linux-kernel - Re: [PATCH net-next v9 4/8] netmem: use netmem_desc instead of page to access ->pp in __netmem_get

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Message-ID: <20250711011700.GD40145@system.software.com>
Date: Fri, 11 Jul 2025 10:17:00 +0900
From: Byungchul Park <byungchul@...com>
To: Mina Almasry <almasrymina@...gle.com>
Cc: willy@...radead.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
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Subject: Re: [PATCH net-next v9 4/8] netmem: use netmem_desc instead of page
 to access ->pp in __netmem_get_pp()

On Thu, Jul 10, 2025 at 11:25:12AM -0700, Mina Almasry wrote:
> On Thu, Jul 10, 2025 at 1:28 AM Byungchul Park <byungchul@...com> wrote:
> >
> > To eliminate the use of the page pool fields in struct page, the page
> > pool code should use netmem descriptor and APIs instead.
> >
> > However, __netmem_get_pp() still accesses ->pp via struct page.  So
> > change it to use struct netmem_desc instead, since ->pp no longer will
> > be available in struct page.
> >
> > Signed-off-by: Byungchul Park <byungchul@...com>
> > ---
> >  include/net/netmem.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/net/netmem.h b/include/net/netmem.h
> > index 11e9de45efcb..283b4a997fbc 100644
> > --- a/include/net/netmem.h
> > +++ b/include/net/netmem.h
> > @@ -306,7 +306,7 @@ static inline struct net_iov *__netmem_clear_lsb(netmem_ref netmem)
> >   */
> >  static inline struct page_pool *__netmem_get_pp(netmem_ref netmem)
> >  {
> > -       return __netmem_to_page(netmem)->pp;
> > +       return __netmem_to_nmdesc(netmem)->pp;
> >  }
> >
> 
> __netmem_to_nmdesc should introduced with this patch.

Okay.

> But also, I wonder why not modify all the callsites of
> __netmem_to_page to the new __netmem_to_nmdesc and delete the
> __nemem_to_page helper?

It'd be better.  I will.  Thanks.

	Byungchul
> 
> 
> --
> Thanks,
> Mina