Re: [igb] netconsole triggers warning in netpoll_poll_dev

[Jesse Brandeburg]

Alexander Duyck wrote:

> On Sun, Apr 25, 2021 at 11:47 PM Oleksandr Natalenko
> <oleksandr@xxxxxxxxxxxxxx> wrote:
> >
> > Hello.
> >
> > On Fri, Apr 23, 2021 at 03:58:36PM -0700, Jakub Kicinski wrote:
> > > On Fri, 23 Apr 2021 10:19:44 +0200 Oleksandr Natalenko wrote:
> > > > On Wed, Apr 07, 2021 at 04:06:29PM -0700, Alexander Duyck wrote:
> > > > > On Wed, Apr 7, 2021 at 11:07 AM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
> > > > > > Sure, that's simplest. I wasn't sure something is supposed to prevent
> > > > > > this condition or if it's okay to cover it up.
> > > > >
> > > > > I'm pretty sure it is okay to cover it up. In this case the "budget -
> > > > > 1" is supposed to be the upper limit on what can be reported. I think
> > > > > it was assuming an unsigned value anyway.
> > > > >
> > > > > Another alternative would be to default clean_complete to !!budget.
> > > > > Then if budget is 0 clean_complete would always return false.
> > > >
> > > > So, among all the variants, which one to try? Or there was a separate
> > > > patch sent to address this?
> > >
> > > Alex's suggestion is probably best.
> > >
> > > I'm not aware of the fix being posted. Perhaps you could take over and
> > > post the patch if Intel doesn't chime in?
> >
> > So, IIUC, Alex suggests this:
> >
> > ```
> > diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> > index a45cd2b416c8..7503d5bf168a 100644
> > --- a/drivers/net/ethernet/intel/igb/igb_main.c
> > +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> > @@ -7981,7 +7981,7 @@ static int igb_poll(struct napi_struct *napi, int budget)
> >                                                      struct igb_q_vector,
> >                                                      napi);
> >         bool clean_complete = true;
> > -       int work_done = 0;
> > +       unsigned int work_done = 0;
> >
> >  #ifdef CONFIG_IGB_DCA
> >         if (q_vector->adapter->flags & IGB_FLAG_DCA_ENABLED)
> > @@ -8008,7 +8008,7 @@ static int igb_poll(struct napi_struct *napi, int budget)
> >         if (likely(napi_complete_done(napi, work_done)))
> >                 igb_ring_irq_enable(q_vector);
> >
> > -       return min(work_done, budget - 1);
> > +       return min_t(unsigned int, work_done, budget - 1);
> >  }
> >
> >  /**
> > ```
> >
> > Am I right?
> >
> > Thanks.
> 
> Actually a better way to go would be to probably just initialize
> "clean_complete = !!budget". With that we don't have it messing with
> the interrupt enables which would probably be a better behavior.


Thanks guys for the suggestions here! Finally got some time for
this, so here is the patch I'm going to queue shortly.