linux-kernel - Re: [PATCH net-next RFC 01/13] devlink: Add reload level option to devlink reload command

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Message-ID: <20200810095305.0b9661ec@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Mon, 10 Aug 2020 09:53:05 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Moshe Shemesh <moshe@...lanox.com>
Cc:     Jiri Pirko <jiri@...nulli.us>,
        Jacob Keller <jacob.e.keller@...el.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Jiri Pirko <jiri@...lanox.com>,
        Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Subject: Re: [PATCH net-next RFC 01/13] devlink: Add reload level option to
 devlink reload command

On Sun, 9 Aug 2020 16:21:29 +0300 Moshe Shemesh wrote:
> Okay, so devlink reload default for mlx5 will include also fw-activate 
> to align with mlxsw default.
> 
> Meaning drivers that supports fw-activate will add it to the default.

No per-driver default.

Maybe the difference between mlxsw and mlx5 can be simply explained by
the fact that mlxsw loads firmware from /lib/firmware on every probe
(more or less).

It's only natural for a driver which loads FW from disk to load it on
driver reload.

> The flow of devlink reload default on mlx5 will be:
> 
> If there is FW image pending and live patch is suitable to apply, do 
> live patch and driver re-initialization.
> 
> If there is FW image pending but live patch doesn't fit do fw-reset and 
> driver-initialization.
> 
> If no FW image pending just do driver-initialization.

This sounds too complicated. Don't try to guess what the user wants.

> I still think I should on top of that add the level option to be 
> selected by the user if he prefers a specific action, so the uAPI would be:
> 
> devlink dev reload [ netns { PID | NAME | ID } ] [ level { fw-live-patch 
> | driver-reinit |fw-activate } ]

I'm all for the level/action.

> But I am still missing something: fw-activate implies that it will 
> activate a new FW image stored on flash, pending activation. What if the 
> user wants to reset and reload the FW if no new FW pending ? Should we 
> add --force option to fw-activate level ?

Since reload does not check today if anything changed - i.e. if reload
is actually needed, neither should fw-activate, IMO. I'd expect the
"--force behavior" to be the default.