Re: [RFC] netlink broadcast return value

[Pablo Neira Ayuso <pablo@netfilter.org>]

Patrick McHardy wrote:
> David Miller wrote:
>> From: Pablo Neira Ayuso <pablo@netfilter.org>
>> Date: Sun, 01 Feb 2009 14:33:57 +0100
>>
>>> In short, I think that the change that I'm proposing would also require
>>> to fix some netlink_broadcast() clients to skip ENOBUFS errors: they are
>>> not meaningful for them since they assume that Netlink is unreliable and
>>> so the return value does not provide any useful information.
>>
>> I think this analysis is accurate.
> 
> We have at least one case where the caller wants to know of
> any successful delivery. Keymanager queries done by xfrm_state
> want to know whether an acquire was delivered to any keymanager.
> So we need to continue to indicate this, maybe using a different
> errno code than -ENOBUFS. I don't have a suggestion which one to
> use though.

Indeed, I have missed that spot. I'm not very familiar with that code,
however, I see that the creation of a state depends on the netlink
broadcast return value, but how useful is that? I think that the state
should be created even if the broadcast fails, the userspace daemon
should request a resync to the kernel as soon as it hits ENOBUFS, then
it would be in sync again with that state.

-- 
"Los honestos son inadaptados sociales" -- Les Luthiers