FreeBSD/Linux Kernel Cross Reference
sys/kernel/posix-timers.c

     /*
      * linux/kernel/posix-timers.c
      *
      *
      * 2002-10-15  Posix Clocks & timers
      *                           by George Anzinger george@mvista.com
      *
      *                           Copyright (C) 2002 2003 by MontaVista Software.
      *
     * 2004-06-01  Fix CLOCK_REALTIME clock/timer TIMER_ABSTIME bug.
     *                           Copyright (C) 2004 Boris Hu
     *
     * This program is free software; you can redistribute it and/or modify
     * it under the terms of the GNU General Public License as published by
     * the Free Software Foundation; either version 2 of the License, or (at
     * your option) any later version.
     *
     * This program is distributed in the hope that it will be useful, but
     * WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
     * General Public License for more details.
    
     * You should have received a copy of the GNU General Public License
     * along with this program; if not, write to the Free Software
     * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
     *
     * MontaVista Software | 1237 East Arques Avenue | Sunnyvale | CA 94085 | USA
     */
    
    /* These are all the functions necessary to implement
     * POSIX clocks & timers
     */
    #include <linux/mm.h>
    #include <linux/interrupt.h>
    #include <linux/slab.h>
    #include <linux/time.h>
    #include <linux/mutex.h>
    
    #include <asm/uaccess.h>
    #include <linux/list.h>
    #include <linux/init.h>
    #include <linux/compiler.h>
    #include <linux/idr.h>
    #include <linux/posix-clock.h>
    #include <linux/posix-timers.h>
    #include <linux/syscalls.h>
    #include <linux/wait.h>
    #include <linux/workqueue.h>
    #include <linux/export.h>
    
    /*
     * Management arrays for POSIX timers.   Timers are kept in slab memory
     * Timer ids are allocated by an external routine that keeps track of the
     * id and the timer.  The external interface is:
     *
     * void *idr_find(struct idr *idp, int id);           to find timer_id <id>
     * int idr_get_new(struct idr *idp, void *ptr);       to get a new id and
     *                                                    related it to <ptr>
     * void idr_remove(struct idr *idp, int id);          to release <id>
     * void idr_init(struct idr *idp);                    to initialize <idp>
     *                                                    which we supply.
     * The idr_get_new *may* call slab for more memory so it must not be
     * called under a spin lock.  Likewise idr_remore may release memory
     * (but it may be ok to do this under a lock...).
     * idr_find is just a memory look up and is quite fast.  A -1 return
     * indicates that the requested id does not exist.
     */
    
    /*
     * Lets keep our timers in a slab cache :-)
     */
    static struct kmem_cache *posix_timers_cache;
    static struct idr posix_timers_id;
    static DEFINE_SPINLOCK(idr_lock);
    
    /*
     * we assume that the new SIGEV_THREAD_ID shares no bits with the other
     * SIGEV values.  Here we put out an error if this assumption fails.
     */
    #if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
                           ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
    #error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
    #endif
    
    /*
     * parisc wants ENOTSUP instead of EOPNOTSUPP
     */
    #ifndef ENOTSUP
    # define ENANOSLEEP_NOTSUP EOPNOTSUPP
    #else
    # define ENANOSLEEP_NOTSUP ENOTSUP
    #endif
    
    /*
     * The timer ID is turned into a timer address by idr_find().
     * Verifying a valid ID consists of:
     *
     * a) checking that idr_find() returns other than -1.
     * b) checking that the timer id matches the one in the timer itself.
    * c) that the timer owner is in the callers thread group.
    */
   
