# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1275546654 -3600
# Node ID 4ab68bf4c37e4c97e12efe7aced616ce6946578f
# Parent 5aabc6f94df5f275647d55caa24780eff0c81355
timer: Migrate timers from dying CPU on CPU_DYING notification.
Otherwise timer_lock() can race a timer's ->cpu field being updated by
migrate_timers_from_cpu().
The rest of this patch is all debug paranoia.
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
xen/common/timer.c | 35 ++++++++++++++++++++++++++++-------
1 files changed, 28 insertions(+), 7 deletions(-)
diff -r 5aabc6f94df5 -r 4ab68bf4c37e xen/common/timer.c
--- a/xen/common/timer.c Wed Jun 02 13:13:11 2010 +0100
+++ b/xen/common/timer.c Thu Jun 03 07:30:54 2010 +0100
@@ -40,6 +40,8 @@ struct timers {
static DEFINE_PER_CPU(struct timers, timers);
+static cpumask_t timer_valid_cpumask;
+
DEFINE_PER_CPU(s_time_t, timer_deadline_start);
DEFINE_PER_CPU(s_time_t, timer_deadline_end);
@@ -238,6 +240,7 @@ static inline void timer_lock(struct tim
for ( ; ; )
{
cpu = timer->cpu;
+ ASSERT(cpu_isset(cpu, timer_valid_cpumask));
spin_lock(&per_cpu(timers, cpu).lock);
if ( likely(timer->cpu == cpu) )
break;
@@ -329,6 +332,9 @@ void migrate_timer(struct timer *timer,
{
if ( (old_cpu = timer->cpu) == new_cpu )
return;
+
+ ASSERT(cpu_isset(old_cpu, timer_valid_cpumask));
+ ASSERT(cpu_isset(new_cpu, timer_valid_cpumask));
if ( old_cpu < new_cpu )
{
@@ -553,23 +559,27 @@ static struct keyhandler dump_timerq_key
.desc = "dump timer queues"
};
-static void migrate_timers_from_cpu(unsigned int cpu)
+static unsigned int migrate_timers_from_cpu(unsigned int cpu)
{
struct timers *ts;
struct timer *t;
+ bool_t notify = 0;
+ unsigned int nr_migrated = 0;
+ unsigned long flags;
ASSERT((cpu != 0) && cpu_online(0));
ts = &per_cpu(timers, cpu);
- spin_lock_irq(&per_cpu(timers, 0).lock);
+ spin_lock_irqsave(&per_cpu(timers, 0).lock, flags);
spin_lock(&ts->lock);
while ( (t = GET_HEAP_SIZE(ts->heap) ? ts->heap[1] : ts->list) != NULL )
{
remove_entry(t);
t->cpu = 0;
- add_entry(t);
+ notify |= add_entry(t);
+ nr_migrated++;
}
while ( !list_empty(&ts->inactive) )
@@ -578,12 +588,16 @@ static void migrate_timers_from_cpu(unsi
list_del(&t->inactive);
t->cpu = 0;
list_add(&t->inactive, &per_cpu(timers, 0).inactive);
+ nr_migrated++;
}
spin_unlock(&ts->lock);
- spin_unlock_irq(&per_cpu(timers, 0).lock);
-
- cpu_raise_softirq(0, TIMER_SOFTIRQ);
+ spin_unlock_irqrestore(&per_cpu(timers, 0).lock, flags);
+
+ if ( notify )
+ cpu_raise_softirq(0, TIMER_SOFTIRQ);
+
+ return nr_migrated;
}
static struct timer *dummy_heap;
@@ -600,10 +614,17 @@ static int cpu_callback(
INIT_LIST_HEAD(&ts->inactive);
spin_lock_init(&ts->lock);
ts->heap = &dummy_heap;
+ cpu_set(cpu, timer_valid_cpumask);
+ break;
+ case CPU_DYING:
+ cpu_clear(cpu, timer_valid_cpumask);
+ migrate_timers_from_cpu(cpu);
break;
case CPU_UP_CANCELED:
case CPU_DEAD:
- migrate_timers_from_cpu(cpu);
+ cpu_clear(cpu, timer_valid_cpumask);
+ if ( migrate_timers_from_cpu(cpu) )
+ BUG();
break;
default:
break;
_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog
|
Home