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-timers.h>
  45#include <linux/syscalls.h>
  46#include <linux/wait.h>
  47#include <linux/workqueue.h>
  48#include <linux/module.h>
  49
  50/*
  51 * Management arrays for POSIX timers.   Timers are kept in slab memory
  52 * Timer ids are allocated by an external routine that keeps track of the
  53 * id and the timer.  The external interface is:
  54 *
  55 * void *idr_find(struct idr *idp, int id);           to find timer_id <id>
  56 * int idr_get_new(struct idr *idp, void *ptr);       to get a new id and
  57 *                                                    related it to <ptr>
  58 * void idr_remove(struct idr *idp, int id);          to release <id>
  59 * void idr_init(struct idr *idp);                    to initialize <idp>
  60 *                                                    which we supply.
  61 * The idr_get_new *may* call slab for more memory so it must not be
  62 * called under a spin lock.  Likewise idr_remore may release memory
  63 * (but it may be ok to do this under a lock...).
  64 * idr_find is just a memory look up and is quite fast.  A -1 return
  65 * indicates that the requested id does not exist.
  66 */
  67
  68/*
  69 * Lets keep our timers in a slab cache :-)
  70 */
  71static struct kmem_cache *posix_timers_cache;
  72static struct idr posix_timers_id;
  73static DEFINE_SPINLOCK(idr_lock);
  74
  75/*
  76 * we assume that the new SIGEV_THREAD_ID shares no bits with the other
  77 * SIGEV values.  Here we put out an error if this assumption fails.
  78 */
  79#if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
  80                       ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
  81#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
  82#endif
  83
  84
  85/*
  86 * The timer ID is turned into a timer address by idr_find().
  87 * Verifying a valid ID consists of:
  88 *
  89 * a) checking that idr_find() returns other than -1.
  90 * b) checking that the timer id matches the one in the timer itself.
  91 * c) that the timer owner is in the callers thread group.
  92 */
  93
  94/*
  95 * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
  96 *          to implement others.  This structure defines the various
  97 *          clocks and allows the possibility of adding others.  We
  98 *          provide an interface to add clocks to the table and expect
  99 *          the "arch" code to add at least one clock that is high
 100 *          resolution.  Here we define the standard CLOCK_REALTIME as a
 101 *          1/HZ resolution clock.
 102 *
 103 * RESOLUTION: Clock resolution is used to round up timer and interval
 104 *          times, NOT to report clock times, which are reported with as
 105 *          much resolution as the system can muster.  In some cases this
 106 *          resolution may depend on the underlying clock hardware and
 107 *          may not be quantifiable until run time, and only then is the
 108 *          necessary code is written.  The standard says we should say
 109 *          something about this issue in the documentation...
 110 *
 111 * FUNCTIONS: The CLOCKs structure defines possible functions to handle
 112 *          various clock functions.  For clocks that use the standard
 113 *          system timer code these entries should be NULL.  This will
 114 *          allow dispatch without the overhead of indirect function
 115 *          calls.  CLOCKS that depend on other sources (e.g. WWV or GPS)
 116 *          must supply functions here, even if the function just returns
 117 *          ENOSYS.  The standard POSIX timer management code assumes the
 118 *          following: 1.) The k_itimer struct (sched.h) is used for the
 119 *          timer.  2.) The list, it_lock, it_clock, it_id and it_pid
 120 *          fields are not modified by timer code.
 121 *
 122 *          At this time all functions EXCEPT clock_nanosleep can be
 123 *          redirected by the CLOCKS structure.  Clock_nanosleep is in
 124 *          there, but the code ignores it.
 125 *
 126 * Permissions: It is assumed that the clock_settime() function defined
 127 *          for each clock will take care of permission checks.  Some
 128 *          clocks may be set able by any user (i.e. local process
 129 *          clocks) others not.  Currently the only set able clock we
 130 *          have is CLOCK_REALTIME and its high res counter part, both of
 131 *          which we beg off on and pass to do_sys_settimeofday().
 132 */
 133
 134static struct k_clock posix_clocks[MAX_CLOCKS];
 135
 136/*
 137 * These ones are defined below.
