On Tue, Jun 11, 2024 at 11:22:04AM -0600, Keith Busch wrote: > > 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..). > > Good call, you are absolutely right that a sync should happen between > the del and the add for readers to consistently iterate this list. > > I might be able to weasel out of this though: our namespace list is > sorted, and this function wants to append everything from this element > all the way to the end to the "rm_list": a reader should get the same > result either way, whether if it was torn at this element or the move > happened without the reader seeing it. > > Now if there was a way to rcu split the list so we don't have to do it > element by element... Isn't that exactly what the list_splice helpers do? We'd just need to do that exactly once at the cutoff point and not once per namespace.
