[Intel-wired-lan] [PATCH v1 iwl-net] igc: unregister netdev when igc_led_setup() fails in igc_probe()

[Kohei Enju]

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 <en...@amazon.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c 
b/drivers/net/ethernet/intel/igc/igc_main.c
index e79b14d50b24..95c415d0917d 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -7336,11 +7336,13 @@ static int igc_probe(struct pci_dev *pdev,
        if (IS_ENABLED(CONFIG_IGC_LEDS)) {
                err = igc_led_setup(adapter);
                if (err)
-                       goto err_register;
+                       goto err_led_setup;
        }
 
        return 0;
 
+err_led_setup:
+       unregister_netdev(netdev);
 err_register:
        igc_release_hw_control(adapter);
        igc_ptp_stop(adapter);
-- 
2.48.1