Messages in this thread | | | Date | Wed, 20 Jul 2016 18:02:54 -0400 | From | Waiman Long <> | Subject | Re: [PATCH v3 1/4] lib/dlock-list: Distributed and lock-protected lists |
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On 07/19/2016 03:23 PM, Tejun Heo wrote: > Hello, > > On Tue, Jul 19, 2016 at 02:42:31PM -0400, Waiman Long wrote: >>>> +int alloc_dlock_list_head(struct dlock_list_head *dlist) >>>> +{ >>>> + struct dlock_list_head dlist_tmp; >>>> + int cpu; >>>> + >>>> + dlist_tmp.head = alloc_percpu(struct dlock_list_head_percpu); >>>> + if (!dlist_tmp.head) >>>> + return -ENOMEM; >>>> + >>>> + for_each_possible_cpu(cpu) { >>>> + struct dlock_list_head_percpu *head; >>>> + >>>> + head = per_cpu_ptr(dlist_tmp.head, cpu); >>>> + INIT_LIST_HEAD(&head->list); >>>> + head->lock = __SPIN_LOCK_UNLOCKED(&head->lock); >>>> + lockdep_set_class(&head->lock,&dlock_list_key); >>>> + } >>>> + >>>> + dlist->head = dlist_tmp.head; >>> Just use dlist->head directly or use local __perpcu head pointer? >> I just don't want to expose the structure to world until it is fully >> initialized. If you think I am over-cautious, I can use dlist->head as >> suggested. > I don't think it makes any actual difference. No strong opinion > either way. Just use local __percpu head pointer then?
I have run sparse on dlock_list.c. There is no need to use the __percpu tag here. The head gets assigned the result of per_cpu_ptr() which has no __percpu annotation. I actually got sparse warning if I used the __percpu tag.
Cheers, Longman
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