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 cputime_lt(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 = cputime_add(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 = cputime_sub(a.cpu, b.cpu);
102    }
103    return a;
104}
105
106/*
107 * Divide and limit the result to res >= 1
108 *
109 * This is necessary to prevent signal delivery starvation, when the result of
110 * the division would be rounded down to 0.
111 */
112static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
113{
114    cputime_t res = cputime_div(time, div);
115
116    return max_t(cputime_t, res, 1);
117}
118
119/*
120 * Update expiry time from increment, and increase overrun count,
121 * given the current clock sample.
122 */
123static void bump_cpu_timer(struct k_itimer *timer,
124                  union cpu_time_count now)
125{
126    int i;
127
128    if (timer->it.cpu.incr.sched == 0)
129        return;
130
131    if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
132        unsigned long long delta, incr;
133
134        if (now.sched < timer->it.cpu.expires.sched)
135            return;
136        incr = timer->it.cpu.incr.sched;
137        delta = now.sched + incr - timer->it.cpu.expires.sched;
138        /* Don't use (incr*2 < delta), incr*2 might overflow. */
139        for (i = 0; incr < delta - incr; i++)
140            incr = incr << 1;
141        for (; i >= 0; incr >>= 1, i--) {
142            if (delta < incr)
143                continue;
144            timer->it.cpu.expires.sched += incr;
145            timer->it_overrun += 1 << i;
146            delta -= incr;
147        }
148    } else {
149        cputime_t delta, incr;
150
151        if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
152            return;
153        incr = timer->it.cpu.incr.cpu;
154        delta = cputime_sub(cputime_add(now.cpu, incr),
155                    timer->it.cpu.expires.cpu);
156        /* Don't use (incr*2 < delta), incr*2 might overflow. */
157        for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
158                 incr = cputime_add(incr, incr);
159        for (; i >= 0; incr = cputime_halve(incr), i--) {
160            if (cputime_lt(delta, incr))
161                continue;
162            timer->it.cpu.expires.cpu =
163                cputime_add(timer->it.cpu.expires.cpu, incr);
164            timer->it_overrun += 1 << i;
165            delta = cputime_sub(delta, incr);
166        }
167    }
168}
169
170static inline cputime_t prof_ticks(struct task_struct *p)
171{
172    return cputime_add(p->utime, p->stime);
173}
174static inline cputime_t virt_ticks(struct task_struct *p)
175{
176    return p->utime;
177}
178
179static int
180posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
181{
182    int error = check_clock(which_clock);
183    if (!error) {
184        tp->tv_sec = 0;
185        tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
186        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
187            /*
188             * If sched_clock is using a cycle counter, we
189             * don't have any idea of its true resolution
190             * exported, but it is much more than 1s/HZ.
191             */
192            tp->tv_nsec = 1;
193        }
194    }
195    return error;
196}
197
198static int
199posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
200{
201    /*
202     * You can never reset a CPU clock, but we check for other errors
203     * in the call before failing with EPERM.
204     */
205    int error = check_clock(which_clock);
206    if (error == 0) {
207        error = -EPERM;
208    }
209    return error;
210}
211
212
213/*
214 * Sample a per-thread clock for the given task.
215 */
216static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
217                union cpu_time_count *cpu)
218{
219    switch (CPUCLOCK_WHICH(which_clock)) {
220    default:
221        return -EINVAL;
222    case CPUCLOCK_PROF:
223        cpu->cpu = prof_ticks(p);
224        break;
225    case CPUCLOCK_VIRT:
226        cpu->cpu = virt_ticks(p);
227        break;
228    case CPUCLOCK_SCHED:
229        cpu->sched = task_sched_runtime(p);
230        break;
231    }
232    return 0;
233}
234
235void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
236{
237    struct signal_struct *sig = tsk->signal;
238    struct task_struct *t;
239
240    times->utime = sig->utime;
241    times->stime = sig->stime;
242    times->sum_exec_runtime = sig->sum_sched_runtime;
243
244    rcu_read_lock();
245    /* make sure we can trust tsk->thread_group list */
246    if (!likely(pid_alive(tsk)))
247        goto out;
248
249    t = tsk;
250    do {
251        times->utime = cputime_add(times->utime, t->utime);
252        times->stime = cputime_add(times->stime, t->stime);
253        times->sum_exec_runtime += t->se.sum_exec_runtime;
254    } while_each_thread(tsk, t);
255out:
256    rcu_read_unlock();
257}
258
259static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
260{
261    if (cputime_gt(b->utime, a->utime))
262        a->utime = b->utime;
263
264    if (cputime_gt(b->stime, a->stime))
265        a->stime = b->stime;
266
267    if (b->sum_exec_runtime > a->sum_exec_runtime)
268        a->sum_exec_runtime = b->sum_exec_runtime;
269}
270
271void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
272{
273    struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
274    struct task_cputime sum;
275    unsigned long flags;
276
277    spin_lock_irqsave(&cputimer->lock, flags);
278    if (!cputimer->running) {
279        cputimer->running = 1;
280        /*
281         * The POSIX timer interface allows for absolute time expiry
282         * values through the TIMER_ABSTIME flag, therefore we have
283         * to synchronize the timer to the clock every time we start
284         * it.
285         */
286        thread_group_cputime(tsk, &sum);
287        update_gt_cputime(&cputimer->cputime, &sum);
288    }
289    *times = cputimer->cputime;
290    spin_unlock_irqrestore(&cputimer->lock, flags);
291}
292
293/*
294 * Sample a process (thread group) clock for the given group_leader task.
295 * Must be called with tasklist_lock held for reading.
