netdev - Re: [RFC net-next v3 05/29] net: bvec specific path in zerocopy_sg_from

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Message-ID: <e453322f-bf33-d7c5-26c2-06896fb1a691@gmail.com>
Date:   Tue, 5 Jul 2022 15:03:26 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     David Ahern <dsahern@...nel.org>
Cc:     io-uring@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Jens Axboe <axboe@...nel.dk>, kernel-team@...com
Subject: Re: [RFC net-next v3 05/29] net: bvec specific path in
 zerocopy_sg_from_iter

On 7/5/22 03:28, David Ahern wrote:
> On 7/4/22 7:31 AM, Pavel Begunkov wrote:
>> If the series is going to be picked up for 5.20, how about we delay
>> this one for 5.21? I'll have time to think about it (maybe moving
>> the skb managed flag setup inside?), and will anyway need to send
>> some omitted patches then.
>>
> 
> I think it reads better for io_uring and future extensions for io_uring
> to contain the optimized bvec iter handler and setting the managed flag.
> Too many disjointed assumptions the way the code is now. By pulling that
> into io_uring, core code does not make assumptions that "managed" means
> bvec and no page references - rather that is embedded in the code that
> cares.

Core code would still need to know when to remove the skb's managed
flag, e.g. in case of mixing. Can be worked out but with assumptions,
which doesn't look better that it currently is. I'll post a 5.20
rebased version and will iron it out on the way then.

-- 
Pavel Begunkov