linux-kernel - Re: [PATCH v3 0/8] kernel: taint when the driver firmware crashes

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Message-ID: <20200526163031.5c43fc1d@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
Date:   Tue, 26 May 2020 16:30:31 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Luis Chamberlain <mcgrof@...nel.org>
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Subject: Re: [PATCH v3 0/8] kernel: taint when the driver firmware crashes

On Tue, 26 May 2020 23:07:48 +0000 Luis Chamberlain wrote:
> On Tue, May 26, 2020 at 03:46:06PM -0700, Jakub Kicinski wrote:
> > On Tue, 26 May 2020 14:58:07 +0000 Luis Chamberlain wrote:  
> > > To those new on CC -- this is intended to be a simple generic interface
> > > to the kernel to annotate when the firwmare has crashed leaving the
> > > driver or system in a questionable state, in the worst case requiring
> > > full system reboot. This series is first addressing only a few
> > > networking patches, however, I already have an idea of where such
> > > firmware crashes happen across the tree. The goal with this series then
> > > is to first introduce the simple framework, and only if that moves
> > > forward will I continue to chug on with the rest of the drivers /
> > > subsystems.
> > > 
> > > This is *not* a networking specific problem only.
> > > 
> > > This v3 augments the last series by introducing the uevent for panic
> > > events, one of them is during tainting. The uvent mechanism is
> > > independent from any of this firmware taint mechanism. I've also
> > > addressed Jessica Yu's feedback. Given I've extended the patches a bit
> > > with other minor cleanup which checkpatch.pl complains over, and since
> > > this infrastructure is still being discussed, I've trimmed the patch
> > > series size to only cover drivers for which I've received an Acked-by
> > > from the respective driver maintainer, or where we have bug reports to
> > > support such dire situations on the driver such as ath10k.
> > > 
> > > During the last v2 it was discussed that we should instead use devlink
> > > for this work, however the initial RFC patches produced by Jakub
> > > Kicinski [0] shows how devlink is networking specific, and the intent
> > > behind this series is to produce simple helpers which can be used by *any*
> > > device driver, for any subsystem, not just networking. Subsystem
> > > specific infrastructure to help address firwmare crashes may still make
> > > sense, however that does not mean we *don't* need something even more
> > > generic regardless of the subsystem the issue happens on. Since uevents
> > > for taints are exposed, we now expose these through uapi as well, and
> > > that was something which eventually had to happen given that the current
> > > scheme of relying on sensible character representations for each taint
> > > will not scale beyond the alphabet.  
> > 
> > Nacked-by: Jakub Kicinski <kuba@...nel.org>  
> 
> Care to elaborate?

I elaborated in the previous thread and told you I will nack this, 
but sure let's go over this again.

For the third time saying the devlink is networking specific is not
true. It was created as a netlink configuration channel for devices
when there is no networking reference that could be used. It can be
compiled in or out much like sysfs.

And as I've shown you devlink already has the uAPI for what you're
trying to achieve.

Regardless of your opinions about wider interfaces, networking drivers
should implement devlink, and not have to sprinkle magic taint calls.