296 */
297static int cpu_clock_sample_group(const clockid_t which_clock,
298                  struct task_struct *p,
299                  union cpu_time_count *cpu)
300{
301    struct task_cputime cputime;
302
303    switch (CPUCLOCK_WHICH(which_clock)) {
304    default:
305        return -EINVAL;
306    case CPUCLOCK_PROF:
307        thread_group_cputime(p, &cputime);
308        cpu->cpu = cputime_add(cputime.utime, cputime.stime);
309        break;
310    case CPUCLOCK_VIRT:
311        thread_group_cputime(p, &cputime);
312        cpu->cpu = cputime.utime;
313        break;
314    case CPUCLOCK_SCHED:
315        cpu->sched = thread_group_sched_runtime(p);
316        break;
317    }
318    return 0;
319}
320
321
322static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
323{
324    const pid_t pid = CPUCLOCK_PID(which_clock);
325    int error = -EINVAL;
326    union cpu_time_count rtn;
327
328    if (pid == 0) {
329        /*
330         * Special case constant value for our own clocks.
331         * We don't have to do any lookup to find ourselves.
332         */
333        if (CPUCLOCK_PERTHREAD(which_clock)) {
334            /*
335             * Sampling just ourselves we can do with no locking.
336             */
337            error = cpu_clock_sample(which_clock,
338                         current, &rtn);
339        } else {
340            read_lock(&tasklist_lock);
341            error = cpu_clock_sample_group(which_clock,
342                               current, &rtn);
343            read_unlock(&tasklist_lock);
344        }
345    } else {
346        /*
347         * Find the given PID, and validate that the caller
348         * should be able to see it.
349         */
350        struct task_struct *p;
351        rcu_read_lock();
352        p = find_task_by_vpid(pid);
353        if (p) {
354            if (CPUCLOCK_PERTHREAD(which_clock)) {
355                if (same_thread_group(p, current)) {
356                    error = cpu_clock_sample(which_clock,
357                                 p, &rtn);
358                }
359            } else {
360                read_lock(&tasklist_lock);
361                if (thread_group_leader(p) && p->sighand) {
362                    error =
363                        cpu_clock_sample_group(which_clock,
364                                       p, &rtn);
365                }
366                read_unlock(&tasklist_lock);
367            }
368        }
369        rcu_read_unlock();
370    }
371
372    if (error)
373        return error;
374    sample_to_timespec(which_clock, rtn, tp);
375    return 0;
376}
377
378
379/*
380 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
381 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
382 * new timer already all-zeros initialized.
383 */
384static int posix_cpu_timer_create(struct k_itimer *new_timer)
385{
386    int ret = 0;
387    const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
388    struct task_struct *p;
389
390    if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
391        return -EINVAL;
392
393    INIT_LIST_HEAD(&new_timer->it.cpu.entry);
394
395    rcu_read_lock();
396    if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
397        if (pid == 0) {
398            p = current;
399        } else {
400            p = find_task_by_vpid(pid);
401            if (p && !same_thread_group(p, current))
402                p = NULL;
403        }
404    } else {
405        if (pid == 0) {
406            p = current->group_leader;
407        } else {
408            p = find_task_by_vpid(pid);
409            if (p && !has_group_leader_pid(p))
410                p = NULL;
411        }
412    }
413    new_timer->it.cpu.task = p;
414    if (p) {
415        get_task_struct(p);
416    } else {
417        ret = -EINVAL;
418    }
419    rcu_read_unlock();
420
421    return ret;
422}
423
424/*
425 * Clean up a CPU-clock timer that is about to be destroyed.
426 * This is called from timer deletion with the timer already locked.
427 * If we return TIMER_RETRY, it's necessary to release the timer's lock
428 * and try again. (This happens when the timer is in the middle of firing.)
429 */
430static int posix_cpu_timer_del(struct k_itimer *timer)
431{
432    struct task_struct *p = timer->it.cpu.task;
433    int ret = 0;
434
435    if (likely(p != NULL)) {
436        read_lock(&tasklist_lock);
437        if (unlikely(p->sighand == NULL)) {
438            /*
439             * We raced with the reaping of the task.
440             * The deletion should have cleared us off the list.
441             */
442            BUG_ON(!list_empty(&timer->it.cpu.entry));
443        } else {
444            spin_lock(&p->sighand->siglock);
445            if (timer->it.cpu.firing)
446                ret = TIMER_RETRY;
447            else
448                list_del(&timer->it.cpu.entry);
449            spin_unlock(&p->sighand->siglock);
450        }
451        read_unlock(&tasklist_lock);
452
453        if (!ret)
454            put_task_struct(p);
455    }
456
457    return ret;
458}
459
460/*
461 * Clean out CPU timers still ticking when a thread exited. The task
462 * pointer is cleared, and the expiry time is replaced with the residual
463 * time for later timer_gettime calls to return.
464 * This must be called with the siglock held.
465 */
466static void cleanup_timers(struct list_head *head,
467               cputime_t utime, cputime_t stime,
468               unsigned long long sum_exec_runtime)
469{
470    struct cpu_timer_list *timer, *next;
471    cputime_t ptime = cputime_add(utime, stime);
472
473    list_for_each_entry_safe(timer, next, head, entry) {
474        list_del_init(&timer->entry);
475        if (cputime_lt(timer->expires.cpu, ptime)) {
476            timer->expires.cpu = cputime_zero;
477        } else {
478            timer->expires.cpu = cputime_sub(timer->expires.cpu,
479                             ptime);
480        }
481    }
482
483    ++head;
484    list_for_each_entry_safe(timer, next, head, entry) {
485        list_del_init(&timer->entry);
486        if (cputime_lt(timer->expires.cpu, utime)) {
487            timer->expires.cpu = cputime_zero;
488        } else {
489            timer->expires.cpu = cputime_sub(timer->expires.cpu,
490                             utime);
491        }
492    }
493
494    ++head;
495    list_for_each_entry_safe(timer, next, head, entry) {
496        list_del_init(&timer->entry);
497        if (timer->expires.sched < sum_exec_runtime) {
498            timer->expires.sched = 0;
499        } else {
500            timer->expires.sched -= sum_exec_runtime;
501        }
502    }
503}
504
505/*
506 * These are both called with the siglock held, when the current thread
507 * is being reaped. When the final (leader) thread in the group is reaped,
508 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
509 */
510void posix_cpu_timers_exit(struct task_struct *tsk)
511{
512    cleanup_timers(tsk->cpu_timers,
513               tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
514
515}
516void posix_cpu_timers_exit_group(struct task_struct *tsk)
517{
518    struct signal_struct *const sig = tsk->signal;
519
520    cleanup_timers(tsk->signal->cpu_timers,
521               cputime_add(tsk->utime, sig->utime),
522               cputime_add(tsk->stime, sig->stime),
523               tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
524}
525
526static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
527{
528    /*
529     * That's all for this thread or process.
