Hello, Sasha. On Thu, Aug 23, 2012 at 02:24:32AM +0200, Sasha Levin wrote: > > I think the almost trivial nature of hlist hashtables makes this a bit > > tricky and I'm not very sure but having this combinatory explosion is > > a bit dazzling when the same functionality can be achieved by simply > > combining operations which are already defined and named considering > > hashtable. I'm not feeling too strong about this tho. What do others > > think? > > I'm thinking that this hashtable API will have 2 purposes: First, it would > prevent the excessive duplication of hashtable implementations all around the code. > > Second, it will allow more easily interchangeable hashtable implementations to > find their way into the kernel. There are several maintainers who would be happy > to see dynamically sized RCU hashtable, and I'm guessing that several more > variants could be added based on needs in specific modules. > > The second reason is why several things you've mentioned look the way they are: > > - No DEFINE_HASHTABLE(): I wanted to force the use of hash_init() since > initialization for other hashtables may be more complicated than the static > initialization for this implementation, which means that any place that used > DEFINE_HASHTABLE() and didn't do hash_init() will be buggy. I think this is problematic. It looks exactly like other existing DEFINE macros yet what its semantics is different. I don't think that's a good idea. > I'm actually tempted in hiding hlist completely from hashtable users, probably > by simply defining a hash_head/hash_node on top of the hlist_ counterparts. I think that it would be best to keep this one simple & obvious, which already has enough in-kernel users to justify its existence. There are significant benefits in being trivially understandable and expectable. If we want more advanced ones - say resizing, hybrid or what not, let's make that a separate one. No need to complicate the common straight-forward case for that. So, I think it would be best to keep this one as straight-forward and trivial as possible. Helper macros to help its users are fine but let's please not go for full encapsulation. Thanks. -- tejun -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
