linux-kernel - Re: [PATCH v1 14/14] net/mlx4: Use irq_update_affinity

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Message-ID: <CAFki+L=2nVA3FB03BjuXbj+di28LhVUzo9P9WoJyxoQFggt0VQ@mail.gmail.com>
Date:   Fri, 25 Jun 2021 17:08:03 -0400
From:   Nitesh Lal <nilal@...hat.com>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Nitesh Narayan Lal <nitesh@...hat.com>,
        linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
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Subject: Re: [PATCH v1 14/14] net/mlx4: Use irq_update_affinity_hint

On Mon, Jun 21, 2021 at 4:02 AM Leon Romanovsky <leon@...nel.org> wrote:
>
> On Thu, Jun 17, 2021 at 02:22:42PM -0400, Nitesh Narayan Lal wrote:
> > The driver uses irq_set_affinity_hint() to update the affinity_hint mask
> > that is consumed by the userspace to distribute the interrupts. However,
> > under the hood irq_set_affinity_hint() also applies the provided cpumask
> > (if not NULL) as the affinity for the given interrupt which is an
> > undocumented side effect.
> >
> > To remove this side effect irq_set_affinity_hint() has been marked
> > as deprecated and new interfaces have been introduced. Hence, replace the
> > irq_set_affinity_hint() with the new interface irq_update_affinity_hint()
> > that only updates the affinity_hint pointer.
> >
> > Signed-off-by: Nitesh Narayan Lal <nitesh@...hat.com>
> > ---
> >  drivers/net/ethernet/mellanox/mlx4/eq.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/mellanox/mlx4/eq.c b/drivers/net/ethernet/mellanox/mlx4/eq.c
> > index 9e48509ed3b2..f549d697ca95 100644
> > --- a/drivers/net/ethernet/mellanox/mlx4/eq.c
> > +++ b/drivers/net/ethernet/mellanox/mlx4/eq.c
> > @@ -244,9 +244,9 @@ static void mlx4_set_eq_affinity_hint(struct mlx4_priv *priv, int vec)
> >           cpumask_empty(eq->affinity_mask))
> >               return;
> >
> > -     hint_err = irq_set_affinity_hint(eq->irq, eq->affinity_mask);
> > +     hint_err = irq_update_affinity_hint(eq->irq, eq->affinity_mask);
> >       if (hint_err)
> > -             mlx4_warn(dev, "irq_set_affinity_hint failed, err %d\n", hint_err);
> > +             mlx4_warn(dev, "irq_update_affinity_hint failed, err %d\n", hint_err);
> >  }
> >  #endif
> >
> > @@ -1124,7 +1124,7 @@ static void mlx4_free_irqs(struct mlx4_dev *dev)
> >               if (eq_table->eq[i].have_irq) {
> >                       free_cpumask_var(eq_table->eq[i].affinity_mask);
> >  #if defined(CONFIG_SMP)
> > -                     irq_set_affinity_hint(eq_table->eq[i].irq, NULL);
> > +                     irq_update_affinity_hint(eq_table->eq[i].irq, NULL);
> >  #endif
>
> This #if/endif can be deleted.

I think we also can get rid of the other #if/endif CONFIG_SMP
occurrences that are present around mlx4_set_eq_affinity_hint()
definition and call, isn't it?
There is already a check-in interrupt.h so doing it again in the
driver looks like an unwanted repetition IMHO.

>
> Thanks,
> Reviewed-by: Leon Romanovsky <leonro@...dia.com>
>


-- 
Thanks
Nitesh