linux/kernel/posix-timers.c
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   1/*
   2 * linux/kernel/posix-timers.c
   3 *
   4 *
   5 * 2002-10-15  Posix Clocks & timers
   6 *                           by George Anzinger george@mvista.com
   7 *
   8 *                           Copyright (C) 2002 2003 by MontaVista Software.
   9 *
  10 * 2004-06-01  Fix CLOCK_REALTIME clock/timer TIMER_ABSTIME bug.
  11 *                           Copyright (C) 2004 Boris Hu
  12 *
  13 * This program is free software; you can redistribute it and/or modify
  14 * it under the terms of the GNU General Public License as published by
  15 * the Free Software Foundation; either version 2 of the License, or (at
  16 * your option) any later version.
  17 *
  18 * This program is distributed in the hope that it will be useful, but
  19 * WITHOUT ANY WARRANTY; without even the implied warranty of
  20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  21 * General Public License for more details.
  22
  23 * You should have received a copy of the GNU General Public License
  24 * along with this program; if not, write to the Free Software
  25 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  26 *
  27 * MontaVista Software | 1237 East Arques Avenue | Sunnyvale | CA 94085 | USA
  28 */
  29
  30/* These are all the functions necessary to implement
  31 * POSIX clocks & timers
  32 */
  33#include <linux/mm.h>
  34#include <linux/interrupt.h>
  35#include <linux/slab.h>
  36#include <linux/time.h>
  37#include <linux/mutex.h>
  38
  39#include <asm/uaccess.h>
  40#include <linux/list.h>
  41#include <linux/init.h>
  42#include <linux/compiler.h>
  43#include <linux/idr.h>
  44#include <linux/posix-clock.h>
  45#include <linux/posix-timers.h>
  46#include <linux/syscalls.h>
  47#include <linux/wait.h>
  48#include <linux/workqueue.h>
  49#include <linux/export.h>
  50
  51/*
  52 * Management arrays for POSIX timers.   Timers are kept in slab memory
  53 * Timer ids are allocated by an external routine that keeps track of the
  54 * id and the timer.  The external interface is:
  55 *
  56 * void *idr_find(struct idr *idp, int id);           to find timer_id <id>
  57 * int idr_get_new(struct idr *idp, void *ptr);       to get a new id and
  58 *                                                    related it to <ptr>
  59 * void idr_remove(struct idr *idp, int id);          to release <id>
  60 * void idr_init(struct idr *idp);                    to initialize <idp>
  61 *                                                    which we supply.
  62 * The idr_get_new *may* call slab for more memory so it must not be
  63 * called under a spin lock.  Likewise idr_remore may release memory
  64 * (but it may be ok to do this under a lock...).
  65 * idr_find is just a memory look up and is quite fast.  A -1 return
  66 * indicates that the requested id does not exist.
  67 */
  68
  69/*
  70 * Lets keep our timers in a slab cache :-)
  71 */
  72static struct kmem_cache *posix_timers_cache;
  73static struct idr posix_timers_id;
  74static DEFINE_SPINLOCK(idr_lock);
  75
  76/*
  77 * we assume that the new SIGEV_THREAD_ID shares no bits with the other
  78 * SIGEV values.  Here we put out an error if this assumption fails.
  79 */
  80#if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
  81                       ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
  82#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
  83#endif
  84
  85/*
  86 * parisc wants ENOTSUP instead of EOPNOTSUPP
  87 */
  88#ifndef ENOTSUP
  89# define ENANOSLEEP_NOTSUP EOPNOTSUPP
  90#else
  91# define ENANOSLEEP_NOTSUP ENOTSUP
  92#endif
  93
  94/*
  95 * The timer ID is turned into a timer address by idr_find().
  96 * Verifying a valid ID consists of:
  97 *
  98 * a) checking that idr_find() returns other than -1.
  99 * b) checking that the timer id matches the one in the timer itself.
 100 * c) that the timer owner is in the callers thread group.
 101 */
 102
 103/*
 104 * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
 105 *          to implement others.  This structure defines the various
 106 *          clocks.
 107 *
 108 * RESOLUTION: Clock resolution is used to round up timer and interval
 109 *          times, NOT to report clock times, which are reported with as
 110 *          much resolution as the system can muster.  In some cases this
 111 *          resolution may depend on the underlying clock hardware and
 112 *          may not be quantifiable until run time, and only then is the
 113 *          necessary code is written.  The standard says we should say
 114 *          something about this issue in the documentation...
 115 *
 116 * FUNCTIONS: The CLOCKs structure defines possible functions to
 117 *          handle various clock functions.
