8 files changed, 150 insertions, 45 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index f80dec3f1875..efd30ccf3858 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -118,6 +118,8 @@ static void __exit_signal(struct task_struct *tsk)
                  * We won't ever get here for the group leader, since it
                  * will have been the last reference on the signal_struct.
                  */
+                sig->utime = cputime_add(sig->utime, task_utime(tsk));
+                sig->stime = cputime_add(sig->stime, task_stime(tsk));
                 sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));
                 sig->min_flt += tsk->min_flt;
                 sig->maj_flt += tsk->maj_flt;
@@ -126,6 +128,7 @@ static void __exit_signal(struct task_struct *tsk)
                 sig->inblock += task_io_get_inblock(tsk);
                 sig->oublock += task_io_get_oublock(tsk);
                 task_io_accounting_add(&sig->ioac, &tsk->ioac);
+                sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
                 sig = NULL; /* Marker for below. */
         }
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 6d5dbb7a13e2..bb5fe56a7a9c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -851,13 +851,14 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
         sig->tty_old_pgrp = NULL;
         sig->tty = NULL;
 
-        sig->cutime = sig->cstime = cputime_zero;
+        sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
         sig->gtime = cputime_zero;
         sig->cgtime = cputime_zero;
         sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
         sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
         sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
         task_io_accounting_init(&sig->ioac);
+        sig->sum_sched_runtime = 0;
         taskstats_tgid_init(sig);
 
         task_lock(current->group_leader);
diff --git a/kernel/itimer.c b/kernel/itimer.c
index 6a5fe93dd8bd..58762f7077ec 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -62,7 +62,7 @@ int do_getitimer(int which, struct itimerval *value)
                         struct task_cputime cputime;
                         cputime_t utime;
 
-                        thread_group_cputime(tsk, &cputime);
+                        thread_group_cputimer(tsk, &cputime);
                         utime = cputime.utime;
                         if (cputime_le(cval, utime)) { /* about to fire */
                                 cval = jiffies_to_cputime(1);
@@ -82,7 +82,7 @@ int do_getitimer(int which, struct itimerval *value)
                         struct task_cputime times;
                         cputime_t ptime;
 
-                        thread_group_cputime(tsk, &times);
+                        thread_group_cputimer(tsk, &times);
                         ptime = cputime_add(times.utime, times.stime);
                         if (cputime_le(cval, ptime)) { /* about to fire */
                                 cval = jiffies_to_cputime(1);
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index fa07da94d7be..db107c9bbc05 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -230,6 +230,37 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
         return 0;
 }
 
+void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
+{
+        struct sighand_struct *sighand;
+        struct signal_struct *sig;
+        struct task_struct *t;
+
+        *times = INIT_CPUTIME;
+
+        rcu_read_lock();
+        sighand = rcu_dereference(tsk->sighand);
+        if (!sighand)
+                goto out;
+
+        sig = tsk->signal;
+
+        t = tsk;
+        do {
+                times->utime = cputime_add(times->utime, t->utime);
+                times->stime = cputime_add(times->stime, t->stime);
+                times->sum_exec_runtime += t->se.sum_exec_runtime;
+
+                t = next_thread(t);
+        } while (t != tsk);
+
+        times->utime = cputime_add(times->utime, sig->utime);
+        times->stime = cputime_add(times->stime, sig->stime);
+        times->sum_exec_runtime += sig->sum_sched_runtime;
+out:
+        rcu_read_unlock();
+}
+
 /*
  * Sample a process (thread group) clock for the given group_leader task.
  * Must be called with tasklist_lock held for reading.
@@ -476,6 +507,29 @@ static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
 }
 
 /*
+ * Enable the process wide cpu timer accounting.
+ *
+ * serialized using ->sighand->siglock
+ */
+static void start_process_timers(struct task_struct *tsk)
+{
+        tsk->signal->cputimer.running = 1;
+        barrier();
+}
+
+/*
+ * Release the process wide timer accounting -- timer stops ticking when
+ * nobody cares about it.
+ *
+ * serialized using ->sighand->siglock
+ */
+static void stop_process_timers(struct task_struct *tsk)
+{
+        tsk->signal->cputimer.running = 0;
+        barrier();
+}
+
+/*
  * Insert the timer on the appropriate list before any timers that
  * expire later.  This must be called with the tasklist_lock held
  * for reading, and interrupts disabled.
@@ -495,6 +549,9 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
         BUG_ON(!irqs_disabled());
         spin_lock(&p->sighand->siglock);
 
