Messages in this thread | | | Date | Thu, 01 Apr 2010 13:59:14 +0900 | From | Tejun Heo <> | Subject | Re: [Patch] workqueue: move lockdep annotations up to destroy_workqueue() |
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Hello,
On 04/01/2010 01:28 PM, Cong Wang wrote: >> Hmmm... can you please try to see whether this circular locking >> warning involving wq->lockdep_map is reproducible w/ the bonding >> locking fixed? I still can't see where wq -> cpu_add_remove_lock >> dependency is created. >> > > I thought this is obvious. > > Here it is: > > void destroy_workqueue(struct workqueue_struct *wq) > { > const struct cpumask *cpu_map = wq_cpu_map(wq); > int cpu; > > cpu_maps_update_begin(); <----------------- Hold > cpu_add_remove_lock here > spin_lock(&workqueue_lock); > list_del(&wq->list); > spin_unlock(&workqueue_lock); > > for_each_cpu(cpu, cpu_map) > cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu)); > <------ See below > cpu_maps_update_done(); <----------------- Release > cpu_add_remove_lock here > > ... > static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) > { > /* > * Our caller is either destroy_workqueue() or CPU_POST_DEAD, > * cpu_add_remove_lock protects cwq->thread. > */ > if (cwq->thread == NULL) > return; > > lock_map_acquire(&cwq->wq->lockdep_map); <-------------- Lockdep > complains here. > lock_map_release(&cwq->wq->lockdep_map); > ...
Yeap, the above is cpu_add_remove_lock -> wq->lockdep_map dependency. I can see that but I'm failing to see where the dependency the other direction is created.
Thanks.
-- tejun
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