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Date: Thu, 30 Jan 2025 10:13:57 -0800
From: Jakub Kicinski <kuba@kernel.org>
To: Joe Damato <jdamato@fastly.com>
Cc: netdev@vger.kernel.org, sridhar.samudrala@intel.com, Donald Hunter
 <donald.hunter@gmail.com>, "David S. Miller" <davem@davemloft.net>, Eric
 Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>, Simon
 Horman <horms@kernel.org>, Andrew Lunn <andrew+netdev@lunn.ch>, Xuan Zhuo
 <xuanzhuo@linux.alibaba.com>, Mina Almasry <almasrymina@google.com>, Martin
 Karsten <mkarsten@uwaterloo.ca>, Amritha Nambiar
 <amritha.nambiar@intel.com>, Stanislav Fomichev <sdf@fomichev.me>, Daniel
 Jurgens <danielj@nvidia.com>, open list <linux-kernel@vger.kernel.org>
Subject: Re: [RFC net-next 1/2] netdev-genl: Add an XSK attribute to queues
Message-ID: <20250130101357.2cd1bbc5@kernel.org>
In-Reply-To: <Z5u_t7Rw77X6VAEs@LQ3V64L9R2>
References: <20250129172431.65773-1-jdamato@fastly.com>
	<20250129172431.65773-2-jdamato@fastly.com>
	<20250129175224.1613aac1@kernel.org>
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On Thu, 30 Jan 2025 13:06:47 -0500 Joe Damato wrote:
> On Wed, Jan 29, 2025 at 05:52:24PM -0800, Jakub Kicinski wrote:
> > On Wed, 29 Jan 2025 17:24:24 +0000 Joe Damato wrote:  
> > > Expose a new per-queue attribute, xsk, which indicates that a queue is
> > > being used for AF_XDP. Update the documentation to more explicitly state
> > > which queue types are linked.  
> > 
> > Let's do the same thing we did for io_uring queues? An empty nest:
> > https://lore.kernel.org/all/20250116231704.2402455-6-dw@davidwei.uk/
> > 
> > At the protocol level nest is both smaller and more flexible.
> > It's just 4B with zero length and a "this is a nest" flag.
> > We can add attributes to it as we think of things to express.  
> 
> I got a thing working locally, but just to make sure I'm
> following... you are saying that the attribute will exist (but have
> nothing in it) when the queue has a pool, and when !q->pool the
> attribute will not exist?
> 
> For example:
> 
> [{'id': 0, 'ifindex': 5, 'napi-id': 8266, 'type': 'rx', 'xsk': {}},
>  {'id': 1, 'ifindex': 5, 'napi-id': 8267, 'type': 'rx'},
>  ...
> 
> Is that what you are thinking?

Yup! That's it.

> Completely fine with me as I haven't read enough of the xsk code to
> really have a good sense of what attributes might be helpful to
> expose at this point.