On Tue, Sep 18, 2018 at 2:56 PM Song Liu <songliubrav...@fb.com> wrote:
>
>
>
> > On Sep 18, 2018, at 2:46 PM, Eric Dumazet <eduma...@google.com> wrote:
> >
> > On Tue, Sep 18, 2018 at 2:41 PM Song Liu <songliubrav...@fb.com> wrote:
> >>
> >>
> >>
> >>>
> >> I would submit the patch if Eric prefer not to. :)
> >
> >
> > Hmmm.... maybe the bug is really in ixgbe_netpoll()
> >
> > This whole ndo_poll_controller() stuff is crazy.
> >
> > All sane implementations should only call napi_schedule()
>
> Current implement is about identical to napi_schedule_irqoff(). Do
> we really need napi_schedule() instead?
>
> On the other hand, I think we should check napi_complete_done() in
> ixgbe_poll() anyway.
It seems the netpoll code is racy, since another cpu might be calling
ixgbe poll(),
and return early from napi_complete_done() :
if (unlikely(n->state & (NAPIF_STATE_NPSVC |
NAPIF_STATE_IN_BUSY_POLL)))
return false;
This is why netpoll enabled drivers _must_ check the
napi_complete[_done]() return value,
otherwise they might re-enable IRQs why they should not.
