On 6/11/24 22:09, Christoph Hellwig wrote:
> On Tue, Jun 11, 2024 at 08:20:55AM -0700, Keith Busch wrote:
>> mutex_lock(&ctrl->namespaces_lock);
>> list_for_each_entry_safe(ns, next, &ctrl->namespaces, list) {
>> - if (ns->head->ns_id > nsid)
>> - list_splice_init_rcu(&ns->list, &rm_list,
>> - synchronize_rcu);
>> + if (ns->head->ns_id > nsid) {
>> + list_del_rcu(&ns->list);
>> + list_add_tail_rcu(&ns->list, &rm_list);
>> + }
>
> Is this actually valid for a (S)RCU protected list? If the entry gets
> added to the new list before the grace period has completed, we could
> trick a concurrent traversal into following the new list unless I'm
> mistaken (although chances I'm mistaken on RCU corner cases aren't that
> low..).
>
>
I think we need synchronize_srcu() before we add deleted ns to rm_list.
Thanks,
--Nilay