   /*
    * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
    *          to implement others.  This structure defines the various
    *          clocks.
    *
    * RESOLUTION: Clock resolution is used to round up timer and interval
    *          times, NOT to report clock times, which are reported with as
    *          much resolution as the system can muster.  In some cases this
    *          resolution may depend on the underlying clock hardware and
    *          may not be quantifiable until run time, and only then is the
    *          necessary code is written.  The standard says we should say
    *          something about this issue in the documentation...
    *
    * FUNCTIONS: The CLOCKs structure defines possible functions to
    *          handle various clock functions.
    *
    *          The standard POSIX timer management code assumes the
    *          following: 1.) The k_itimer struct (sched.h) is used for
    *          the timer.  2.) The list, it_lock, it_clock, it_id and
    *          it_pid fields are not modified by timer code.
    *
    * Permissions: It is assumed that the clock_settime() function defined
    *          for each clock will take care of permission checks.  Some
    *          clocks may be set able by any user (i.e. local process
    *          clocks) others not.  Currently the only set able clock we
    *          have is CLOCK_REALTIME and its high res counter part, both of
    *          which we beg off on and pass to do_sys_settimeofday().
    */
   
   static struct k_clock posix_clocks[MAX_CLOCKS];
   
   /*
    * These ones are defined below.
    */
   static int common_nsleep(const clockid_t, int flags, struct timespec *t,
                            struct timespec __user *rmtp);
   static int common_timer_create(struct k_itimer *new_timer);
   static void common_timer_get(struct k_itimer *, struct itimerspec *);
   static int common_timer_set(struct k_itimer *, int,
                               struct itimerspec *, struct itimerspec *);
   static int common_timer_del(struct k_itimer *timer);
   
   static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
   
   static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
   
   #define lock_timer(tid, flags)                                             \
   ({      struct k_itimer *__timr;                                           \
           __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags));  \
           __timr;                                                            \
   })
   
   static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
   {
           spin_unlock_irqrestore(&timr->it_lock, flags);
   }
   
   /* Get clock_realtime */
   static int posix_clock_realtime_get(clockid_t which_clock, struct timespec *tp)
   {
           ktime_get_real_ts(tp);
           return 0;
   }
   
   /* Set clock_realtime */
   static int posix_clock_realtime_set(const clockid_t which_clock,
                                       const struct timespec *tp)
   {
           return do_sys_settimeofday(tp, NULL);
   }
   
   static int posix_clock_realtime_adj(const clockid_t which_clock,
                                       struct timex *t)
   {
           return do_adjtimex(t);
   }
   
   /*
    * Get monotonic time for posix timers
    */
   static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
   {
           ktime_get_ts(tp);
           return 0;
   }
   
   /*
    * Get monotonic-raw time for posix timers
    */
   static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
   {
           getrawmonotonic(tp);
           return 0;
   }
   
   
   static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
   {
           *tp = current_kernel_time();
           return 0;
   }
   
   static int posix_get_monotonic_coarse(clockid_t which_clock,
                                                   struct timespec *tp)
   {
           *tp = get_monotonic_coarse();
           return 0;
   }
   
   static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp)
   {
           *tp = ktime_to_timespec(KTIME_LOW_RES);
           return 0;
   }
   
   static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
   {
           get_monotonic_boottime(tp);
           return 0;
   }
   
   
   /*
    * Initialize everything, well, just everything in Posix clocks/timers ;)
    */
   static __init int init_posix_timers(void)
   {
           struct k_clock clock_realtime = {
                   .clock_getres   = hrtimer_get_res,
                   .clock_get      = posix_clock_realtime_get,
                   .clock_set      = posix_clock_realtime_set,
                   .clock_adj      = posix_clock_realtime_adj,
                   .nsleep         = common_nsleep,
                   .nsleep_restart = hrtimer_nanosleep_restart,
                   .timer_create   = common_timer_create,
                   .timer_set      = common_timer_set,
                   .timer_get      = common_timer_get,
                   .timer_del      = common_timer_del,
           };
           struct k_clock clock_monotonic = {
                   .clock_getres   = hrtimer_get_res,
                   .clock_get      = posix_ktime_get_ts,
                   .nsleep         = common_nsleep,
                   .nsleep_restart = hrtimer_nanosleep_restart,
                   .timer_create   = common_timer_create,
                   .timer_set      = common_timer_set,
                   .timer_get      = common_timer_get,
                   .timer_del      = common_timer_del,
           };
           struct k_clock clock_monotonic_raw = {
                   .clock_getres   = hrtimer_get_res,
                   .clock_get      = posix_get_monotonic_raw,
           };
           struct k_clock clock_realtime_coarse = {
                   .clock_getres   = posix_get_coarse_res,
                   .clock_get      = posix_get_realtime_coarse,
           };
           struct k_clock clock_monotonic_coarse = {
                   .clock_getres   = posix_get_coarse_res,
                   .clock_get      = posix_get_monotonic_coarse,
           };
           struct k_clock clock_boottime = {
                   .clock_getres   = hrtimer_get_res,
                   .clock_get      = posix_get_boottime,
                   .nsleep         = common_nsleep,
                   .nsleep_restart = hrtimer_nanosleep_restart,
                   .timer_create   = common_timer_create,
                   .timer_set      = common_timer_set,
                   .timer_get      = common_timer_get,
                   .timer_del      = common_timer_del,
           };
   
