rcu: Fix day-one dyntick-idle stall-warning bug
[linux-2.6.git] / kernel / posix-timers.c
index 588c99d..69185ae 100644 (file)
 #include <linux/mutex.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-clock.h>
 #include <linux/posix-timers.h>
 #include <linux/syscalls.h>
 #include <linux/wait.h>
 #include <linux/workqueue.h>
-#include <linux/module.h>
+#include <linux/export.h>
 
 /*
  * Management arrays for POSIX timers.  Timers are kept in slab memory
@@ -82,6 +82,14 @@ static DEFINE_SPINLOCK(idr_lock);
 #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().
@@ -95,11 +103,7 @@ static DEFINE_SPINLOCK(idr_lock);
 /*
  * 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.
+ *         clocks.
  *
  * RESOLUTION: Clock resolution is used to round up timer and interval
  *         times, NOT to report clock times, which are reported with as
@@ -109,20 +113,13 @@ static DEFINE_SPINLOCK(idr_lock);
  *         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.
+ * FUNCTIONS: The CLOCKs structure defines possible functions to
+ *         handle various clock functions.
  *
- *          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.
+ *         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
@@ -139,6 +136,7 @@ static struct k_clock posix_clocks[MAX_CLOCKS];
  */
 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 *);
@@ -146,102 +144,144 @@ 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);
+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);
 }
 
-/*
- * 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))
+/* 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);
+}
 
 /*
- * 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.
+ * Get monotonic time for posix timers
  */
-
-static inline int common_clock_getres(const clockid_t which_clock,
-                                     struct timespec *tp)
+static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
 {
-       tp->tv_sec = 0;
-       tp->tv_nsec = posix_clocks[which_clock].res;
+       ktime_get_ts(tp);
        return 0;
 }
 
 /*
- * Get real time for posix timers
+ * Get monotonic-raw time for posix timers
  */
-static int common_clock_get(clockid_t which_clock, struct timespec *tp)
+static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
 {
-       ktime_get_real_ts(tp);
+       getrawmonotonic(tp);
        return 0;
 }
 
-static inline int common_clock_set(const clockid_t which_clock,
-                                  struct timespec *tp)
+
+static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
 {
-       return do_sys_settimeofday(tp, NULL);
+       *tp = current_kernel_time();
+       return 0;
 }
 
-static int common_timer_create(struct k_itimer *new_timer)
+static int posix_get_monotonic_coarse(clockid_t which_clock,
+                                               struct timespec *tp)
 {
-       hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
+       *tp = get_monotonic_coarse();
        return 0;
 }
 
-/*
- * Return nonzero if we know a priori this clockid_t value is bogus.
- */
-static inline int invalid_clockid(const clockid_t which_clock)
+static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp)
 {
-       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;
-       if (posix_clocks[which_clock].res != 0)
-               return 0;
-       return 1;
+       *tp = ktime_to_timespec(KTIME_LOW_RES);
+       return 0;
 }
 
-/*
- * Get monotonic time for posix timers
- */
-static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
+static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
 {
-       ktime_get_ts(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_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,
-               .clock_set = do_posix_clock_nosettime,
+               .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,
        };
 
-       register_posix_clock(CLOCK_REALTIME, &clock_realtime);
-       register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic);
+       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, 0, NULL, NULL);
+                                       sizeof (struct k_itimer), 0, SLAB_PANIC,
+                                       NULL);
        idr_init(&posix_timers_id);
        return 0;
 }
@@ -255,8 +295,9 @@ static void schedule_next_timer(struct k_itimer *timr)
        if (timr->it.real.interval.tv64 == 0)
                return;
 
-       timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(),
-                                           timr->it.real.interval);
+       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;
@@ -272,7 +313,7 @@ static void schedule_next_timer(struct k_itimer *timr)
  * 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,
+ * 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)
@@ -288,41 +329,39 @@ void do_schedule_next_timer(struct siginfo *info)
                else
                        schedule_next_timer(timr);
 
