Re: RFC: softint-based if_input

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

On Tue, Feb 9, 2016 at 11:11 AM, Taylor R Campbell
<campbell+netbsd-tech-kern%mumble.net@localhost> wrote:
>    Date: Tue, 9 Feb 2016 10:30:57 +0900
>    From: Ryota Ozaki <ozaki-r%netbsd.org@localhost>
>
>    On Tue, Feb 9, 2016 at 1:34 AM, Taylor R Campbell
>    <campbell+netbsd-tech-kern%mumble.net@localhost> wrote:
>    > (For the record, the issues were spurious reinitialization of
>    > ifp->if_percpuq in if_iwm and if_rtwn causing a memory leak, and a
>    > needless whitespace change in if_otus -- all residual from earlier
>    > drafts.)
>
>    Allocating ifp->if_percpuq in if_iwm and if_rtwn is correct because
>    if_initialize/if_register don't allocate it.
>
> Oops.  I sit corrected!
>
>    > Are there any ieee80211 drivers that already do anything in softint?
>    > At a cursory glance, I don't see any.  So the conditional is probably
>    > not necessary
>
>    No, not yet (except USB drivers). I can remove the conditional (but
>    we have to keep in mind to change there when we change ieee80211
>    and/or individual Wifi drivers).
>
> Sure.
>
>    > -- and this is an argument for (in a future change)
>    > exposing the callback for if_percpuq so that ieee80211 can do
>    > if_perpcuq_dequeue/ieee80211_input, not if_percpuq_dequeue/if_input,
>    > in a loop.
>
>    I'm worried we would have to make rxintr of Wifi drivers softint
>    in order to run all bpf hooks in softint because bpf hooks exit
>    before ieee80211_input. If we can move them into ieee80211_input,
>    we don't need such big changes though, I'm not sure yet if we can.
>
> It sounds reasonable to me to push ieee80211_input into softint, in a
> future change.  It is not substantially different from ether_input,
> except we usually call ieee80211_input directly whereas we usually
> call ether_input via ifp->if_input -- mainly, I suspect, so that it
> can be replaced by bridge_input.

Yeah I think so (though I don't know when we will work on it :-/).


...so it's time to commit? :)

  ozaki-r