 138 */
 139static int common_nsleep(const clockid_t, int flags, struct timespec *t,
 140                         struct timespec __user *rmtp);
 141static void common_timer_get(struct k_itimer *, struct itimerspec *);
 142static int common_timer_set(struct k_itimer *, int,
 143                            struct itimerspec *, struct itimerspec *);
 144static int common_timer_del(struct k_itimer *timer);
 145
 146static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
 147
 148static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags);
 149
 150static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
 151{
 152        spin_unlock_irqrestore(&timr->it_lock, flags);
 153}
 154
 155/*
 156 * Call the k_clock hook function if non-null, or the default function.
 157 */
 158#define CLOCK_DISPATCH(clock, call, arglist) \
 159        ((clock) < 0 ? posix_cpu_##call arglist : \
 160         (posix_clocks[clock].call != NULL \
 161          ? (*posix_clocks[clock].call) arglist : common_##call arglist))
 162
 163/*
 164 * Default clock hook functions when the struct k_clock passed
 165 * to register_posix_clock leaves a function pointer null.
 166 *
 167 * The function common_CALL is the default implementation for
 168 * the function pointer CALL in struct k_clock.
 169 */
 170
 171static inline int common_clock_getres(const clockid_t which_clock,
 172                                      struct timespec *tp)
 173{
 174        tp->tv_sec = 0;
 175        tp->tv_nsec = posix_clocks[which_clock].res;
 176        return 0;
 177}
 178
 179/*
 180 * Get real time for posix timers
 181 */
 182static int common_clock_get(clockid_t which_clock, struct timespec *tp)
 183{
 184        ktime_get_real_ts(tp);
 185        return 0;
 186}
 187
 188static inline int common_clock_set(const clockid_t which_clock,
 189                                   struct timespec *tp)
 190{
 191        return do_sys_settimeofday(tp, NULL);
 192}
 193
 194static int common_timer_create(struct k_itimer *new_timer)
 195{
 196        hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
 197        return 0;
 198}
 199
 200static int no_timer_create(struct k_itimer *new_timer)
 201{
 202        return -EOPNOTSUPP;
 203}
 204
 205/*
 206 * Return nonzero if we know a priori this clockid_t value is bogus.
 207 */
 208static inline int invalid_clockid(const clockid_t which_clock)
 209{
 210        if (which_clock < 0)    /* CPU clock, posix_cpu_* will check it */
 211                return 0;
 212        if ((unsigned) which_clock >= MAX_CLOCKS)
 213                return 1;
 214        if (posix_clocks[which_clock].clock_getres != NULL)
 215                return 0;
 216        if (posix_clocks[which_clock].res != 0)
 217                return 0;
 218        return 1;
 219}
 220
 221/*
 222 * Get monotonic time for posix timers
 223 */
 224static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
 225{
 226        ktime_get_ts(tp);
 227        return 0;
 228}
 229
 230/*
 231 * Get monotonic time for posix timers
 232 */
 233static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
 234{
 235        getrawmonotonic(tp);
 236        return 0;
 237}
 238
 239/*
 240 * Initialize everything, well, just everything in Posix clocks/timers ;)
 241 */
 242static __init int init_posix_timers(void)
 243{
 244        struct k_clock clock_realtime = {
 245                .clock_getres = hrtimer_get_res,
 246        };
 247        struct k_clock clock_monotonic = {
 248                .clock_getres = hrtimer_get_res,
 249                .clock_get = posix_ktime_get_ts,
 250                .clock_set = do_posix_clock_nosettime,
 251        };
 252        struct k_clock clock_monotonic_raw = {
 253                .clock_getres = hrtimer_get_res,
 254                .clock_get = posix_get_monotonic_raw,
 255                .clock_set = do_posix_clock_nosettime,
 256                .timer_create = no_timer_create,
 257        };
 258
 259        register_posix_clock(CLOCK_REALTIME, &clock_realtime);
 260        register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic);
 261        register_posix_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
 262
 263        posix_timers_cache = kmem_cache_create("posix_timers_cache",
 264                                        sizeof (struct k_itimer), 0, SLAB_PANIC,
 265                                        NULL);
 266        idr_init(&posix_timers_id);
 267        return 0;
 268}
 269
 270__initcall(init_posix_timers);
 271
 272static void schedule_next_timer(struct k_itimer *timr)
 273{
 274        struct hrtimer *timer = &timr->it.real.timer;
 275
 276        if (timr->it.real.interval.tv64 == 0)
 277                return;
 278
 279        timr->it_overrun += (unsigned int) hrtimer_forward(timer,
 280                                                timer->base->get_time(),
 281                                                timr->it.real.interval);
 282
 283        timr->it_overrun_last = timr->it_overrun;
 284        timr->it_overrun = -1;
 285        ++timr->it_requeue_pending;
 286        hrtimer_restart(timer);
 287}
 288
 289/*
 290 * This function is exported for use by the signal deliver code.  It is
 291 * called just prior to the info block being released and passes that
 292 * block to us.  It's function is to update the overrun entry AND to
 293 * restart the timer.  It should only be called if the timer is to be
 294 * restarted (i.e. we have flagged this in the sys_private entry of the
 295 * info block).