           posix_timers_register_clock(CLOCK_REALTIME, &clock_realtime);
           posix_timers_register_clock(CLOCK_MONOTONIC, &clock_monotonic);
           posix_timers_register_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
           posix_timers_register_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
           posix_timers_register_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
           posix_timers_register_clock(CLOCK_BOOTTIME, &clock_boottime);
   
           posix_timers_cache = kmem_cache_create("posix_timers_cache",
                                           sizeof (struct k_itimer), 0, SLAB_PANIC,
                                           NULL);
           idr_init(&posix_timers_id);
           return 0;
   }
   
   __initcall(init_posix_timers);
   
   static void schedule_next_timer(struct k_itimer *timr)
   {
           struct hrtimer *timer = &timr->it.real.timer;
   
           if (timr->it.real.interval.tv64 == 0)
                   return;
   
           timr->it_overrun += (unsigned int) hrtimer_forward(timer,
                                                   timer->base->get_time(),
                                                   timr->it.real.interval);
   
           timr->it_overrun_last = timr->it_overrun;
           timr->it_overrun = -1;
           ++timr->it_requeue_pending;
           hrtimer_restart(timer);
   }
   
   /*
    * This function is exported for use by the signal deliver code.  It is
    * called just prior to the info block being released and passes that
    * block to us.  It's function is to update the overrun entry AND to
    * restart the timer.  It should only be called if the timer is to be
    * restarted (i.e. we have flagged this in the sys_private entry of the
    * info block).
    *
    * To protect against the timer going away while the interrupt is queued,
    * we require that the it_requeue_pending flag be set.
    */
   void do_schedule_next_timer(struct siginfo *info)
   {
           struct k_itimer *timr;
           unsigned long flags;
   
           timr = lock_timer(info->si_tid, &flags);
   
           if (timr && timr->it_requeue_pending == info->si_sys_private) {
                   if (timr->it_clock < 0)
                           posix_cpu_timer_schedule(timr);
                   else
                           schedule_next_timer(timr);
   
                   info->si_overrun += timr->it_overrun_last;
           }
   
           if (timr)
                   unlock_timer(timr, flags);
   }
   
   int posix_timer_event(struct k_itimer *timr, int si_private)
   {
           struct task_struct *task;
           int shared, ret = -1;
           /*
            * FIXME: if ->sigq is queued we can race with
            * dequeue_signal()->do_schedule_next_timer().
            *
            * If dequeue_signal() sees the "right" value of
            * si_sys_private it calls do_schedule_next_timer().
            * We re-queue ->sigq and drop ->it_lock().
            * do_schedule_next_timer() locks the timer
            * and re-schedules it while ->sigq is pending.
            * Not really bad, but not that we want.
            */
           timr->sigq->info.si_sys_private = si_private;
   
           rcu_read_lock();
           task = pid_task(timr->it_pid, PIDTYPE_PID);
           if (task) {
                   shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID);
                   ret = send_sigqueue(timr->sigq, task, shared);
           }
           rcu_read_unlock();
           /* If we failed to send the signal the timer stops. */
           return ret > 0;
   }
   EXPORT_SYMBOL_GPL(posix_timer_event);
   
   /*
    * This function gets called when a POSIX.1b interval timer expires.  It
    * is used as a callback from the kernel internal timer.  The
    * run_timer_list code ALWAYS calls with interrupts on.
   
    * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
    */
   static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
   {
           struct k_itimer *timr;
           unsigned long flags;
           int si_private = 0;
           enum hrtimer_restart ret = HRTIMER_NORESTART;
   
           timr = container_of(timer, struct k_itimer, it.real.timer);
           spin_lock_irqsave(&timr->it_lock, flags);
   
           if (timr->it.real.interval.tv64 != 0)
                   si_private = ++timr->it_requeue_pending;
   
           if (posix_timer_event(timr, si_private)) {
                   /*
                    * signal was not sent because of sig_ignor
                    * we will not get a call back to restart it AND
                    * it should be restarted.
                    */
                   if (timr->it.real.interval.tv64 != 0) {
                           ktime_t now = hrtimer_cb_get_time(timer);
   
                           /*
                            * FIXME: What we really want, is to stop this
                            * timer completely and restart it in case the
                            * SIG_IGN is removed. This is a non trivial
                            * change which involves sighand locking
                            * (sigh !), which we don't want to do late in
                            * the release cycle.
                            *
                            * For now we just let timers with an interval
                            * less than a jiffie expire every jiffie to
                            * avoid softirq starvation in case of SIG_IGN
                            * and a very small interval, which would put
                            * the timer right back on the softirq pending
                            * list. By moving now ahead of time we trick
                            * hrtimer_forward() to expire the timer
                            * later, while we still maintain the overrun
                            * accuracy, but have some inconsistency in
                            * the timer_gettime() case. This is at least
                            * better than a starved softirq. A more
                            * complex fix which solves also another related
                            * inconsistency is already in the pipeline.
                            */
   #ifdef CONFIG_HIGH_RES_TIMERS
                           {
                                   ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ);
   
                                   if (timr->it.real.interval.tv64 < kj.tv64)
                                           now = ktime_add(now, kj);
                           }
   #endif
                           timr->it_overrun += (unsigned int)
                                   hrtimer_forward(timer, now,
                                                   timr->it.real.interval);
                           ret = HRTIMER_RESTART;
                           ++timr->it_requeue_pending;
                   }
           }
   
           unlock_timer(timr, flags);
           return ret;
   }
   
   static struct pid *good_sigevent(sigevent_t * event)
   {
           struct task_struct *rtn = current->group_leader;
   
           if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
                   (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) ||
                    !same_thread_group(rtn, current) ||
                    (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
                   return NULL;
   
           if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
               ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
                   return NULL;
   
           return task_pid(rtn);
   }
   
   void posix_timers_register_clock(const clockid_t clock_id,
                                    struct k_clock *new_clock)
   {
           if ((unsigned) clock_id >= MAX_CLOCKS) {
                   printk(KERN_WARNING "POSIX clock register failed for clock_id %d\n",
                          clock_id);
                   return;
           }
   
           if (!new_clock->clock_get) {
                   printk(KERN_WARNING "POSIX clock id %d lacks clock_get()\n",
                          clock_id);
                   return;
           }
           if (!new_clock->clock_getres) {
                   printk(KERN_WARNING "POSIX clock id %d lacks clock_getres()\n",
                          clock_id);
                   return;
           }
   
           posix_clocks[clock_id] = *new_clock;
   }
   EXPORT_SYMBOL_GPL(posix_timers_register_clock);
   
   static struct k_itimer * alloc_posix_timer(void)
   {
           struct k_itimer *tmr;
           tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
           if (!tmr)
                   return tmr;
           if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
                   kmem_cache_free(posix_timers_cache, tmr);
                   return NULL;
           }
           memset(&tmr->sigq->info, 0, sizeof(siginfo_t));
           return tmr;
   }
   
   static void k_itimer_rcu_free(struct rcu_head *head)
   {
           struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu);
   
           kmem_cache_free(posix_timers_cache, tmr);
   }
   
   #define IT_ID_SET       1
   #define IT_ID_NOT_SET   0
   static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
   {
           if (it_id_set) {
                   unsigned long flags;
                   spin_lock_irqsave(&idr_lock, flags);
                   idr_remove(&posix_timers_id, tmr->it_id);
                   spin_unlock_irqrestore(&idr_lock, flags);
           }
           put_pid(tmr->it_pid);
           sigqueue_free(tmr->sigq);
           call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
   }
   
