Re: [PATCH net v2 1/2] octeontx2-pf: Fix aura BPID assignment when CONFIG_DCB is enabled

[Jakub Kicinski <kuba@kernel.org>]

On Thu,  6 Aug 2026 08:26:50 -0700 Jakub Kicinski wrote:
> > diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
> > index 3d253132a17f0..b4691472d2a3e 100644
> > --- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
> > +++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
> > @@ -1132,10 +1132,10 @@ int otx2_cq_init(struct otx2_nic *pfvf, u16 qidx)
> >  		if (!is_otx2_lbkvf(pfvf->pdev)) {
> >  			/* Enable receive CQ backpressure */
> >  			aq->cq.bp_ena = 1;
> > -#ifdef CONFIG_DCB
> > -			aq->cq.bpid = pfvf->bpid[pfvf->queue_to_pfc_map[qidx]];
> > -#else
> >  			aq->cq.bpid = pfvf->bpid[0];
> > +#ifdef CONFIG_DCB
> > +			if (pfvf->queue_to_pfc_map)
> > +				aq->cq.bpid = pfvf->bpid[pfvf->queue_to_pfc_map[qidx]];
> >  #endif  
> 
> [Severity: Low]
> This isn't a bug, but the same #ifdef CONFIG_DCB plus NULL test idiom now
> appears in three places: cn20k_aura_bpid_idx(), otx2_cq_init() and
> otx2_aura_aq_init().  cn20k_aura_bpid_idx() already encapsulates exactly this
> logic.  Would it be cleaner to generalize it into a single accessor, say
> otx2_get_bpid_idx(pfvf, qidx), and use it from all three sites?
> 
> Alternatively, could queue_to_pfc_map simply be allocated unconditionally
> (it is only pfvf->hw.rx_queues bytes) instead of being tied to dcbnl_ops

AI is getting better I guess. I was going to suggest this as well.
Please avoid hiding struct members under ifdefs unless there's a major
size win on the structures. If you care about runtime cost you can use
IS_ENABLED() inside the if () condition and compiler will eliminate it.
No ifdefs needed at that point.