec __user *rmtp)
1544{
1545    return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1546}
1547static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1548{
1549    return -EINVAL;
1550}
1551static int thread_cpu_clock_getres(const clockid_t which_clock,
1552                   struct timespec *tp)
1553{
1554    return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1555}
1556static int thread_cpu_clock_get(const clockid_t which_clock,
1557                struct timespec *tp)
1558{
1559    return posix_cpu_clock_get(THREAD_CLOCK, tp);
1560}
1561static int thread_cpu_timer_create(struct k_itimer *timer)
1562{
1563    timer->it_clock = THREAD_CLOCK;
1564    return posix_cpu_timer_create(timer);
1565}
1566
1567struct k_clock clock_posix_cpu = {
1568    .clock_getres = posix_cpu_clock_getres,
1569    .clock_set = posix_cpu_clock_set,
1570    .clock_get = posix_cpu_clock_get,
1571    .timer_create = posix_cpu_timer_create,
1572    .nsleep = posix_cpu_nsleep,
1573    .nsleep_restart = posix_cpu_nsleep_restart,
1574    .timer_set = posix_cpu_timer_set,
1575    .timer_del = posix_cpu_timer_del,
1576    .timer_get = posix_cpu_timer_get,
1577};
1578
1579static __init int init_posix_cpu_timers(void)
1580{
1581    struct k_clock process = {
1582        .clock_getres = process_cpu_clock_getres,
1583        .clock_get = process_cpu_clock_get,
1584        .timer_create = process_cpu_timer_create,
1585        .nsleep = process_cpu_nsleep,
1586        .nsleep_restart = process_cpu_nsleep_restart,
1587    };
1588    struct k_clock thread = {
1589        .clock_getres = thread_cpu_clock_getres,
1590        .clock_get = thread_cpu_clock_get,
1591        .timer_create = thread_cpu_timer_create,
1592    };
1593    struct timespec ts;
1594
1595    posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1596    posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1597
1598    cputime_to_timespec(cputime_one_jiffy, &ts);
1599    onecputick = ts.tv_nsec;
1600    WARN_ON(ts.tv_sec != 0);
1601
1602    return 0;
1603}
1604__initcall(init_posix_cpu_timers);
1605

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