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Message-Id: <20240411-igc_led_deadlock-v1-1-0da98a3c68c5@linutronix.de>
Date: Sun, 14 Apr 2024 09:44:10 +0200
From: Kurt Kanzenbach <kurt@...utronix.de>
To: Jesse Brandeburg <jesse.brandeburg@...el.com>, 
 Tony Nguyen <anthony.l.nguyen@...el.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Andrew Lunn <andrew@...n.ch>
Cc: Lukas Wunner <lukas@...ner.de>, Sasha Neftin <sasha.neftin@...el.com>, 
 intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org, 
 Kurt Kanzenbach <kurt@...utronix.de>
Subject: [PATCH iwl-net] igc: Fix deadlock on module removal

The removal of the igc module leads to a deadlock:

|[Mon Apr  8 17:38:55 2024]  __mutex_lock.constprop.0+0x3e5/0x7a0
|[Mon Apr  8 17:38:55 2024]  ? preempt_count_add+0x85/0xd0
|[Mon Apr  8 17:38:55 2024]  __mutex_lock_slowpath+0x13/0x20
|[Mon Apr  8 17:38:55 2024]  mutex_lock+0x3b/0x50
|[Mon Apr  8 17:38:55 2024]  rtnl_lock+0x19/0x20
|[Mon Apr  8 17:38:55 2024]  unregister_netdevice_notifier+0x2a/0xc0
|[Mon Apr  8 17:38:55 2024]  netdev_trig_deactivate+0x25/0x70
|[Mon Apr  8 17:38:55 2024]  led_trigger_set+0xe2/0x2d0
|[Mon Apr  8 17:38:55 2024]  led_classdev_unregister+0x4f/0x100
|[Mon Apr  8 17:38:55 2024]  devm_led_classdev_release+0x15/0x20
|[Mon Apr  8 17:38:55 2024]  release_nodes+0x47/0xc0
|[Mon Apr  8 17:38:55 2024]  devres_release_all+0x9f/0xe0
|[Mon Apr  8 17:38:55 2024]  device_del+0x272/0x3c0
|[Mon Apr  8 17:38:55 2024]  netdev_unregister_kobject+0x8c/0xa0
|[Mon Apr  8 17:38:55 2024]  unregister_netdevice_many_notify+0x530/0x7c0
|[Mon Apr  8 17:38:55 2024]  unregister_netdevice_queue+0xad/0xf0
|[Mon Apr  8 17:38:55 2024]  unregister_netdev+0x21/0x30
|[Mon Apr  8 17:38:55 2024]  igc_remove+0xfb/0x1f0 [igc]
|[Mon Apr  8 17:38:55 2024]  pci_device_remove+0x42/0xb0
|[Mon Apr  8 17:38:55 2024]  device_remove+0x43/0x70

unregister_netdev() acquires the RNTL lock and releases the LEDs bound
to that netdevice. However, netdev_trig_deactivate() and later
unregister_netdevice_notifier() try to acquire the RTNL lock again.

Avoid this situation by not using the device-managed LED class
functions.

Suggested-by: Lukas Wunner <lukas@...ner.de>
Fixes: ea578703b03d ("igc: Add support for LEDs on i225/i226")
Signed-off-by: Kurt Kanzenbach <kurt@...utronix.de>
---
 drivers/net/ethernet/intel/igc/igc.h      |  4 ++++
 drivers/net/ethernet/intel/igc/igc_leds.c | 37 ++++++++++++++++++++++++-------
 drivers/net/ethernet/intel/igc/igc_main.c |  3 +++
 3 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index 90316dc58630..9f352cbe5d56 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -164,6 +164,8 @@ struct igc_ring {
 	struct xsk_buff_pool *xsk_pool;
 } ____cacheline_internodealigned_in_smp;
 
+struct igc_led_classdev;
+
 /* Board specific private data structure */
 struct igc_adapter {
 	struct net_device *netdev;
@@ -298,6 +300,7 @@ struct igc_adapter {
 