   static struct k_clock *clockid_to_kclock(const clockid_t id)
   {
           if (id < 0)
                   return (id & CLOCKFD_MASK) == CLOCKFD ?
                           &clock_posix_dynamic : &clock_posix_cpu;
   
           if (id >= MAX_CLOCKS || !posix_clocks[id].clock_getres)
                   return NULL;
           return &posix_clocks[id];
   }
   
   static int common_timer_create(struct k_itimer *new_timer)
   {
           hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
           return 0;
   }
   
   /* Create a POSIX.1b interval timer. */
   
   SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
                   struct sigevent __user *, timer_event_spec,
                   timer_t __user *, created_timer_id)
   {
           struct k_clock *kc = clockid_to_kclock(which_clock);
           struct k_itimer *new_timer;
           int error, new_timer_id;
           sigevent_t event;
           int it_id_set = IT_ID_NOT_SET;
   
           if (!kc)
                   return -EINVAL;
           if (!kc->timer_create)
                   return -EOPNOTSUPP;
   
           new_timer = alloc_posix_timer();
           if (unlikely(!new_timer))
                   return -EAGAIN;
   
           spin_lock_init(&new_timer->it_lock);
    retry:
           if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) {
                   error = -EAGAIN;
                   goto out;
           }
           spin_lock_irq(&idr_lock);
           error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
           spin_unlock_irq(&idr_lock);
           if (error) {
                   if (error == -EAGAIN)
                           goto retry;
                   /*
                    * Weird looking, but we return EAGAIN if the IDR is
                    * full (proper POSIX return value for this)
                    */
                   error = -EAGAIN;
                   goto out;
           }
   
           it_id_set = IT_ID_SET;
           new_timer->it_id = (timer_t) new_timer_id;
           new_timer->it_clock = which_clock;
           new_timer->it_overrun = -1;
   
           if (timer_event_spec) {
                   if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
                           error = -EFAULT;
                           goto out;
                   }
                   rcu_read_lock();
                   new_timer->it_pid = get_pid(good_sigevent(&event));
                   rcu_read_unlock();
                   if (!new_timer->it_pid) {
                           error = -EINVAL;
                           goto out;
                   }
           } else {
                   event.sigev_notify = SIGEV_SIGNAL;
                   event.sigev_signo = SIGALRM;
                   event.sigev_value.sival_int = new_timer->it_id;
                   new_timer->it_pid = get_pid(task_tgid(current));
           }
   
           new_timer->it_sigev_notify     = event.sigev_notify;
           new_timer->sigq->info.si_signo = event.sigev_signo;
           new_timer->sigq->info.si_value = event.sigev_value;
           new_timer->sigq->info.si_tid   = new_timer->it_id;
           new_timer->sigq->info.si_code  = SI_TIMER;
   
           if (copy_to_user(created_timer_id,
                            &new_timer_id, sizeof (new_timer_id))) {
                   error = -EFAULT;
                   goto out;
           }
   
           error = kc->timer_create(new_timer);
           if (error)
                   goto out;
   
           spin_lock_irq(&current->sighand->siglock);
           new_timer->it_signal = current->signal;
           list_add(&new_timer->list, &current->signal->posix_timers);
           spin_unlock_irq(&current->sighand->siglock);
   
           return 0;
           /*
            * In the case of the timer belonging to another task, after
            * the task is unlocked, the timer is owned by the other task
            * and may cease to exist at any time.  Don't use or modify
            * new_timer after the unlock call.
            */
   out:
           release_posix_timer(new_timer, it_id_set);
           return error;
   }
   
