On Fri, 15 Dec 2006 09:31:12 +0100
Ingo Molnar <[EMAIL PROTECTED]> wrote:
>
> * [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
> > - mutex_lock(&workqueue_mutex);
> > + preempt_disable(); /* CPU hotplug */
> > for_each_online_cpu(cpu) {
> > INIT_WORK(per_cpu_ptr(works, cpu), func);
> > __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu),
> > per_cpu_ptr(works, cpu));
> > }
> > - mutex_unlock(&workqueue_mutex);
> > + preempt_enable();
>
> Why not cpu_hotplug_lock()?
>
Because the workqueue code was explicitly switched over to per-subsystem
cpu-hotplug locking.
Because lock_cpu_hotplug() is a complete turkey, source of deadlocks and
overall bad idea.
This is actually a pretty simple problem. A subsystem has per-cpu reosurces,
and it needs to lock them while using them. duh. We know how to do that
sort of thing. But because the first implementation of lock_cpu_hotplug()
was conceived with magical properties, we seem to think we need to retain
magical properties. We don't...
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