530     * We leave our residual in expires to be reported.
531     */
532    put_task_struct(timer->it.cpu.task);
533    timer->it.cpu.task = NULL;
534    timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
535                         timer->it.cpu.expires,
536                         now);
537}
538
539static inline int expires_gt(cputime_t expires, cputime_t new_exp)
540{
541    return cputime_eq(expires, cputime_zero) ||
542           cputime_gt(expires, new_exp);
543}
544
545/*
546 * Insert the timer on the appropriate list before any timers that
547 * expire later. This must be called with the tasklist_lock held
548 * for reading, interrupts disabled and p->sighand->siglock taken.
549 */
550static void arm_timer(struct k_itimer *timer)
551{
552    struct task_struct *p = timer->it.cpu.task;
553    struct list_head *head, *listpos;
554    struct task_cputime *cputime_expires;
555    struct cpu_timer_list *const nt = &timer->it.cpu;
556    struct cpu_timer_list *next;
557
558    if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
559        head = p->cpu_timers;
560        cputime_expires = &p->cputime_expires;
561    } else {
562        head = p->signal->cpu_timers;
563        cputime_expires = &p->signal->cputime_expires;
564    }
565    head += CPUCLOCK_WHICH(timer->it_clock);
566
567    listpos = head;
568    list_for_each_entry(next, head, entry) {
569        if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
570            break;
571        listpos = &next->entry;
572    }
573    list_add(&nt->entry, listpos);
574
575    if (listpos == head) {
576        union cpu_time_count *exp = &nt->expires;
577
578        /*
579         * We are the new earliest-expiring POSIX 1.b timer, hence
580         * need to update expiration cache. Take into account that
581         * for process timers we share expiration cache with itimers
582         * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
583         */
584
585        switch (CPUCLOCK_WHICH(timer->it_clock)) {
586        case CPUCLOCK_PROF:
587            if (expires_gt(cputime_expires->prof_exp, exp->cpu))
588                cputime_expires->prof_exp = exp->cpu;
589            break;
590        case CPUCLOCK_VIRT:
591            if (expires_gt(cputime_expires->virt_exp, exp->cpu))
592                cputime_expires->virt_exp = exp->cpu;
593            break;
594        case CPUCLOCK_SCHED:
595            if (cputime_expires->sched_exp == 0 ||
596                cputime_expires->sched_exp > exp->sched)
597                cputime_expires->sched_exp = exp->sched;
598            break;
599        }
600    }
601}
602
603/*
604 * The timer is locked, fire it and arrange for its reload.
605 */
606static void cpu_timer_fire(struct k_itimer *timer)
607{
608    if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
609        /*
610         * User don't want any signal.
611         */
612        timer->it.cpu.expires.sched = 0;
613    } else if (unlikely(timer->sigq == NULL)) {
614        /*
615         * This a special case for clock_nanosleep,
616         * not a normal timer from sys_timer_create.
617         */
618        wake_up_process(timer->it_process);
619        timer->it.cpu.expires.sched = 0;
620    } else if (timer->it.cpu.incr.sched == 0) {
621        /*
622         * One-shot timer. Clear it as soon as it's fired.
623         */
624        posix_timer_event(timer, 0);
625        timer->it.cpu.expires.sched = 0;
626    } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
627        /*
628         * The signal did not get queued because the signal
629         * was ignored, so we won't get any callback to
630         * reload the timer. But we need to keep it
631         * ticking in case the signal is deliverable next time.
632         */
633        posix_cpu_timer_schedule(timer);
634    }
635}
636
637/*
638 * Sample a process (thread group) timer for the given group_leader task.
639 * Must be called with tasklist_lock held for reading.
640 */
641static int cpu_timer_sample_group(const clockid_t which_clock,
642                  struct task_struct *p,
643                  union cpu_time_count *cpu)
644{
645    struct task_cputime cputime;
646
647    thread_group_cputimer(p, &cputime);
648    switch (CPUCLOCK_WHICH(which_clock)) {
649    default:
650        return -EINVAL;
651    case CPUCLOCK_PROF:
652        cpu->cpu = cputime_add(cputime.utime, cputime.stime);
653        break;
654    case CPUCLOCK_VIRT:
655        cpu->cpu = cputime.utime;
656        break;
657    case CPUCLOCK_SCHED:
658        cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
659        break;
660    }
661    return 0;
662}
663
664/*
665 * Guts of sys_timer_settime for CPU timers.
666 * This is called with the timer locked and interrupts disabled.
667 * If we return TIMER_RETRY, it's necessary to release the timer's lock
668 * and try again. (This happens when the timer is in the middle of firing.)
669 */
670static int posix_cpu_timer_set(struct k_itimer *timer, int flags,
671                   struct itimerspec *new, struct itimerspec *old)
672{
673    struct task_struct *p = timer->it.cpu.task;
674    union cpu_time_count old_expires, new_expires, old_incr, val;
675    int ret;
676
677    if (unlikely(p == NULL)) {
678        /*
679         * Timer refers to a dead task's clock.
680         */
681        return -ESRCH;
682    }
683
684    new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
685
686    read_lock(&tasklist_lock);
687    /*
688     * We need the tasklist_lock to protect against reaping that
689     * clears p->sighand. If p has just been reaped, we can no
690     * longer get any information about it at all.
