diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2009-12-10 15:35:10 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2009-12-11 10:28:08 +0100 |
| commit | bb6eddf7676e1c1f3e637aa93c5224488d99036f (patch) | |
| tree | 3256cb7ea6954f28b0bb3ccee2db570e3d0ff762 | |
| parent | e9c0748b687aa70179a9e6d8ffc24b2874fe350b (diff) | |
clockevents: Prevent clockevent_devices list corruption on cpu hotplug
Xiaotian Feng triggered a list corruption in the clock events list on
CPU hotplug and debugged the root cause.
If a CPU registers more than one per cpu clock event device, then only
the active clock event device is removed on CPU_DEAD. The unused
devices are kept in the clock events device list.
On CPU up the clock event devices are registered again, which means
that we list_add an already enqueued list_head. That results in list
corruption.
Resolve this by removing all devices which are associated to the dead
CPU on CPU_DEAD.
Reported-by: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Xiaotian Feng <dfeng@redhat.com>
Cc: stable@kernel.org
| -rw-r--r-- | kernel/time/clockevents.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 20a8920029e..91db2e33d86 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -238,8 +238,9 @@ void clockevents_exchange_device(struct clock_event_device *old, */ void clockevents_notify(unsigned long reason, void *arg) { - struct list_head *node, *tmp; + struct clock_event_device *dev, *tmp; unsigned long flags; + int cpu; spin_lock_irqsave(&clockevents_lock, flags); clockevents_do_notify(reason, arg); @@ -250,8 +251,19 @@ void clockevents_notify(unsigned long reason, void *arg) * Unregister the clock event devices which were * released from the users in the notify chain. */ - list_for_each_safe(node, tmp, &clockevents_released) - list_del(node); + list_for_each_entry_safe(dev, tmp, &clockevents_released, list) + list_del(&dev->list); + /* + * Now check whether the CPU has left unused per cpu devices + */ + cpu = *((int *)arg); + list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) { + if (cpumask_test_cpu(cpu, dev->cpumask) && + cpumask_weight(dev->cpumask) == 1) { + BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); + list_del(&dev->list); + } + } break; default: break; |