1 files changed, 1584 insertions, 0 deletions

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
new file mode 100644
index 000000000000..fd316c272260
--- /dev/null
+++ b/kernel/posix-timers.c
@@ -0,0 +1,1584 @@
+/*
+ * 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/smp_lock.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/compiler.h>
+#include <linux/idr.h>
+#include <linux/posix-timers.h>
+#include <linux/syscalls.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <linux/module.h>
+
+#ifndef div_long_long_rem
+#include <asm/div64.h>
+
+#define div_long_long_rem(dividend,divisor,remainder) ({ \
+                       u64 result = dividend;           \
+                       *remainder = do_div(result,divisor); \
+                       result; })
+
+#endif
+#define CLOCK_REALTIME_RES TICK_NSEC  /* In nano seconds. */
+
+static inline u64  mpy_l_X_l_ll(unsigned long mpy1,unsigned long mpy2)
+{
+        return (u64)mpy1 * mpy2;
+}
+/*
+ * 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 kmem_cache_t *posix_timers_cache;
+static struct idr posix_timers_id;
+static DEFINE_SPINLOCK(idr_lock);
+
+/*
+ * Just because the timer is not in the timer list does NOT mean it is
+ * inactive.  It could be in the "fire" routine getting a new expire time.
+ */
+#define TIMER_INACTIVE 1
+
+#ifdef CONFIG_SMP
+# define timer_active(tmr) \
+                ((tmr)->it.real.timer.entry.prev != (void *)TIMER_INACTIVE)
+# define set_timer_inactive(tmr) \
+                do { \
+                        (tmr)->it.real.timer.entry.prev = (void *)TIMER_INACTIVE; \
+                } while (0)
+#else
+# define timer_active(tmr) BARFY        // error to use outside of SMP
+# define set_timer_inactive(tmr) do { } while (0)
+#endif
+/*
+ * 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
+
+
+/*
+ * 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 and allows the possibility of adding others.  We
+ *          provide an interface to add clocks to the table and expect
+ *          the "arch" code to add at least one clock that is high
+ *          resolution.  Here we define the standard CLOCK_REALTIME as a
+ *          1/HZ resolution clock.
+ *
+ * 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.  For clocks that use the standard
+ *          system timer code these entries should be NULL.  This will
+ *          allow dispatch without the overhead of indirect function
+ *          calls.  CLOCKS that depend on other sources (e.g. WWV or GPS)
+ *          must supply functions here, even if the function just returns
+ *          ENOSYS.  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_process
+ *          fields are not modified by timer code.
+ *
+ *          At this time all functions EXCEPT clock_nanosleep can be
+ *          redirected by the CLOCKS structure.  Clock_nanosleep is in
+ *          there, but the code ignores it.
+ *
+ * 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];
+/*
+ * We only have one real clock that can be set so we need only one abs list,
+ * even if we should want to have several clocks with differing resolutions.
+ */
+static struct k_clock_abs abs_list = {.list = LIST_HEAD_INIT(abs_list.list),
+                                      .lock = SPIN_LOCK_UNLOCKED};
+
+static void posix_timer_fn(unsigned long);
+static u64 do_posix_clock_monotonic_gettime_parts(
+        struct timespec *tp, struct timespec *mo);
+int do_posix_clock_monotonic_gettime(struct timespec *tp);
+static int do_posix_clock_monotonic_get(clockid_t, struct timespec *tp);
+
+static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags);
+
+static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
+{
+        spin_unlock_irqrestore(&timr->it_lock, flags);
+}
+
+/*
+ * Call the k_clock hook function if non-null, or the default function.
+ */
+#define CLOCK_DISPATCH(clock, call, arglist) \
+        ((clock) < 0 ? posix_cpu_##call arglist : \
+         (posix_clocks[clock].call != NULL \
+          ? (*posix_clocks[clock].call) arglist : common_##call arglist))
+
+/*
+ * Default clock hook functions when the struct k_clock passed
+ * to register_posix_clock leaves a function pointer null.
+ *
+ * The function common_CALL is the default implementation for
+ * the function pointer CALL in struct k_clock.
+ */
+
+static inline int common_clock_getres(clockid_t which_clock,
+                                      struct timespec *tp)
+{
+        tp->tv_sec = 0;
+        tp->tv_nsec = posix_clocks[which_clock].res;
+        return 0;
+}
+
+static inline int common_clock_get(clockid_t which_clock, struct timespec *tp)
+{
+        getnstimeofday(tp);
+        return 0;
+}
+
+static inline int common_clock_set(clockid_t which_clock, struct timespec *tp)
+{
+        return do_sys_settimeofday(tp, NULL);
+}
+
+static inline int common_timer_create(struct k_itimer *new_timer)
+{
+        INIT_LIST_HEAD(&new_timer->it.real.abs_timer_entry);
+        init_timer(&new_timer->it.real.timer);
+        new_timer->it.real.timer.data = (unsigned long) new_timer;
+        new_timer->it.real.timer.function = posix_timer_fn;
+        set_timer_inactive(new_timer);
+        return 0;
+}
+
+/*
+ * These ones are defined below.
+ */
+static int common_nsleep(clockid_t, int flags, struct timespec *t);
+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);
+
+/*
+ * Return nonzero iff we know a priori this clockid_t value is bogus.