 118 *
 119 *          The standard POSIX timer management code assumes the
 120 *          following: 1.) The k_itimer struct (sched.h) is used for
 121 *          the timer.  2.) The list, it_lock, it_clock, it_id and
 122 *          it_pid fields are not modified by timer code.
 123 *
 124 * Permissions: It is assumed that the clock_settime() function defined
 125 *          for each clock will take care of permission checks.  Some
 126 *          clocks may be set able by any user (i.e. local process
 127 *          clocks) others not.  Currently the only set able clock we
 128 *          have is CLOCK_REALTIME and its high res counter part, both of
 129 *          which we beg off on and pass to do_sys_settimeofday().
 130 */
 131
 132static struct k_clock posix_clocks[MAX_CLOCKS];
 133
 134/*
 135 * These ones are defined below.
 136 */
 137static int common_nsleep(const clockid_t, int flags, struct timespec *t,
 138                         struct timespec __user *rmtp);
 139static int common_timer_create(struct k_itimer *new_timer);
 140static void common_timer_get(struct k_itimer *, struct itimerspec *);
 141static int common_timer_set(struct k_itimer *, int,
 142                            struct itimerspec *, struct itimerspec *);
 143static int common_timer_del(struct k_itimer *timer);
 144
 145static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
 146
 147static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
 148
 149#define lock_timer(tid, flags)                                             \
 150({      struct k_itimer *__timr;                                           \
 151        __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags));  \
 152        __timr;                                                            \
 153})
 154
 155static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
 156{
 157        spin_unlock_irqrestore(&timr->it_lock, flags);
 158}
 159
 160/* Get clock_realtime */
 161static int posix_clock_realtime_get(clockid_t which_clock, struct timespec *tp)
 162{
 163        ktime_get_real_ts(tp);
 164        return 0;
 165}
 166
 167/* Set clock_realtime */
 168static int posix_clock_realtime_set(const clockid_t which_clock,
 169                                    const struct timespec *tp)
 170{
 171        return do_sys_settimeofday(tp, NULL);
 172}
 173
 174static int posix_clock_realtime_adj(const clockid_t which_clock,
 175                                    struct timex *t)
 176{
 177        return do_adjtimex(t);
 178}
 179
 180/*
 181 * Get monotonic time for posix timers
 182 */
 183static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
 184{
 185        ktime_get_ts(tp);
 186        return 0;
 187}
 188
 189/*
 190 * Get monotonic-raw time for posix timers
 191 */
 192static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
 193{
 194        getrawmonotonic(tp);
 195        return 0;
 196}
 197
 198
 199static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
 200{
 201        *tp = current_kernel_time();
 202        return 0;
 203}
 204
 205static int posix_get_monotonic_coarse(clockid_t which_clock,
 206                                                struct timespec *tp)
 207{
 208        *tp = get_monotonic_coarse();
 209        return 0;
 210}
 211
 212static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp)
 213{
 214        *tp = ktime_to_timespec(KTIME_LOW_RES);
 215        return 0;
 216}
 217
 218static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
 219{
 220        get_monotonic_boottime(tp);
 221        return 0;
 222}
 223
 224
 225/*
 226 * Initialize everything, well, just everything in Posix clocks/timers ;)
 227 */
 228static __init int init_posix_timers(void)
 229{
 230        struct k_clock clock_realtime = {
 231                .clock_getres   = hrtimer_get_res,
 232                .clock_get      = posix_clock_realtime_get,
 233                .clock_set      = posix_clock_realtime_set,
 234                .clock_adj      = posix_clock_realtime_adj,
 235                .nsleep         = common_nsleep,
 236                .nsleep_restart = hrtimer_nanosleep_restart,
 237                .timer_create   = common_timer_create,
 238                .timer_set      = common_timer_set,
 239                .timer_get      = common_timer_get,
 240                .timer_del      = common_timer_del,
 241        };
 242        struct k_clock clock_monotonic = {
 243                .clock_getres   = hrtimer_get_res,
 244                .clock_get      = posix_ktime_get_ts,
 245                .nsleep         = common_nsleep,
 246                .nsleep_restart = hrtimer_nanosleep_restart,
 247                .timer_create   = common_timer_create,
 248                .timer_set      = common_timer_set,
 249                .timer_get      = common_timer_get,
 250                .timer_del      = common_timer_del,
 251        };
 252        struct k_clock clock_monotonic_raw = {
 253                .clock_getres   = hrtimer_get_res,