 296 *
 297 * To protect aginst the timer going away while the interrupt is queued,
 298 * we require that the it_requeue_pending flag be set.
 299 */
 300void do_schedule_next_timer(struct siginfo *info)
 301{
 302        struct k_itimer *timr;
 303        unsigned long flags;
 304
 305        timr = lock_timer(info->si_tid, &flags);
 306
 307        if (timr && timr->it_requeue_pending == info->si_sys_private) {
 308                if (timr->it_clock < 0)
 309                        posix_cpu_timer_schedule(timr);
 310                else
 311                        schedule_next_timer(timr);
 312
 313                info->si_overrun += timr->it_overrun_last;
 314        }
 315
 316        if (timr)
 317                unlock_timer(timr, flags);
 318}
 319
 320int posix_timer_event(struct k_itimer *timr, int si_private)
 321{
 322        struct task_struct *task;
 323        int shared, ret = -1;
 324        /*
 325         * FIXME: if ->sigq is queued we can race with
 326         * dequeue_signal()->do_schedule_next_timer().
 327         *
 328         * If dequeue_signal() sees the "right" value of
 329         * si_sys_private it calls do_schedule_next_timer().
 330         * We re-queue ->sigq and drop ->it_lock().
 331         * do_schedule_next_timer() locks the timer
 332         * and re-schedules it while ->sigq is pending.
 333         * Not really bad, but not that we want.
 334         */
 335        timr->sigq->info.si_sys_private = si_private;
 336
 337        rcu_read_lock();
 338        task = pid_task(timr->it_pid, PIDTYPE_PID);
 339        if (task) {
 340                shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
 341                ret = send_sigqueue(timr->sigq, task, shared);
 342        }
 343        rcu_read_unlock();
 344        /* If we failed to send the signal the timer stops. */
 345        return ret > 0;
 346}
 347EXPORT_SYMBOL_GPL(posix_timer_event);
 348
 349/*
 350 * This function gets called when a POSIX.1b interval timer expires.  It
 351 * is used as a callback from the kernel internal timer.  The
 352 * run_timer_list code ALWAYS calls with interrupts on.
 353
 354 * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
 355 */
 356static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
 357{
 358        struct k_itimer *timr;
 359        unsigned long flags;
 360        int si_private = 0;
 361        enum hrtimer_restart ret = HRTIMER_NORESTART;
 362
 363        timr = container_of(timer, struct k_itimer, it.real.timer);
 364        spin_lock_irqsave(&timr->it_lock, flags);
 365
 366        if (timr->it.real.interval.tv64 != 0)
 367                si_private = ++timr->it_requeue_pending;
 368
 369        if (posix_timer_event(timr, si_private)) {
 370                /*
 371                 * signal was not sent because of sig_ignor
 372                 * we will not get a call back to restart it AND
 373                 * it should be restarted.