+ */
+static inline int invalid_clockid(clockid_t which_clock)
+{
+        if (which_clock < 0)    /* CPU clock, posix_cpu_* will check it */
+                return 0;
+        if ((unsigned) which_clock >= MAX_CLOCKS)
+                return 1;
+        if (posix_clocks[which_clock].clock_getres != NULL)
+                return 0;
+#ifndef CLOCK_DISPATCH_DIRECT
+        if (posix_clocks[which_clock].res != 0)
+                return 0;
+#endif
+        return 1;
+}
+
+
+/*
+ * Initialize everything, well, just everything in Posix clocks/timers ;)
+ */
+static __init int init_posix_timers(void)
+{
+        struct k_clock clock_realtime = {.res = CLOCK_REALTIME_RES,
+                                         .abs_struct = &abs_list
+        };
+        struct k_clock clock_monotonic = {.res = CLOCK_REALTIME_RES,
+                .abs_struct = NULL,
+                .clock_get = do_posix_clock_monotonic_get,
+                .clock_set = do_posix_clock_nosettime
+        };
+
+        register_posix_clock(CLOCK_REALTIME, &clock_realtime);
+        register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic);
+
+        posix_timers_cache = kmem_cache_create("posix_timers_cache",
+                                        sizeof (struct k_itimer), 0, 0, NULL, NULL);
+        idr_init(&posix_timers_id);
+        return 0;
+}
+
+__initcall(init_posix_timers);
+
+static void tstojiffie(struct timespec *tp, int res, u64 *jiff)
+{
+        long sec = tp->tv_sec;
+        long nsec = tp->tv_nsec + res - 1;
+
+        if (nsec > NSEC_PER_SEC) {
+                sec++;
+                nsec -= NSEC_PER_SEC;
+        }
+
+        /*
+         * The scaling constants are defined in <linux/time.h>
+         * The difference between there and here is that we do the
+         * res rounding and compute a 64-bit result (well so does that
+         * but it then throws away the high bits).
+         */
+        *jiff =  (mpy_l_X_l_ll(sec, SEC_CONVERSION) +
+                  (mpy_l_X_l_ll(nsec, NSEC_CONVERSION) >> 
+                   (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
+}
+
+/*
+ * This function adjusts the timer as needed as a result of the clock
+ * being set.  It should only be called for absolute timers, and then
+ * under the abs_list lock.  It computes the time difference and sets
+ * the new jiffies value in the timer.  It also updates the timers
+ * reference wall_to_monotonic value.  It is complicated by the fact
+ * that tstojiffies() only handles positive times and it needs to work
+ * with both positive and negative times.  Also, for negative offsets,
+ * we need to defeat the res round up.
+ *
+ * Return is true if there is a new time, else false.
+ */
+static long add_clockset_delta(struct k_itimer *timr,
+                               struct timespec *new_wall_to)
+{
+        struct timespec delta;
+        int sign = 0;
+        u64 exp;
+
+        set_normalized_timespec(&delta,
+                                new_wall_to->tv_sec -
+                                timr->it.real.wall_to_prev.tv_sec,
+                                new_wall_to->tv_nsec -
+                                timr->it.real.wall_to_prev.tv_nsec);
+        if (likely(!(delta.tv_sec | delta.tv_nsec)))
+                return 0;
+        if (delta.tv_sec < 0) {
+                set_normalized_timespec(&delta,
+                                        -delta.tv_sec,
+                                        1 - delta.tv_nsec -
+                                        posix_clocks[timr->it_clock].res);
+                sign++;
+        }
+        tstojiffie(&delta, posix_clocks[timr->it_clock].res, &exp);
+        timr->it.real.wall_to_prev = *new_wall_to;
+        timr->it.real.timer.expires += (sign ? -exp : exp);
+        return 1;
+}
+
+static void remove_from_abslist(struct k_itimer *timr)
+{
+        if (!list_empty(&timr->it.real.abs_timer_entry)) {
+                spin_lock(&abs_list.lock);
+                list_del_init(&timr->it.real.abs_timer_entry);
+                spin_unlock(&abs_list.lock);
+        }
+}
+
+static void schedule_next_timer(struct k_itimer *timr)
+{
+        struct timespec new_wall_to;
+        struct now_struct now;
+        unsigned long seq;
+
+        /*
+         * Set up the timer for the next interval (if there is one).
+         * Note: this code uses the abs_timer_lock to protect
+         * it.real.wall_to_prev and must hold it until exp is set, not exactly
+         * obvious...
+
+         * This function is used for CLOCK_REALTIME* and
+         * CLOCK_MONOTONIC* timers.  If we ever want to handle other
+         * CLOCKs, the calling code (do_schedule_next_timer) would need
+         * to pull the "clock" info from the timer and dispatch the
+         * "other" CLOCKs "next timer" code (which, I suppose should
+         * also be added to the k_clock structure).
+         */
+        if (!timr->it.real.incr)
+                return;
+
+        do {
+                seq = read_seqbegin(&xtime_lock);
+                new_wall_to =   wall_to_monotonic;
+                posix_get_now(&now);
+        } while (read_seqretry(&xtime_lock, seq));
+
+        if (!list_empty(&timr->it.real.abs_timer_entry)) {
+                spin_lock(&abs_list.lock);
+                add_clockset_delta(timr, &new_wall_to);
+
+                posix_bump_timer(timr, now);
+
+                spin_unlock(&abs_list.lock);
+        } else {
+                posix_bump_timer(timr, now);
+        }
+        timr->it_overrun_last = timr->it_overrun;
+        timr->it_overrun = -1;
+        ++timr->it_requeue_pending;
+        add_timer(&timr->it.real.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 aginst 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)
+                goto exit;
+
+        if (timr->it_clock < 0) /* CPU clock */
+                posix_cpu_timer_schedule(timr);
+        else
+                schedule_next_timer(timr);
+        info->si_overrun = timr->it_overrun_last;
+exit:
+        if (timr)
+                unlock_timer(timr, flags);
+}
+
+int posix_timer_event(struct k_itimer *timr,int si_private)
+{
+        memset(&timr->sigq->info, 0, sizeof(siginfo_t));
+        timr->sigq->info.si_sys_private = si_private;
+        /*
+         * Send signal to the process that owns this timer.