 254                .clock_get      = posix_get_monotonic_raw,
 255        };
 256        struct k_clock clock_realtime_coarse = {
 257                .clock_getres   = posix_get_coarse_res,
 258                .clock_get      = posix_get_realtime_coarse,
 259        };
 260        struct k_clock clock_monotonic_coarse = {
 261                .clock_getres   = posix_get_coarse_res,
 262                .clock_get      = posix_get_monotonic_coarse,
 263        };
 264        struct k_clock clock_boottime = {
 265                .clock_getres   = hrtimer_get_res,
 266                .clock_get      = posix_get_boottime,
 267                .nsleep         = common_nsleep,
 268                .nsleep_restart = hrtimer_nanosleep_restart,
 269                .timer_create   = common_timer_create,
 270                .timer_set      = common_timer_set,
 271                .timer_get      = common_timer_get,
 272                .timer_del      = common_timer_del,
 273        };
 274
 275        posix_timers_register_clock(CLOCK_REALTIME, &clock_realtime);
 276        posix_timers_register_clock(CLOCK_MONOTONIC, &clock_monotonic);
 277        posix_timers_register_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
 278        posix_timers_register_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
 279        posix_timers_register_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
 280        posix_timers_register_clock(CLOCK_BOOTTIME, &clock_boottime);
 281
 282        posix_timers_cache = kmem_cache_create("posix_timers_cache",
 283                                        sizeof (struct k_itimer), 0, SLAB_PANIC,
 284                                        NULL);
 285        idr_init(&posix_timers_id);
 286        return 0;
 287}
 288
 289__initcall(init_posix_timers);
 290
 291static void schedule_next_timer(struct k_itimer *timr)
 292{
 293        struct hrtimer *timer = &timr->it.real.timer;
 294
 295        if (timr->it.real.interval.tv64 == 0)
 296                return;
 297
 298        timr->it_overrun += (unsigned int) hrtimer_forward(timer,
 299                                                timer->base->get_time(),
 300                                                timr->it.real.interval);
 301
 302        timr->it_overrun_last = timr->it_overrun;
 303        timr->it_overrun = -1;
 304        ++timr->it_requeue_pending;
 305        hrtimer_restart(timer);
 306}
 307
 308/*
 309 * This function is exported for use by the signal deliver code.  It is
 310 * called just prior to the info block being released and passes that
 311 * block to us.  It's function is to update the overrun entry AND to
 312 * restart the timer.  It should only be called if the timer is to be
 313 * restarted (i.e. we have flagged this in the sys_private entry of the
 314 * info block).
 315 *
 316 * To protect against the timer going away while the interrupt is queued,
 317 * we require that the it_requeue_pending flag be set.
 318 */
 319void do_schedule_next_timer(struct siginfo *info)
 320{
 321        struct k_itimer *timr;
 322        unsigned long flags;
 323
 324        timr = lock_timer(info->si_tid, &flags);
 325
 326        if (timr && timr->it_requeue_pending == info->si_sys_private) {
 327                if (timr->it_clock < 0)
 328                        posix_cpu_timer_schedule(timr);
 329                else
 330                        schedule_next_timer(timr);
 331
 332                info->si_overrun += timr->it_overrun_last;
 333        }
 334
 335        if (timr)
 336                unlock_timer(timr, flags);
 337}
 338
 339int posix_timer_event(struct k_itimer *timr, int si_private)
 340{
 341        struct task_struct *task;
 342        int shared, ret = -1;
 343        /*
 344         * FIXME: if ->sigq is queued we can race with
 345         * dequeue_signal()->do_schedule_next_timer().
 346         *
 347         * If dequeue_signal() sees the "right" value of
 348         * si_sys_private it calls do_schedule_next_timer().
 349         * We re-queue ->sigq and drop ->it_lock().
 350         * do_schedule_next_timer() locks the timer
 351         * and re-schedules it while ->sigq is pending.
 352         * Not really bad, but not that we want.
 353         */
 354        timr->sigq->info.si_sys_private = si_private;
 355
 356        rcu_read_lock();
 357        task = pid_task(timr->it_pid, PIDTYPE_PID);
 358        if (task) {
 359                shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
 360                ret = send_sigqueue(timr->sigq, task, shared);
 361        }
 362        rcu_read_unlock();
 363        /* If we failed to send the signal the timer stops. */
 364        return ret > 0;
 365}
 366EXPORT_SYMBOL_GPL(posix_timer_event);
 367
 368/*
 369 * This function gets called when a POSIX.1b interval timer expires.  It
 370 * is used as a callback from the kernel internal timer.  The
 371 * run_timer_list code ALWAYS calls with interrupts on.
