6 files changed, 36 insertions, 109 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index bf0cef8bbdf2..242a706e7721 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -817,17 +817,17 @@ static void posix_cpu_timers_init_group(struct signal_struct *sig)
 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
 {
         struct signal_struct *sig;
-        int ret;
 
         if (clone_flags & CLONE_THREAD) {
-                ret = thread_group_cputime_clone_thread(current);
-                if (likely(!ret)) {
-                        atomic_inc(&current->signal->count);
-                        atomic_inc(&current->signal->live);
-                }
-                return ret;
+                atomic_inc(&current->signal->count);
+                atomic_inc(&current->signal->live);
+                return 0;
         }
         sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
+
+        if (sig)
+                posix_cpu_timers_init_group(sig);
+
         tsk->signal = sig;
         if (!sig)
                 return -ENOMEM;
@@ -864,8 +864,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
         memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
         task_unlock(current->group_leader);
 
-        posix_cpu_timers_init_group(sig);
-
         acct_init_pacct(&sig->pacct);
 
         tty_audit_fork(sig);
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 2dc30c59c5fd..f33afb0407bc 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -614,7 +614,9 @@ void clock_was_set(void)
  */
 void hres_timers_resume(void)
 {
-        /* Retrigger the CPU local events: */
+        WARN_ONCE(!irqs_disabled(),
+                  KERN_INFO "hres_timers_resume() called with IRQs enabled!");
+
         retrigger_next_event(NULL);
 }
 
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 157de3a47832..fa07da94d7be 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -10,76 +10,6 @@
 #include <linux/kernel_stat.h>
 
 /*
- * Allocate the thread_group_cputime structure appropriately and fill in the
- * current values of the fields.  Called from copy_signal() via
- * thread_group_cputime_clone_thread() when adding a second or subsequent
- * thread to a thread group.  Assumes interrupts are enabled when called.
- */
-int thread_group_cputime_alloc(struct task_struct *tsk)
-{
-        struct signal_struct *sig = tsk->signal;
-        struct task_cputime *cputime;
-
-        /*
-         * If we have multiple threads and we don't already have a
-         * per-CPU task_cputime struct (checked in the caller), allocate
-         * one and fill it in with the times accumulated so far.  We may
-         * race with another thread so recheck after we pick up the sighand
-         * lock.
-         */
-        cputime = alloc_percpu(struct task_cputime);
-        if (cputime == NULL)
-                return -ENOMEM;
-        spin_lock_irq(&tsk->sighand->siglock);
-        if (sig->cputime.totals) {
-                spin_unlock_irq(&tsk->sighand->siglock);
-                free_percpu(cputime);
-                return 0;
-        }
-        sig->cputime.totals = cputime;
-        cputime = per_cpu_ptr(sig->cputime.totals, smp_processor_id());
-        cputime->utime = tsk->utime;
-        cputime->stime = tsk->stime;
-        cputime->sum_exec_runtime = tsk->se.sum_exec_runtime;
-        spin_unlock_irq(&tsk->sighand->siglock);
-        return 0;
-}
-
-/**
- * thread_group_cputime - Sum the thread group time fields across all CPUs.
- *
- * @tsk:        The task we use to identify the thread group.
- * @times:      task_cputime structure in which we return the summed fields.
- *
- * Walk the list of CPUs to sum the per-CPU time fields in the thread group
- * time structure.
- */
-void thread_group_cputime(
-        struct task_struct *tsk,
-        struct task_cputime *times)
-{
-        struct task_cputime *totals, *tot;
-        int i;
-
-        totals = tsk->signal->cputime.totals;
-        if (!totals) {
-                times->utime = tsk->utime;
-                times->stime = tsk->stime;
-                times->sum_exec_runtime = tsk->se.sum_exec_runtime;
-                return;
-        }
-
-        times->stime = times->utime = cputime_zero;
-        times->sum_exec_runtime = 0;
-        for_each_possible_cpu(i) {
-                tot = per_cpu_ptr(totals, i);
-                times->utime = cputime_add(times->utime, tot->utime);
-                times->stime = cputime_add(times->stime, tot->stime);
-                times->sum_exec_runtime += tot->sum_exec_runtime;
-        }
-}
-
-/*
  * Called after updating RLIMIT_CPU to set timer expiration if necessary.
  */
 void update_rlimit_cpu(unsigned long rlim_new)
diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h
index f2773b5d1226..8ab0cef8ecab 100644
--- a/kernel/sched_stats.h
+++ b/kernel/sched_stats.h
@@ -296,6 +296,7 @@ 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;
 
