| Date | Sun, 28 Feb 2010 17:00:05 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 16/43] workqueue: kill cpu_populated_map |
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On 02/26, Tejun Heo wrote: > > @@ -1023,41 +991,40 @@ struct workqueue_struct *__create_workqueue_key(const char *name, > ... > + cpu_maps_update_done(); > ... > + > + spin_lock(&workqueue_lock); > + list_add(&wq->list, &workqueues); > + spin_unlock(&workqueue_lock);
OK, but if cpu_up() happens right after we drop cpu_maps_update_done(), cwq->thread on the new CPU will run unbound?
> @@ -1127,47 +1091,30 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, > ... > list_for_each_entry(wq, &workqueues, list) {
this becomes unsafe. create/destroy can modify workqueues list in parallel.
> case CPU_ONLINE: > - start_workqueue_thread(cwq, cpu); > + __set_cpus_allowed(cwq->thread, get_cpu_mask(cpu), > + true);
if the thread doesn't have PF_THREAD_BOUND, who will set it?
> case CPU_POST_DEAD: > - cleanup_workqueue_thread(cwq); > + lock_map_acquire(&cwq->wq->lockdep_map); > + lock_map_release(&cwq->wq->lockdep_map); > + flush_cpu_workqueue(cwq);
This can race with destroy_workqueue(), no?
I guess this patch is preparation, probably these problems should go away later...
Oleg.
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