 372
 373 * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
 374 */
 375static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
 376{
 377        struct k_itimer *timr;
 378        unsigned long flags;
 379        int si_private = 0;
 380        enum hrtimer_restart ret = HRTIMER_NORESTART;
 381
 382        timr = container_of(timer, struct k_itimer, it.real.timer);
 383        spin_lock_irqsave(&timr->it_lock, flags);
 384
 385        if (timr->it.real.interval.tv64 != 0)
 386                si_private = ++timr->it_requeue_pending;
 387
 388        if (posix_timer_event(timr, si_private)) {
 389                /*
 390                 * signal was not sent because of sig_ignor
 391                 * we will not get a call back to restart it AND
 392                 * it should be restarted.
 393                 */
 394                if (timr->it.real.interval.tv64 != 0) {
 395                        ktime_t now = hrtimer_cb_get_time(timer);
 396
 397                        /*
 398                         * FIXME: What we really want, is to stop this
 399                         * timer completely and restart it in case the
 400                         * SIG_IGN is removed. This is a non trivial
 401                         * change which involves sighand locking
 402                         * (sigh !), which we don't want to do late in
 403                         * the release cycle.
 404                         *
 405                         * For now we just let timers with an interval
 406                         * less than a jiffie expire every jiffie to
 407                         * avoid softirq starvation in case of SIG_IGN
 408                         * and a very small interval, which would put
 409                         * the timer right back on the softirq pending
 410                         * list. By moving now ahead of time we trick
 411                         * hrtimer_forward() to expire the timer
 412                         * later, while we still maintain the overrun
 413                         * accuracy, but have some inconsistency in
 414                         * the timer_gettime() case. This is at least
 415                         * better than a starved softirq. A more
 416                         * complex fix which solves also another related
 417                         * inconsistency is already in the pipeline.
 418                         */
 419#ifdef CONFIG_HIGH_RES_TIMERS
 420                        {
 421                                ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ);
 422
 423                                if (timr->it.real.interval.tv64 < kj.tv64)
 424                                        now = ktime_add(now, kj);
 425                        }
 426#endif
 427                        timr->it_overrun += (unsigned int)
 428                                hrtimer_forward(timer, now,
 429                                                timr->it.real.interval);
 430                        ret = HRTIMER_RESTART;
 431                        ++timr->it_requeue_pending;
 432                }
 433        }
 434
 435        unlock_timer(timr, flags);
 436        return ret;
 437}
 438
 439static struct pid *good_sigevent(sigevent_t * event)
 440{
 441        struct task_struct *rtn = current->group_leader;
 442
 443        if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
 444                (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) ||
 445                 !same_thread_group(rtn, current) ||
 446                 (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
 447                return NULL;
 448
 449        if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
 450            ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
 451                return NULL;
 452
 453        return task_pid(rtn);
 454}
 455
 456void posix_timers_register_clock(const clockid_t clock_id,
 457                                 struct k_clock *new_clock)
 458{
 459        if ((unsigned) clock_id >= MAX_CLOCKS) {
 460                printk(KERN_WARNING "POSIX clock register failed for clock_id %d\n",
 461                       clock_id);
 462                return;
 463        }
 464
 465        if (!new_clock->clock_get) {
 466                printk(KERN_WARNING "POSIX clock id %d lacks clock_get()\n",
 467                       clock_id);
 468                return;
 469        }
 470        if (!new_clock->clock_getres) {
 471                printk(KERN_WARNING "POSIX clock id %d lacks clock_getres()\n",
 472                       clock_id);
 473                return;
 474        }
 475
 476        posix_clocks[clock_id] = *new_clock;
 477}
 478EXPORT_SYMBOL_GPL(posix_timers_register_clock);
 479
 480static struct k_itimer * alloc_posix_timer(void)
 481{
 482        struct k_itimer *tmr;
 483        tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
 484        if (!tmr)
 485                return tmr;
 486        if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
 487                kmem_cache_free(posix_timers_cache, tmr);
 488                return NULL;
 489        }
 490        memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
 491        return tmr;
 492}
 493
 494static void k_itimer_rcu_free(struct rcu_head *head)
 495{
 496        struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu);
 497
 498        kmem_cache_free(posix_timers_cache, tmr);
 499}
 500
 501#define IT_ID_SET       1
 502#define IT_ID_NOT_SET   0
 503static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
 504{
 505        if (it_id_set) {
 506                unsigned long flags;
 507                spin_lock_irqsave(&idr_lock, flags);
 508                idr_remove(&posix_timers_id, tmr->it_id);
 509                spin_unlock_irqrestore(&idr_lock, flags);
 510        }
 511        put_pid(tmr->it_pid);
 512        sigqueue_free(tmr->sigq);
 513        call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
 514}
 515
 516static struct k_clock *clockid_to_kclock(const clockid_t id)
 517{
 518        if (id < 0)
 519                return (id & CLOCKFD_MASK) == CLOCKFD ?
 520                        &clock_posix_dynamic : &clock_posix_cpu;
 521
 522        if (id >= MAX_CLOCKS || !posix_clocks[id].clock_getres)
 523                return NULL;
 524        return &posix_clocks[id];
 525}
 526
 527static int common_timer_create(struct k_itimer *new_timer)
 528{
 529        hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
 530        return 0;
 531}
 532
 533/* Create a POSIX.1b interval timer. */
 534
 535SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
 536                struct sigevent __user *, timer_event_spec,
 537                timer_t __user *, created_timer_id)
 538{
 539        struct k_clock *kc = clockid_to_kclock(which_clock);
 540        struct k_itimer *new_timer;
 541        int error, new_timer_id;
 542        sigevent_t event;
 543        int it_id_set = IT_ID_NOT_SET;
 544
 545        if (!kc)
 546                return -EINVAL;
 547        if (!kc->timer_create)
 548                return -EOPNOTSUPP;
 549
 550        new_timer = alloc_posix_timer();
 551        if (unlikely(!new_timer))
 552                return -EAGAIN;
 553
 554        spin_lock_init(&new_timer->it_lock);
 555 retry:
 556        if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) {
 557                error = -EAGAIN;
 558                goto out;
 559        }
 560        spin_lock_irq(&idr_lock);
 561        error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
 562        spin_unlock_irq(&idr_lock);
 563        if (error) {
 564                if (error == -EAGAIN)
 565                        goto retry;
 566                /*
 567                 * Weird looking, but we return EAGAIN if the IDR is
 568                 * full (proper POSIX return value for this)
 569                 */
 570                error = -EAGAIN;
 571                goto out;
 572        }
 573
 574        it_id_set = IT_ID_SET;
 575        new_timer->it_id = (timer_t) new_timer_id;
 576        new_timer->it_clock = which_clock;
 577        new_timer->it_overrun = -1;
 578
 579        if (timer_event_spec) {
 580                if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
 581                        error = -EFAULT;
 582                        goto out;
 583                }
 584                rcu_read_lock();
 585                new_timer->it_pid = get_pid(good_sigevent(&event));
 586                rcu_read_unlock();
 587                if (!new_timer->it_pid) {
 588                        error = -EINVAL;
 589                        goto out;
 590                }
 591        } else {
 592                event.sigev_notify = SIGEV_SIGNAL;
 593                event.sigev_signo = SIGALRM;
 594                event.sigev_value.sival_int = new_timer->it_id;
 595                new_timer->it_pid = get_pid(task_tgid(current));
 596        }
 597
 598        new_timer->it_sigev_notify     = event.sigev_notify;
 599        new_timer->sigq->info.si_signo = event.sigev_signo;
 600        new_timer->sigq->info.si_value = event.sigev_value;
 601        new_timer->sigq->info.si_tid   = new_timer->it_id;
 602        new_timer->sigq->info.si_code  = SI_TIMER;
 603
 604        if (copy_to_user(created_timer_id,
 605                         &new_timer_id, sizeof (new_timer_id))) {
 606                error = -EFAULT;
 607                goto out;
 608        }
 609
 610        error = kc->timer_create(new_timer);
 611        if (error)
 612                goto out;
 613
 614        spin_lock_irq(&current->sighand->siglock);
 615        new_timer->it_signal = current->signal;
 616        list_add(&new_timer->list, &current->signal->posix_timers);
 617        spin_unlock_irq(&current->sighand->siglock);
 618
 619        return 0;
 620        /*
 621         * In the case of the timer belonging to another task, after
 622         * the task is unlocked, the timer is owned by the other task
 623         * and may cease to exist at any time.  Don't use or modify
 624         * new_timer after the unlock call.
 625         */
 626out:
 627        release_posix_timer(new_timer, it_id_set);
 628        return error;
 629}
 630
 631/*
 632 * Locking issues: We need to protect the result of the id look up until
 633 * we get the timer locked down so it is not deleted under us.  The
 634 * removal is done under the idr spinlock so we use that here to bridge
 635 * the find to the timer lock.  To avoid a dead lock, the timer id MUST
 636 * be release with out holding the timer lock.