-               info->si_overrun = timr->it_overrun_last;
+               info->si_overrun += timr->it_overrun_last;
        }
 
        if (timr)
                unlock_timer(timr, flags);
 }
 
-int posix_timer_event(struct k_itimer *timr,int si_private)
+int posix_timer_event(struct k_itimer *timr, int si_private)
 {
-       memset(&timr->sigq->info, 0, sizeof(siginfo_t));
+       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;
-       /* Send signal to the process that owns this timer.*/
-
-       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) {
-               struct task_struct *leader;
-               int ret = send_sigqueue(timr->it_sigev_signo, timr->sigq,
-                                       timr->it_process);
-
-               if (likely(ret >= 0))
-                       return ret;
-
-               timr->it_sigev_notify = SIGEV_SIGNAL;
-               leader = timr->it_process->group_leader;
-               put_task_struct(timr->it_process);
-               timr->it_process = leader;
-       }
 
-       return send_group_sigqueue(timr->it_sigev_signo, timr->sigq,
-                                  timr->it_process);
+       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);
 
@@ -353,9 +392,40 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
                 * it should be restarted.
                 */
                if (timr->it.real.interval.tv64 != 0) {
-                       timr->it_overrun +=
-                               hrtimer_forward(timer,
-                                               hrtimer_cb_get_time(timer),
+                       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;
@@ -366,13 +436,13 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
        return ret;
 }
 
-static struct task_struct * good_sigevent(sigevent_t * event)
+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_pid(event->sigev_notify_thread_id)) ||
-                rtn->tgid != current->tgid ||
+               (!(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;
 
@@ -380,20 +450,32 @@ static struct task_struct * good_sigevent(sigevent_t * event)
            ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
                return NULL;
 
-       return rtn;
+       return task_pid(rtn);
 }
 
-void register_posix_clock(const clockid_t clock_id, struct k_clock *new_clock)
+void posix_timers_register_clock(const 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",
+               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(register_posix_clock);
+EXPORT_SYMBOL_GPL(posix_timers_register_clock);
 
 static struct k_itimer * alloc_posix_timer(void)
 {
@@ -403,11 +485,19 @@ static struct k_itimer * alloc_posix_timer(void)
                return tmr;
        if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
                kmem_cache_free(posix_timers_cache, tmr);
-               tmr = NULL;
+               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)
@@ -418,30 +508,44 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
                idr_remove(&posix_timers_id, tmr->it_id);
                spin_unlock_irqrestore(&idr_lock, flags);
        }
+       put_pid(tmr->it_pid);
        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);
+       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. */
 
-asmlinkage long
-sys_timer_create(const clockid_t which_clock,
-                struct sigevent __user *timer_event_spec,
-                timer_t __user * created_timer_id)
+SYSCALL_DEFINE3(timer_create, const 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;
+       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 (invalid_clockid(which_clock))
+       if (!kc)
                return -EINVAL;
+       if (!kc->timer_create)
+               return -EOPNOTSUPP;
 
        new_timer = alloc_posix_timer();
        if (unlikely(!new_timer))
@@ -454,14 +558,13 @@ sys_timer_create(const clockid_t which_clock,
                goto out;
        }
        spin_lock_irq(&idr_lock);
-       error = idr_get_new(&posix_timers_id, (void *) new_timer,
-                           &new_timer_id);
+       error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
        spin_unlock_irq(&idr_lock);
-       if (error == -EAGAIN)
-               goto retry;
-       else if (error) {
+       if (error) {
+               if (error == -EAGAIN)
+                       goto retry;
                /*
-                * Wierd looking, but we return EAGAIN if the IDR is
+                * Weird looking, but we return EAGAIN if the IDR is
                 * full (proper POSIX return value for this)
                 */
                error = -EAGAIN;
@@ -472,85 +575,56 @@ sys_timer_create(const clockid_t which_clock,
        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) {
+               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 {
-               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);
+               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:
-       if (error)
-               release_posix_timer(new_timer, it_id_set);
-
+       release_posix_timer(new_timer, it_id_set);
        return error;
 }
 
