Messages in this thread | | | Date | Mon, 11 Dec 2006 10:28:31 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: workqueue deadlock |
| |
On Sun, Dec 10, 2006 at 09:26:16AM +0100, Ingo Molnar wrote: > something like the pseudocode further below - when applied to a data > structure it has semantics and scalability close to that of > preempt_disable(), but it is still preemptible and the lock is specific.
Ingo, The psuedo-code you have provided can still fail to avoid the deadlock reported by Bjorn Helgaas earlier in this thread:
http://lkml.org/lkml/2006/12/6/352
Thread1->flush_workqueue->mutex_lock(cpu4's hotplug_lock)
Thread2(keventd)->run_workqueue->som_work_fn-> .. flush_workqueue->mutex_lock(cpu4's hotplug_lock)
Both deadlock with each other.
All this mess could easily be avoided if we implement a reference-count based cpu_hotplug_lock(), as suggested by Arjan and Linus before and implemented by Gautham here:
http://lkml.org/lkml/2006/10/26/65
-- Regards, vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |