Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  timers: fix TIMER_ABSTIME for process wide cpu timers
  timers: split process wide cpu clocks/timers, fix
  x86: clean up hpet timer reinit
  timers: split process wide cpu clocks/timers, remove spurious warning
  timers: split process wide cpu clocks/timers
  signal: re-add dead task accumulation stats.
  x86: fix hpet timer reinit for x86_64
  sched: fix nohz load balancer on cpu offline

10 files changed, 209 insertions, 75 deletions

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 64d5ad0b8add..388254f69a2a 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -897,7 +897,7 @@ static unsigned long hpet_rtc_flags;
 static int hpet_prev_update_sec;
 static struct rtc_time hpet_alarm_time;
 static unsigned long hpet_pie_count;
-static unsigned long hpet_t1_cmp;
+static u32 hpet_t1_cmp;
 static unsigned long hpet_default_delta;
 static unsigned long hpet_pie_delta;
 static unsigned long hpet_pie_limit;
@@ -905,6 +905,14 @@ static unsigned long hpet_pie_limit;
 static rtc_irq_handler irq_handler;
 
 /*
+ * Check that the hpet counter c1 is ahead of the c2
+ */
+static inline int hpet_cnt_ahead(u32 c1, u32 c2)
+{
+        return (s32)(c2 - c1) < 0;
+}
+
+/*
  * Registers a IRQ handler.
  */
 int hpet_register_irq_handler(rtc_irq_handler handler)
@@ -1075,7 +1083,7 @@ static void hpet_rtc_timer_reinit(void)
                 hpet_t1_cmp += delta;
                 hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
                 lost_ints++;
-        } while ((long)(hpet_readl(HPET_COUNTER) - hpet_t1_cmp) > 0);
+        } while (!hpet_cnt_ahead(hpet_t1_cmp, hpet_readl(HPET_COUNTER)));
 
         if (lost_ints) {
                 if (hpet_rtc_flags & RTC_PIE)
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index ea0ea1a4c36f..e752d973fa21 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -48,12 +48,11 @@ extern struct fs_struct init_fs;
         .posix_timers    = LIST_HEAD_INIT(sig.posix_timers),            \
         .cpu_timers     = INIT_CPU_TIMERS(sig.cpu_timers),              \
         .rlim           = INIT_RLIMITS,                                 \
-        .cputime        = { .totals = {                                 \
-                .utime = cputime_zero,                                  \
-                .stime = cputime_zero,                                  \
-                .sum_exec_runtime = 0,                                  \
-                .lock = __SPIN_LOCK_UNLOCKED(sig.cputime.totals.lock),  \
-        }, },                                                           \
+        .cputimer       = {                                             \
+                .cputime = INIT_CPUTIME,                                \
+                .running = 0,                                           \
+                .lock = __SPIN_LOCK_UNLOCKED(sig.cputimer.lock),        \
+        },                                                              \
 }
 
 extern struct nsproxy init_nsproxy;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2127e959e0f4..8981e52c714f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -443,7 +443,6 @@ struct pacct_struct {
  * @utime:              time spent in user mode, in &cputime_t units
  * @stime:              time spent in kernel mode, in &cputime_t units
  * @sum_exec_runtime:   total time spent on the CPU, in nanoseconds
- * @lock:               lock for fields in this struct
  *
  * This structure groups together three kinds of CPU time that are
  * tracked for threads and thread groups.  Most things considering
@@ -454,23 +453,33 @@ struct task_cputime {
         cputime_t utime;
         cputime_t stime;
         unsigned long long sum_exec_runtime;
-        spinlock_t lock;
 };
 /* Alternate field names when used to cache expirations. */
 #define prof_exp        stime
 #define virt_exp        utime
 #define sched_exp       sum_exec_runtime
 
+#define INIT_CPUTIME    \
+        (struct task_cputime) {                                 \
+                .utime = cputime_zero,                          \
+                .stime = cputime_zero,                          \
+                .sum_exec_runtime = 0,                          \
+        }
+
 /**
- * struct thread_group_cputime - thread group interval timer counts
- * @totals:             thread group interval timers; substructure for
- *                      uniprocessor kernel, per-cpu for SMP kernel.
+ * struct thread_group_cputimer - thread group interval timer counts
+ * @cputime:            thread group interval timers.
+ * @running:            non-zero when there are timers running and
+ *                      @cputime receives updates.
+ * @lock:               lock for fields in this struct.
  *
  * This structure contains the version of task_cputime, above, that is
- * used for thread group CPU clock calculations.
+ * used for thread group CPU timer calculations.
  */
-struct thread_group_cputime {
-        struct task_cputime totals;
+struct thread_group_cputimer {
+        struct task_cputime cputime;
+        int running;
+        spinlock_t lock;
 };
 
 /*
@@ -519,10 +528,10 @@ struct signal_struct {
         cputime_t it_prof_incr, it_virt_incr;
 
