netdev - Re: [PATCH v2 net-next 3/5] ionic: use per-queue xdp

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Message-ID: <4dfae14b-2d92-4561-9c79-688bde2e347a@amd.com>
Date: Tue, 27 Aug 2024 14:40:19 -0700
From: Brett Creeley <bcreeley@....com>
To: Larysa Zaremba <larysa.zaremba@...el.com>,
 Brett Creeley <brett.creeley@....com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
 edumazet@...gle.com, pabeni@...hat.com, shannon.nelson@....com
Subject: Re: [PATCH v2 net-next 3/5] ionic: use per-queue xdp_prog



On 8/27/2024 4:44 AM, Larysa Zaremba wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
> 
> 
> On Mon, Aug 26, 2024 at 11:44:20AM -0700, Brett Creeley wrote:
>> From: Shannon Nelson <shannon.nelson@....com>
>>
>> We originally were using a per-interface xdp_prog variable to track
>> a loaded XDP program since we knew there would never be support for a
>> per-queue XDP program.  With that, we only built the per queue rxq_info
>> struct when an XDP program was loaded and removed it on XDP program unload,
>> and used the pointer as an indicator in the Rx hotpath to know to how build
>> the buffers.  However, that's really not the model generally used, and
>> makes a conversion to page_pool Rx buffer cacheing a little problematic.
>>
>> This patch converts the driver to use the more common approach of using
>> a per-queue xdp_prog pointer to work out buffer allocations and need
>> for bpf_prog_run_xdp().  We jostle a couple of fields in the queue struct
>> in order to keep the new xdp_prog pointer in a warm cacheline.
>>
>> Signed-off-by: Shannon Nelson <shannon.nelson@....com>
>> Signed-off-by: Brett Creeley <brett.creeley@....com>
> 
> Reviewed-by: Larysa Zaremba <larysa.zaremba@...el.com>
> 
> If you happen to send another version, please include in a commit message a note
> about READ_ONCE() removal. The removal itself is OK, but an indication that this
> was intentional would be nice.

Sure, will do. Thanks for the review.

Brett

<snip>