 637 */
 638static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
 639{
 640        struct k_itimer *timr;
 641
 642        rcu_read_lock();
 643        timr = idr_find(&posix_timers_id, (int)timer_id);
 644        if (timr) {
 645                spin_lock_irqsave(&timr->it_lock, *flags);
 646                if (timr->it_signal == current->signal) {
 647                        rcu_read_unlock();
 648                        return timr;
 649                }
 650                spin_unlock_irqrestore(&timr->it_lock, *flags);
 651        }
 652        rcu_read_unlock();
 653
 654        return NULL;
 655}
 656
 657/*
 658 * Get the time remaining on a POSIX.1b interval timer.  This function
 659 * is ALWAYS called with spin_lock_irq on the timer, thus it must not
 660 * mess with irq.
 661 *
 662 * We have a couple of messes to clean up here.  First there is the case
 663 * of a timer that has a requeue pending.  These timers should appear to
 664 * be in the timer list with an expiry as if we were to requeue them
 665 * now.
 666 *
 667 * The second issue is the SIGEV_NONE timer which may be active but is
 668 * not really ever put in the timer list (to save system resources).
 669 * This timer may be expired, and if so, we will do it here.  Otherwise
 670 * it is the same as a requeue pending timer WRT to what we should
 671 * report.
 672 */
 673static void
 674common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
 675{
 676        ktime_t now, remaining, iv;
 677        struct hrtimer *timer = &timr->it.real.timer;
 678
 679        memset(cur_setting, 0, sizeof(struct itimerspec));
 680
 681        iv = timr->it.real.interval;
 682
 683        /* interval timer ? */
 684        if (iv.tv64)
 685                cur_setting->it_interval = ktime_to_timespec(iv);
 686        else if (!hrtimer_active(timer) &&
 687                 (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
 688                return;
 689
 690        now = timer->base->get_time();
 691
 692        /*
 693         * When a requeue is pending or this is a SIGEV_NONE
 694         * timer move the expiry time forward by intervals, so
 695         * expiry is > now.
 696         */
 697        if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
 698            (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
 699                timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
 700
 701        remaining = ktime_sub(hrtimer_get_expires(timer), now);
 702        /* Return 0 only, when the timer is expired and not pending */
 703        if (remaining.tv64 <= 0) {
 704                /*
 705                 * A single shot SIGEV_NONE timer must return 0, when
 706                 * it is expired !
 707                 */
 708                if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
 709                        cur_setting->it_value.tv_nsec = 1;
 710        } else
 711                cur_setting->it_value = ktime_to_timespec(remaining);
 712}
 713
 714/* Get the time remaining on a POSIX.1b interval timer. */
 715SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
 716                struct itimerspec __user *, setting)
 717{
 718        struct itimerspec cur_setting;
 719        struct k_itimer *timr;
 720        struct k_clock *kc;
 721        unsigned long flags;
 722        int ret = 0;
 723
 724        timr = lock_timer(timer_id, &flags);
 725        if (!timr)
 726                return -EINVAL;
 727
 728        kc = clockid_to_kclock(timr->it_clock);
 729        if (WARN_ON_ONCE(!kc || !kc->timer_get))
 730                ret = -EINVAL;
 731        else
 732                kc->timer_get(timr, &cur_setting);
 733
 734        unlock_timer(timr, flags);
 735
 736        if (!ret && copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
 737                return -EFAULT;
 738
 739        return ret;
 740}
 741
 742/*
 743 * Get the number of overruns of a POSIX.1b interval timer.  This is to
 744 * be the overrun of the timer last delivered.  At the same time we are
 745 * accumulating overruns on the next timer.  The overrun is frozen when
 746 * the signal is delivered, either at the notify time (if the info block
 747 * is not queued) or at the actual delivery time (as we are informed by
 748 * the call back to do_schedule_next_timer().  So all we need to do is
 749 * to pick up the frozen overrun.
 750 */
 751SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
 752{
 753        struct k_itimer *timr;
 754        int overrun;
 755        unsigned long flags;
 756
 757        timr = lock_timer(timer_id, &flags);
 758        if (!timr)
 759                return -EINVAL;
 760
 761        overrun = timr->it_overrun_last;
 762        unlock_timer(timr, flags);
 763
 764        return overrun;
 765}
 766
 767/* Set a POSIX.1b interval timer. */
 768/* timr->it_lock is taken. */
 769static int
 770common_timer_set(struct k_itimer *timr, int flags,
 771                 struct itimerspec *new_setting, struct itimerspec *old_setting)
 772{
 773        struct hrtimer *timer = &timr->it.real.timer;
 774        enum hrtimer_mode mode;
 775
 776        if (old_setting)
 777                common_timer_get(timr, old_setting);
 778
 779        /* disable the timer */
 780        timr->it.real.interval.tv64 = 0;
 781        /*
 782         * careful here.  If smp we could be in the "fire" routine which will
 783         * be spinning as we hold the lock.  But this is ONLY an SMP issue.