+
+         * This code assumes that all the possible abs_lists share the
+         * same lock (there is only one list at this time). If this is
+         * not the case, the CLOCK info would need to be used to find
+         * the proper abs list lock.
+         */
+
+        timr->sigq->info.si_signo = timr->it_sigev_signo;
+        timr->sigq->info.si_errno = 0;
+        timr->sigq->info.si_code = SI_TIMER;
+        timr->sigq->info.si_tid = timr->it_id;
+        timr->sigq->info.si_value = timr->it_sigev_value;
+        if (timr->it_sigev_notify & SIGEV_THREAD_ID) {
+                if (unlikely(timr->it_process->flags & PF_EXITING)) {
+                        timr->it_sigev_notify = SIGEV_SIGNAL;
+                        put_task_struct(timr->it_process);
+                        timr->it_process = timr->it_process->group_leader;
+                        goto group;
+                }
+                return send_sigqueue(timr->it_sigev_signo, timr->sigq,
+                        timr->it_process);
+        }
+        else {
+        group:
+                return send_group_sigqueue(timr->it_sigev_signo, timr->sigq,
+                        timr->it_process);
+        }
+}
+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 void posix_timer_fn(unsigned long __data)
+{
+        struct k_itimer *timr = (struct k_itimer *) __data;
+        unsigned long flags;
+        unsigned long seq;
+        struct timespec delta, new_wall_to;
+        u64 exp = 0;
+        int do_notify = 1;
+
+        spin_lock_irqsave(&timr->it_lock, flags);
+        set_timer_inactive(timr);
+        if (!list_empty(&timr->it.real.abs_timer_entry)) {
+                spin_lock(&abs_list.lock);
+                do {
+                        seq = read_seqbegin(&xtime_lock);
+                        new_wall_to =   wall_to_monotonic;
+                } while (read_seqretry(&xtime_lock, seq));
+                set_normalized_timespec(&delta,
+                                        new_wall_to.tv_sec -
+                                        timr->it.real.wall_to_prev.tv_sec,
+                                        new_wall_to.tv_nsec -
+                                        timr->it.real.wall_to_prev.tv_nsec);
+                if (likely((delta.tv_sec | delta.tv_nsec ) == 0)) {
+                        /* do nothing, timer is on time */
+                } else if (delta.tv_sec < 0) {
+                        /* do nothing, timer is already late */
+                } else {
+                        /* timer is early due to a clock set */
+                        tstojiffie(&delta,
+                                   posix_clocks[timr->it_clock].res,
+                                   &exp);
+                        timr->it.real.wall_to_prev = new_wall_to;
+                        timr->it.real.timer.expires += exp;
+                        add_timer(&timr->it.real.timer);
+                        do_notify = 0;
+                }
+                spin_unlock(&abs_list.lock);
+
+        }
+        if (do_notify)  {
+                int si_private=0;
+
+                if (timr->it.real.incr)
+                        si_private = ++timr->it_requeue_pending;
+                else {
+                        remove_from_abslist(timr);
+                }
+
+                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.
+                         */
+                        schedule_next_timer(timr);
+        }
+        unlock_timer(timr, flags); /* hold thru abs lock to keep irq off */
+}
+
+
+static inline struct task_struct * good_sigevent(sigevent_t * event)
+{
+        struct task_struct *rtn = current->group_leader;
+
+        if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
+                (!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) ||
+                 rtn->tgid != current->tgid ||
+                 (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 rtn;
+}
+
+void register_posix_clock(clockid_t clock_id, struct k_clock *new_clock)
+{
+        if ((unsigned) clock_id >= MAX_CLOCKS) {
+                printk("POSIX clock register failed for clock_id %d\n",
+                       clock_id);
+                return;
+        }
+
+        posix_clocks[clock_id] = *new_clock;
+}
+EXPORT_SYMBOL_GPL(register_posix_clock);
+
+static struct k_itimer * alloc_posix_timer(void)
+{
+        struct k_itimer *tmr;
+        tmr = kmem_cache_alloc(posix_timers_cache, GFP_KERNEL);
+        if (!tmr)
+                return tmr;
+        memset(tmr, 0, sizeof (struct k_itimer));
+        if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
+                kmem_cache_free(posix_timers_cache, tmr);
+                tmr = NULL;
+        }
+        return 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);
+        }
+        sigqueue_free(tmr->sigq);
+        if (unlikely(tmr->it_process) &&
+            tmr->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
+                put_task_struct(tmr->it_process);
+        kmem_cache_free(posix_timers_cache, tmr);
+}
+
+/* Create a POSIX.1b interval timer. */
+
+asmlinkage long
+sys_timer_create(clockid_t which_clock,
+                 struct sigevent __user *timer_event_spec,
+                 timer_t __user * created_timer_id)
+{
+        int error = 0;
+        struct k_itimer *new_timer = NULL;
+        int new_timer_id;
+        struct task_struct *process = NULL;
+        unsigned long flags;
+        sigevent_t event;
+        int it_id_set = IT_ID_NOT_SET;
+
+        if (invalid_clockid(which_clock))
+                return -EINVAL;
+
+        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,
+                            (void *) new_timer,
+                            &new_timer_id);
+        spin_unlock_irq(&idr_lock);
+        if (error == -EAGAIN)
+                goto retry;
+        else if (error) {
+                /*
+                 * Wierd 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;
+        error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
+        if (error)
+                goto out;
+
+        /*
+         * return the timer_id now.  The next step is hard to
+         * back out if there is an error.
