netdev - Re: [PATCH net] bnxt_en: eliminate the compile warning in bnxt_request_irq due to CONFIG_RFS

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Message-ID: <CAL+tcoAfV+P3579_uM4mikMkNK4L2dMx0EuXNnTeLwZ3-7Po2Q@mail.gmail.com>
Date: Wed, 2 Jul 2025 08:47:08 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Simon Horman <horms@...nel.org>, davem@...emloft.net, edumazet@...gle.com, 
	pabeni@...hat.com, andrew+netdev@...n.ch, michael.chan@...adcom.com, 
	pavan.chebbi@...adcom.com, netdev@...r.kernel.org, 
	Jason Xing <kernelxing@...cent.com>, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH net] bnxt_en: eliminate the compile warning in
 bnxt_request_irq due to CONFIG_RFS_ACCEL

On Wed, Jul 2, 2025 at 8:15 AM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Mon, 30 Jun 2025 19:47:47 +0800 Jason Xing wrote:
> > > Not for net, but it would be nice to factor the #ifdefs out of this
> > > function entirely.  E.g. by using a helper to perform that part of the
> > > initialisation.
> >
> > Got it. I will cook a patch after this patch is landed on the net-next branch.
>
> Maybe we can fix it right already. The compiler should not complain if
> it sees the read:
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index f621a5bab1ea..6bbe875132b0 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -11616,11 +11616,9 @@ static void bnxt_free_irq(struct bnxt *bp)
>
>  static int bnxt_request_irq(struct bnxt *bp)
>  {
> +       struct cpu_rmap *rmap = NULL;
>         int i, j, rc = 0;
>         unsigned long flags = 0;
> -#ifdef CONFIG_RFS_ACCEL
> -       struct cpu_rmap *rmap;
> -#endif

Sorry, Jakub. I failed to see the positive point of this kind of
change comparatively.

>
>         rc = bnxt_setup_int_mode(bp);
>         if (rc) {

Probably in this position, you expect 'rmap = bp->dev->rx_cpu_rmap;'
to stay there even when CONFIG_RFS_ACCEL is off?

The report says it's 'j' that causes the complaint.

Thanks,
Jason

> @@ -11641,15 +11639,15 @@ static int bnxt_request_irq(struct bnxt *bp)
>                 int map_idx = bnxt_cp_num_to_irq_num(bp, i);
>                 struct bnxt_irq *irq = &bp->irq_tbl[map_idx];
>
> -#ifdef CONFIG_RFS_ACCEL
> -               if (rmap && bp->bnapi[i]->rx_ring) {
> +               if (IS_ENABLED(CONFIG_RFS_ACCEL) &&
> +                   rmap && bp->bnapi[i]->rx_ring) {
>                         rc = irq_cpu_rmap_add(rmap, irq->vector);
>                         if (rc)
>                                 netdev_warn(bp->dev, "failed adding irq rmap for ring %d\n",
>                                             j);
>                         j++;
>                 }
> -#endif
> +
>                 rc = request_irq(irq->vector, irq->handler, flags, irq->name,
>                                  bp->bnapi[i]);
>                 if (rc)
> --
> pw-bot: cr