[PATCH v2 iwl-net] igc: don't fail igc_probe() on LED setup error

[Kohei Enju <enjuk@amazon.com>]

When igc_led_setup() fails, igc_probe() fails and triggers kernel panic
in free_netdev() since unregister_netdev() is not called. [1]
This behavior can be tested using fault-injection framework, especially
the failslab feature. [2]

Since LED support is not mandatory, treat LED setup failures as
non-fatal and continue probe with a warning message, consequently
avoiding 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 <enjuk@amazon.com>
---
Changes:
  v1->v2:
    - don't fail probe when led setup fails
    - rephrase subject and commit message
  v1: https://lore.kernel.org/intel-wired-lan/20250906055239.29396-1-enjuk@amazon.com/
---
 drivers/net/ethernet/intel/igc/igc.h      |  1 +
 drivers/net/ethernet/intel/igc/igc_main.c | 12 +++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index 266bfcf2a28f..a427f05814c1 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -345,6 +345,7 @@ struct igc_adapter {
 	/* LEDs */
 	struct mutex led_mutex;
 	struct igc_led_classdev *leds;
+	bool leds_available;
 };
 
 void igc_up(struct igc_adapter *adapter);
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index e79b14d50b24..728d7ca5338b 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -7335,8 +7335,14 @@ static int igc_probe(struct pci_dev *pdev,
 
 	if (IS_ENABLED(CONFIG_IGC_LEDS)) {
 		err = igc_led_setup(adapter);
-		if (err)
-			goto err_register;
+		if (err) {
+			netdev_warn_once(netdev,
+					 "LED init failed (%d); continuing without LED support\n",
+					 err);
+			adapter->leds_available = false;
+		} else {
+			adapter->leds_available = true;
+		}
 	}
 
 	return 0;
@@ -7392,7 +7398,7 @@ static void igc_remove(struct pci_dev *pdev)
 	cancel_work_sync(&adapter->watchdog_task);
 	hrtimer_cancel(&adapter->hrtimer);
 
-	if (IS_ENABLED(CONFIG_IGC_LEDS))
+	if (IS_ENABLED(CONFIG_IGC_LEDS) && adapter->leds_available)
 		igc_led_free(adapter);
 
 	/* Release control of h/w to f/w.  If f/w is AMT enabled, this
-- 
2.48.1