netdev - [PATCH net] r8169: fix LED-related deadlock on module removal

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Message-ID: <6b6b07f5-250c-415e-bdc4-bd08ac69b24d@gmail.com>
Date: Mon, 15 Apr 2024 08:44:35 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, David Miller <davem@...emloft.net>
Cc: Lukas Wunner <lukas@...ner.de>,
 "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net] r8169: fix LED-related deadlock on module removal

Binding devm_led_classdev_register() to the netdev is problematic
because on module removal we get a RTNL-related deadlock. Fix this
by avoiding the device-managed LED functions.

Note: We can safely call led_classdev_unregister() for a LED even
if registering it failed, because led_classdev_unregister() detects
this and is a no-op in this case.

Fixes: 18764b883e15 ("r8169: add support for LED's on RTL8168/RTL8101")
Cc: <stable@...r.kernel.org> # 6.8.x
Reported-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
The original change was introduced with 6.8, 6.9 added support for
LEDs on RTL8125. Therefore the first version of the fix applied on
6.9-rc only. This is the modified version for 6.8.
---
 drivers/net/ethernet/realtek/r8169.h      |  4 +++-
 drivers/net/ethernet/realtek/r8169_leds.c | 23 +++++++++++++++++------
 drivers/net/ethernet/realtek/r8169_main.c |  7 ++++++-
 3 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169.h b/drivers/net/ethernet/realtek/r8169.h
index 81567fcf3..1ef399287 100644
--- a/drivers/net/ethernet/realtek/r8169.h
+++ b/drivers/net/ethernet/realtek/r8169.h
@@ -72,6 +72,7 @@ enum mac_version {
 };
 
 struct rtl8169_private;
+struct r8169_led_classdev;
 
 void r8169_apply_firmware(struct rtl8169_private *tp);
 u16 rtl8168h_2_get_adc_bias_ioffset(struct rtl8169_private *tp);
@@ -83,4 +84,5 @@ void r8169_get_led_name(struct rtl8169_private *tp, int idx,
 			char *buf, int buf_len);
 int rtl8168_get_led_mode(struct rtl8169_private *tp);
 int rtl8168_led_mod_ctrl(struct rtl8169_private *tp, u16 mask, u16 val);
-void rtl8168_init_leds(struct net_device *ndev);
+struct r8169_led_classdev *rtl8168_init_leds(struct net_device *ndev);
+void r8169_remove_leds(struct r8169_led_classdev *leds);
diff --git a/drivers/net/ethernet/realtek/r8169_leds.c b/drivers/net/ethernet/realtek/r8169_leds.c
index 007d077ed..1c97f3cca 100644
--- a/drivers/net/ethernet/realtek/r8169_leds.c
+++ b/drivers/net/ethernet/realtek/r8169_leds.c
@@ -138,20 +138,31 @@ static void rtl8168_setup_ldev(struct r8169_led_classdev *ldev,
 	led_cdev->hw_control_get_device = r8169_led_hw_control_get_device;
 
 	/* ignore errors */
-	devm_led_classdev_register(&ndev->dev, led_cdev);
+	led_classdev_register(&ndev->dev, led_cdev);
 }
 
-void rtl8168_init_leds(struct net_device *ndev)
+struct r8169_led_classdev *rtl8168_init_leds(struct net_device *ndev)
 {
-	/* bind resource mgmt to netdev */
-	struct device *dev = &ndev->dev;
 	struct r8169_led_classdev *leds;
 	int i;
 
-	leds = devm_kcalloc(dev, RTL8168_NUM_LEDS, sizeof(*leds), GFP_KERNEL);
+	leds = kcalloc(RTL8168_NUM_LEDS + 1, sizeof(*leds), GFP_KERNEL);
 	if (!leds)
-		return;
+		return NULL;
 
 	for (i = 0; i < RTL8168_NUM_LEDS; i++)
 		rtl8168_setup_ldev(leds + i, ndev, i);
+
+	return leds;
+}
+
+void r8169_remove_leds(struct r8169_led_classdev *leds)
+{
+	if (!leds)
+		return;
+
+	for (struct r8169_led_classdev *l = leds; l->ndev; l++)
+		led_classdev_unregister(&l->led);
+
+	kfree(leds);
 }
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 4b6c28576..32b73f398 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -634,6 +634,8 @@ struct rtl8169_private {
 	const char *fw_name;
 	struct rtl_fw *rtl_fw;
 
+	struct r8169_led_classdev *leds;
+
 	u32 ocp_base;
 };
 
@@ -4930,6 +4932,9 @@ static void rtl_remove_one(struct pci_dev *pdev)
 
 	cancel_work_sync(&tp->wk.work);
 
+	if (IS_ENABLED(CONFIG_R8169_LEDS))
+		r8169_remove_leds(tp->leds);
+
 	unregister_netdev(tp->dev);
 
 	if (tp->dash_type != RTL_DASH_NONE)
@@ -5391,7 +5396,7 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (IS_ENABLED(CONFIG_R8169_LEDS) &&
 	    tp->mac_version > RTL_GIGA_MAC_VER_06 &&
 	    tp->mac_version < RTL_GIGA_MAC_VER_61)
-		rtl8168_init_leds(dev);
+		tp->leds = rtl8168_init_leds(dev);
 
 	netdev_info(dev, "%s, %pM, XID %03x, IRQ %d\n",
 		    rtl_chip_infos[chipset].name, dev->dev_addr, xid, tp->irq);
-- 
2.44.0