   /*
    * Locking issues: We need to protect the result of the id look up until
    * we get the timer locked down so it is not deleted under us.  The
    * removal is done under the idr spinlock so we use that here to bridge
    * the find to the timer lock.  To avoid a dead lock, the timer id MUST
    * be release with out holding the timer lock.
    */
   static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
   {
           struct k_itimer *timr;
   
           rcu_read_lock();
           timr = idr_find(&posix_timers_id, (int)timer_id);
           if (timr) {
                   spin_lock_irqsave(&timr->it_lock, *flags);
                   if (timr->it_signal == current->signal) {
                           rcu_read_unlock();
                           return timr;
                   }
                   spin_unlock_irqrestore(&timr->it_lock, *flags);
           }
           rcu_read_unlock();
   
           return NULL;
   }
   
   /*
    * Get the time remaining on a POSIX.1b interval timer.  This function
    * is ALWAYS called with spin_lock_irq on the timer, thus it must not
    * mess with irq.
    *
    * We have a couple of messes to clean up here.  First there is the case
    * of a timer that has a requeue pending.  These timers should appear to
    * be in the timer list with an expiry as if we were to requeue them
    * now.
    *
    * The second issue is the SIGEV_NONE timer which may be active but is
    * not really ever put in the timer list (to save system resources).
    * This timer may be expired, and if so, we will do it here.  Otherwise
    * it is the same as a requeue pending timer WRT to what we should
    * report.
    */
   static void
   common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
   {
           ktime_t now, remaining, iv;
           struct hrtimer *timer = &timr->it.real.timer;
   
           memset(cur_setting, 0, sizeof(struct itimerspec));
   
           iv = timr->it.real.interval;
   
           /* interval timer ? */
           if (iv.tv64)
                   cur_setting->it_interval = ktime_to_timespec(iv);
           else if (!hrtimer_active(timer) &&
                    (timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
                   return;
   
           now = timer->base->get_time();
   
           /*
            * When a requeue is pending or this is a SIGEV_NONE
            * timer move the expiry time forward by intervals, so
            * expiry is > now.
            */
           if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
               (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
                   timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
   
           remaining = ktime_sub(hrtimer_get_expires(timer), now);
           /* Return 0 only, when the timer is expired and not pending */
           if (remaining.tv64 <= 0) {
                   /*
                    * A single shot SIGEV_NONE timer must return 0, when
                    * it is expired !
                    */
                   if ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)
                           cur_setting->it_value.tv_nsec = 1;
           } else
                   cur_setting->it_value = ktime_to_timespec(remaining);
   }
   
   /* Get the time remaining on a POSIX.1b interval timer. */
   SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
                   struct itimerspec __user *, setting)
   {
           struct itimerspec cur_setting;
           struct k_itimer *timr;
           struct k_clock *kc;
           unsigned long flags;
           int ret = 0;
   
           timr = lock_timer(timer_id, &flags);
           if (!timr)
                   return -EINVAL;
   
           kc = clockid_to_kclock(timr->it_clock);
           if (WARN_ON_ONCE(!kc || !kc->timer_get))
                   ret = -EINVAL;
           else
                   kc->timer_get(timr, &cur_setting);
   
           unlock_timer(timr, flags);
   
           if (!ret && copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
                   return -EFAULT;
   
           return ret;
   }
   
   /*
    * Get the number of overruns of a POSIX.1b interval timer.  This is to
    * be the overrun of the timer last delivered.  At the same time we are
    * accumulating overruns on the next timer.  The overrun is frozen when
    * the signal is delivered, either at the notify time (if the info block
    * is not queued) or at the actual delivery time (as we are informed by
    * the call back to do_schedule_next_timer().  So all we need to do is
    * to pick up the frozen overrun.
    */
   SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
   {
           struct k_itimer *timr;
           int overrun;
           unsigned long flags;
   
           timr = lock_timer(timer_id, &flags);
           if (!timr)
                   return -EINVAL;
   
           overrun = timr->it_overrun_last;
           unlock_timer(timr, flags);
   
           return overrun;
   }
   
   /* Set a POSIX.1b interval timer. */
   /* timr->it_lock is taken. */
   static int
   common_timer_set(struct k_itimer *timr, int flags,
                    struct itimerspec *new_setting, struct itimerspec *old_setting)
   {
           struct hrtimer *timer = &timr->it.real.timer;
           enum hrtimer_mode mode;
   
           if (old_setting)
                   common_timer_get(timr, old_setting);
   
