linux-kernel - Re: [RFC net-next] eth: fbnic: use ring->page_pool instead of page->pp in fbnic_clean

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Message-ID: <20251119024546.GA18344@system.software.com>
Date: Wed, 19 Nov 2025 11:45:46 +0900
From: Byungchul Park <byungchul@...com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, kernel_team@...ynix.com, harry.yoo@...cle.com,
	hawk@...nel.org, andrew+netdev@...n.ch, david@...hat.com,
	lorenzo.stoakes@...cle.com, Liam.Howlett@...cle.com, vbabka@...e.cz,
	ziy@...dia.com, willy@...radead.org, toke@...hat.com,
	asml.silence@...il.com, alexanderduyck@...com, kernel-team@...a.com,
	davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
	mohsin.bashr@...il.com, almasrymina@...gle.com, jdamato@...tly.com
Subject: Re: [RFC net-next] eth: fbnic: use ring->page_pool instead of
 page->pp in fbnic_clean_twq1()

On Tue, Nov 18, 2025 at 05:32:16PM -0800, Jakub Kicinski wrote:
> On Wed, 19 Nov 2025 10:11:46 +0900 Byungchul Park wrote:
> > With the planned removal of @pp from struct page, we should access the
> > page pool pointer through other means.  Use @page_pool in struct
> > fbnic_ring instead.
> >
> > Signed-off-by: Byungchul Park <byungchul@...com>
> > ---
> > I should admit I'm not used to the following code.  So I'd like to ask
> > how to alter page->pp to avoid accessing @pp through struct page
> > directly.  Does the following change work?  Or can you suggest other
> > ways to achieve it?
> 
> @ring in this context is the Tx ring, but it's the Rx ring that has the
> page_pool pointer. Each Rx+Tx queue pair has 6 rings in total. You need
> the sub0/sub1 ring of the Rx queue from which the page came here.

Thank you for the explanation.  I'd better make it in the following way
rather than modifying the unfamiliar code.  Looks fine?

	Byungchul
---
diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
index c2d7b67fec28..382573f35408 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
@@ -653,7 +653,7 @@ static void fbnic_clean_twq1(struct fbnic_napi_vector *nv, bool pp_allow_direct,
 				 FBNIC_TWD_TYPE_AL;
 		total_bytes += FIELD_GET(FBNIC_TWD_LEN_MASK, twd);
 
-		page_pool_put_page(page->pp, page, -1, pp_allow_direct);
+		page_pool_put_page(pp_page_to_nmdesc(page)->pp, page, -1, pp_allow_direct);
 next_desc:
 		head++;
 		head &= ring->size_mask;

> > diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
> > index b1e8ce89870f..95f158ba6fa2 100644
> > --- a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
> > +++ b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.c
> > @@ -653,7 +653,7 @@ static void fbnic_clean_twq1(struct fbnic_napi_vector *nv, bool pp_allow_direct,
> >                                FBNIC_TWD_TYPE_AL;
> >               total_bytes += FIELD_GET(FBNIC_TWD_LEN_MASK, twd);
> >
> > -             page_pool_put_page(page->pp, page, -1, pp_allow_direct);
> > +             page_pool_put_page(ring->page_pool, page, -1, pp_allow_direct);
> >  next_desc:
> >               head++;
> >               head &= ring->size_mask;
>