691     */
692    if (unlikely(p->sighand == NULL)) {
693        read_unlock(&tasklist_lock);
694        put_task_struct(p);
695        timer->it.cpu.task = NULL;
696        return -ESRCH;
697    }
698
699    /*
700     * Disarm any old timer after extracting its expiry time.
701     */
702    BUG_ON(!irqs_disabled());
703
704    ret = 0;
705    old_incr = timer->it.cpu.incr;
706    spin_lock(&p->sighand->siglock);
707    old_expires = timer->it.cpu.expires;
708    if (unlikely(timer->it.cpu.firing)) {
709        timer->it.cpu.firing = -1;
710        ret = TIMER_RETRY;
711    } else
712        list_del_init(&timer->it.cpu.entry);
713
714    /*
715     * We need to sample the current value to convert the new
716     * value from to relative and absolute, and to convert the
717     * old value from absolute to relative. To set a process
718     * timer, we need a sample to balance the thread expiry
719     * times (in arm_timer). With an absolute time, we must
720     * check if it's already passed. In short, we need a sample.
721     */
722    if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
723        cpu_clock_sample(timer->it_clock, p, &val);
724    } else {
725        cpu_timer_sample_group(timer->it_clock, p, &val);
726    }
727
728    if (old) {
729        if (old_expires.sched == 0) {
730            old->it_value.tv_sec = 0;
731            old->it_value.tv_nsec = 0;
732        } else {
733            /*
734             * Update the timer in case it has
735             * overrun already. If it has,
736             * we'll report it as having overrun
737             * and with the next reloaded timer
738             * already ticking, though we are
739             * swallowing that pending
740             * notification here to install the
741             * new setting.
742             */
743            bump_cpu_timer(timer, val);
744            if (cpu_time_before(timer->it_clock, val,
745                        timer->it.cpu.expires)) {
746                old_expires = cpu_time_sub(
747                    timer->it_clock,
748                    timer->it.cpu.expires, val);
749                sample_to_timespec(timer->it_clock,
750                           old_expires,
751                           &old->it_value);
752            } else {
753                old->it_value.tv_nsec = 1;
754                old->it_value.tv_sec = 0;
755            }
756        }
757    }
758
759    if (unlikely(ret)) {
760        /*
761         * We are colliding with the timer actually firing.
762         * Punt after filling in the timer's old value, and
763         * disable this firing since we are already reporting
764         * it as an overrun (thanks to bump_cpu_timer above).
765         */
766        spin_unlock(&p->sighand->siglock);
767        read_unlock(&tasklist_lock);
768        goto out;
769    }
770
771    if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
772        cpu_time_add(timer->it_clock, &new_expires, val);
773    }
774
775    /*
776     * Install the new expiry time (or zero).
777     * For a timer with no notification action, we don't actually
778     * arm the timer (we'll just fake it for timer_gettime).
779     */
780    timer->it.cpu.expires = new_expires;
781    if (new_expires.sched != 0 &&
782        cpu_time_before(timer->it_clock, val, new_expires)) {
783        arm_timer(timer);
784    }
785
786    spin_unlock(&p->sighand->siglock);
787    read_unlock(&tasklist_lock);
788
789    /*
790     * Install the new reload setting, and
791     * set up the signal and overrun bookkeeping.
792     */
793    timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
794                        &new->it_interval);
795
796    /*
797     * This acts as a modification timestamp for the timer,
798     * so any automatic reload attempt will punt on seeing
799     * that we have reset the timer manually.
800     */
801    timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
802        ~REQUEUE_PENDING;
803    timer->it_overrun_last = 0;
804    timer->it_overrun = -1;
805
806    if (new_expires.sched != 0 &&
807        !cpu_time_before(timer->it_clock, val, new_expires)) {
808        /*
809         * The designated time already passed, so we notify
810         * immediately, even if the thread never runs to
811         * accumulate more time on this clock.
812         */
813        cpu_timer_fire(timer);
814    }
815
816    ret = 0;
817 out:
818    if (old) {
819        sample_to_timespec(timer->it_clock,
820                   old_incr, &old->it_interval);
821    }
822    return ret;
823}
824
825static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
826{
827    union cpu_time_count now;
828    struct task_struct *p = timer->it.cpu.task;
829    int clear_dead;
830
831    /*
832     * Easy part: convert the reload time.
833     */
834    sample_to_timespec(timer->it_clock,
835               timer->it.cpu.incr, &itp->it_interval);
836
837    if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all. */
838        itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
839        return;
840    }
841
842    if (unlikely(p == NULL)) {
843        /*
844         * This task already died and the timer will never fire.
845         * In this case, expires is actually the dead value.
846         */
847    dead:
848        sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
849                   &itp->it_value);
850        return;
851    }
852
853    /*
854     * Sample the clock to take the difference with the expiry time.
855     */
856    if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
857        cpu_clock_sample(timer->it_clock, p, &now);
858        clear_dead = p->exit_state;
859    } else {
860        read_lock(&tasklist_lock);
861        if (unlikely(p->sighand == NULL)) {
862            /*
863             * The process has been reaped.
864             * We can't even collect a sample any more.
865             * Call the timer disarmed, nothing else to do.
866             */
867            put_task_struct(p);
868            timer->it.cpu.task = NULL;
869            timer->it.cpu.expires.sched = 0;
870            read_unlock(&tasklist_lock);
871            goto dead;
872        } else {
873            cpu_timer_sample_group(timer->it_clock, p, &now);
874            clear_dead = (unlikely(p->exit_state) &&
875                      thread_group_empty(p));
876        }
877        read_unlock(&tasklist_lock);
878    }
879
880    if (unlikely(clear_dead)) {
881        /*
882         * We've noticed that the thread is dead, but
883         * not yet reaped. Take this opportunity to
884         * drop our task ref.
