Re: RFC: softint-based if_input

[Nick Hudson <skrll%netbsd.org@localhost>]

On 02/03/16 04:44, Ryota Ozaki wrote:
> On Tue, Feb 2, 2016 at 8:51 AM, Taylor R Campbell
> <campbell+netbsd-tech-kern%mumble.net@localhost> wrote:
[snip]
> > In this case, it's not a priori clear to me why the caller must be in
> > hardintr context.  Perhaps you want to discourage callers from using
> > this if they're already in softint context.  But even if the caller is
> > in softint context, maybe it's higher-priority softint context than
> > softnet (e.g., I think skrll@ plans to make all USB softints run at
> > softserial instead of softnet), and maybe you don't want ifp->if_input
> > to run at >softnet priority.

I'm still debating what to do here, but it's clear to me that all USB 
callbacks running at splsoftnet
has issues - see

        http://gnats.netbsd.org/50491

and somewhat related

        http://gnats.netbsd.org/49065

> Oh, that's a case I didn't take into account. Running if->if_input
> at >softnet priority would break the assumption that we rely on.

What assumption are you making?

> We may be able to change the assert to
>    KASSERT(cpu_intr_p() || (cpu_softintr_p() && level != SOFTINT_NET))
> though, I think we don't need to be paranoid for the case.
> (And I don't know how to get level. Is there API?).

There isn't an API afaik.
>    ozaki-r
Nick