 374                 */
 375                if (timr->it.real.interval.tv64 != 0) {
 376                        ktime_t now = hrtimer_cb_get_time(timer);
 377
 378                        /*
 379                         * FIXME: What we really want, is to stop this
 380                         * timer completely and restart it in case the
 381                         * SIG_IGN is removed. This is a non trivial
 382                         * change which involves sighand locking
 383                         * (sigh !), which we don't want to do late in
 384                         * the release cycle.
 385                         *
 386                         * For now we just let timers with an interval
 387                         * less than a jiffie expire every jiffie to
 388                         * avoid softirq starvation in case of SIG_IGN
 389                         * and a very small interval, which would put
 390                         * the timer right back on the softirq pending
 391                         * list. By moving now ahead of time we trick
 392                         * hrtimer_forward() to expire the timer
 393                         * later, while we still maintain the overrun
 394                         * accuracy, but have some inconsistency in
 395                         * the timer_gettime() case. This is at least
 396                         * better than a starved softirq. A more
 397                         * complex fix which solves also another related
 398                         * inconsistency is already in the pipeline.
 399                         */
 400#ifdef CONFIG_HIGH_RES_TIMERS
 401                        {
 402                                ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ);
 403
 404                                if (timr->it.real.interval.tv64 < kj.tv64)
 405                                        now = ktime_add(now, kj);
 406                        }
 407#endif
 408                        timr->it_overrun += (unsigned int)
 409                                hrtimer_forward(timer, now,
 410                                                timr->it.real.interval);
 411                        ret = HRTIMER_RESTART;
 412                        ++timr->it_requeue_pending;
 413                }
 414        }
 415
 416        unlock_timer(timr, flags);
 417        return ret;
 418}
 419
 420static struct pid *good_sigevent(sigevent_t * event)
 421{
 422        struct task_struct *rtn = current->group_leader;
 423
 424        if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
 425                (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) ||
 426                 !same_thread_group(rtn, current) ||
 427                 (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
 428                return NULL;
 429
 430        if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
 431            ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
 432                return NULL;
 433
 434        return task_pid(rtn);
 435}
 436
 437void register_posix_clock(const clockid_t clock_id, struct k_clock *new_clock)
 438{
 439        if ((unsigned) clock_id >= MAX_CLOCKS) {
 440                printk("POSIX clock register failed for clock_id %d\n",
 441                       clock_id);
 442                return;
 443        }
 444
 445        posix_clocks[clock_id] = *new_clock;
 446}
 447EXPORT_SYMBOL_GPL(register_posix_clock);
 448
 449static struct k_itimer * alloc_posix_timer(void)
 450{
 451        struct k_itimer *tmr;
 452        tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
 453        if (!tmr)
 454                return tmr;
 455        if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
 456                kmem_cache_free(posix_timers_cache, tmr);
 457                return NULL;
 458        }
 459        memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
 460        return tmr;
 461}
 462
 463#define IT_ID_SET       1
 464#define IT_ID_NOT_SET   0
 465static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
 466{
 467        if (it_id_set) {
 468                unsigned long flags;
 469                spin_lock_irqsave(&idr_lock, flags);
 470                idr_remove(&posix_timers_id, tmr->it_id);
 471                spin_unlock_irqrestore(&idr_lock, flags);
 472        }
 473        put_pid(tmr->it_pid);
 474        sigqueue_free(tmr->sigq);
 475        kmem_cache_free(posix_timers_cache, tmr);
 476}
 477
 478/* Create a POSIX.1b interval timer. */
 479
 480SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
 481                struct sigevent __user *, timer_event_spec,
 482                timer_t __user *, created_timer_id)
 483{
 484        struct k_itimer *new_timer;
 485        int error, new_timer_id;
 486        sigevent_t event;
 487        int it_id_set = IT_ID_NOT_SET;
 488
 489        if (invalid_clockid(which_clock))
 490                return -EINVAL;
 491
 492        new_timer = alloc_posix_timer();
 493        if (unlikely(!new_timer))
 494                return -EAGAIN;
 495
 496        spin_lock_init(&new_timer->it_lock);
 497 retry:
 498        if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) {
 499                error = -EAGAIN;
 500                goto out;
 501        }
 502        spin_lock_irq(&idr_lock);
 503        error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
 504        spin_unlock_irq(&idr_lock);
 505        if (error) {
 506                if (error == -EAGAIN)
 507                        goto retry;
 508                /*
 509                 * Weird looking, but we return EAGAIN if the IDR is
 510                 * full (proper POSIX return value for this)
 511                 */
 512                error = -EAGAIN;
 513                goto out;
 514        }
 515
 516        it_id_set = IT_ID_SET;
 517        new_timer->it_id = (timer_t) new_timer_id;
 518        new_timer->it_clock = which_clock;
 519        new_timer->it_overrun = -1;
 520        error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
 521        if (error)
 522                goto out;
 523
 524        /*
 525         * return the timer_id now.  The next step is hard to
 526         * back out if there is an error.
