Re: MP-safe ifnet with psz & psref

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

On Fri, May 20, 2016 at 5:38 PM, Joerg Sonnenberger <joerg%bec.de@localhost> wrote:
> On Fri, May 20, 2016 at 12:15:10PM +0900, Ryota Ozaki wrote:
>> > Mbufs are slightly different. They can be queued on an interface for a
>> > moderately long time. For this purpose, a "flush" hook would definitely
>> > be needed. I think having such a hook would be useful for other purposes
>> > as well, i.e. to trigger memory compaction. But it is a somewhat
>> > expensive change in that it requires review of a lot of code.
>> >
>> > The final question for me is whether we can get away with just not
>> > deallocating ifnet instances. Reusing them is fine in principle, the
>> > problem is just keeping the memory type safe.
>>
>> What "keeping the memory type safe" means?
>
> Once allocated as ifnet, it will always be an ifnet.

I see.

>
>> The problem "when we can reuse it?" seems to be similar to "when we can
>> deallocate it?". Don't we need to do a similar solution I propose?
>
> The big question is what do we use rcvif for. If it is just a cookie
> used for preventing cycles, it doesn't matter what the content is.

No, rcvif is used arbitrarily.

> Otherwise we should have a field whether it was initialized completely
> or not.

We can have IFF_INITIALIZED...oops, there is no space in if_flags :-<

  ozaki-r