netdev - Re: [PATCH bpf-next 1/2] samples/bpf: fixup xdp_redirect tool to be able to support xdp multibuffer

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Message-ID: <2b9c7d6b-0fa4-404a-9fbb-80f581c2f294@gmail.com>
Date: Wed, 31 May 2023 15:02:17 +0300
From: Tariq Toukan <ttoukan.linux@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: brouer@...hat.com, Daniel Borkmann <daniel@...earbox.net>,
 Jesper Dangaard Brouer <hawk@...nel.org>, bpf@...r.kernel.org,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 netdev@...r.kernel.org, Gal Pressman <gal@...dia.com>,
 Nimrod Oren <noren@...dia.com>, Tariq Toukan <tariqt@...dia.com>,
 Lorenzo Bianconi <lorenzo.bianconi@...hat.com>, drosen@...gle.com,
 Joanne Koong <joannelkoong@...il.com>, henning.fehrmann@....mpg.de,
 oliver.behnke@....mpg.de, Jesper Dangaard Brouer <jbrouer@...hat.com>,
 Alexei Starovoitov <ast@...nel.org>,
 John Fastabend <john.fastabend@...il.com>, Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH bpf-next 1/2] samples/bpf: fixup xdp_redirect tool to be
 able to support xdp multibuffer

On 30/05/2023 20:22, Martin KaFai Lau wrote:
> On 5/30/23 6:40 AM, Tariq Toukan wrote:
>>>> I initiated a discussion on this topic a few months ago. dynptr was 
>>>> accepted since then, but I'm not aware of any in-progress followup 
>>>> work that addresses this.
>>>>
>>>
>>> Are you saying some more work is needed on dynptr?
>>>
>>
>> AFAIU yes.
>> But I might be wrong... I need to revisit this.
>> Do you think/know that dynptr can be used immediately?
> 
> Not sure if you are aware of the bpf_dynptr_slice[_rdwr]() which could 
> be useful here. It only does a copy when the requested slice is across 
> different frags:
> https://lore.kernel.org/all/20230301154953.641654-10-joannelkoong@gmail.com/
> 

Thanks for the pointer. I missed it. Looks promising!
I'll take a deeper look soon and do some perf tests.