 527         */
 528        if (copy_to_user(created_timer_id,
 529                         &new_timer_id, sizeof (new_timer_id))) {
 530                error = -EFAULT;
 531                goto out;
 532        }
 533        if (timer_event_spec) {
 534                if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
 535                        error = -EFAULT;
 536                        goto out;
 537                }
 538                rcu_read_lock();
 539                new_timer->it_pid = get_pid(good_sigevent(&event));
 540                rcu_read_unlock();
 541                if (!new_timer->it_pid) {
 542                        error = -EINVAL;
 543                        goto out;
 544                }
 545        } else {
 546                event.sigev_notify = SIGEV_SIGNAL;
 547                event.sigev_signo = SIGALRM;
 548                event.sigev_value.sival_int = new_timer->it_id;
 549                new_timer->it_pid = get_pid(task_tgid(current));
 550        }
 551
 552        new_timer->it_sigev_notify     = event.sigev_notify;
 553        new_timer->sigq->info.si_signo = event.sigev_signo;
 554        new_timer->sigq->info.si_value = event.sigev_value;
 555        new_timer->sigq->info.si_tid   = new_timer->it_id;
 556        new_timer->sigq->info.si_code  = SI_TIMER;
 557
 558        spin_lock_irq(&current->sighand->siglock);
 559        new_timer->it_signal = current->signal;
 560        list_add(&new_timer->list, &current->signal->posix_timers);
 561        spin_unlock_irq(&current->sighand->siglock);
 562
 563        return 0;
 564        /*
 565         * In the case of the timer belonging to another task, after
 566         * the task is unlocked, the timer is owned by the other task
 567         * and may cease to exist at any time.  Don't use or modify
 568         * new_timer after the unlock call.
 569         */
 570out:
 571        release_posix_timer(new_timer, it_id_set);
 572        return error;
 573}
 574
 575/*
 576 * Locking issues: We need to protect the result of the id look up until
 577 * we get the timer locked down so it is not deleted under us.  The
 578 * removal is done under the idr spinlock so we use that here to bridge
 579 * the find to the timer lock.  To avoid a dead lock, the timer id MUST
 580 * be release with out holding the timer lock.
 581 */
 582static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags)
 583{
 584        struct k_itimer *timr;
 585        /*
 586         * Watch out here.  We do a irqsave on the idr_lock and pass the
 587         * flags part over to the timer lock.  Must not let interrupts in
 588         * while we are moving the lock.
 589         */
 590        spin_lock_irqsave(&idr_lock, *flags);
 591        timr = idr_find(&posix_timers_id, (int)timer_id);
 592        if (timr) {
 593                spin_lock(&timr->it_lock);
 594                if (timr->it_signal == current->signal) {
 595                        spin_unlock(&idr_lock);
 596                        return timr;
 597                }
 598                spin_unlock(&timr->it_lock);
 599        }
 600        spin_unlock_irqrestore(&idr_lock, *flags);
 601
 602        return NULL;
 603}
 604
 605/*
 606 * Get the time remaining on a POSIX.1b interval timer.  This function
 607 * is ALWAYS called with spin_lock_irq on the timer, thus it must not
 608 * mess with irq.
