Cpusets would be using timer migration code to isolate/quiese a CPU. And hence
that should be changed a bit as the CPU in question would be online now. Also we
need to make sure that we don't remove pinned timers.

Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
---
 kernel/timer.c | 54 +++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 43 insertions(+), 11 deletions(-)

diff --git a/kernel/timer.c b/kernel/timer.c
index a7f8b99..81d64e0 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1602,18 +1602,27 @@ static int init_timers_cpu(int cpu)
        return 0;
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-static void migrate_timer_list(struct tvec_base *new_base, struct list_head 
*head)
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_CPUSETS)
+static void migrate_timer_list(struct tvec_base *new_base,
+                              struct list_head *head, bool remove_pinned)
 {
        struct timer_list *timer;
+       struct list_head pinned_list;
        int is_pinned;
 
+       INIT_LIST_HEAD(&pinned_list);
+
        while (!list_empty(head)) {
                timer = list_first_entry(head, struct timer_list, entry);
-               /* We ignore the accounting on the dying cpu */
-               detach_timer(timer, false);
 
                is_pinned = tbase_get_pinned(timer->base);
+               if (!remove_pinned && is_pinned) {
+                       list_move_tail(&timer->entry, &pinned_list);
+                       continue;
+               } else {
+                       /* We ignore the accounting on the dying cpu */
+                       detach_timer(timer, false);
+               }
 
                /* Check if CPU still has pinned timers */
                if (is_pinned) {
@@ -1625,15 +1634,18 @@ static void migrate_timer_list(struct tvec_base 
*new_base, struct list_head *hea
                timer_set_base(timer, new_base);
                internal_add_timer(new_base, timer);
        }
+
+       if (!list_empty(&pinned_list))
+               list_splice_tail(&pinned_list, head);
 }
 
-static void migrate_timers(int cpu)
+/* Migrate timers from 'cpu' to this_cpu */
+static void __migrate_timers(int cpu, bool remove_pinned)
 {
        struct tvec_base *old_base;
        struct tvec_base *new_base;
        int i;
 
-       BUG_ON(cpu_online(cpu));
        old_base = per_cpu(tvec_bases, cpu);
        new_base = get_cpu_var(tvec_bases);
        /*
@@ -1646,20 +1658,40 @@ static void migrate_timers(int cpu)
        BUG_ON(old_base->running_timer);
 
        for (i = 0; i < TVR_SIZE; i++)
-               migrate_timer_list(new_base, old_base->tv1.vec + i);
+               migrate_timer_list(new_base, old_base->tv1.vec + i,
+                               remove_pinned);
        for (i = 0; i < TVN_SIZE; i++) {
-               migrate_timer_list(new_base, old_base->tv2.vec + i);
-               migrate_timer_list(new_base, old_base->tv3.vec + i);
-               migrate_timer_list(new_base, old_base->tv4.vec + i);
-               migrate_timer_list(new_base, old_base->tv5.vec + i);
+               migrate_timer_list(new_base, old_base->tv2.vec + i,
+                               remove_pinned);
+               migrate_timer_list(new_base, old_base->tv3.vec + i,
+                               remove_pinned);
+               migrate_timer_list(new_base, old_base->tv4.vec + i,
+                               remove_pinned);
+               migrate_timer_list(new_base, old_base->tv5.vec + i,
+                               remove_pinned);
        }
 
        spin_unlock(&old_base->lock);
        spin_unlock_irq(&new_base->lock);
        put_cpu_var(tvec_bases);
 }
+#endif /* CONFIG_HOTPLUG_CPU || CONFIG_CPUSETS */
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void migrate_timers(int cpu)
+{
+       BUG_ON(cpu_online(cpu));
+       __migrate_timers(cpu, true);
+}
 #endif /* CONFIG_HOTPLUG_CPU */
 
+#ifdef CONFIG_CPUSETS
+void timer_quiesce_cpu(void *data)
+{
+       __migrate_timers((int)data, false);
+}
+#endif /* CONFIG_CPUSETS */
+
 static int timer_cpu_notify(struct notifier_block *self,
                                unsigned long action, void *hcpu)
 {
-- 
1.7.12.rc2.18.g61b472e

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