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From: Leon Romanovsky <leon@kernel.org>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Shannon Nelson <snelson@pensando.io>,
	"David S . Miller" <davem@davemloft.net>,
	Michal Kalderon <michal.kalderon@marvell.com>,
	linux-netdev <netdev@vger.kernel.org>,
	RDMA mailing list <linux-rdma@vger.kernel.org>
Subject: Re: [PATCH net-next] net/core: Replace driver version to be kernel version
Date: Sun, 26 Jan 2020 23:08:50 +0200	[thread overview]
Message-ID: <20200126210850.GB3870@unreal> (raw)
In-Reply-To: <20200126124957.78a31463@cakuba>

On Sun, Jan 26, 2020 at 12:49:57PM -0800, Jakub Kicinski wrote:
> On Sun, 26 Jan 2020 21:41:10 +0200, Leon Romanovsky wrote:
> > > This will end up affecting out-of-tree drivers as well, where it is useful
> > > to know what the version number is, most especially since it is different
> > > from what the kernel provided driver is.  How else are we to get this
> > > information out to the user?  If this feature gets squashed, we'll end up
> > > having to abuse some other mechanism so we can get the live information from
> > > the driver, and probably each vendor will find a different way to sneak it
> > > out, giving us more chaos than where we started.  At least the ethtool
> > > version field is a known and consistent place for the version info.
> > >
> > > Of course, out-of-tree drivers are not first class citizens, so I probably
> > > lose that argument as well.
> > >
> > > So if you are so all fired up about not allowing the drivers to report their
> > > own version number, then why report anything at all? Maybe just report a
> > > blank field.  As some have said, the uname info is already available else
> > > where, why are we sticking it here?
> > >
> > > Personally, I think this is a rather arbitrary, heavy handed and unnecessary
> > > slam on the drivers, and will make support more difficult in the long run.
> >
> > The thing is that leaving this field as empty, for sure will break all
> > applications. I have a feeling that it can be close to 100% hit rate.
> > So, kernel version was chosen as an option, because it is already
> > successfully in use by at least two drivers (nfp and hns).
>
> Shannon does have a point that out of tree drivers still make use of
> this field. Perhaps it would be a more suitable first step to print the
> kernel version as default and add a comment saying upstream modules
> shouldn't overwrite it (perhaps one day CI can catch new violators).

Jakub,

Shannon proposed to remove this field and it was me who said no :)
My plan is to overwrite ->version, delete all users and add
WARN_ONEC(strcpy(..->version_)...) inside net/ethtool/ to catch
abusers.

>
> The NFP reports the git hash of the driver source plus the string
> "(oot)" for out-of-tree:
>
> https://github.com/Netronome/nfp-drv-kmods/blob/master/src/Kbuild#L297
> https://github.com/Netronome/nfp-drv-kmods/blob/master/src/Kbuild#L315

I was inspired by upstream code.
https://elixir.bootlin.com/linux/v5.5-rc7/source/drivers/net/ethernet/netronome/nfp/nfp_net_ethtool.c#L184

>
> > Leaving to deal with driver version to vendors is not an option too,
> > because they prove for more than once that they are not capable to
> > define user visible interfaces. It comes due to their natural believe
> > that their company is alone in the world and user visible interface
> > should be suitable for them only.
> >
> > It is already impossible for users to distinguish properly versions
> > of different vendors, because they use arbitrary strings with some
> > numbers.
>
> That is true. But reporting the kernel version without even as much as
> in-tree/out-of-tree indication makes the field entirely meaningless.

The long-standing policy in kernel that we don't really care about
out-of-tree code.

Thanks

  reply	other threads:[~2020-01-26 21:08 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-23 13:05 Leon Romanovsky
2020-01-23 14:40 ` Jakub Kicinski
2020-01-23 14:54   ` Leon Romanovsky
2020-01-23 15:17     ` Jakub Kicinski
2020-01-25  9:13 ` David Miller
2020-01-26 18:56 ` Shannon Nelson
2020-01-26 19:41   ` Leon Romanovsky
2020-01-26 20:49     ` Jakub Kicinski
2020-01-26 21:08       ` Leon Romanovsky [this message]
2020-01-26 21:17         ` Shannon Nelson
2020-01-26 21:24           ` Leon Romanovsky
2020-01-26 22:12             ` Shannon Nelson
2020-01-26 22:22               ` Michal Kubecek
2020-01-26 22:57                 ` Shannon Nelson
2020-01-27  6:08                   ` Michal Kubecek
2020-01-27  6:42                     ` Leon Romanovsky
2020-01-27  5:18                 ` Leon Romanovsky
2020-01-26 21:33         ` Jakub Kicinski
2020-01-26 22:21           ` Shannon Nelson
2020-01-27  5:34             ` Leon Romanovsky
2020-01-27  6:45               ` Leon Romanovsky
2020-01-27 14:21                 ` Jakub Kicinski
2020-01-27 15:39                   ` Leon Romanovsky
2020-01-27  5:49           ` Leon Romanovsky
2020-01-27 12:21             ` David Miller
2020-01-27 12:42               ` Leon Romanovsky
2020-01-27 12:47                 ` David Miller
2020-01-27 17:57             ` Shannon Nelson
2020-01-26 20:52     ` Shannon Nelson
2020-01-26 21:19       ` Leon Romanovsky

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