           /* disable the timer */
           timr->it.real.interval.tv64 = 0;
           /*
            * careful here.  If smp we could be in the "fire" routine which will
            * be spinning as we hold the lock.  But this is ONLY an SMP issue.
            */
           if (hrtimer_try_to_cancel(timer) < 0)
                   return TIMER_RETRY;
   
           timr->it_requeue_pending = (timr->it_requeue_pending + 2) & 
                   ~REQUEUE_PENDING;
           timr->it_overrun_last = 0;
   
           /* switch off the timer when it_value is zero */
           if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
                   return 0;
   
           mode = flags & TIMER_ABSTIME ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
           hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
           timr->it.real.timer.function = posix_timer_fn;
   
           hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value));
   
           /* Convert interval */
           timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);
   
           /* SIGEV_NONE timers are not queued ! See common_timer_get */
           if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
                   /* Setup correct expiry time for relative timers */
                   if (mode == HRTIMER_MODE_REL) {
                           hrtimer_add_expires(timer, timer->base->get_time());
                   }
                   return 0;
           }
   
           hrtimer_start_expires(timer, mode);
           return 0;
   }
   
   /* Set a POSIX.1b interval timer */
   SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
                   const struct itimerspec __user *, new_setting,
                   struct itimerspec __user *, old_setting)
   {
           struct k_itimer *timr;
           struct itimerspec new_spec, old_spec;
           int error = 0;
           unsigned long flag;
           struct itimerspec *rtn = old_setting ? &old_spec : NULL;
           struct k_clock *kc;
   
           if (!new_setting)
                   return -EINVAL;
   
           if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
                   return -EFAULT;
   
           if (!timespec_valid(&new_spec.it_interval) ||
               !timespec_valid(&new_spec.it_value))
                   return -EINVAL;
   retry:
           timr = lock_timer(timer_id, &flag);
           if (!timr)
                   return -EINVAL;
   
           kc = clockid_to_kclock(timr->it_clock);
           if (WARN_ON_ONCE(!kc || !kc->timer_set))
                   error = -EINVAL;
           else
                   error = kc->timer_set(timr, flags, &new_spec, rtn);
   
           unlock_timer(timr, flag);
           if (error == TIMER_RETRY) {
                   rtn = NULL;     // We already got the old time...
                   goto retry;
           }
   
           if (old_setting && !error &&
               copy_to_user(old_setting, &old_spec, sizeof (old_spec)))
                   error = -EFAULT;
   
           return error;
   }
   
   static int common_timer_del(struct k_itimer *timer)
   {
           timer->it.real.interval.tv64 = 0;
   
           if (hrtimer_try_to_cancel(&timer->it.real.timer) < 0)
                   return TIMER_RETRY;
           return 0;
   }
   
   static inline int timer_delete_hook(struct k_itimer *timer)
   {
           struct k_clock *kc = clockid_to_kclock(timer->it_clock);
   
           if (WARN_ON_ONCE(!kc || !kc->timer_del))
                   return -EINVAL;
           return kc->timer_del(timer);
   }
   
   /* Delete a POSIX.1b interval timer. */
   SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
   {
           struct k_itimer *timer;
           unsigned long flags;
   
   retry_delete:
           timer = lock_timer(timer_id, &flags);
           if (!timer)
                   return -EINVAL;
   
           if (timer_delete_hook(timer) == TIMER_RETRY) {
                   unlock_timer(timer, flags);
                   goto retry_delete;
           }
   
           spin_lock(&current->sighand->siglock);
           list_del(&timer->list);
           spin_unlock(&current->sighand->siglock);
           /*
            * This keeps any tasks waiting on the spin lock from thinking
            * they got something (see the lock code above).
            */
           timer->it_signal = NULL;
   
           unlock_timer(timer, flags);
           release_posix_timer(timer, IT_ID_SET);
           return 0;
   }
   