+        if (!CPUCLOCK_PERTHREAD(timer->it_clock))
+                start_process_timers(p);
+
         listpos = head;
         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
                 list_for_each_entry(next, head, entry) {
@@ -987,13 +1044,15 @@ static void check_process_timers(struct task_struct *tsk,
             sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
             list_empty(&timers[CPUCLOCK_VIRT]) &&
             cputime_eq(sig->it_virt_expires, cputime_zero) &&
-            list_empty(&timers[CPUCLOCK_SCHED]))
+            list_empty(&timers[CPUCLOCK_SCHED])) {
+                stop_process_timers(tsk);
                 return;
+        }
 
         /*
          * Collect the current process totals.
          */
-        thread_group_cputime(tsk, &cputime);
+        thread_group_cputimer(tsk, &cputime);
         utime = cputime.utime;
         ptime = cputime_add(utime, cputime.stime);
         sum_sched_runtime = cputime.sum_exec_runtime;
@@ -1259,7 +1318,7 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
         if (!task_cputime_zero(&sig->cputime_expires)) {
                 struct task_cputime group_sample;
 
-                thread_group_cputime(tsk, &group_sample);
+                thread_group_cputimer(tsk, &group_sample);
                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
                         return 1;
         }
@@ -1329,6 +1388,33 @@ void run_posix_cpu_timers(struct task_struct *tsk)
 }
 
 /*
+ * Sample a process (thread group) timer for the given group_leader task.
+ * Must be called with tasklist_lock held for reading.
+ */
+static int cpu_timer_sample_group(const clockid_t which_clock,
+                                  struct task_struct *p,
+                                  union cpu_time_count *cpu)
+{
+        struct task_cputime cputime;
+
+        thread_group_cputimer(p, &cputime);
+        switch (CPUCLOCK_WHICH(which_clock)) {
+        default:
+                return -EINVAL;
+        case CPUCLOCK_PROF:
+                cpu->cpu = cputime_add(cputime.utime, cputime.stime);
+                break;
+        case CPUCLOCK_VIRT:
+                cpu->cpu = cputime.utime;
+                break;
+        case CPUCLOCK_SCHED:
+                cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
+                break;
+        }
+        return 0;
+}
+
+/*
  * Set one of the process-wide special case CPU timers.
  * The tsk->sighand->siglock must be held by the caller.
  * The *newval argument is relative and we update it to be absolute, *oldval
@@ -1341,7 +1427,8 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
         struct list_head *head;
 
         BUG_ON(clock_idx == CPUCLOCK_SCHED);
-        cpu_clock_sample_group(clock_idx, tsk, &now);
+        start_process_timers(tsk);
+        cpu_timer_sample_group(clock_idx, tsk, &now);
 
         if (oldval) {
                 if (!cputime_eq(*oldval, cputime_zero)) {
diff --git a/kernel/sched.c b/kernel/sched.c
index 8ee437a5ec1d..e72485033c48 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3890,19 +3890,24 @@ int select_nohz_load_balancer(int stop_tick)
         int cpu = smp_processor_id();
 
         if (stop_tick) {
-                cpumask_set_cpu(cpu, nohz.cpu_mask);
                 cpu_rq(cpu)->in_nohz_recently = 1;
 
-                /*
-                 * If we are going offline and still the leader, give up!
-                 */
-                if (!cpu_active(cpu) &&
-                    atomic_read(&nohz.load_balancer) == cpu) {
+                if (!cpu_active(cpu)) {
+                        if (atomic_read(&nohz.load_balancer) != cpu)
+                                return 0;
+
+                        /*
+                         * If we are going offline and still the leader,
+                         * give up!
+                         */
                         if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
                                 BUG();
+
                         return 0;
                 }
 
+                cpumask_set_cpu(cpu, nohz.cpu_mask);
+
                 /* time for ilb owner also to sleep */
                 if (cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
                         if (atomic_read(&nohz.load_balancer) == cpu)
diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h
index 8ab0cef8ecab..a8f93dd374e1 100644
--- a/kernel/sched_stats.h
+++ b/kernel/sched_stats.h
@@ -296,19 +296,21 @@ sched_info_switch(struct task_struct *prev, struct task_struct *next)
 static inline void account_group_user_time(struct task_struct *tsk,
                                            cputime_t cputime)
 {
-        struct task_cputime *times;
-        struct signal_struct *sig;
+        struct thread_group_cputimer *cputimer;
 
         /* tsk == current, ensure it is safe to use ->signal */
         if (unlikely(tsk->exit_state))
                 return;
 
