netdev - Re: [PATCH v1 07/15] net: page pool: add helper creating area from pages

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Message-ID: <6e14c383-6cbc-4eb5-9580-74fba17ec36e@gmail.com>
Date: Wed, 9 Oct 2024 22:34:43 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: Mina Almasry <almasrymina@...gle.com>, David Wei <dw@...idwei.uk>
Cc: io-uring@...r.kernel.org, netdev@...r.kernel.org,
 Jens Axboe <axboe@...nel.dk>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jesper Dangaard Brouer
 <hawk@...nel.org>, David Ahern <dsahern@...nel.org>
Subject: Re: [PATCH v1 07/15] net: page pool: add helper creating area from
 pages

On 10/9/24 22:11, Mina Almasry wrote:
> On Mon, Oct 7, 2024 at 3:16 PM David Wei <dw@...idwei.uk> wrote:
>>
>> From: Pavel Begunkov <asml.silence@...il.com>
>>
>> Add a helper that takes an array of pages and initialises passed in
>> memory provider's area with them, where each net_iov takes one page.
>> It's also responsible for setting up dma mappings.
>>
>> We keep it in page_pool.c not to leak netmem details to outside
>> providers like io_uring, which don't have access to netmem_priv.h
>> and other private helpers.
>>
> 
> Initial feeling is that this belongs somewhere in the provider. The
> functions added here don't seem generically useful to the page pool to
> be honest.
> 
> The challenge seems to be netmem/net_iov dependencies. The only thing
> I see you're calling is net_iov_to_netmem() and friends. Are these the
> issue? I think these are in netmem.h actually. Consider including that
> in the provider implementation, if it makes sense to you.

io_uring would need bits from netmem_priv.h and page_pool_priv.h,
and Jakub was pushing hard for the devmem patches to hide all of it
under net/core/. It's a last week change, I believe Jakub doesn't
want any of those leaked outside, in which case net/ needs to
provide a helper.

-- 
Pavel Begunkov