Subject: Re: interface destruction issues with multicast membership
To: Greg Troxel <gdt@ir.bbn.com>
From: Matt Thomas <matt@3am-software.com>
List: tech-net
Date: 05/10/2005 14:40:33
Greg Troxel wrote:
> [handle PRU_PURGEIF in all protocols]
>
> I think that is perfectly reasonable. What is the alternative? To have
> the last interface address removal code handle it?
>
> I can see either:
>
> Purge on last address removal. This seems like it has to happen on
> all protocols in a domain, so it has the same issue. (I don't
> understand why the panic I got doesn't happen without my change,
> since I thought all protocols in the domain were called if there was
> an address in the domain.) Has a touch of elegance, but I'm not
> optimistic that such a complicated invariant can be maintained over
> time as code changes.
>
> Have a per-protocol NEEDS_PURGEIF flag, and only invoke the method
> on such protocols. But this seems inelegant to me.
>
>
> So, I'll start down the path of (not) handling PRU_PURGEIF in \forall
> foo \in protocols: foo_usrreq, and submit a patch with that and the
> new for loop I just sent.
That seem wrong. The proper solution is to add a PR_PURGEIF flags and
add that to the appropriate protosw entries.
Adding "dead" code is wrong.
--
Matt Thomas email: matt@3am-software.com
3am Software Foundry www: http://3am-software.com/bio/matt/
Cupertino, CA disclaimer: I avow all knowledge of this message.