   /*
    * return timer owned by the process, used by exit_itimers
    */
   static void itimer_delete(struct k_itimer *timer)
   {
           unsigned long flags;
   
   retry_delete:
           spin_lock_irqsave(&timer->it_lock, flags);
   
           if (timer_delete_hook(timer) == TIMER_RETRY) {
                   unlock_timer(timer, flags);
                   goto retry_delete;
           }
           list_del(&timer->list);
           /*
            * This keeps any tasks waiting on the spin lock from thinking
            * they got something (see the lock code above).
            */
           timer->it_signal = NULL;
   
           unlock_timer(timer, flags);
           release_posix_timer(timer, IT_ID_SET);
   }
   
   /*
    * This is called by do_exit or de_thread, only when there are no more
    * references to the shared signal_struct.
    */
   void exit_itimers(struct signal_struct *sig)
   {
           struct k_itimer *tmr;
   
           while (!list_empty(&sig->posix_timers)) {
                   tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
                   itimer_delete(tmr);
           }
   }
   
   SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
                   const struct timespec __user *, tp)
   {
           struct k_clock *kc = clockid_to_kclock(which_clock);
           struct timespec new_tp;
   
           if (!kc || !kc->clock_set)
                   return -EINVAL;
   
           if (copy_from_user(&new_tp, tp, sizeof (*tp)))
                   return -EFAULT;
   
           return kc->clock_set(which_clock, &new_tp);
   }
   
   SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
                   struct timespec __user *,tp)
   {
           struct k_clock *kc = clockid_to_kclock(which_clock);
           struct timespec kernel_tp;
           int error;
   
           if (!kc)
                   return -EINVAL;
   
           error = kc->clock_get(which_clock, &kernel_tp);
   
           if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
                   error = -EFAULT;
   
           return error;
   }
   
   SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
                   struct timex __user *, utx)
   {
           struct k_clock *kc = clockid_to_kclock(which_clock);
           struct timex ktx;
           int err;
   
           if (!kc)
                   return -EINVAL;
           if (!kc->clock_adj)
                   return -EOPNOTSUPP;
   
           if (copy_from_user(&ktx, utx, sizeof(ktx)))
                   return -EFAULT;
   
           err = kc->clock_adj(which_clock, &ktx);
   
          if (!err && copy_to_user(utx, &ktx, sizeof(ktx)))
                  return -EFAULT;
  
          return err;
  }
  
  SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
                  struct timespec __user *, tp)
  {
          struct k_clock *kc = clockid_to_kclock(which_clock);
          struct timespec rtn_tp;
          int error;
  
          if (!kc)
                  return -EINVAL;
  
          error = kc->clock_getres(which_clock, &rtn_tp);
  
          if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp)))
                  error = -EFAULT;
  
          return error;
  }
  
  /*
   * nanosleep for monotonic and realtime clocks
   */
  static int common_nsleep(const clockid_t which_clock, int flags,
                           struct timespec *tsave, struct timespec __user *rmtp)
  {
          return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
                                   HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
                                   which_clock);
  }
  
  SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
                  const struct timespec __user *, rqtp,
                  struct timespec __user *, rmtp)
  {
          struct k_clock *kc = clockid_to_kclock(which_clock);
          struct timespec t;
  
          if (!kc)
                  return -EINVAL;
          if (!kc->nsleep)
                  return -ENANOSLEEP_NOTSUP;
  
          if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
                  return -EFAULT;
  
          if (!timespec_valid(&t))
                  return -EINVAL;
  
          return kc->nsleep(which_clock, flags, &t, rmtp);
  }
  
  /*
   * This will restart clock_nanosleep. This is required only by
   * compat_clock_nanosleep_restart for now.
   */
  long clock_nanosleep_restart(struct restart_block *restart_block)
  {
          clockid_t which_clock = restart_block->nanosleep.clockid;
          struct k_clock *kc = clockid_to_kclock(which_clock);
  
          if (WARN_ON_ONCE(!kc || !kc->nsleep_restart))
                  return -EINVAL;
  
          return kc->nsleep_restart(restart_block);
  }

Cache object: 653ffc847ad60ac5f7b5b5ff815727a2