linux-kernel - Re: [PATCH net-next 03/10] devlink: Serialize access to rate domains

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <qygqjbhvk5ycigyxcojzakllelokkos3rgpolhpebmfiqzsajp@jxle4qz4ajxz>
Date: Wed, 5 Mar 2025 12:48:33 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Tariq Toukan <tariqt@...dia.com>, 
	"David S. Miller" <davem@...emloft.net>, Paolo Abeni <pabeni@...hat.com>, 
	Eric Dumazet <edumazet@...gle.com>, Andrew Lunn <andrew+netdev@...n.ch>, 
	Jiri Pirko <jiri@...dia.com>, Cosmin Ratiu <cratiu@...dia.com>, 
	Carolina Jubran <cjubran@...dia.com>, Gal Pressman <gal@...dia.com>, Mark Bloch <mbloch@...dia.com>, 
	Donald Hunter <donald.hunter@...il.com>, Jonathan Corbet <corbet@....net>, 
	Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: Re: [PATCH net-next 03/10] devlink: Serialize access to rate domains

Wed, Mar 05, 2025 at 01:04:12AM +0100, kuba@...nel.org wrote:
>On Tue, 4 Mar 2025 14:11:40 +0100 Jiri Pirko wrote:
>> Mon, Mar 03, 2025 at 11:06:23PM +0100, kuba@...nel.org wrote:
>> >On Thu, 27 Feb 2025 13:22:25 +0100 Jiri Pirko wrote:  
>> >> Depends. On normal host sr-iov, no. On smartnic where you have PF in
>> >> host, yes.  
>> >
>> >Yet another "great choice" in mlx5 other drivers have foreseen
>> >problems with and avoided.  
>> 
>> What do you mean? How else to model it? Do you suggest having PF devlink
>> port for the PF that instantiates? That would sound like Uroboros to me.
>
>I reckon it was always more obvious to those of us working on
>NPU-derived devices, to which a PCIe port is just a PCIe port,
>with no PCIe<>MAC "pipeline" to speak of.
>
>The reason why having the "PF port" is a good idea is exactly
>why we're having this conversation. If you don't you'll assign
>to the global scope attributes which are really just port attributes.

Well, we have devlink port for uplink for this purpose. Why isn't that
enough?


>
>> >> Looks like pretty much all current NICs are multi-PFs, aren't they?  
>> >
>> >Not in a way which requires cross-port state sharing, no.
>> >You should know this.  
>> 
>> This is not about cross-port state sharing. This is about per-PF
>> configuration. What am I missing?
>
>Maybe we lost the thread of the conversation.. :)
>I'm looking at the next patch in this series and it says:
>
>  devlink: Introduce shared rate domains
>
>  The underlying idea is modeling a piece of hardware which:
>  1. Exposes multiple functions as separate devlink objects.
>  2. Is capable of instantiating a transmit scheduling tree spanning
>     multiple functions.
>
>  Modeling this requires devlink rate nodes with parents across other
>  devlink objects.
>
>Are these domains are not cross port?

Sure. Cross PF even. What I suggest is, if we have devlink instance of
which these 2 PFs are nested, we have this "domain" explicitly defined
and we don't need any other construct.