         /* tsk == current, ensure it is safe to use ->signal */
@@ -303,13 +304,11 @@ static inline void account_group_user_time(struct task_struct *tsk,
                 return;
 
         sig = tsk->signal;
-        if (sig->cputime.totals) {
-                struct task_cputime *times;
+        times = &sig->cputime.totals;
 
-                times = per_cpu_ptr(sig->cputime.totals, get_cpu());
-                times->utime = cputime_add(times->utime, cputime);
-                put_cpu_no_resched();
-        }
+        spin_lock(&times->lock);
+        times->utime = cputime_add(times->utime, cputime);
+        spin_unlock(&times->lock);
 }
 
 /**
@@ -325,6 +324,7 @@ 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;
 
         /* tsk == current, ensure it is safe to use ->signal */
@@ -332,13 +332,11 @@ static inline void account_group_system_time(struct task_struct *tsk,
                 return;
 
         sig = tsk->signal;
-        if (sig->cputime.totals) {
-                struct task_cputime *times;
+        times = &sig->cputime.totals;
 
-                times = per_cpu_ptr(sig->cputime.totals, get_cpu());
-                times->stime = cputime_add(times->stime, cputime);
-                put_cpu_no_resched();
-        }
+        spin_lock(&times->lock);
+        times->stime = cputime_add(times->stime, cputime);
+        spin_unlock(&times->lock);
 }
 
 /**
@@ -354,6 +352,7 @@ 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 signal_struct *sig;
 
         sig = tsk->signal;
@@ -362,11 +361,9 @@ static inline void account_group_exec_runtime(struct task_struct *tsk,
         if (unlikely(!sig))
                 return;
 
-        if (sig->cputime.totals) {
-                struct task_cputime *times;
+        times = &sig->cputime.totals;
 
-                times = per_cpu_ptr(sig->cputime.totals, get_cpu());
-                times->sum_exec_runtime += ns;
-                put_cpu_no_resched();
-        }
+        spin_lock(&times->lock);
+        times->sum_exec_runtime += ns;
+        spin_unlock(&times->lock);
 }
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 1b6c05bd0d0a..d3f1ef4d5cbe 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -134,7 +134,7 @@ __setup("nohz=", setup_tick_nohz);
  * value. We do this unconditionally on any cpu, as we don't know whether the
  * cpu, which has the update task assigned is in a long sleep.
  */
-void tick_nohz_update_jiffies(void)
+static void tick_nohz_update_jiffies(void)
 {
         int cpu = smp_processor_id();
         struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 2f445833ae37..1f0c509b40d3 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -971,6 +971,8 @@ undo:
 }
 
 #ifdef CONFIG_SMP
+static struct workqueue_struct *work_on_cpu_wq __read_mostly;
+
 struct work_for_cpu {
         struct work_struct work;
         long (*fn)(void *);
@@ -991,8 +993,8 @@ static void do_work_for_cpu(struct work_struct *w)
  * @fn: the function to run
  * @arg: the function arg
  *
- * This will return -EINVAL in the cpu is not online, or the return value
- * of @fn otherwise.
+ * This will return the value @fn returns.
+ * It is up to the caller to ensure that the cpu doesn't go offline.
  */
 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 {
@@ -1001,14 +1003,8 @@ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
         INIT_WORK(&wfc.work, do_work_for_cpu);
         wfc.fn = fn;
         wfc.arg = arg;
-        get_online_cpus();
-        if (unlikely(!cpu_online(cpu)))
-                wfc.ret = -EINVAL;
-        else {
-                schedule_work_on(cpu, &wfc.work);
-                flush_work(&wfc.work);
-        }
-        put_online_cpus();
+        queue_work_on(cpu, work_on_cpu_wq, &wfc.work);
+        flush_work(&wfc.work);
 
         return wfc.ret;
 }
@@ -1025,4 +1021,8 @@ void __init init_workqueues(void)
         hotcpu_notifier(workqueue_cpu_callback, 0);
         keventd_wq = create_workqueue("events");
         BUG_ON(!keventd_wq);
+#ifdef CONFIG_SMP
+        work_on_cpu_wq = create_workqueue("work_on_cpu");
+        BUG_ON(!work_on_cpu_wq);
+#endif
 }