+         */
+        if (copy_to_user(created_timer_id,
+                         &new_timer_id, sizeof (new_timer_id))) {
+                error = -EFAULT;
+                goto out;
+        }
+        if (timer_event_spec) {
+                if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
+                        error = -EFAULT;
+                        goto out;
+                }
+                new_timer->it_sigev_notify = event.sigev_notify;
+                new_timer->it_sigev_signo = event.sigev_signo;
+                new_timer->it_sigev_value = event.sigev_value;
+
+                read_lock(&tasklist_lock);
+                if ((process = good_sigevent(&event))) {
+                        /*
+                         * We may be setting up this process for another
+                         * thread.  It may be exiting.  To catch this
+                         * case the we check the PF_EXITING flag.  If
+                         * the flag is not set, the siglock will catch
+                         * him before it is too late (in exit_itimers).
+                         *
+                         * The exec case is a bit more invloved but easy
+                         * to code.  If the process is in our thread
+                         * group (and it must be or we would not allow
+                         * it here) and is doing an exec, it will cause
+                         * us to be killed.  In this case it will wait
+                         * for us to die which means we can finish this
+                         * linkage with our last gasp. I.e. no code :)
+                         */
+                        spin_lock_irqsave(&process->sighand->siglock, flags);
+                        if (!(process->flags & PF_EXITING)) {
+                                new_timer->it_process = process;
+                                list_add(&new_timer->list,
+                                         &process->signal->posix_timers);
+                                spin_unlock_irqrestore(&process->sighand->siglock, flags);
+                                if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
+                                        get_task_struct(process);
+                        } else {
+                                spin_unlock_irqrestore(&process->sighand->siglock, flags);
+                                process = NULL;
+                        }
+                }
+                read_unlock(&tasklist_lock);
+                if (!process) {
+                        error = -EINVAL;
+                        goto out;
+                }
+        } else {
+                new_timer->it_sigev_notify = SIGEV_SIGNAL;
+                new_timer->it_sigev_signo = SIGALRM;
+                new_timer->it_sigev_value.sival_int = new_timer->it_id;
+                process = current->group_leader;
+                spin_lock_irqsave(&process->sighand->siglock, flags);
+                new_timer->it_process = process;
+                list_add(&new_timer->list, &process->signal->posix_timers);
+                spin_unlock_irqrestore(&process->sighand->siglock, flags);
+        }
+
+        /*
+         * 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:
+        if (error)
+                release_posix_timer(new_timer, it_id_set);
+
+        return error;
+}
+
+/*
+ * good_timespec
+ *
+ * This function checks the elements of a timespec structure.
+ *
+ * Arguments:
+ * ts        : Pointer to the timespec structure to check
+ *
+ * Return value:
+ * If a NULL pointer was passed in, or the tv_nsec field was less than 0
+ * or greater than NSEC_PER_SEC, or the tv_sec field was less than 0,
+ * this function returns 0. Otherwise it returns 1.
+ */
+static int good_timespec(const struct timespec *ts)
+{
+        if ((!ts) || (ts->tv_sec < 0) ||
+                        ((unsigned) ts->tv_nsec >= NSEC_PER_SEC))
+                return 0;
+        return 1;
+}
+
+/*
+ * 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;
+        /*
+         * Watch out here.  We do a irqsave on the idr_lock and pass the
+         * flags part over to the timer lock.  Must not let interrupts in
+         * while we are moving the lock.
+         */
+
+        spin_lock_irqsave(&idr_lock, *flags);
+        timr = (struct k_itimer *) idr_find(&posix_timers_id, (int) timer_id);
+        if (timr) {
+                spin_lock(&timr->it_lock);
+                spin_unlock(&idr_lock);
+
+                if ((timr->it_id != timer_id) || !(timr->it_process) ||
+                                timr->it_process->tgid != current->tgid) {
+                        unlock_timer(timr, *flags);
+                        timr = NULL;
+                }
+        } else
+                spin_unlock_irqrestore(&idr_lock, *flags);
+
+        return timr;
+}
+
+/*
+ * 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)
+{
+        unsigned long expires;
+        struct now_struct now;
+
+        do
+                expires = timr->it.real.timer.expires;
+        while ((volatile long) (timr->it.real.timer.expires) != expires);
+
+        posix_get_now(&now);
+
+        if (expires &&
+            ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) &&
+            !timr->it.real.incr &&
+            posix_time_before(&timr->it.real.timer, &now))
+                timr->it.real.timer.expires = expires = 0;
+        if (expires) {
+                if (timr->it_requeue_pending & REQUEUE_PENDING ||
+                    (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
+                        posix_bump_timer(timr, now);
+                        expires = timr->it.real.timer.expires;
+                }
+                else
+                        if (!timer_pending(&timr->it.real.timer))
+                                expires = 0;
+                if (expires)
+                        expires -= now.jiffies;
+        }
+        jiffies_to_timespec(expires, &cur_setting->it_value);
+        jiffies_to_timespec(timr->it.real.incr, &cur_setting->it_interval);
+
+        if (cur_setting->it_value.tv_sec < 0) {
+                cur_setting->it_value.tv_nsec = 1;
+                cur_setting->it_value.tv_sec = 0;
+        }
+}
+
+/* Get the time remaining on a POSIX.1b interval timer. */
+asmlinkage long
+sys_timer_gettime(timer_t timer_id, struct itimerspec __user *setting)
+{
+        struct k_itimer *timr;
+        struct itimerspec cur_setting;
+        unsigned long flags;
+
+        timr = lock_timer(timer_id, &flags);
+        if (!timr)
+                return -EINVAL;
+
+        CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting));
+
+        unlock_timer(timr, flags);
+
+        if (copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
+                return -EFAULT;
+
+        return 0;
+}
+/*
+ * 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.
