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| author | Sebastien Dugue <sebastien.dugue@bull.net> | 2008-12-01 14:09:07 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-01-30 22:35:29 +0100 |
| commit | 94df7de0289bc2df3d6e85cd2ece52bf42682f45 (patch) | |
| tree | b3f614b015adfb9574959687bb9b7ac4c884e23a /kernel/hrtimer.c | |
| parent | 7f22391cbe82a80a9f891d8bd10fc28ff248d1e2 (diff) | |
| download | lwn-94df7de0289bc2df3d6e85cd2ece52bf42682f45.tar.gz lwn-94df7de0289bc2df3d6e85cd2ece52bf42682f45.zip | |
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.c | 4 |
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, break; #ifdef CONFIG_HOTPLUG_CPU + case CPU_DYING: + case CPU_DYING_FROZEN: + clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu); + break; case CPU_DEAD: case CPU_DEAD_FROZEN: { |