@@ -561,30 +635,23 @@ out:
  * 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)
+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);
+       rcu_read_lock();
+       timr = 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;
+               spin_lock_irqsave(&timr->it_lock, *flags);
+               if (timr->it_signal == current->signal) {
+                       rcu_read_unlock();
+                       return timr;
                }
-       } else
-               spin_unlock_irqrestore(&idr_lock, *flags);
+               spin_unlock_irqrestore(&timr->it_lock, *flags);
+       }
+       rcu_read_unlock();
 
-       return timr;
+       return NULL;
 }
 
 /*
@@ -629,9 +696,9 @@ common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
         */
        if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
            (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
-               timr->it_overrun += hrtimer_forward(timer, now, iv);
+               timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
 
-       remaining = ktime_sub(timer->expires, now);
+       remaining = ktime_sub(hrtimer_get_expires(timer), now);
        /* Return 0 only, when the timer is expired and not pending */
        if (remaining.tv64 <= 0) {
                /*
@@ -645,25 +712,31 @@ common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
 }
 
 /* Get the time remaining on a POSIX.1b interval timer. */
-asmlinkage long
-sys_timer_gettime(timer_t timer_id, struct itimerspec __user *setting)
+SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
+               struct itimerspec __user *, setting)
 {
-       struct k_itimer *timr;
        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;
 
-       CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting));
+       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 (copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
+       if (!ret && copy_to_user(setting, &cur_setting, sizeof (cur_setting)))
                return -EFAULT;
 
-       return 0;
+       return ret;
 }
 
 /*
@@ -675,12 +748,11 @@ sys_timer_gettime(timer_t timer_id, struct itimerspec __user *setting)
  * 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)
+SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
 {
        struct k_itimer *timr;
        int overrun;
-       long flags;
+       unsigned long flags;
 
        timr = lock_timer(timer_id, &flags);
        if (!timr)
@@ -725,7 +797,7 @@ common_timer_set(struct k_itimer *timr, int flags,
        hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
        timr->it.real.timer.function = posix_timer_fn;
 
-       timer->expires = timespec_to_ktime(new_setting->it_value);
+       hrtimer_set_expires(timer, timespec_to_ktime(new_setting->it_value));
 
        /* Convert interval */
        timr->it.real.interval = timespec_to_ktime(new_setting->it_interval);
@@ -733,27 +805,27 @@ common_timer_set(struct k_itimer *timr, int flags,
        /* 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)
-                       timer->expires = ktime_add(timer->expires,
-                                                  timer->base->get_time());
+               if (mode == HRTIMER_MODE_REL) {
+                       hrtimer_add_expires(timer, timer->base->get_time());
+               }
                return 0;
        }
 
-       hrtimer_start(timer, timer->expires, mode);
+       hrtimer_start_expires(timer, mode);
        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)
+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;
-       long flag;
+       unsigned long flag;
        struct itimerspec *rtn = old_setting ? &old_spec : NULL;
+       struct k_clock *kc;
 
        if (!new_setting)
                return -EINVAL;
@@ -769,8 +841,11 @@ retry:
        if (!timr)
                return -EINVAL;
 
-       error = CLOCK_DISPATCH(timr->it_clock, timer_set,
-                              (timr, flags, &new_spec, rtn));
+       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) {
@@ -785,7 +860,7 @@ retry:
        return error;
 }
 
-static inline int common_timer_del(struct k_itimer *timer)
+static int common_timer_del(struct k_itimer *timer)
 {
        timer->it.real.interval.tv64 = 0;
 