+ */
+
+asmlinkage long
+sys_timer_getoverrun(timer_t timer_id)
+{
+        struct k_itimer *timr;
+        int overrun;
+        long flags;
+
+        timr = lock_timer(timer_id, &flags);
+        if (!timr)
+                return -EINVAL;
+
+        overrun = timr->it_overrun_last;
+        unlock_timer(timr, flags);
+
+        return overrun;
+}
+/*
+ * Adjust for absolute time
+ *
+ * If absolute time is given and it is not CLOCK_MONOTONIC, we need to
+ * adjust for the offset between the timer clock (CLOCK_MONOTONIC) and
+ * what ever clock he is using.
+ *
+ * If it is relative time, we need to add the current (CLOCK_MONOTONIC)
+ * time to it to get the proper time for the timer.
+ */
+static int adjust_abs_time(struct k_clock *clock, struct timespec *tp, 
+                           int abs, u64 *exp, struct timespec *wall_to)
+{
+        struct timespec now;
+        struct timespec oc = *tp;
+        u64 jiffies_64_f;
+        int rtn =0;
+
+        if (abs) {
+                /*
+                 * The mask pick up the 4 basic clocks 
+                 */
+                if (!((clock - &posix_clocks[0]) & ~CLOCKS_MASK)) {
+                        jiffies_64_f = do_posix_clock_monotonic_gettime_parts(
+                                &now,  wall_to);
+                        /*
+                         * If we are doing a MONOTONIC clock
+                         */
+                        if((clock - &posix_clocks[0]) & CLOCKS_MONO){
+                                now.tv_sec += wall_to->tv_sec;
+                                now.tv_nsec += wall_to->tv_nsec;
+                        }
+                } else {
+                        /*
+                         * Not one of the basic clocks
+                         */
+                        clock->clock_get(clock - posix_clocks, &now);
+                        jiffies_64_f = get_jiffies_64();
+                }
+                /*
+                 * Take away now to get delta
+                 */
+                oc.tv_sec -= now.tv_sec;
+                oc.tv_nsec -= now.tv_nsec;
+                /*
+                 * Normalize...
+                 */
+                while ((oc.tv_nsec - NSEC_PER_SEC) >= 0) {
+                        oc.tv_nsec -= NSEC_PER_SEC;
+                        oc.tv_sec++;
+                }
+                while ((oc.tv_nsec) < 0) {
+                        oc.tv_nsec += NSEC_PER_SEC;
+                        oc.tv_sec--;
+                }
+        }else{
+                jiffies_64_f = get_jiffies_64();
+        }
+        /*
+         * Check if the requested time is prior to now (if so set now)
+         */
+        if (oc.tv_sec < 0)
+                oc.tv_sec = oc.tv_nsec = 0;
+
+        if (oc.tv_sec | oc.tv_nsec)
+                set_normalized_timespec(&oc, oc.tv_sec,
+                                        oc.tv_nsec + clock->res);
+        tstojiffie(&oc, clock->res, exp);
+
+        /*
+         * Check if the requested time is more than the timer code
+         * can handle (if so we error out but return the value too).
+         */
+        if (*exp > ((u64)MAX_JIFFY_OFFSET))
+                        /*
+                         * This is a considered response, not exactly in
+                         * line with the standard (in fact it is silent on
+                         * possible overflows).  We assume such a large 
+                         * value is ALMOST always a programming error and
+                         * try not to compound it by setting a really dumb
+                         * value.
+                         */
+                        rtn = -EINVAL;
+        /*
+         * return the actual jiffies expire time, full 64 bits
+         */
+        *exp += jiffies_64_f;
+        return rtn;
+}
+
+/* Set a POSIX.1b interval timer. */
+/* timr->it_lock is taken. */
+static inline int
+common_timer_set(struct k_itimer *timr, int flags,
+                 struct itimerspec *new_setting, struct itimerspec *old_setting)
+{
+        struct k_clock *clock = &posix_clocks[timr->it_clock];
+        u64 expire_64;
+
+        if (old_setting)
+                common_timer_get(timr, old_setting);
+
+        /* disable the timer */
+        timr->it.real.incr = 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.
+         */
+#ifdef CONFIG_SMP
+        if (timer_active(timr) && !del_timer(&timr->it.real.timer))
+                /*
+                 * It can only be active if on an other cpu.  Since
+                 * we have cleared the interval stuff above, it should
+                 * clear once we release the spin lock.  Of course once
+                 * we do that anything could happen, including the
+                 * complete melt down of the timer.  So return with
+                 * a "retry" exit status.
+                 */
+                return TIMER_RETRY;
+
+        set_timer_inactive(timr);
+#else
+        del_timer(&timr->it.real.timer);
+#endif
+        remove_from_abslist(timr);
+
+        timr->it_requeue_pending = (timr->it_requeue_pending + 2) & 
+                ~REQUEUE_PENDING;
+        timr->it_overrun_last = 0;
+        timr->it_overrun = -1;
+        /*
+         *switch off the timer when it_value is zero
+         */
+        if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec) {
+                timr->it.real.timer.expires = 0;
+                return 0;
+        }
+
+        if (adjust_abs_time(clock,
+                            &new_setting->it_value, flags & TIMER_ABSTIME, 
+                            &expire_64, &(timr->it.real.wall_to_prev))) {
+                return -EINVAL;
+        }
+        timr->it.real.timer.expires = (unsigned long)expire_64;
+        tstojiffie(&new_setting->it_interval, clock->res, &expire_64);
+        timr->it.real.incr = (unsigned long)expire_64;
+
+        /*
+         * We do not even queue SIGEV_NONE timers!  But we do put them
+         * in the abs list so we can do that right.