885         */
886        clear_dead_task(timer, now);
887        goto dead;
888    }
889
890    if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
891        sample_to_timespec(timer->it_clock,
892                   cpu_time_sub(timer->it_clock,
893                        timer->it.cpu.expires, now),
894                   &itp->it_value);
895    } else {
896        /*
897         * The timer should have expired already, but the firing
898         * hasn't taken place yet. Say it's just about to expire.
899         */
900        itp->it_value.tv_nsec = 1;
901        itp->it_value.tv_sec = 0;
902    }
903}
904
905/*
906 * Check for any per-thread CPU timers that have fired and move them off
907 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
908 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
909 */
910static void check_thread_timers(struct task_struct *tsk,
911                struct list_head *firing)
912{
913    int maxfire;
914    struct list_head *timers = tsk->cpu_timers;
915    struct signal_struct *const sig = tsk->signal;
916    unsigned long soft;
917
918    maxfire = 20;
919    tsk->cputime_expires.prof_exp = cputime_zero;
920    while (!list_empty(timers)) {
921        struct cpu_timer_list *t = list_first_entry(timers,
922                              struct cpu_timer_list,
923                              entry);
924        if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
925            tsk->cputime_expires.prof_exp = t->expires.cpu;
926            break;
927        }
928        t->firing = 1;
929        list_move_tail(&t->entry, firing);
930    }
931
932    ++timers;
933    maxfire = 20;
934    tsk->cputime_expires.virt_exp = cputime_zero;
935    while (!list_empty(timers)) {
936        struct cpu_timer_list *t = list_first_entry(timers,
937                              struct cpu_timer_list,
938                              entry);
939        if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
940            tsk->cputime_expires.virt_exp = t->expires.cpu;
941            break;
942        }
943        t->firing = 1;
944        list_move_tail(&t->entry, firing);
945    }
946
947    ++timers;
948    maxfire = 20;
949    tsk->cputime_expires.sched_exp = 0;
950    while (!list_empty(timers)) {
951        struct cpu_timer_list *t = list_first_entry(timers,
952                              struct cpu_timer_list,
953                              entry);
954        if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
955            tsk->cputime_expires.sched_exp = t->expires.sched;
956            break;
957        }
958        t->firing = 1;
959        list_move_tail(&t->entry, firing);
960    }
961
962    /*
963     * Check for the special case thread timers.
964     */
965    soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
966    if (soft != RLIM_INFINITY) {
967        unsigned long hard =
968            ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
969
970        if (hard != RLIM_INFINITY &&
971            tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
972            /*
973             * At the hard limit, we just die.
974             * No need to calculate anything else now.
975             */
976            __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
977            return;
978        }
979        if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
980            /*
981             * At the soft limit, send a SIGXCPU every second.
982             */
983            if (soft < hard) {
984                soft += USEC_PER_SEC;
985                sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
986            }
987            printk(KERN_INFO
988                "RT Watchdog Timeout: %s[%d]\n",
989                tsk->comm, task_pid_nr(tsk));
990            __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
991        }
992    }
993}
994
995static void stop_process_timers(struct signal_struct *sig)
996{
997    struct thread_group_cputimer *cputimer = &sig->cputimer;
998    unsigned long flags;
999
1000    spin_lock_irqsave(&cputimer->lock, flags);
1001    cputimer->running = 0;
1002    spin_unlock_irqrestore(&cputimer->lock, flags);
1003}
1004
1005static u32 onecputick;
1006
1007static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
1008                 cputime_t *expires, cputime_t cur_time, int signo)
1009{
1010    if (cputime_eq(it->expires, cputime_zero))
1011        return;
1012
1013    if (cputime_ge(cur_time, it->expires)) {
1014        if (!cputime_eq(it->incr, cputime_zero)) {
1015            it->expires = cputime_add(it->expires, it->incr);
1016            it->error += it->incr_error;
1017            if (it->error >= onecputick) {
1018                it->expires = cputime_sub(it->expires,
1019                              cputime_one_jiffy);
1020                it->error -= onecputick;
1021            }
1022        } else {
1023            it->expires = cputime_zero;
1024        }
1025
1026        trace_itimer_expire(signo == SIGPROF ?
1027                    ITIMER_PROF : ITIMER_VIRTUAL,
1028                    tsk->signal->leader_pid, cur_time);
1029        __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1030    }
1031
1032    if (!cputime_eq(it->expires, cputime_zero) &&
1033        (cputime_eq(*expires, cputime_zero) ||
1034         cputime_lt(it->expires, *expires))) {
1035        *expires = it->expires;
1036    }
1037}
1038
1039/**
1040 * task_cputime_zero - Check a task_cputime struct for all zero fields.
1041 *
1042 * @cputime: The struct to compare.
1043 *
1044 * Checks @cputime to see if all fields are zero. Returns true if all fields
1045 * are zero, false if any field is nonzero.
1046 */
1047static inline int task_cputime_zero(const struct task_cputime *cputime)
1048{
1049    if (cputime_eq(cputime->utime, cputime_zero) &&
1050        cputime_eq(cputime->stime, cputime_zero) &&
1051        cputime->sum_exec_runtime == 0)
1052        return 1;
1053    return 0;
1054}
1055
1056/*
1057 * Check for any per-thread CPU timers that have fired and move them
1058 * off the tsk->*_timers list onto the firing list. Per-thread timers
1059 * have already been taken off.
1060 */
1061static void check_process_timers(struct task_struct *tsk,
1062                 struct list_head *firing)
1063{
1064    int maxfire;
1065    struct signal_struct *const sig = tsk->signal;
1066    cputime_t utime, ptime, virt_expires, prof_expires;
1067    unsigned long long sum_sched_runtime, sched_expires;
1068    struct list_head *timers = sig->cpu_timers;
1069    struct task_cputime cputime;
1070    unsigned long soft;
1071
1072    /*
1073     * Collect the current process totals.