 784         */
 785        if (hrtimer_try_to_cancel(timer) < 0)
 786                return TIMER_RETRY;
 787
 788        timr->it_requeue_pending = (timr->it_requeue_pending + 2) & 
 789                ~REQUEUE_PENDING;
 790        timr->it_overrun_last = 0;
 791
 792        /* switch off the timer when it_value is zero */
 793        if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
 794                return 0;
 795
 796        mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
 797        hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
 798        timr->it.real.timer.function = posix_timer_fn;
 799
 800        hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value));
 801
 802        /* Convert interval */
 803        timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);
 804
 805        /* SIGEV_NONE timers are not queued ! See common_timer_get */
 806        if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
 807                /* Setup correct expiry time for relative timers */
 808                if (mode == HRTIMER_MODE_REL) {
 809                        hrtimer_add_expires(timer, timer->base->get_time());
 810                }
 811                return 0;
 812        }
 813
 814        hrtimer_start_expires(timer, mode);
 815        return 0;
 816}
 817
 818/* Set a POSIX.1b interval timer */
 819SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
 820                const struct itimerspec __user *, new_setting,
 821                struct itimerspec __user *, old_setting)
 822{
 823        struct k_itimer *timr;
 824        struct itimerspec new_spec, old_spec;
 825        int error = 0;
 826        unsigned long flag;
 827        struct itimerspec *rtn = old_setting ? &old_spec : NULL;
 828        struct k_clock *kc;
 829
 830        if (!new_setting)
 831                return -EINVAL;
 832
 833        if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
 834                return -EFAULT;
 835
 836        if (!timespec_valid(&new_spec.it_interval) ||
 837            !timespec_valid(&new_spec.it_value))
 838                return -EINVAL;
 839retry:
 840        timr = lock_timer(timer_id, &flag);
 841        if (!timr)
 842                return -EINVAL;
 843
 844        kc = clockid_to_kclock(timr->it_clock);
 845        if (WARN_ON_ONCE(!kc || !kc->timer_set))
 846                error = -EINVAL;
 847        else
 848                error = kc->timer_set(timr, flags, &new_spec, rtn);
 849
 850        unlock_timer(timr, flag);
 851        if (error == TIMER_RETRY) {
 852                rtn = NULL;     // We already got the old time...
 853                goto retry;
 854        }
 855
 856        if (old_setting && !error &&
 857            copy_to_user(old_setting, &old_spec, sizeof (old_spec)))
 858                error = -EFAULT;
 859
 860        return error;
 861}
 862
 863static int common_timer_del(struct k_itimer *timer)
 864{
 865        timer->it.real.interval.tv64 = 0;
 866
 867        if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
 868                return TIMER_RETRY;
 869        return 0;
 870}
 871
 872static inline int timer_delete_hook(struct k_itimer *timer)
 873{
 874        struct k_clock *kc = clockid_to_kclock(timer->it_clock);
 875
 876        if (WARN_ON_ONCE(!kc || !kc->timer_del))
 877                return -EINVAL;
 878        return kc->timer_del(timer);
 879}
 880
 881/* Delete a POSIX.1b interval timer. */
 882SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
 883{
 884        struct k_itimer *timer;
 885        unsigned long flags;
 886
 887retry_delete:
 888        timer = lock_timer(timer_id, &flags);
 889        if (!timer)
 890                return -EINVAL;
 891
 892        if (timer_delete_hook(timer) == TIMER_RETRY) {
 893                unlock_timer(timer, flags);
 894                goto retry_delete;
 895        }
 896
 897        spin_lock(&current->sighand->siglock);
 898        list_del(&timer->list);
 899        spin_unlock(&current->sighand->siglock);
 900        /*
 901         * This keeps any tasks waiting on the spin lock from thinking
 902         * they got something (see the lock code above).