+         */
+        if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE))
+                add_timer(&timr->it.real.timer);
+
+        if (flags & TIMER_ABSTIME && clock->abs_struct) {
+                spin_lock(&clock->abs_struct->lock);
+                list_add_tail(&(timr->it.real.abs_timer_entry),
+                              &(clock->abs_struct->list));
+                spin_unlock(&clock->abs_struct->lock);
+        }
+        return 0;
+}
+
+/* Set a POSIX.1b interval timer */
+asmlinkage long
+sys_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;
+        long flag;
+        struct itimerspec *rtn = old_setting ? &old_spec : NULL;
+
+        if (!new_setting)
+                return -EINVAL;
+
+        if (copy_from_user(&new_spec, new_setting, sizeof (new_spec)))
+                return -EFAULT;
+
+        if ((!good_timespec(&new_spec.it_interval)) ||
+            (!good_timespec(&new_spec.it_value)))
+                return -EINVAL;
+retry:
+        timr = lock_timer(timer_id, &flag);
+        if (!timr)
+                return -EINVAL;
+
+        error = CLOCK_DISPATCH(timr->it_clock, 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 inline int common_timer_del(struct k_itimer *timer)
+{
+        timer->it.real.incr = 0;
+#ifdef CONFIG_SMP
+        if (timer_active(timer) && !del_timer(&timer->it.real.timer))
+                /*
+                 * It can only be active if on an other cpu.  Since
+                 * we have cleared the interval stuff above, it should
+                 * clear once we release the spin lock.  Of course once
+                 * we do that anything could happen, including the
+                 * complete melt down of the timer.  So return with
+                 * a "retry" exit status.
+                 */
+                return TIMER_RETRY;
+#else
+        del_timer(&timer->it.real.timer);
+#endif
+        remove_from_abslist(timer);
+
+        return 0;
+}
+
+static inline int timer_delete_hook(struct k_itimer *timer)
+{
+        return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer));
+}
+
+/* Delete a POSIX.1b interval timer. */
+asmlinkage long
+sys_timer_delete(timer_t timer_id)
+{
+        struct k_itimer *timer;
+        long flags;
+
+#ifdef CONFIG_SMP
+        int error;
+retry_delete:
+#endif
+        timer = lock_timer(timer_id, &flags);
+        if (!timer)
+                return -EINVAL;
+
+#ifdef CONFIG_SMP
+        error = timer_delete_hook(timer);
+
+        if (error == TIMER_RETRY) {
+                unlock_timer(timer, flags);
+                goto retry_delete;
+        }
+#else
+        timer_delete_hook(timer);
+#endif
+        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).
+         */
+        if (timer->it_process) {
+                if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
+                        put_task_struct(timer->it_process);
+                timer->it_process = 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 inline void itimer_delete(struct k_itimer *timer)
+{
+        unsigned long flags;
+
+#ifdef CONFIG_SMP
+        int error;
+retry_delete:
+#endif
+        spin_lock_irqsave(&timer->it_lock, flags);
+
+#ifdef CONFIG_SMP
+        error = timer_delete_hook(timer);
+
+        if (error == TIMER_RETRY) {
+                unlock_timer(timer, flags);
+                goto retry_delete;
+        }
+#else
+        timer_delete_hook(timer);
+#endif
+        list_del(&timer->list);
+        /*
+         * This keeps any tasks waiting on the spin lock from thinking
+         * they got something (see the lock code above).
+         */
+        if (timer->it_process) {
+                if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID))
+                        put_task_struct(timer->it_process);
+                timer->it_process = NULL;
+        }
+        unlock_timer(timer, flags);
+        release_posix_timer(timer, IT_ID_SET);
+}
+
+/*
+ * This is called by __exit_signal, 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);
+        }
+}
+
+/*
+ * And now for the "clock" calls
+ *
+ * These functions are called both from timer functions (with the timer
+ * spin_lock_irq() held and from clock calls with no locking.   They must
+ * use the save flags versions of locks.
+ */
+
+/*
+ * We do ticks here to avoid the irq lock ( they take sooo long).
+ * The seqlock is great here.  Since we a reader, we don't really care
+ * if we are interrupted since we don't take lock that will stall us or
+ * any other cpu. Voila, no irq lock is needed.