 609 *
 610 * We have a couple of messes to clean up here.  First there is the case
 611 * of a timer that has a requeue pending.  These timers should appear to
 612 * be in the timer list with an expiry as if we were to requeue them
 613 * now.
 614 *
 615 * The second issue is the SIGEV_NONE timer which may be active but is
 616 * not really ever put in the timer list (to save system resources).
 617 * This timer may be expired, and if so, we will do it here.  Otherwise
 618 * it is the same as a requeue pending timer WRT to what we should
 619 * report.
 620 */
 621static void
 622common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
 623{
 624        ktime_t now, remaining, iv;
 625        struct hrtimer *timer = &timr->it.real.timer;
 626
 627        memset(cur_setting, 0, sizeof(struct itimerspec));
 628
 629        iv = timr->it.real.interval;
 630
 631        /* interval timer ? */
 632        if (iv.tv64)
 633                cur_setting->it_interval = ktime_to_timespec(iv);
 634        else if (!hrtimer_active(timer) &&
 635                 (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
 636                return;
 637
 638        now = timer->base->get_time();
 639
 640        /*
 641         * When a requeue is pending or this is a SIGEV_NONE
 642         * timer move the expiry time forward by intervals, so
 643         * expiry is > now.
 644         */
 645        if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
 646            (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
 647                timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
 648
 649        remaining = ktime_sub(hrtimer_get_expires(timer), now);
 650        /* Return 0 only, when the timer is expired and not pending */
 651        if (remaining.tv64 <= 0) {
 652                /*
 653                 * A single shot SIGEV_NONE timer must return 0, when
 654                 * it is expired !
 655                 */
 656                if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
 657                        cur_setting->it_value.tv_nsec = 1;
 658        } else
 659                cur_setting->it_value = ktime_to_timespec(remaining);
 660}
 661
 662/* Get the time remaining on a POSIX.1b interval timer. */
 663SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
 664                struct itimerspec __user *, setting)
 665{
 666        struct k_itimer *timr;
 667        struct itimerspec cur_setting;
 668        unsigned long flags;
 669
 670        timr = lock_timer(timer_id, &flags);
 671        if (!timr)
 672                return -EINVAL;
 673
 674        CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting));
 675
 676        unlock_timer(timr, flags);
 677
 678        if (copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
 679                return -EFAULT;
 680
 681        return 0;
 682}
 683
 684/*
 685 * Get the number of overruns of a POSIX.1b interval timer.  This is to
 686 * be the overrun of the timer last delivered.  At the same time we are
 687 * accumulating overruns on the next timer.  The overrun is frozen when
 688 * the signal is delivered, either at the notify time (if the info block
 689 * is not queued) or at the actual delivery time (as we are informed by
 690 * the call back to do_schedule_next_timer().  So all we need to do is
 691 * to pick up the frozen overrun.
 692 */
 693SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
 694{
 695        struct k_itimer *timr;
 696        int overrun;
 697        unsigned long flags;
 698
 699        timr = lock_timer(timer_id, &flags);
 700        if (!timr)
 701                return -EINVAL;
 702
 703        overrun = timr->it_overrun_last;
 704        unlock_timer(timr, flags);
 705
 706        return overrun;
 707}
 708
 709/* Set a POSIX.1b interval timer. */
 710/* timr->it_lock is taken. */
 711static int
 712common_timer_set(struct k_itimer *timr, int flags,
 713                 struct itimerspec *new_setting, struct itimerspec *old_setting)
 714{
 715        struct hrtimer *timer = &timr->it.real.timer;
 716        enum hrtimer_mode mode;
 717
 718        if (old_setting)
 719                common_timer_get(timr, old_setting);
 720
 721        /* disable the timer */
 722        timr->it.real.interval.tv64 = 0;
 723        /*
 724         * careful here.  If smp we could be in the "fire" routine which will
 725         * be spinning as we hold the lock.  But this is ONLY an SMP issue.