1074     */
1075    thread_group_cputimer(tsk, &cputime);
1076    utime = cputime.utime;
1077    ptime = cputime_add(utime, cputime.stime);
1078    sum_sched_runtime = cputime.sum_exec_runtime;
1079    maxfire = 20;
1080    prof_expires = cputime_zero;
1081    while (!list_empty(timers)) {
1082        struct cpu_timer_list *tl = list_first_entry(timers,
1083                              struct cpu_timer_list,
1084                              entry);
1085        if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) {
1086            prof_expires = tl->expires.cpu;
1087            break;
1088        }
1089        tl->firing = 1;
1090        list_move_tail(&tl->entry, firing);
1091    }
1092
1093    ++timers;
1094    maxfire = 20;
1095    virt_expires = cputime_zero;
1096    while (!list_empty(timers)) {
1097        struct cpu_timer_list *tl = list_first_entry(timers,
1098                              struct cpu_timer_list,
1099                              entry);
1100        if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) {
1101            virt_expires = tl->expires.cpu;
1102            break;
1103        }
1104        tl->firing = 1;
1105        list_move_tail(&tl->entry, firing);
1106    }
1107
1108    ++timers;
1109    maxfire = 20;
1110    sched_expires = 0;
1111    while (!list_empty(timers)) {
1112        struct cpu_timer_list *tl = list_first_entry(timers,
1113                              struct cpu_timer_list,
1114                              entry);
1115        if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1116            sched_expires = tl->expires.sched;
1117            break;
1118        }
1119        tl->firing = 1;
1120        list_move_tail(&tl->entry, firing);
1121    }
1122
1123    /*
1124     * Check for the special case process timers.
1125     */
1126    check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1127             SIGPROF);
1128    check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1129             SIGVTALRM);
1130    soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1131    if (soft != RLIM_INFINITY) {
1132        unsigned long psecs = cputime_to_secs(ptime);
1133        unsigned long hard =
1134            ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1135        cputime_t x;
1136        if (psecs >= hard) {
1137            /*
1138             * At the hard limit, we just die.
1139             * No need to calculate anything else now.
1140             */
1141            __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1142            return;
1143        }
1144        if (psecs >= soft) {
1145            /*
1146             * At the soft limit, send a SIGXCPU every second.
1147             */
1148            __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1149            if (soft < hard) {
1150                soft++;
1151                sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1152            }
1153        }
1154        x = secs_to_cputime(soft);
1155        if (cputime_eq(prof_expires, cputime_zero) ||
1156            cputime_lt(x, prof_expires)) {
1157            prof_expires = x;
1158        }
1159    }
1160
1161    sig->cputime_expires.prof_exp = prof_expires;
1162    sig->cputime_expires.virt_exp = virt_expires;
1163    sig->cputime_expires.sched_exp = sched_expires;
1164    if (task_cputime_zero(&sig->cputime_expires))
1165        stop_process_timers(sig);
1166}
1167
1168/*
1169 * This is called from the signal code (via do_schedule_next_timer)
1170 * when the last timer signal was delivered and we have to reload the timer.
1171 */
1172void posix_cpu_timer_schedule(struct k_itimer *timer)
1173{
1174    struct task_struct *p = timer->it.cpu.task;
1175    union cpu_time_count now;
1176
1177    if (unlikely(p == NULL))
1178        /*
1179         * The task was cleaned up already, no future firings.
1180         */
1181        goto out;
1182
1183    /*
1184     * Fetch the current sample and update the timer's expiry time.
1185     */
1186    if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1187        cpu_clock_sample(timer->it_clock, p, &now);
1188        bump_cpu_timer(timer, now);
1189        if (unlikely(p->exit_state)) {
1190            clear_dead_task(timer, now);
1191            goto out;
1192        }
1193        read_lock(&tasklist_lock); /* arm_timer needs it. */
1194        spin_lock(&p->sighand->siglock);
1195    } else {
1196        read_lock(&tasklist_lock);
1197        if (unlikely(p->sighand == NULL)) {
1198            /*
1199             * The process has been reaped.
1200             * We can't even collect a sample any more.
1201             */
1202            put_task_struct(p);
1203            timer->it.cpu.task = p = NULL;
1204            timer->it.cpu.expires.sched = 0;
1205            goto out_unlock;
1206        } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1207            /*
1208             * We've noticed that the thread is dead, but
1209             * not yet reaped. Take this opportunity to
1210             * drop our task ref.
1211             */
1212            clear_dead_task(timer, now);
1213            goto out_unlock;
1214        }
1215        spin_lock(&p->sighand->siglock);
1216        cpu_timer_sample_group(timer->it_clock, p, &now);
1217        bump_cpu_timer(timer, now);
1218        /* Leave the tasklist_lock locked for the call below. */
1219    }
1220
1221    /*
1222     * Now re-arm for the new expiry time.
1223     */
1224    BUG_ON(!irqs_disabled());
1225    arm_timer(timer);
1226    spin_unlock(&p->sighand->siglock);
1227
1228out_unlock:
1229    read_unlock(&tasklist_lock);
1230
1231out:
1232    timer->it_overrun_last = timer->it_overrun;
1233    timer->it_overrun = -1;
1234    ++timer->it_requeue_pending;
1235}
1236
1237/**
1238 * task_cputime_expired - Compare two task_cputime entities.
1239 *
1240 * @sample: The task_cputime structure to be checked for expiration.
1241 * @expires: Expiration times, against which @sample will be checked.
1242 *
1243 * Checks @sample against @expires to see if any field of @sample has expired.
1244 * Returns true if any field of the former is greater than the corresponding
1245 * field of the latter if the latter field is set. Otherwise returns false.
1246 */
1247static inline int task_cputime_expired(const struct task_cputime *sample,
1248                    const struct task_cputime *expires)
1249{
1250    if (!cputime_eq(expires->utime, cputime_zero) &&
1251        cputime_ge(sample->utime, expires->utime))
1252        return 1;
1253    if (!cputime_eq(expires->stime, cputime_zero) &&
1254        cputime_ge(cputime_add(sample->utime, sample->stime),
1255               expires->stime))
1256        return 1;
1257    if (expires->sum_exec_runtime != 0 &&
1258        sample->sum_exec_runtime >= expires->sum_exec_runtime)
1259        return 1;
1260    return 0;
1261}
1262
1263/**
1264 * fastpath_timer_check - POSIX CPU timers fast path.