+ *
+ */
+
+static u64 do_posix_clock_monotonic_gettime_parts(
+        struct timespec *tp, struct timespec *mo)
+{
+        u64 jiff;
+        unsigned int seq;
+
+        do {
+                seq = read_seqbegin(&xtime_lock);
+                getnstimeofday(tp);
+                *mo = wall_to_monotonic;
+                jiff = jiffies_64;
+
+        } while(read_seqretry(&xtime_lock, seq));
+
+        return jiff;
+}
+
+static int do_posix_clock_monotonic_get(clockid_t clock, struct timespec *tp)
+{
+        struct timespec wall_to_mono;
+
+        do_posix_clock_monotonic_gettime_parts(tp, &wall_to_mono);
+
+        tp->tv_sec += wall_to_mono.tv_sec;
+        tp->tv_nsec += wall_to_mono.tv_nsec;
+
+        if ((tp->tv_nsec - NSEC_PER_SEC) > 0) {
+                tp->tv_nsec -= NSEC_PER_SEC;
+                tp->tv_sec++;
+        }
+        return 0;
+}
+
+int do_posix_clock_monotonic_gettime(struct timespec *tp)
+{
+        return do_posix_clock_monotonic_get(CLOCK_MONOTONIC, tp);
+}
+
+int do_posix_clock_nosettime(clockid_t clockid, struct timespec *tp)
+{
+        return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(do_posix_clock_nosettime);
+
+int do_posix_clock_notimer_create(struct k_itimer *timer)
+{
+        return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(do_posix_clock_notimer_create);
+
+int do_posix_clock_nonanosleep(clockid_t clock, int flags, struct timespec *t)
+{
+#ifndef ENOTSUP
+        return -EOPNOTSUPP;     /* aka ENOTSUP in userland for POSIX */
+#else  /*  parisc does define it separately.  */
+        return -ENOTSUP;
+#endif
+}
+EXPORT_SYMBOL_GPL(do_posix_clock_nonanosleep);
+
+asmlinkage long
+sys_clock_settime(clockid_t which_clock, const struct timespec __user *tp)
+{
+        struct timespec new_tp;
+
+        if (invalid_clockid(which_clock))
+                return -EINVAL;
+        if (copy_from_user(&new_tp, tp, sizeof (*tp)))
+                return -EFAULT;
+
+        return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp));
+}
+
+asmlinkage long
+sys_clock_gettime(clockid_t which_clock, struct timespec __user *tp)
+{
+        struct timespec kernel_tp;
+        int error;
+
+        if (invalid_clockid(which_clock))
+                return -EINVAL;
+        error = CLOCK_DISPATCH(which_clock, clock_get,
+                               (which_clock, &kernel_tp));
+        if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp)))
+                error = -EFAULT;
+
+        return error;
+
+}
+
+asmlinkage long
+sys_clock_getres(clockid_t which_clock, struct timespec __user *tp)
+{
+        struct timespec rtn_tp;
+        int error;
+
+        if (invalid_clockid(which_clock))
+                return -EINVAL;
+
+        error = CLOCK_DISPATCH(which_clock, clock_getres,
+                               (which_clock, &rtn_tp));
+
+        if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) {
+                error = -EFAULT;
+        }
+
+        return error;
+}
+
+static void nanosleep_wake_up(unsigned long __data)
+{
+        struct task_struct *p = (struct task_struct *) __data;
+
+        wake_up_process(p);
+}
+
+/*
+ * The standard says that an absolute nanosleep call MUST wake up at
+ * the requested time in spite of clock settings.  Here is what we do:
+ * For each nanosleep call that needs it (only absolute and not on
+ * CLOCK_MONOTONIC* (as it can not be set)) we thread a little structure
+ * into the "nanosleep_abs_list".  All we need is the task_struct pointer.
+ * When ever the clock is set we just wake up all those tasks.   The rest
+ * is done by the while loop in clock_nanosleep().
+ *
+ * On locking, clock_was_set() is called from update_wall_clock which
+ * holds (or has held for it) a write_lock_irq( xtime_lock) and is
+ * called from the timer bh code.  Thus we need the irq save locks.
+ *
+ * Also, on the call from update_wall_clock, that is done as part of a
+ * softirq thing.  We don't want to delay the system that much (possibly
+ * long list of timers to fix), so we defer that work to keventd.
+ */
+
+static DECLARE_WAIT_QUEUE_HEAD(nanosleep_abs_wqueue);
+static DECLARE_WORK(clock_was_set_work, (void(*)(void*))clock_was_set, NULL);
+
+static DECLARE_MUTEX(clock_was_set_lock);
+
+void clock_was_set(void)
+{
+        struct k_itimer *timr;
+        struct timespec new_wall_to;
+        LIST_HEAD(cws_list);
+        unsigned long seq;
+
+
+        if (unlikely(in_interrupt())) {
+                schedule_work(&clock_was_set_work);
+                return;
+        }
+        wake_up_all(&nanosleep_abs_wqueue);
+
+        /*
+         * Check if there exist TIMER_ABSTIME timers to correct.
+         *
+         * Notes on locking: This code is run in task context with irq
+         * on.  We CAN be interrupted!  All other usage of the abs list
+         * lock is under the timer lock which holds the irq lock as
+         * well.  We REALLY don't want to scan the whole list with the
+         * interrupt system off, AND we would like a sequence lock on
+         * this code as well.  Since we assume that the clock will not
+         * be set often, it seems ok to take and release the irq lock
+         * for each timer.  In fact add_timer will do this, so this is
+         * not an issue.  So we know when we are done, we will move the
+         * whole list to a new location.  Then as we process each entry,
+         * we will move it to the actual list again.  This way, when our
+         * copy is empty, we are done.  We are not all that concerned
+         * about preemption so we will use a semaphore lock to protect
+         * aginst reentry.  This way we will not stall another
+         * processor.  It is possible that this may delay some timers
+         * that should have expired, given the new clock, but even this
+         * will be minimal as we will always update to the current time,
+         * even if it was set by a task that is waiting for entry to
+         * this code.  Timers that expire too early will be caught by
+         * the expire code and restarted.
+
+         * Absolute timers that repeat are left in the abs list while
+         * waiting for the task to pick up the signal.  This means we
+         * may find timers that are not in the "add_timer" list, but are
+         * in the abs list.  We do the same thing for these, save
+         * putting them back in the "add_timer" list.  (Note, these are
+         * left in the abs list mainly to indicate that they are
+         * ABSOLUTE timers, a fact that is used by the re-arm code, and
+         * for which we have no other flag.)
