linux-kernel - Re: [PATCH net-next v10 02/12] netmem: use netmem_desc instead of page to access ->pp in __netmem_get

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Message-ID: <325c6297-b47f-43ad-8d2f-276cf70f3d57@gmail.com>
Date: Thu, 17 Jul 2025 10:23:25 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: Mina Almasry <almasrymina@...gle.com>, Byungchul Park <byungchul@...com>,
 "Lobakin, Aleksander" <aleksander.lobakin@...el.com>
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Subject: Re: [PATCH net-next v10 02/12] netmem: use netmem_desc instead of
 page to access ->pp in __netmem_get_pp()

On 7/17/25 10:17, Pavel Begunkov wrote:
> On 7/16/25 20:41, Mina Almasry wrote:
> ...>> I will kill __netmem_get_pp() as you and I prefer.  However,
>>> __netmem_get_pp() users e.i. libeth_xdp_return_va() and
>>> libeth_xdp_tx_fill_buf() should be altered.  I will modify the code like:
>>>
>>> as is: __netmem_get_pp(netmem)
>>> to be: __netmem_nmdesc(netmem)->pp
>>>
>>> Is it okay with you?
>>>
>>
>> When Pavel and I were saying 'remove __netmem_get_pp', I think we
>> meant to remove the entire concept of unsafe netmem -> page
>> conversions. I think we both don't like them. From this perspective,
>> __netmem_nmdesc(netmem)->pp is just as bad as __netmem_get_pp(netmem).
> 
> Yes. It'd great to have all of them gone. IMHO it's much better
> to let the caller do the casting so at least it's explicit and
> assumptions are not hidden. E.g. instead of
> 
> pp = __netmem_nmdesc(netmem)->pp;
> 
> It'd be
> 
> struct page *page = __netmem_to_page(netmem);
> 
> page_to_nmdesc(page)->pp;
> // or page_get_pp(page), or whatever the helper is
> 
> That might be easier as well.

FWIW, no need to respin a v12 for that

-- 
Pavel Begunkov