 903         */
 904        timer->it_signal = NULL;
 905
 906        unlock_timer(timer, flags);
 907        release_posix_timer(timer, IT_ID_SET);
 908        return 0;
 909}
 910
 911/*
 912 * return timer owned by the process, used by exit_itimers
 913 */
 914static void itimer_delete(struct k_itimer *timer)
 915{
 916        unsigned long flags;
 917
 918retry_delete:
 919        spin_lock_irqsave(&timer->it_lock, flags);
 920
 921        if (timer_delete_hook(timer) == TIMER_RETRY) {
 922                unlock_timer(timer, flags);
 923                goto retry_delete;
 924        }
 925        list_del(&timer->list);
 926        /*
 927         * This keeps any tasks waiting on the spin lock from thinking
 928         * they got something (see the lock code above).
 929         */
 930        timer->it_signal = NULL;
 931
 932        unlock_timer(timer, flags);
 933        release_posix_timer(timer, IT_ID_SET);
 934}
 935
 936/*
 937 * This is called by do_exit or de_thread, only when there are no more
 938 * references to the shared signal_struct.
 939 */
 940void exit_itimers(struct signal_struct *sig)
 941{
 942        struct k_itimer *tmr;
 943
 944        while (!list_empty(&sig->posix_timers)) {
 945                tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
 946                itimer_delete(tmr);
 947        }
 948}
 949
 950SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
 951                const struct timespec __user *, tp)
 952{
 953        struct k_clock *kc = clockid_to_kclock(which_clock);
 954        struct timespec new_tp;
 955
 956        if (!kc || !kc->clock_set)
 957                return -EINVAL;
 958
 959        if (copy_from_user(&new_tp, tp, sizeof (*tp)))
 960                return -EFAULT;
 961
 962        return kc->clock_set(which_clock, &new_tp);
 963}
 964
 965SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 966                struct timespec __user *,tp)
 967{
 968        struct k_clock *kc = clockid_to_kclock(which_clock);
 969        struct timespec kernel_tp;
 970        int error;
 971
 972        if (!kc)
 973                return -EINVAL;
 974
 975        error = kc->clock_get(which_clock, &kernel_tp);
 976
 977        if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
 978                error = -EFAULT;
 979
 980        return error;
 981}
 982
 983SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
 984                struct timex __user *, utx)
 985{
 986        struct k_clock *kc = clockid_to_kclock(which_clock);
 987        struct timex ktx;
 988        int err;
 989
 990        if (!kc)
 991                return -EINVAL;
 992        if (!kc->clock_adj)
 993                return -EOPNOTSUPP;
 994
 995        if (copy_from_user(&ktx, utx, sizeof(ktx)))
 996                return -EFAULT;
 997
 998        err = kc->clock_adj(which_clock, &ktx);
 999
1000        if (!err && copy_to_user(utx, &ktx, sizeof(ktx)))
1001                return -EFAULT;
1002
1003        return err;
1004}
1005
1006SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
1007                struct timespec __user *, tp)
1008{
1009        struct k_clock *kc = clockid_to_kclock(which_clock);
1010        struct timespec rtn_tp;
1011        int error;
1012
1013        if (!kc)
1014                return -EINVAL;
1015
1016        error = kc->clock_getres(which_clock, &rtn_tp);
1017
1018        if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp)))
1019                error = -EFAULT;
1020
1021        return error;
1022}
1023
1024/*
1025 * nanosleep for monotonic and realtime clocks
1026 */
1027static int common_nsleep(const clockid_t which_clock, int flags,
1028                         struct timespec *tsave, struct timespec __user *rmtp)
1029{
1030        return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
1031                                 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
1032                                 which_clock);
1033}
1034
1035SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
1036                const struct timespec __user *, rqtp,
1037                struct timespec __user *, rmtp)
1038{
1039        struct k_clock *kc = clockid_to_kclock(which_clock);
1040        struct timespec t;
1041
1042        if (!kc)
1043                return -EINVAL;
1044        if (!kc->nsleep)
1045                return -ENANOSLEEP_NOTSUP;
1046
1047        if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
1048                return -EFAULT;
1049
1050        if (!timespec_valid(&t))
1051                return -EINVAL;
1052
1053        return kc->nsleep(which_clock, flags, &t, rmtp);
1054}
1055
1056/*
1057 * This will restart clock_nanosleep. This is required only by
1058 * compat_clock_nanosleep_restart for now.
1059 */
1060long clock_nanosleep_restart(struct restart_block *restart_block)
1061{
1062        clockid_t which_clock = restart_block->nanosleep.clockid;
1063        struct k_clock *kc = clockid_to_kclock(which_clock);
1064
1065        if (WARN_ON_ONCE(!kc || !kc->nsleep_restart))
1066                return -EINVAL;
1067
1068        return kc->nsleep_restart(restart_block);
1069}
1070
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