1265 *
1266 * @tsk: The task (thread) being checked.
1267 *
1268 * Check the task and thread group timers. If both are zero (there are no
1269 * timers set) return false. Otherwise snapshot the task and thread group
1270 * timers and compare them with the corresponding expiration times. Return
1271 * true if a timer has expired, else return false.
1272 */
1273static inline int fastpath_timer_check(struct task_struct *tsk)
1274{
1275    struct signal_struct *sig;
1276
1277    if (!task_cputime_zero(&tsk->cputime_expires)) {
1278        struct task_cputime task_sample = {
1279            .utime = tsk->utime,
1280            .stime = tsk->stime,
1281            .sum_exec_runtime = tsk->se.sum_exec_runtime
1282        };
1283
1284        if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1285            return 1;
1286    }
1287
1288    sig = tsk->signal;
1289    if (sig->cputimer.running) {
1290        struct task_cputime group_sample;
1291
1292        spin_lock(&sig->cputimer.lock);
1293        group_sample = sig->cputimer.cputime;
1294        spin_unlock(&sig->cputimer.lock);
1295
1296        if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1297            return 1;
1298    }
1299
1300    return 0;
1301}
1302
1303/*
1304 * This is called from the timer interrupt handler. The irq handler has
1305 * already updated our counts. We need to check if any timers fire now.
1306 * Interrupts are disabled.
1307 */
1308void run_posix_cpu_timers(struct task_struct *tsk)
1309{
1310    LIST_HEAD(firing);
1311    struct k_itimer *timer, *next;
1312    unsigned long flags;
1313
1314    BUG_ON(!irqs_disabled());
1315
1316    /*
1317     * The fast path checks that there are no expired thread or thread
1318     * group timers. If that's so, just return.
1319     */
1320    if (!fastpath_timer_check(tsk))
1321        return;
1322
1323    if (!lock_task_sighand(tsk, &flags))
1324        return;
1325    /*
1326     * Here we take off tsk->signal->cpu_timers[N] and
1327     * tsk->cpu_timers[N] all the timers that are firing, and
1328     * put them on the firing list.
1329     */
1330    check_thread_timers(tsk, &firing);
1331    /*
1332     * If there are any active process wide timers (POSIX 1.b, itimers,
1333     * RLIMIT_CPU) cputimer must be running.
1334     */
1335    if (tsk->signal->cputimer.running)
1336        check_process_timers(tsk, &firing);
1337
1338    /*
1339     * We must release these locks before taking any timer's lock.
1340     * There is a potential race with timer deletion here, as the
1341     * siglock now protects our private firing list. We have set
1342     * the firing flag in each timer, so that a deletion attempt
1343     * that gets the timer lock before we do will give it up and
1344     * spin until we've taken care of that timer below.
1345     */
1346    unlock_task_sighand(tsk, &flags);
1347
1348    /*
1349     * Now that all the timers on our list have the firing flag,
1350     * no one will touch their list entries but us. We'll take
1351     * each timer's lock before clearing its firing flag, so no
1352     * timer call will interfere.
1353     */
1354    list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1355        int cpu_firing;
1356
1357        spin_lock(&timer->it_lock);
1358        list_del_init(&timer->it.cpu.entry);
1359        cpu_firing = timer->it.cpu.firing;
1360        timer->it.cpu.firing = 0;
1361        /*
1362         * The firing flag is -1 if we collided with a reset
1363         * of the timer, which already reported this
1364         * almost-firing as an overrun. So don't generate an event.
1365         */
1366        if (likely(cpu_firing >= 0))
1367            cpu_timer_fire(timer);
1368        spin_unlock(&timer->it_lock);
1369    }
1370}
1371
1372/*
1373 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1374 * The tsk->sighand->siglock must be held by the caller.
1375 */
1376void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1377               cputime_t *newval, cputime_t *oldval)
1378{
1379    union cpu_time_count now;
1380
1381    BUG_ON(clock_idx == CPUCLOCK_SCHED);
1382    cpu_timer_sample_group(clock_idx, tsk, &now);
1383
1384    if (oldval) {
1385        /*
1386         * We are setting itimer. The *oldval is absolute and we update
1387         * it to be relative, *newval argument is relative and we update
1388         * it to be absolute.
1389         */
1390        if (!cputime_eq(*oldval, cputime_zero)) {
1391            if (cputime_le(*oldval, now.cpu)) {
1392                /* Just about to fire. */
1393                *oldval = cputime_one_jiffy;
1394            } else {
1395                *oldval = cputime_sub(*oldval, now.cpu);
1396            }
1397        }
1398
1399        if (cputime_eq(*newval, cputime_zero))
1400            return;
1401        *newval = cputime_add(*newval, now.cpu);
1402    }
1403
1404    /*
1405     * Update expiration cache if we are the earliest timer, or eventually
1406     * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1407     */
1408    switch (clock_idx) {
1409    case CPUCLOCK_PROF:
1410        if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1411            tsk->signal->cputime_expires.prof_exp = *newval;
1412        break;
1413    case CPUCLOCK_VIRT:
1414        if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1415            tsk->signal->cputime_expires.virt_exp = *newval;
1416        break;
1417    }
1418}
1419
1420static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1421                struct timespec *rqtp, struct itimerspec *it)
1422{
1423    struct k_itimer timer;
1424    int error;
1425
1426    /*
1427     * Set up a temporary timer and then wait for it to go off.
