On 9/8/2025 9:26 AM, Kurt Kanzenbach wrote:
On Sat Sep 06 2025, Kohei Enju wrote:
Currently igc_probe() doesn't unregister netdev when igc_led_setup()
fails, causing BUG_ON() in free_netdev() and then kernel panics. [1]
This behavior can be tested using fault-injection framework. I used the
failslab feature to test the issue. [2]
Call unregister_netdev() when igc_led_setup() fails to avoid the kernel
panic.
[1]
kernel BUG at net/core/dev.c:12047!
Oops: invalid opcode: 0000 [#1] SMP NOPTI
CPU: 0 UID: 0 PID: 937 Comm: repro-igc-led-e Not tainted
6.17.0-rc4-enjuk-tnguy-00865-gc4940196ab02 #64 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:free_netdev+0x278/0x2b0
[...]
Call Trace:
<TASK>
igc_probe+0x370/0x910
local_pci_probe+0x3a/0x80
pci_device_probe+0xd1/0x200
[...]
[2]
#!/bin/bash -ex
FAILSLAB_PATH=/sys/kernel/debug/failslab/
DEVICE=0000:00:05.0
START_ADDR=$(grep " igc_led_setup" /proc/kallsyms \
| awk '{printf("0x%s", $1)}')
END_ADDR=$(printf "0x%x" $((START_ADDR + 0x100)))
echo $START_ADDR > $FAILSLAB_PATH/require-start
echo $END_ADDR > $FAILSLAB_PATH/require-end
echo 1 > $FAILSLAB_PATH/times
echo 100 > $FAILSLAB_PATH/probability
echo N > $FAILSLAB_PATH/ignore-gfp-wait
echo $DEVICE > /sys/bus/pci/drivers/igc/bind
Fixes: ea578703b03d ("igc: Add support for LEDs on i225/i226")
Signed-off-by: Kohei Enju <[email protected]>
Reviewed-by: Kurt Kanzenbach <[email protected]>
Thank you for the patch and for identifying this issue!
I was wondering whether we could avoid failing the probe in cases where
igc_led_setup fails. It seems to me that a failure in the LED class
functionality shouldn't prevent the device's core functionality from
working properly.
From what I understand, errors in this function are not due to hardware
malfunctions. Therefore, I suggest we remove the error propagation.
Alternatively, if feasible, we could consider reordering the function
calls so that the LED class setup occurs before the netdev registration.