 	/* LEDs */
 	struct mutex led_mutex;
+	struct igc_led_classdev *leds;
 };
 
 void igc_up(struct igc_adapter *adapter);
@@ -723,6 +726,7 @@ void igc_ptp_read(struct igc_adapter *adapter, struct timespec64 *ts);
 void igc_ptp_tx_tstamp_event(struct igc_adapter *adapter);
 
 int igc_led_setup(struct igc_adapter *adapter);
+void igc_led_free(struct igc_adapter *adapter);
 
 #define igc_rx_pg_size(_ring) (PAGE_SIZE << igc_rx_pg_order(_ring))
 
diff --git a/drivers/net/ethernet/intel/igc/igc_leds.c b/drivers/net/ethernet/intel/igc/igc_leds.c
index bf240c5daf86..eee550cdb1d5 100644
--- a/drivers/net/ethernet/intel/igc/igc_leds.c
+++ b/drivers/net/ethernet/intel/igc/igc_leds.c
@@ -236,8 +236,8 @@ static void igc_led_get_name(struct igc_adapter *adapter, int index, char *buf,
 		 pci_dev_id(adapter->pdev), index);
 }
 
-static void igc_setup_ldev(struct igc_led_classdev *ldev,
-			   struct net_device *netdev, int index)
+static int igc_setup_ldev(struct igc_led_classdev *ldev,
+			  struct net_device *netdev, int index)
 {
 	struct igc_adapter *adapter = netdev_priv(netdev);
 	struct led_classdev *led_cdev = &ldev->led;
@@ -257,24 +257,45 @@ static void igc_setup_ldev(struct igc_led_classdev *ldev,
 	led_cdev->hw_control_get = igc_led_hw_control_get;
 	led_cdev->hw_control_get_device = igc_led_hw_control_get_device;
 
-	devm_led_classdev_register(&netdev->dev, led_cdev);
+	return led_classdev_register(&netdev->dev, led_cdev);
 }
 
 int igc_led_setup(struct igc_adapter *adapter)
 {
 	struct net_device *netdev = adapter->netdev;
-	struct device *dev = &netdev->dev;
 	struct igc_led_classdev *leds;
-	int i;
+	int i, err;
 
 	mutex_init(&adapter->led_mutex);
 
-	leds = devm_kcalloc(dev, IGC_NUM_LEDS, sizeof(*leds), GFP_KERNEL);
+	leds = kcalloc(IGC_NUM_LEDS, sizeof(*leds), GFP_KERNEL);
 	if (!leds)
 		return -ENOMEM;
 
-	for (i = 0; i < IGC_NUM_LEDS; i++)
-		igc_setup_ldev(leds + i, netdev, i);
+	for (i = 0; i < IGC_NUM_LEDS; i++) {
+		err = igc_setup_ldev(leds + i, netdev, i);
+		if (err)
+			goto err;
+	}
+
+	adapter->leds = leds;
 
 	return 0;
+
+err:
+	for (i--; i >= 0; i--)
+		led_classdev_unregister(&((leds + i)->led));
+
+	return err;
+}
+
+void igc_led_free(struct igc_adapter *adapter)
+{
+	struct igc_led_classdev *leds = adapter->leds;
+	int i;
+
+	for (i = 0; i < IGC_NUM_LEDS; i++)
+		led_classdev_unregister(&((leds + i)->led));
+
+	kfree(leds);
 }
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 35ad40a803cb..4d975d620a8e 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -7021,6 +7021,9 @@ static void igc_remove(struct pci_dev *pdev)
 	cancel_work_sync(&adapter->watchdog_task);
 	hrtimer_cancel(&adapter->hrtimer);
 
+	if (IS_ENABLED(CONFIG_IGC_LEDS))
+		igc_led_free(adapter);
+
 	/* Release control of h/w to f/w.  If f/w is AMT enabled, this
 	 * would have already happened in close and is redundant.
 	 */

---
base-commit: 7efd0a74039fb6b584be2cb91c1d0ef0bd796ee1
change-id: 20240411-igc_led_deadlock-7abd85954f5e

Best regards,
-- 
Kurt Kanzenbach <kurt@...utronix.de>


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