 726         */
 727        if (hrtimer_try_to_cancel(timer) < 0)
 728                return TIMER_RETRY;
 729
 730        timr->it_requeue_pending = (timr->it_requeue_pending + 2) & 
 731                ~REQUEUE_PENDING;
 732        timr->it_overrun_last = 0;
 733
 734        /* switch off the timer when it_value is zero */
 735        if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
 736                return 0;
 737
 738        mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
 739        hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
 740        timr->it.real.timer.function = posix_timer_fn;
 741
 742        hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value));
 743
 744        /* Convert interval */
 745        timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);
 746
 747        /* SIGEV_NONE timers are not queued ! See common_timer_get */
 748        if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
 749                /* Setup correct expiry time for relative timers */
 750                if (mode == HRTIMER_MODE_REL) {
 751                        hrtimer_add_expires(timer, timer->base->get_time());
 752                }
 753                return 0;
 754        }
 755
 756        hrtimer_start_expires(timer, mode);
 757        return 0;
 758}
 759
 760/* Set a POSIX.1b interval timer */
 761SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
 762                const struct itimerspec __user *, new_setting,
 763                struct itimerspec __user *, old_setting)
 764{
 765        struct k_itimer *timr;
 766        struct itimerspec new_spec, old_spec;
 767        int error = 0;
 768        unsigned long flag;
 769        struct itimerspec *rtn = old_setting ? &old_spec : NULL;
 770
 771        if (!new_setting)
 772                return -EINVAL;
 773
 774        if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
 775                return -EFAULT;
 776
 777        if (!timespec_valid(&new_spec.it_interval) ||
 778            !timespec_valid(&new_spec.it_value))
 779                return -EINVAL;
 780retry:
 781        timr = lock_timer(timer_id, &flag);
 782        if (!timr)
 783                return -EINVAL;
 784
 785        error = CLOCK_DISPATCH(timr->it_clock, timer_set,
 786                               (timr, flags, &new_spec, rtn));
 787
 788        unlock_timer(timr, flag);
 789        if (error == TIMER_RETRY) {
 790                rtn = NULL;     // We already got the old time...
 791                goto retry;
 792        }
 793
 794        if (old_setting && !error &&
 795            copy_to_user(old_setting, &old_spec, sizeof (old_spec)))
 796                error = -EFAULT;
 797
 798        return error;
 799}
 800
 801static inline int common_timer_del(struct k_itimer *timer)
 802{
 803        timer->it.real.interval.tv64 = 0;
 804
 805        if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
 806                return TIMER_RETRY;
 807        return 0;
 808}
 809
 810static inline int timer_delete_hook(struct k_itimer *timer)
 811{
 812        return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer));
 813}
 814
 815/* Delete a POSIX.1b interval timer. */
 816SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
 817{
 818        struct k_itimer *timer;
 819        unsigned long flags;
 820
 821retry_delete:
 822        timer = lock_timer(timer_id, &flags);
 823        if (!timer)
 824                return -EINVAL;
 825
 826        if (timer_delete_hook(timer) == TIMER_RETRY) {
 827                unlock_timer(timer, flags);
 828                goto retry_delete;
 829        }
 830
 831        spin_lock(&current->sighand->siglock);
 832        list_del(&timer->list);
 833        spin_unlock(&current->sighand->siglock);
 834        /*
 835         * This keeps any tasks waiting on the spin lock from thinking
 836         * they got something (see the lock code above).
 837         */
 838        timer->it_signal = NULL;
 839
 840        unlock_timer(timer, flags);
 841        release_posix_timer(timer, IT_ID_SET);
 842        return 0;
 843}
 844
 845/*
 846 * return timer owned by the process, used by exit_itimers
 847 */
 848static void itimer_delete(struct k_itimer *timer)
 849{
 850        unsigned long flags;
 851
 852retry_delete:
 853        spin_lock_irqsave(&timer->it_lock, flags);
 854
 855        if (timer_delete_hook(timer) == TIMER_RETRY) {
 856                unlock_timer(timer, flags);
 857                goto retry_delete;
 858        }
 859        list_del(&timer->list);
 860        /*
 861         * This keeps any tasks waiting on the spin lock from thinking
 862         * they got something (see the lock code above).
