[PATCH net-next 0/2] Fix phy_link_topology initialization

[Russell King (Oracle)]

On Sun, May 12, 2024 at 11:36:36PM -0700, Nathan Chancellor wrote:
> Hi Maxime,
> 
> On Tue, May 07, 2024 at 12:28:19PM +0200, Maxime Chevallier wrote:
> > Nathan and Heiner reported issues that occur when phylib and phy drivers
> > built as modules expect the phy_link_topology to be initialized, due to
> > wrong use of IS_REACHABLE.
> > 
> > This small fixup series addresses that by moving the initialization code
> > into net/core/dev.c, but at the same time implementing lazy
> > initialization to only allocate the topology upon the first PHY
> > insertion.
> > 
> > This needed some refactoring, namely pass the netdevice itself as a
> > parameter for phy_link_topology helpers.
> > 
> > Thanks Heiner for the help on untangling this, and Nathan for the
> > report.
> 
> Are you able to prioritize getting this series merged? This has been a
> problem in -next for over a month now and the merge window is now open.
> I would hate to see this regress in mainline, as my main system may be
> affected by it (not sure, I got a new test machine that got bit by it in
> addition to the other two I noticed it on).

... and Maxime has been working on trying to get an acceptable fix for
it over that time, with to-and-fro discussions. Maxime still hasn't got
an ack from Heiner for the fixes, and changes are still being
requested.

I think, sadly, the only way forward at this point would be to revert
the original commit. I've just tried reverting 6916e461e793 in my
net-next tree and it's possible, although a little noisy:

$ git revert 6916e461e793
Performing inexact rename detection: 100% (8904/8904), done.
Auto-merging net/core/dev.c
Auto-merging include/uapi/linux/ethtool.h
Removing include/linux/phy_link_topology_core.h
Removing include/linux/phy_link_topology.h
Auto-merging include/linux/phy.h
Auto-merging include/linux/netdevice.h
Removing drivers/net/phy/phy_link_topology.c
Auto-merging drivers/net/phy/phy_device.c
Auto-merging MAINTAINERS
hint: Waiting for your editor to close the file...

I haven't checked whether that ends up with something that's buildable.

Any views Jakub/Dave/Paolo?

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