Re: 2.6.25-rc9 -- INFO: possible circular locking dependencydetected

From: Gautham R Shenoy
Date: Mon Apr 14 2008 - 10:48:17 EST


On Mon, Apr 14, 2008 at 02:42:27PM +0200, Peter Zijlstra wrote:
>
> void __init cpu_hotplug_init(void)
> {
> +#ifdef CONFIG_DEBUG_LOCK_ALLOC
> + static struct lockdep_class_key __key;
^^^^^^^^^^^^^^^^^
should be lock_class_key.

> +
> + lockdep_init_map(&cpu_hotplug.dep_map, "cpu_hotplug", &__key, 0);
> +#endif
> cpu_hotplug.active_writer = NULL;
> spin_lock_init(&cpu_hotplug.lock);
> cpu_hotplug.refcount = 0;
> @@ -54,6 +62,8 @@ void get_online_cpus(void)
> {
> might_sleep();
>
> + cpu_hotplug_acquire_read(&cpu_hotplug.dep_map, 0, 0, _THIS_IP_);
> +
> spin_lock(&cpu_hotplug.lock);
> if (cpu_hotplug.active_writer == current)
> goto unlock;
> @@ -80,6 +90,8 @@ EXPORT_SYMBOL_GPL(get_online_cpus);
>
> void put_online_cpus(void)
> {
> + cpu_hotplug_release(&cpu_hotplug.lock, 1, _THIS_IP_);
> +
> spin_lock(&cpu_hotplug.lock);
> if (cpu_hotplug.active_writer == current)
> goto unlock;
> @@ -119,6 +131,8 @@ static void cpu_hotplug_begin(void)
> {
> might_sleep();
>
> + cpu_hotplug_acquire(&cpu_hotplug.dep_map, 0, 0, _THIS_IP_);
> +
> spin_lock(&cpu_hotplug.lock);
> if (cpu_hotplug.refcount || cpu_hotplug.active_writer) {
> DEFINE_WAIT(wait);
> @@ -140,6 +154,8 @@ static void cpu_hotplug_begin(void)
>
> static void cpu_hotplug_done(void)
> {
> + cpu_hotplug_release(&cpu_hotplug.lock, 1, _THIS_IP_);
> +
> spin_lock(&cpu_hotplug.lock);
> cpu_hotplug.active_writer = NULL;
> if (!list_empty(&cpu_hotplug.writer_queue.task_list))
>

--
Thanks and Regards
gautham
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