Messages in this thread | | | From | NeilBrown <> | Date | Wed, 28 Mar 2018 08:54:41 +1100 | Subject | Re: [PATCH 4/6] rhashtable: allow a walk of the hash table without missing objects. |
| |
On Tue, Mar 27 2018, Herbert Xu wrote:
> On Tue, Mar 27, 2018 at 10:33:04AM +1100, NeilBrown wrote: >> >> -int rhashtable_walk_start_check(struct rhashtable_iter *iter) >> +int rhashtable_walk_start_continue(struct rhashtable_iter *iter, struct rhash_head *obj) >> __acquires(RCU) >> { >> struct rhashtable *ht = iter->ht; >> >> rcu_read_lock(); >> >> + if (!obj || iter->p != obj) >> + iter->p = NULL; > > Why bother with this check at all? Couldn't we make it so that > if you call continue then you continue with the cursor otherwise > you set it to NULL as we currently do.
Possibly. I particularly want the interface to require that you pass the previously returned object to _continue. That makes it easy to see that the object is still being used. If someone changes to code to delete the object before the _continue, there should be a strong hint that it won't work.
Maybe it would be better to make it a WARN_ON()
if (!obj || WARN_ON(iter->p != obj)) iter->p = NULL;
??
Thanks, NeilBrown [unhandled content-type:application/pgp-signature] | |