netdev - Re: [PATCH net-next 01/11] net: ethtool: let drivers remove lost RSS contexts

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Message-ID: <c22f9b2b-cbcd-d77a-2a9a-cf62c2af8882@gmail.com>
Date: Wed, 3 Jul 2024 12:08:36 +0100
From: Edward Cree <ecree.xilinx@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, davem@...emloft.net
Cc: netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com,
 michael.chan@...adcom.com
Subject: Re: [PATCH net-next 01/11] net: ethtool: let drivers remove lost RSS
 contexts

On 03/07/2024 00:47, Jakub Kicinski wrote:
> RSS contexts may get lost from a device, in various extreme circumstances.
> Specifically if the firmware leaks resources and resets, or crashes and
> either recovers in partially working state or the crash causes a
> different FW version to run - creating the context again may fail.

So, I deliberately *didn't* do this, on the grounds that if the user
 fixed things by updating FW and resetting again, their contexts could
 get restored.  I suppose big users like Meta will have orchestration
 doing all that work anyway so it doesn't matter.

> Drivers should do their absolute best to prevent this from happening.
> When it does, however, telling user that a context exists, when it can't
> possibly be used any more is counter productive. Add a helper for
> drivers to discard contexts. Print an error, in the future netlink
> notification will also be sent.
Possibility of a netlink notification makes the idea of a broken flag
 a bit more workable imho.  But it's up to you which way to go.