Re: [PATCH] Fix deadlock in __create_workqueue

[Andrew Morton <akpm@osdl.org>]

Srivatsa Vaddagiri <vatsa@in.ibm.com> wrote:
>
> Noticed a possible deadlock in __create_workqueue when CONFIG_HOTPLUG_CPU is
> set.  This can happen when create_workqueue_thread fails to create a worker
> thread. In that case, we call destroy_workqueue with cpu hotplug lock held.
> destroy_workqueue however also attempts to take the same lock.
> 
> Patch below address this deadlock as well as a kthread_stop race. 

Fixing a kthread_stop() race is a quite different thing from fixing a
create-workqueue() error-path deadlock and hence should be a separate
patch.

And the description of that separate patch should explain the race which
it is fixing!  Yes, the logic in worker_thread() is a bit dorky, but I
don't believe that there is a race in there.

I dropped that part of your patch.  Please resend, with justification, if
you disagree.

Thanks.