         /*
-         * Thread group totals for process CPU clocks.
-         * See thread_group_cputime(), et al, for details.
+         * Thread group totals for process CPU timers.
+         * See thread_group_cputimer(), et al, for details.
          */
-        struct thread_group_cputime cputime;
+        struct thread_group_cputimer cputimer;
 
         /* Earliest-expiration cache. */
         struct task_cputime cputime_expires;
@@ -559,7 +568,7 @@ struct signal_struct {
          * Live threads maintain their own counters and add to these
          * in __exit_signal, except for the group leader.
          */
-        cputime_t cutime, cstime;
+        cputime_t utime, stime, cutime, cstime;
         cputime_t gtime;
         cputime_t cgtime;
         unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
@@ -568,6 +577,14 @@ struct signal_struct {
         struct task_io_accounting ioac;
 
         /*
+         * Cumulative ns of schedule CPU time fo dead threads in the
+         * group, not including a zombie group leader, (This only differs
+         * from jiffies_to_ns(utime + stime) if sched_clock uses something
+         * other than jiffies.)
+         */
+        unsigned long long sum_sched_runtime;
+
+        /*
          * We don't bother to synchronize most readers of this at all,
          * because there is no reader checking a limit that actually needs
          * to get both rlim_cur and rlim_max atomically, and either one
@@ -2183,27 +2200,14 @@ static inline int spin_needbreak(spinlock_t *lock)
 /*
  * Thread group CPU time accounting.
  */
-
-static inline
-void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
-{
-        struct task_cputime *totals = &tsk->signal->cputime.totals;
-        unsigned long flags;
-
-        spin_lock_irqsave(&totals->lock, flags);
-        *times = *totals;
-        spin_unlock_irqrestore(&totals->lock, flags);
-}
+void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
+void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);
 
 static inline void thread_group_cputime_init(struct signal_struct *sig)
 {
-        sig->cputime.totals = (struct task_cputime){
-                .utime = cputime_zero,
-                .stime = cputime_zero,
-                .sum_exec_runtime = 0,
-        };
-
-        spin_lock_init(&sig->cputime.totals.lock);
+        sig->cputimer.cputime = INIT_CPUTIME;
+        spin_lock_init(&sig->cputimer.lock);
+        sig->cputimer.running = 0;
 }
 
 static inline void thread_group_cputime_free(struct signal_struct *sig)
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 d624d50f7729..a66fbde20715 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..2313a4cc14ea 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -230,6 +230,71 @@ 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();
+}
+
+static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
+{
+        if (cputime_gt(b->utime, a->utime))
+                a->utime = b->utime;
+
+        if (cputime_gt(b->stime, a->stime))
+                a->stime = b->stime;
+
+        if (b->sum_exec_runtime > a->sum_exec_runtime)
+                a->sum_exec_runtime = b->sum_exec_runtime;
+}
+
+void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
+{
+        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+        struct task_cputime sum;
+        unsigned long flags;
+
+        spin_lock_irqsave(&cputimer->lock, flags);
+        if (!cputimer->running) {
+                cputimer->running = 1;
+                /*
+                 * The POSIX timer interface allows for absolute time expiry
+                 * values through the TIMER_ABSTIME flag, therefore we have
+                 * to synchronize the timer to the clock every time we start
+                 * it.
+                 */
+                thread_group_cputime(tsk, &sum);
+                update_gt_cputime(&cputimer->cputime, &sum);
+        }
+        *times = cputimer->cputime;
+        spin_unlock_irqrestore(&cputimer->lock, flags);
+}
+
 /*
  * Sample a process (thread group) clock for the given group_leader task.
  * Must be called with tasklist_lock held for reading.
@@ -457,7 +522,7 @@ void posix_cpu_timers_exit_group(struct task_struct *tsk)
 {
         struct task_cputime cputime;
 
-        thread_group_cputime(tsk, &cputime);
+        thread_group_cputimer(tsk, &cputime);
         cleanup_timers(tsk->signal->cpu_timers,
                        cputime.utime, cputime.stime, cputime.sum_exec_runtime);
 }
@@ -964,6 +1029,19 @@ static void check_thread_timers(struct task_struct *tsk,
         }
 }
 
+static void stop_process_timers(struct task_struct *tsk)
+{
+        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+        unsigned long flags;
+
+        if (!cputimer->running)
+                return;
+
+        spin_lock_irqsave(&cputimer->lock, flags);
+        cputimer->running = 0;
+        spin_unlock_irqrestore(&cputimer->lock, flags);
+}
+
 /*
  * Check for any per-thread CPU timers that have fired and move them
  * off the tsk->*_timers list onto the firing list.  Per-thread timers
@@ -987,13 +1065,15 @@ 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 +1339,7 @@ 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 +1409,33 @@ 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 +1448,7 @@ 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);
+        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)