@@ -796,15 +871,18 @@ static inline int common_timer_del(struct k_itimer *timer)
 
 static inline int timer_delete_hook(struct k_itimer *timer)
 {
-       return CLOCK_DISPATCH(timer->it_clock, timer_del, (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. */
-asmlinkage long
-sys_timer_delete(timer_t timer_id)
+SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
 {
        struct k_itimer *timer;
-       long flags;
+       unsigned long flags;
 
 retry_delete:
        timer = lock_timer(timer_id, &flags);
@@ -823,11 +901,8 @@ retry_delete:
         * 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;
-       }
+       timer->it_signal = NULL;
+
        unlock_timer(timer, flags);
        release_posix_timer(timer, IT_ID_SET);
        return 0;
@@ -852,11 +927,8 @@ retry_delete:
         * 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;
-       }
+       timer->it_signal = NULL;
+
        unlock_timer(timer, flags);
        release_posix_timer(timer, IT_ID_SET);
 }
@@ -875,69 +947,76 @@ void exit_itimers(struct signal_struct *sig)
        }
 }
 
-/* Not available / possible... functions */
-int do_posix_clock_nosettime(const clockid_t clockid, struct timespec *tp)
-{
-       return -EINVAL;
-}
-EXPORT_SYMBOL_GPL(do_posix_clock_nosettime);
-
-int do_posix_clock_nonanosleep(const clockid_t clock, int flags,
-                              struct timespec *t, struct timespec __user *r)
-{
-#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(const clockid_t which_clock,
-                                 const struct timespec __user *tp)
+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 (invalid_clockid(which_clock))
+       if (!kc || !kc->clock_set)
                return -EINVAL;
+
        if (copy_from_user(&new_tp, tp, sizeof (*tp)))
                return -EFAULT;
 
-       return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp));
+       return kc->clock_set(which_clock, &new_tp);
 }
 
-asmlinkage long
-sys_clock_gettime(const clockid_t which_clock, struct timespec __user *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 (invalid_clockid(which_clock))
+       if (!kc)
                return -EINVAL;
-       error = CLOCK_DISPATCH(which_clock, clock_get,
-                              (which_clock, &kernel_tp));
+
+       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;
 }
 
-asmlinkage long
-sys_clock_getres(const clockid_t which_clock, struct timespec __user *tp)
+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 (invalid_clockid(which_clock))
+       if (!kc)
                return -EINVAL;
 
-       error = CLOCK_DISPATCH(which_clock, clock_getres,
-                              (which_clock, &rtn_tp));
+       error = kc->clock_getres(which_clock, &rtn_tp);
 
-       if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) {
+       if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp)))
                error = -EFAULT;
-       }
 
        return error;
 }
@@ -953,15 +1032,17 @@ static int common_nsleep(const clockid_t which_clock, int flags,
                                 which_clock);
 }
 
-asmlinkage long
-sys_clock_nanosleep(const clockid_t which_clock, int flags,
-                   const struct timespec __user *rqtp,
-                   struct timespec __user *rmtp)
+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 (invalid_clockid(which_clock))
+       if (!kc)
                return -EINVAL;
+       if (!kc->nsleep)
+               return -ENANOSLEEP_NOTSUP;
 
        if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
                return -EFAULT;
@@ -969,27 +1050,20 @@ sys_clock_nanosleep(const clockid_t which_clock, int flags,
        if (!timespec_valid(&t))
                return -EINVAL;
 
-       return CLOCK_DISPATCH(which_clock, nsleep,
-                             (which_clock, flags, &t, rmtp));
-}
-
-/*
- * nanosleep_restart for monotonic and realtime clocks
- */
-static int common_nsleep_restart(struct restart_block *restart_block)
-{
-       return hrtimer_nanosleep_restart(restart_block);
+       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)
+long clock_nanosleep_restart(struct restart_block *restart_block)
 {
-       clockid_t which_clock = restart_block->arg0;
+       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 CLOCK_DISPATCH(which_clock, nsleep_restart,
-                             (restart_block));
+       return kc->nsleep_restart(restart_block);
 }