1428     */
1429    memset(&timer, 0, sizeof timer);
1430    spin_lock_init(&timer.it_lock);
1431    timer.it_clock = which_clock;
1432    timer.it_overrun = -1;
1433    error = posix_cpu_timer_create(&timer);
1434    timer.it_process = current;
1435    if (!error) {
1436        static struct itimerspec zero_it;
1437
1438        memset(it, 0, sizeof *it);
1439        it->it_value = *rqtp;
1440
1441        spin_lock_irq(&timer.it_lock);
1442        error = posix_cpu_timer_set(&timer, flags, it, NULL);
1443        if (error) {
1444            spin_unlock_irq(&timer.it_lock);
1445            return error;
1446        }
1447
1448        while (!signal_pending(current)) {
1449            if (timer.it.cpu.expires.sched == 0) {
1450                /*
1451                 * Our timer fired and was reset.
1452                 */
1453                spin_unlock_irq(&timer.it_lock);
1454                return 0;
1455            }
1456
1457            /*
1458             * Block until cpu_timer_fire (or a signal) wakes us.
1459             */
1460            __set_current_state(TASK_INTERRUPTIBLE);
1461            spin_unlock_irq(&timer.it_lock);
1462            schedule();
1463            spin_lock_irq(&timer.it_lock);
1464        }
1465
1466        /*
1467         * We were interrupted by a signal.
1468         */
1469        sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1470        posix_cpu_timer_set(&timer, 0, &zero_it, it);
1471        spin_unlock_irq(&timer.it_lock);
1472
1473        if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1474            /*
1475             * It actually did fire already.
1476             */
1477            return 0;
1478        }
1479
1480        error = -ERESTART_RESTARTBLOCK;
1481    }
1482
1483    return error;
1484}
1485
1486static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1487
1488static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1489                struct timespec *rqtp, struct timespec __user *rmtp)
1490{
1491    struct restart_block *restart_block =
1492        &current_thread_info()->restart_block;
1493    struct itimerspec it;
1494    int error;
1495
1496    /*
1497     * Diagnose required errors first.
1498     */
1499    if (CPUCLOCK_PERTHREAD(which_clock) &&
1500        (CPUCLOCK_PID(which_clock) == 0 ||
1501         CPUCLOCK_PID(which_clock) == current->pid))
1502        return -EINVAL;
1503
1504    error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1505
1506    if (error == -ERESTART_RESTARTBLOCK) {
1507
1508        if (flags & TIMER_ABSTIME)
1509            return -ERESTARTNOHAND;
1510        /*
1511         * Report back to the user the time still remaining.
1512         */
1513        if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1514            return -EFAULT;
1515
1516        restart_block->fn = posix_cpu_nsleep_restart;
1517        restart_block->nanosleep.clockid = which_clock;
1518        restart_block->nanosleep.rmtp = rmtp;
1519        restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1520    }
1521    return error;
1522}
1523
1524static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1525{
1526    clockid_t which_clock = restart_block->nanosleep.clockid;
1527    struct timespec t;
1528    struct itimerspec it;
1529    int error;
1530
1531    t = ns_to_timespec(restart_block->nanosleep.expires);
1532
1533    error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1534
1535    if (error == -ERESTART_RESTARTBLOCK) {
1536        struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1537        /*
1538         * Report back to the user the time still remaining.
1539         */
1540        if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1541            return -EFAULT;
1542
1543        restart_block->nanosleep.expires = timespec_to_ns(&t);
1544    }
1545    return error;
1546
1547}
1548
1549#define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1550#define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1551
1552static int process_cpu_clock_getres(const clockid_t which_clock,
1553                    struct timespec *tp)
1554{
1555    return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1556}
1557static int process_cpu_clock_get(const clockid_t which_clock,
1558                 struct timespec *tp)
1559{
1560    return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1561}
1562static int process_cpu_timer_create(struct k_itimer *timer)
1563{
1564    timer->it_clock = PROCESS_CLOCK;
1565    return posix_cpu_timer_create(timer);
1566}
1567static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1568                  struct timespec *rqtp,
1569                  struct timespec __user *rmtp)
1570{
1571    return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1572}
1573static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1574{
1575    return -EINVAL;
1576}
1577static int thread_cpu_clock_getres(const clockid_t which_clock,
1578                   struct timespec *tp)
1579{
1580    return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1581}
1582static int thread_cpu_clock_get(const clockid_t which_clock,
1583                struct timespec *tp)
1584{
1585    return posix_cpu_clock_get(THREAD_CLOCK, tp);
1586}
1587static int thread_cpu_timer_create(struct k_itimer *timer)
1588{
1589    timer->it_clock = THREAD_CLOCK;
1590    return posix_cpu_timer_create(timer);
1591}
1592
1593struct k_clock clock_posix_cpu = {
1594    .clock_getres = posix_cpu_clock_getres,
1595    .clock_set = posix_cpu_clock_set,
1596    .clock_get = posix_cpu_clock_get,
1597    .timer_create = posix_cpu_timer_create,
1598    .nsleep = posix_cpu_nsleep,
1599    .nsleep_restart = posix_cpu_nsleep_restart,
1600    .timer_set = posix_cpu_timer_set,
1601    .timer_del = posix_cpu_timer_del,
1602    .timer_get = posix_cpu_timer_get,
1603};
1604
1605static __init int init_posix_cpu_timers(void)
1606{
1607    struct k_clock process = {
1608        .clock_getres = process_cpu_clock_getres,
1609        .clock_get = process_cpu_clock_get,
1610        .timer_create = process_cpu_timer_create,
1611        .nsleep = process_cpu_nsleep,
1612        .nsleep_restart = process_cpu_nsleep_restart,
1613    };
1614    struct k_clock thread = {
1615        .clock_getres = thread_cpu_clock_getres,
1616        .clock_get = thread_cpu_clock_get,
1617        .timer_create = thread_cpu_timer_create,
1618    };
1619    struct timespec ts;
1620
1621    posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1622    posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1623
1624    cputime_to_timespec(cputime_one_jiffy, &ts);
1625    onecputick = ts.tv_nsec;
1626    WARN_ON(ts.tv_sec != 0);
1627
1628    return 0;
1629}
1630__initcall(init_posix_cpu_timers);
1631

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