On Fri, Jul 18, 2025 at 4:37 PM Jakub Kicinski [off-list ref] wrote:

On Fri, 18 Jul 2025 13:20:14 -0700 Haiyang Zhang wrote:

quoted

The loop in default_device_exit_net() won't be able to properly detect the
head then stop, and will hit NULL pointer, when a driver, like hv_netvsc,
automatically moves the slave device together with the master device.

To fix this, add a helper function to return the first migratable netdev
correctly, no matter one or two devices were removed from this net's list
in the last iteration.

FTR I think that what the driver is trying to do is way too hacky, and
it should be fixed instead. But I defer to Kuniyuki for the final word,
maybe this change is useful for other reasons..

I agree that it should be fixed on the driver side.  I don't
think of a good reason for the change.