netdev - Re: [PATCH v2 3/5] io_uring/zcrx: share an ifq between rings

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Message-ID: <3a7a2318-09fb-41d2-9ba1-9d60c7e417a6@kernel.dk>
Date: Sun, 26 Oct 2025 07:16:29 -0600
From: Jens Axboe <axboe@...nel.dk>
To: David Wei <dw@...idwei.uk>, io-uring@...r.kernel.org,
 netdev@...r.kernel.org
Cc: Pavel Begunkov <asml.silence@...il.com>
Subject: Re: [PATCH v2 3/5] io_uring/zcrx: share an ifq between rings

On 10/25/25 10:12 PM, David Wei wrote:
> Sorry I missed this during the splitting. Will include in v3.
> 
>>
>>> +    ifq->proxy = src_ifq;
>>
>> For this, since the ifq is shared and reference counted, why don't they
>> just point at the same memory here? Would avoid having this ->proxy
>> thing and just skipping to that in other spots where the actual
>> io_zcrx_ifq is required?
>>
> 
> I wanted a way to separate src and dst rings, while also decrementing
> refcounts once and only once. I used separate ifq objects to do this,
> but having learnt about xarray marks, I think I can use that instead.

I'm confused, why do you even need that? You already have
ifq->proxy which is just a "link" to the shared queue, why aren't both
rings just using the same ifq structure? You already increment the
refcount when you add proxy, why can't the new ring just store the same
ifq?

-- 
Jens Axboe