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

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Date:   Fri, 11 Nov 2022 00:53:16 +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 21:00, Leon Romanovsky <leon@...nel.org> wrote:
> On Thu, Nov 10, 2022 at 08:43:25PM +0900, Vincent MAILHOL wrote:
> > 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"
>
> BTW, in some of the callbacks, if driver doesn't exists, they print "N/A",
> while in your patch it will be empty string.

Indeed and this is inconsistent. For example, no one sets
.erom_version to "N/A". So you will have some of the fields set to
"N/A" and some others set to an empty string. The "N/A" thing was a
mistake to begin with. I will not change my patch.