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authorSebastien Dugue <sebastien.dugue@bull.net>2008-12-01 08:09:07 -0500
committerIngo Molnar <mingo@elte.hu>2009-01-30 16:35:29 -0500
commit94df7de0289bc2df3d6e85cd2ece52bf42682f45 (patch)
treeb3f614b015adfb9574959687bb9b7ac4c884e23a /kernel/hrtimer.c
parent7f22391cbe82a80a9f891d8bd10fc28ff248d1e2 (diff)
hrtimers: allow the hot-unplugging of all cpus
Impact: fix CPU hotplug hang on Power6 testbox On architectures that support offlining all cpus (at least powerpc/pseries), hot-unpluging the tick_do_timer_cpu can result in a system hang. This comes from the fact that if the cpu going down happens to be the cpu doing the tick, then as the tick_do_timer_cpu handover happens after the cpu is dead (via the CPU_DEAD notification), we're left without ticks, jiffies are frozen and any task relying on timers (msleep, ...) is stuck. That's particularly the case for the cpu looping in __cpu_die() waiting for the dying cpu to be dead. This patch addresses this by having the tick_do_timer_cpu handover happen earlier during the CPU_DYING notification. For this, a new clockevent notification type is introduced (CLOCK_EVT_NOTIFY_CPU_DYING) which is triggered in hrtimer_cpu_notify(). Signed-off-by: Sebastien Dugue <sebastien.dugue@bull.net> Cc: <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/hrtimer.c')
-rw-r--r--kernel/hrtimer.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 8fea312ca36c..647a40e2fea1 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1608,6 +1608,10 @@ static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,
1608 break; 1608 break;
1609 1609
1610#ifdef CONFIG_HOTPLUG_CPU 1610#ifdef CONFIG_HOTPLUG_CPU
1611 case CPU_DYING:
1612 case CPU_DYING_FROZEN:
1613 clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);
1614 break;
1611 case CPU_DEAD: 1615 case CPU_DEAD:
1612 case CPU_DEAD_FROZEN: 1616 case CPU_DEAD_FROZEN:
1613 { 1617 {