1 files changed, 204 insertions, 175 deletions

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 9ca4973f736d..4556182527f3 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -41,6 +41,7 @@
 #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>
@@ -81,6 +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().
@@ -94,11 +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
@@ -108,20 +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_pid
- *          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
@@ -138,6 +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 *);
@@ -145,83 +144,37 @@ 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))
-
-/*
- * 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(const clockid_t which_clock,
-                                      struct timespec *tp)
-{
-        tp->tv_sec = 0;
-        tp->tv_nsec = posix_clocks[which_clock].res;
-        return 0;
-}
-
-/*
- * Get real time for posix timers
- */
-static int common_clock_get(clockid_t which_clock, struct timespec *tp)
+/* Get clock_realtime */
+static int posix_clock_realtime_get(clockid_t which_clock, struct timespec *tp)
 {
         ktime_get_real_ts(tp);
         return 0;
 }
 
-static inline int common_clock_set(const clockid_t which_clock,
-                                   struct timespec *tp)
+/* 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 common_timer_create(struct k_itimer *new_timer)
-{
-        hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
-        return 0;
-}
-
-static int no_timer_create(struct k_itimer *new_timer)
-{
-        return -EOPNOTSUPP;
-}
-
-static int no_nsleep(const clockid_t which_clock, int flags,
-                     struct timespec *tsave, struct timespec __user *rmtp)
+static int posix_clock_realtime_adj(const clockid_t which_clock,
+                                    struct timex *t)
 {
-        return -EOPNOTSUPP;
-}
-
-/*
- * Return nonzero if we know a priori this clockid_t value is bogus.
- */
-static inline int invalid_clockid(const 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;
-        if (posix_clocks[which_clock].res != 0)
-                return 0;
-        return 1;
+        return do_adjtimex(t);
 }
 
 /*
@@ -234,7 +187,7 @@ static int posix_ktime_get_ts(clockid_t which_clock, struct timespec *tp)
 }
 
 /*
- * Get monotonic time for posix timers
+ * Get monotonic-raw time for posix timers
  */
 static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
 {
@@ -261,46 +214,70 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp
         *tp = ktime_to_timespec(KTIME_LOW_RES);
         return 0;
 }
+
+static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
+{
+        get_monotonic_boottime(tp);
+        return 0;
+}
+
+
 /*
  * Initialize everything, well, just everything in Posix clocks/timers ;)
  */
 static __init int init_posix_timers(void)
 {
         struct k_clock clock_realtime = {
-                .clock_getres = hrtimer_get_res,
+                .clock_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,
-                .clock_set = do_posix_clock_nosettime,
-                .timer_create = no_timer_create,
-                .nsleep = no_nsleep,
+                .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,
-                .clock_set = do_posix_clock_nosettime,
-                .timer_create = no_timer_create,
-                .nsleep = no_nsleep,
+                .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,
-                .clock_set = do_posix_clock_nosettime,
-                .timer_create = no_timer_create,
-                .nsleep = no_nsleep,
+                .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);
-        register_posix_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
-        register_posix_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
-        register_posix_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
+        posix_timers_register_clock(CLOCK_REALTIME, &clock_realtime);
+        posix_timers_register_clock(CLOCK_MONOTONIC, &clock_monotonic);
+        posix_timers_register_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
+        posix_timers_register_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
+        posix_timers_register_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
+        posix_timers_register_clock(CLOCK_BOOTTIME, &clock_boottime);
 
         posix_timers_cache = kmem_cache_create("posix_timers_cache",
                                         sizeof (struct k_itimer), 0, SLAB_PANIC,
@@ -336,7 +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)
@@ -476,17 +453,29 @@ static struct pid *good_sigevent(sigevent_t * event)
         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)
 {
@@ -502,6 +491,13 @@ static struct k_itimer * alloc_posix_timer(void)
         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)
@@ -514,7 +510,24 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
         }
         put_pid(tmr->it_pid);
         sigqueue_free(tmr->sigq);
-        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. */
@@ -523,13 +536,16 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
                 struct sigevent __user *, timer_event_spec,
                 timer_t __user *, created_timer_id)
 {
+        struct k_clock *kc = clockid_to_kclock(which_clock);
         struct k_itimer *new_timer;
         int error, new_timer_id;
         sigevent_t event;
         int it_id_set = IT_ID_NOT_SET;
 
-        if (invalid_clockid(which_clock))
+        if (!kc)
                 return -EINVAL;
+        if (!kc->timer_create)
+                return -EOPNOTSUPP;
 
         new_timer = alloc_posix_timer();
         if (unlikely(!new_timer))
@@ -591,7 +607,7 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
                 goto out;
         }
 
-        error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
+        error = kc->timer_create(new_timer);
         if (error)
                 goto out;
 
@@ -601,7 +617,7 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
         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
@@ -619,25 +635,21 @@ 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);
+
+        rcu_read_lock();
         timr = idr_find(&posix_timers_id, (int)timer_id);
         if (timr) {
-                spin_lock(&timr->it_lock);
+                spin_lock_irqsave(&timr->it_lock, *flags);
                 if (timr->it_signal == current->signal) {
-                        spin_unlock(&idr_lock);
+                        rcu_read_unlock();
                         return timr;
                 }
-                spin_unlock(&timr->it_lock);
+                spin_unlock_irqrestore(&timr->it_lock, *flags);
         }
-        spin_unlock_irqrestore(&idr_lock, *flags);
+        rcu_read_unlock();
 
         return NULL;
 }
@@ -703,22 +715,28 @@ common_timer_get(struct k_itimer *timr, struct itimerspec *cur_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;
 }
 
 /*
@@ -807,6 +825,7 @@ SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
         int error = 0;
         unsigned long flag;
         struct itimerspec *rtn = old_setting ? &old_spec : NULL;
+        struct k_clock *kc;
 
         if (!new_setting)
                 return -EINVAL;
@@ -822,8 +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) {
@@ -838,7 +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;
 
@@ -849,7 +871,11 @@ 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. */
@@ -921,69 +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);
-
 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);
 }
 
 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;
 }
 
 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;
 }
@@ -1003,10 +1036,13 @@ 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;
@@ -1014,27 +1050,20 @@ SYSCALL_DEFINE4(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);
 }