+
+         */
+
+        down(&clock_was_set_lock);
+        spin_lock_irq(&abs_list.lock);
+        list_splice_init(&abs_list.list, &cws_list);
+        spin_unlock_irq(&abs_list.lock);
+        do {
+                do {
+                        seq = read_seqbegin(&xtime_lock);
+                        new_wall_to =   wall_to_monotonic;
+                } while (read_seqretry(&xtime_lock, seq));
+
+                spin_lock_irq(&abs_list.lock);
+                if (list_empty(&cws_list)) {
+                        spin_unlock_irq(&abs_list.lock);
+                        break;
+                }
+                timr = list_entry(cws_list.next, struct k_itimer,
+                                  it.real.abs_timer_entry);
+
+                list_del_init(&timr->it.real.abs_timer_entry);
+                if (add_clockset_delta(timr, &new_wall_to) &&
+                    del_timer(&timr->it.real.timer))  /* timer run yet? */
+                        add_timer(&timr->it.real.timer);
+                list_add(&timr->it.real.abs_timer_entry, &abs_list.list);
+                spin_unlock_irq(&abs_list.lock);
+        } while (1);
+
+        up(&clock_was_set_lock);
+}
+
+long clock_nanosleep_restart(struct restart_block *restart_block);
+
+asmlinkage long
+sys_clock_nanosleep(clockid_t which_clock, int flags,
+                    const struct timespec __user *rqtp,
+                    struct timespec __user *rmtp)
+{
+        struct timespec t;
+        struct restart_block *restart_block =
+            &(current_thread_info()->restart_block);
+        int ret;
+
+        if (invalid_clockid(which_clock))
+                return -EINVAL;
+
+        if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
+                return -EFAULT;
+
+        if ((unsigned) t.tv_nsec >= NSEC_PER_SEC || t.tv_sec < 0)
+                return -EINVAL;
+
+        /*
+         * Do this here as nsleep function does not have the real address.
+         */
+        restart_block->arg1 = (unsigned long)rmtp;
+
+        ret = CLOCK_DISPATCH(which_clock, nsleep, (which_clock, flags, &t));
+
+        if ((ret == -ERESTART_RESTARTBLOCK) && rmtp &&
+                                        copy_to_user(rmtp, &t, sizeof (t)))
+                return -EFAULT;
+        return ret;
+}
+
+
+static int common_nsleep(clockid_t which_clock,
+                         int flags, struct timespec *tsave)
+{
+        struct timespec t, dum;
+        struct timer_list new_timer;
+        DECLARE_WAITQUEUE(abs_wqueue, current);
+        u64 rq_time = (u64)0;
+        s64 left;
+        int abs;
+        struct restart_block *restart_block =
+            &current_thread_info()->restart_block;
+
+        abs_wqueue.flags = 0;
+        init_timer(&new_timer);
+        new_timer.expires = 0;
+        new_timer.data = (unsigned long) current;
+        new_timer.function = nanosleep_wake_up;
+        abs = flags & TIMER_ABSTIME;
+
+        if (restart_block->fn == clock_nanosleep_restart) {
+                /*
+                 * Interrupted by a non-delivered signal, pick up remaining
+                 * time and continue.  Remaining time is in arg2 & 3.
+                 */
+                restart_block->fn = do_no_restart_syscall;
+
+                rq_time = restart_block->arg3;
+                rq_time = (rq_time << 32) + restart_block->arg2;
+                if (!rq_time)
+                        return -EINTR;
+                left = rq_time - get_jiffies_64();
+                if (left <= (s64)0)
+                        return 0;       /* Already passed */
+        }
+
+        if (abs && (posix_clocks[which_clock].clock_get !=
+                            posix_clocks[CLOCK_MONOTONIC].clock_get))
+                add_wait_queue(&nanosleep_abs_wqueue, &abs_wqueue);
+
+        do {
+                t = *tsave;
+                if (abs || !rq_time) {
+                        adjust_abs_time(&posix_clocks[which_clock], &t, abs,
+                                        &rq_time, &dum);
+                }
+
+                left = rq_time - get_jiffies_64();
+                if (left >= (s64)MAX_JIFFY_OFFSET)
+                        left = (s64)MAX_JIFFY_OFFSET;
+                if (left < (s64)0)
+                        break;
+
+                new_timer.expires = jiffies + left;
+                __set_current_state(TASK_INTERRUPTIBLE);
+                add_timer(&new_timer);
+
+                schedule();
+
+                del_timer_sync(&new_timer);
+                left = rq_time - get_jiffies_64();
+        } while (left > (s64)0 && !test_thread_flag(TIF_SIGPENDING));
+
+        if (abs_wqueue.task_list.next)
+                finish_wait(&nanosleep_abs_wqueue, &abs_wqueue);
+
+        if (left > (s64)0) {
+
+                /*
+                 * Always restart abs calls from scratch to pick up any
+                 * clock shifting that happened while we are away.
+                 */
+                if (abs)
+                        return -ERESTARTNOHAND;
+
+                left *= TICK_NSEC;
+                tsave->tv_sec = div_long_long_rem(left, 
+                                                  NSEC_PER_SEC, 
+                                                  &tsave->tv_nsec);
+                /*
+                 * Restart works by saving the time remaing in 
+                 * arg2 & 3 (it is 64-bits of jiffies).  The other
+                 * info we need is the clock_id (saved in arg0). 
+                 * The sys_call interface needs the users 
+                 * timespec return address which _it_ saves in arg1.
+                 * Since we have cast the nanosleep call to a clock_nanosleep
+                 * both can be restarted with the same code.
+                 */
+                restart_block->fn = clock_nanosleep_restart;
+                restart_block->arg0 = which_clock;
+                /*
+                 * Caller sets arg1
+                 */
+                restart_block->arg2 = rq_time & 0xffffffffLL;
+                restart_block->arg3 = rq_time >> 32;
+
+                return -ERESTART_RESTARTBLOCK;
+        }
+
+        return 0;
+}
+/*
+ * This will restart clock_nanosleep.
+ */
+long
+clock_nanosleep_restart(struct restart_block *restart_block)
+{
+        struct timespec t;
+        int ret = common_nsleep(restart_block->arg0, 0, &t);
+
+        if ((ret == -ERESTART_RESTARTBLOCK) && restart_block->arg1 &&
+            copy_to_user((struct timespec __user *)(restart_block->arg1), &t,
+                         sizeof (t)))
+                return -EFAULT;
+        return ret;
+}