topic Re: kernel panic in fec network driver on iMX6ULL in i.MX Processors

kernel panic in fec network driver on iMX6ULL

dallasfoley — Thu, 31 Oct 2019 00:24:10 GMT

I'm currently seeing kernel panics in the fec driver when configuring and re-configuring my network with netplan.io in ubuntu.

I'm seeing this on our own hardware as well as the iMX6ULL EVK. The kernel version is 4.14.98. I've also tried using 5.4 from git://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux.git.

I noticed the panic happens when unbinding and then binding the device to the driver, which netplan.io seems to by running strace.

eg. running the following commands can cause the kernel panic.

~# echo -n "20b4000.ethernet" > /sys/bus/platform/drivers/fec/ubind
~# echo -n "20b4000.ethernet" > /sys/bus/platform/drivers/fec/bind

Re: kernel panic in fec network driver on iMX6ULL

igorpadykov — Tue, 05 Nov 2019 09:52:51 GMT

Hi Dallas

nxp does not support netplan on its linux releases, issue may be posted

on netplan wiki: https://launchpad.net/netplan/+filebug

Best regards
igor
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Re: kernel panic in fec network driver on iMX6ULL

dallasfoley — Tue, 05 Nov 2019 17:14:00 GMT

It's the unbinding/binding from sysfs that exposes the bug in the driver.

Re: kernel panic in fec network driver on iMX6ULL

fabio_estevam — Thu, 27 Feb 2020 12:36:03 GMT

Hi Dallas,

Performing unbind/bind operation on the FEC driver is not safe. Please check the details in this commit where I disable the unbind operation in the driver:

kernel/git/netdev/net-next.git - David Miller's -next networking tree

You can still build the FEC driver as module and load/unload it.

Regards,

Fabio Estevam

Re: kernel panic in fec network driver on iMX6ULL

dallasfoley — Tue, 10 Mar 2020 16:55:25 GMT

Thanks Fabio, I've applied the patch and now blocks unbinding the driver. It looks like netplan.io is aware of SOC's that don't support network driver unbinding.

Bug #1706680 “add config file to list drivers that do not suppor...” : Bugs : nplan package : Ubuntu

Bug #1756322 “'netplan apply' fails when trying to activate anot...” : Bugs : netplan