-        sig = tsk->signal;
-        times = &sig->cputime.totals;
+        cputimer = &tsk->signal->cputimer;
 
-        spin_lock(&times->lock);
-        times->utime = cputime_add(times->utime, cputime);
-        spin_unlock(&times->lock);
+        if (!cputimer->running)
+                return;
+
+        spin_lock(&cputimer->lock);
+        cputimer->cputime.utime =
+                cputime_add(cputimer->cputime.utime, cputime);
+        spin_unlock(&cputimer->lock);
 }
 
 /**
@@ -324,19 +326,21 @@ static inline void account_group_user_time(struct task_struct *tsk,
 static inline void account_group_system_time(struct task_struct *tsk,
                                              cputime_t cputime)
 {
-        struct task_cputime *times;
-        struct signal_struct *sig;
+        struct thread_group_cputimer *cputimer;
 
         /* tsk == current, ensure it is safe to use ->signal */
         if (unlikely(tsk->exit_state))
                 return;
 
-        sig = tsk->signal;
-        times = &sig->cputime.totals;
+        cputimer = &tsk->signal->cputimer;
+
+        if (!cputimer->running)
+                return;
 
-        spin_lock(&times->lock);
-        times->stime = cputime_add(times->stime, cputime);
-        spin_unlock(&times->lock);
+        spin_lock(&cputimer->lock);
+        cputimer->cputime.stime =
+                cputime_add(cputimer->cputime.stime, cputime);
+        spin_unlock(&cputimer->lock);
 }
 
 /**
@@ -352,7 +356,7 @@ static inline void account_group_system_time(struct task_struct *tsk,
 static inline void account_group_exec_runtime(struct task_struct *tsk,
                                               unsigned long long ns)
 {
-        struct task_cputime *times;
+        struct thread_group_cputimer *cputimer;
         struct signal_struct *sig;
 
         sig = tsk->signal;
@@ -361,9 +365,12 @@ static inline void account_group_exec_runtime(struct task_struct *tsk,
         if (unlikely(!sig))
                 return;
 
-        times = &sig->cputime.totals;
+        cputimer = &sig->cputimer;
+
+        if (!cputimer->running)
+                return;
 
-        spin_lock(&times->lock);
-        times->sum_exec_runtime += ns;
-        spin_unlock(&times->lock);
+        spin_lock(&cputimer->lock);
+        cputimer->cputime.sum_exec_runtime += ns;
+        spin_unlock(&cputimer->lock);
 }
diff --git a/kernel/signal.c b/kernel/signal.c
index b6b36768b758..2a74fe87c0dd 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1367,7 +1367,6 @@ int do_notify_parent(struct task_struct *tsk, int sig)
         struct siginfo info;
         unsigned long flags;
         struct sighand_struct *psig;
-        struct task_cputime cputime;
         int ret = sig;
 
         BUG_ON(sig == -1);
@@ -1397,9 +1396,10 @@ int do_notify_parent(struct task_struct *tsk, int sig)
         info.si_uid = __task_cred(tsk)->uid;
         rcu_read_unlock();
 
-        thread_group_cputime(tsk, &cputime);
-        info.si_utime = cputime_to_jiffies(cputime.utime);
-        info.si_stime = cputime_to_jiffies(cputime.stime);
+        info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
+                                tsk->signal->utime));
+        info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
+                                tsk->signal->stime));
 
         info.si_status = tsk->exit_code & 0x7f;
         if (tsk->exit_code & 0x80)
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index ea2f48af83cf..d13be216a790 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -68,6 +68,17 @@ void clockevents_set_mode(struct clock_event_device *dev,
         if (dev->mode != mode) {
                 dev->set_mode(mode, dev);
                 dev->mode = mode;
+
+                /*
+                 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
+                 * on it, so fix it up and emit a warning:
+                 */
+                if (mode == CLOCK_EVT_MODE_ONESHOT) {
+                        if (unlikely(!dev->mult)) {
+                                dev->mult = 1;
+                                WARN_ON(1);
+                        }
+                }
         }
 }
 
@@ -168,15 +179,6 @@ void clockevents_register_device(struct clock_event_device *dev)
         BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
         BUG_ON(!dev->cpumask);
 
-        /*
-         * A nsec2cyc multiplicator of 0 is invalid and we'd crash
-         * on it, so fix it up and emit a warning:
-         */
-        if (unlikely(!dev->mult)) {
-                dev->mult = 1;
-                WARN_ON(1);
-        }
-
         spin_lock(&clockevents_lock);
 
         list_add(&dev->list, &clockevent_devices);