netdev - Re: [PATCH net-next v1] ethtool: ethtool_get_drvinfo: populate drvinfo fields even if callback exits

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Date:   Thu, 10 Nov 2022 20:43:25 +0900
From:   Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Guangbin Huang <huangguangbin2@...wei.com>,
        Sean Anderson <sean.anderson@...o.com>,
        Tom Rix <trix@...hat.com>,
        Tonghao Zhang <xiangxia.m.yue@...il.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Marco Bonelli <marco@...eim.net>
Subject: Re: [PATCH net-next v1] ethtool: ethtool_get_drvinfo: populate
 drvinfo fields even if callback exits

On Thu. 10 Nov. 2022 at 18:11, Leon Romanovsky <leon@...nel.org> wrote:
> On Thu, Nov 10, 2022 at 05:34:55PM +0900, Vincent MAILHOL wrote:
> > On Thu. 10 nov. 2022 at 05:26, Jakub Kicinski <kuba@...nel.org> wrote:
> > > On Wed, 9 Nov 2022 19:52:13 +0200 Leon Romanovsky wrote:
> > > > On Tue, Nov 08, 2022 at 12:57:54PM +0900, Vincent Mailhol wrote:
> > > > > If ethtool_ops::get_drvinfo() callback isn't set,
> > > > > ethtool_get_drvinfo() will fill the ethtool_drvinfo::name and
> > > > > ethtool_drvinfo::bus_info fields.
> > > > >
> > > > > However, if the driver provides the callback function, those two
> > > > > fields are not touched. This means that the driver has to fill these
> > > > > itself.
> > > >
> > > > Can you please point to such drivers?
> > >
> > > What you mean by "such drivers" is not clear from the quoted context,
> > > at least to me.
> >
> > An example:
> > https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/broadcom/bnx2.c#L7041
> >
> > This driver wants to set fw_version but needs to also fill the driver
> > name and bus_info. My patch will enable *such drivers* to only fill
> > the fw_version and delegate the rest to the core.
>
> Sorry for being misleading, It looks like I typed only part of the sentence
> which I had in my mind. I wanted to see if any driver exists which prints
> drv_name and bus_info different from default.
>
> >
> > > > One can argue that they don't need to touch these fields in a first
> > > > place and ethtool_drvinfo should always overwrite them.
> > >
> > > Quite likely most driver prints to .driver and .bus_info can be dropped
> > > with this patch in place. Then again, I'm suspecting it's a bit of a
> > > chicken and an egg problem with people adding new drivers not having
> > > an incentive to add the print in the core and people who want to add
> > > the print in the core not having any driver that would benefit.
> > > Therefore I'd lean towards accepting Vincent's patch as is even if
> > > the submission can likely be more thorough and strict.
> >
> > If we can agree that no drivers should ever print .driver and
> > .bus_info, then I am fine to send a clean-up patch to remove all this
> > after this one gets accepted. However, I am not willing to invest time
> > for nothing. So would one of you be ready to sign-off such a  clean-up
> > patch?
>
> I will be happy to see such patch and will review it, but can't add sign-off
> as I'm not netdev maintainer.

Well, if you want to review, just have a look at:
  $ git grep -W "get_drvinfo(struct"

Unless some driver names their callback function in some non standard
way, that should be pretty it. Regardless, this will give you a fair
representation of the current situation.

There are a few nuances. For example, some drivers use dev_name() for
the .bus_info, while some others use pci_name(). I am not sure if this
makes a difference... Also, there are many hardcoded names for .driver
and I do not have the courage to check all of them. I am OK to blindly
remove all that mess but no more.


Yours sincerely,
Vincent Mailhol