 863         */
 864        timer->it_signal = NULL;
 865
 866        unlock_timer(timer, flags);
 867        release_posix_timer(timer, IT_ID_SET);
 868}
 869
 870/*
 871 * This is called by do_exit or de_thread, only when there are no more
 872 * references to the shared signal_struct.
 873 */
 874void exit_itimers(struct signal_struct *sig)
 875{
 876        struct k_itimer *tmr;
 877
 878        while (!list_empty(&sig->posix_timers)) {
 879                tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
 880                itimer_delete(tmr);
 881        }
 882}
 883
 884/* Not available / possible... functions */
 885int do_posix_clock_nosettime(const clockid_t clockid, struct timespec *tp)
 886{
 887        return -EINVAL;
 888}
 889EXPORT_SYMBOL_GPL(do_posix_clock_nosettime);
 890
 891int do_posix_clock_nonanosleep(const clockid_t clock, int flags,
 892                               struct timespec *t, struct timespec __user *r)
 893{
 894#ifndef ENOTSUP
 895        return -EOPNOTSUPP;     /* aka ENOTSUP in userland for POSIX */
 896#else  /*  parisc does define it separately.  */
 897        return -ENOTSUP;
 898#endif
 899}
 900EXPORT_SYMBOL_GPL(do_posix_clock_nonanosleep);
 901
 902SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
 903                const struct timespec __user *, tp)
 904{
 905        struct timespec new_tp;
 906
 907        if (invalid_clockid(which_clock))
 908                return -EINVAL;
 909        if (copy_from_user(&new_tp, tp, sizeof (*tp)))
 910                return -EFAULT;
 911
 912        return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp));
 913}
 914
 915SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
 916                struct timespec __user *,tp)
 917{
 918        struct timespec kernel_tp;
 919        int error;
 920
 921        if (invalid_clockid(which_clock))
 922                return -EINVAL;
 923        error = CLOCK_DISPATCH(which_clock, clock_get,
 924                               (which_clock, &kernel_tp));
 925        if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
 926                error = -EFAULT;
 927
 928        return error;
 929
 930}
 931
 932SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
 933                struct timespec __user *, tp)
 934{
 935        struct timespec rtn_tp;
 936        int error;
 937
 938        if (invalid_clockid(which_clock))
 939                return -EINVAL;
 940
 941        error = CLOCK_DISPATCH(which_clock, clock_getres,
 942                               (which_clock, &rtn_tp));
 943
 944        if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) {
 945                error = -EFAULT;
 946        }
 947
 948        return error;
 949}
 950
 951/*
 952 * nanosleep for monotonic and realtime clocks
 953 */
 954static int common_nsleep(const clockid_t which_clock, int flags,
 955                         struct timespec *tsave, struct timespec __user *rmtp)
 956{
 957        return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
 958                                 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
 959                                 which_clock);
 960}
 961
 962SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 963                const struct timespec __user *, rqtp,
 964                struct timespec __user *, rmtp)
 965{
 966        struct timespec t;
 967
 968        if (invalid_clockid(which_clock))
 969                return -EINVAL;
 970
 971        if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
 972                return -EFAULT;
 973
 974        if (!timespec_valid(&t))
 975                return -EINVAL;
 976
 977        return CLOCK_DISPATCH(which_clock, nsleep,
 978                              (which_clock, flags, &t, rmtp));
 979}
 980
 981/*
 982 * nanosleep_restart for monotonic and realtime clocks
 983 */
 984static int common_nsleep_restart(struct restart_block *restart_block)
 985{
 986        return hrtimer_nanosleep_restart(restart_block);
 987}
 988
 989/*
 990 * This will restart clock_nanosleep. This is required only by
 991 * compat_clock_nanosleep_restart for now.
 992 */
 993long
 994clock_nanosleep_restart(struct restart_block *restart_block)
 995{
 996        clockid_t which_clock = restart_block->arg0;
 997
 998        return CLOCK_DISPATCH(which_clock, nsleep_restart,
 999                              (restart_block));
1000}
1001
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