[PATCH 00/13] wifi: drop redundant USB device references

[PATCH 00/13] wifi: drop redundant USB device references

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop redundant device references to reduce cargo culting, make it easier
to spot drivers where an extra reference is needed, and reduce the risk
of memory leaks when drivers fail to release them.

Note that I sent an ath9k patch separately here:

	https://lore.kernel.org/all/20260305105803.17011-1-johan@kernel.org/

but I guess these can all be picked up by Johannes.

Johan


Johan Hovold (13):
  wifi: at76c50x: drop redundant device reference
  wifi: libertas: drop redundant device reference
  wifi: libertas_tf: drop redundant device reference
  wifi: mwifiex: drop redundant device reference
  wifi: mt76: drop redundant device reference
  wifi: mt76x0u: drop redundant device reference
  wifi: mt76x2u: drop redundant device reference
  wifi: mt76: mt792xu: drop redundant device reference
  wifi: mt7601u: drop redundant device reference
  wifi: rt2x00: drop redundant device reference
  wifi: rtl818x: drop redundant device reference
  wifi: rtl8xxxu: drop redundant device reference
  wifi: rtlwifi: usb: drop redundant device reference

 drivers/net/wireless/atmel/at76c50x-usb.c          | 12 ++++--------
 drivers/net/wireless/marvell/libertas/if_usb.c     |  3 ---
 drivers/net/wireless/marvell/libertas_tf/if_usb.c  |  2 --
 drivers/net/wireless/marvell/mwifiex/usb.c         |  4 ----
 drivers/net/wireless/mediatek/mt76/mt7615/usb.c    |  3 ---
 drivers/net/wireless/mediatek/mt76/mt76x0/usb.c    |  3 ---
 drivers/net/wireless/mediatek/mt76/mt76x2/usb.c    |  4 ----
 drivers/net/wireless/mediatek/mt76/mt7921/usb.c    |  2 --
 drivers/net/wireless/mediatek/mt76/mt7925/usb.c    |  2 --
 drivers/net/wireless/mediatek/mt76/mt792x_usb.c    |  1 -
 drivers/net/wireless/mediatek/mt7601u/usb.c        |  3 ---
 drivers/net/wireless/ralink/rt2x00/rt2x00usb.c     | 12 +-----------
 drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c |  4 ----
 drivers/net/wireless/realtek/rtl8xxxu/core.c       | 11 +++--------
 drivers/net/wireless/realtek/rtlwifi/usb.c         |  4 ----
 15 files changed, 8 insertions(+), 62 deletions(-)

-- 
2.52.0

[PATCH 01/13] wifi: at76c50x: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/atmel/at76c50x-usb.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/atmel/at76c50x-usb.c b/drivers/net/wireless/atmel/at76c50x-usb.c
index 6445332801a4..44b04ea3cc8b 100644
--- a/drivers/net/wireless/atmel/at76c50x-usb.c
+++ b/drivers/net/wireless/atmel/at76c50x-usb.c
@@ -2440,13 +2440,11 @@ static int at76_probe(struct usb_interface *interface,
 	struct mib_fw_version *fwv;
 	int board_type = (int)id->driver_info;
 
-	udev = usb_get_dev(interface_to_usbdev(interface));
+	udev = interface_to_usbdev(interface);
 
 	fwv = kmalloc_obj(*fwv);
-	if (!fwv) {
-		ret = -ENOMEM;
-		goto exit;
-	}
+	if (!fwv)
+		return -ENOMEM;
 
 	/* Load firmware into kernel memory */
 	fwe = at76_load_firmware(udev, board_type);
@@ -2534,8 +2532,7 @@ static int at76_probe(struct usb_interface *interface,
 
 exit:
 	kfree(fwv);
-	if (ret < 0)
-		usb_put_dev(udev);
+
 	return ret;
 }
 
@@ -2552,7 +2549,6 @@ static void at76_disconnect(struct usb_interface *interface)
 
 	wiphy_info(priv->hw->wiphy, "disconnecting\n");
 	at76_delete_device(priv);
-	usb_put_dev(interface_to_usbdev(interface));
 	dev_info(&interface->dev, "disconnected\n");
 }
 
-- 
2.52.0

[PATCH 02/13] wifi: libertas: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/marvell/libertas/if_usb.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas/if_usb.c b/drivers/net/wireless/marvell/libertas/if_usb.c
index 8a6bf1365cfa..05fcf9cc28fa 100644
--- a/drivers/net/wireless/marvell/libertas/if_usb.c
+++ b/drivers/net/wireless/marvell/libertas/if_usb.c
@@ -276,7 +276,6 @@ static int if_usb_probe(struct usb_interface *intf,
 
 	cardp->boot2_version = udev->descriptor.bcdDevice;
 
-	usb_get_dev(udev);
 	usb_set_intfdata(intf, cardp);
 
 	r = lbs_get_firmware_async(priv, &udev->dev, cardp->model,
@@ -287,7 +286,6 @@ static int if_usb_probe(struct usb_interface *intf,
 	return 0;
 
 err_get_fw:
-	usb_put_dev(udev);
 	lbs_remove_card(priv);
 err_add_card:
 	if_usb_reset_device(cardp);
@@ -321,7 +319,6 @@ static void if_usb_disconnect(struct usb_interface *intf)
 	kfree(cardp);
 
 	usb_set_intfdata(intf, NULL);
-	usb_put_dev(interface_to_usbdev(intf));
 }
 
 /**
-- 
2.52.0

[PATCH 03/13] wifi: libertas_tf: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/marvell/libertas_tf/if_usb.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas_tf/if_usb.c b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
index f49151c18b79..07b38f2b8f58 100644
--- a/drivers/net/wireless/marvell/libertas_tf/if_usb.c
+++ b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
@@ -223,7 +223,6 @@ static int if_usb_probe(struct usb_interface *intf,
 	if (!priv)
 		goto dealloc;
 
-	usb_get_dev(udev);
 	usb_set_intfdata(intf, cardp);
 
 	return 0;
@@ -258,7 +257,6 @@ static void if_usb_disconnect(struct usb_interface *intf)
 	kfree(cardp);
 
 	usb_set_intfdata(intf, NULL);
-	usb_put_dev(interface_to_usbdev(intf));
 
 	lbtf_deb_leave(LBTF_DEB_MAIN);
 }
-- 
2.52.0

[PATCH 04/13] wifi: mwifiex: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/marvell/mwifiex/usb.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/usb.c b/drivers/net/wireless/marvell/mwifiex/usb.c
index 947ecb0a7b40..f4b94a1054f6 100644
--- a/drivers/net/wireless/marvell/mwifiex/usb.c
+++ b/drivers/net/wireless/marvell/mwifiex/usb.c
@@ -520,8 +520,6 @@ static int mwifiex_usb_probe(struct usb_interface *intf,
 		return ret;
 	}
 
-	usb_get_dev(udev);
-
 	return 0;
 }
 
@@ -666,8 +664,6 @@ static void mwifiex_usb_disconnect(struct usb_interface *intf)
 	mwifiex_dbg(adapter, FATAL,
 		    "%s: removing card\n", __func__);
 	mwifiex_remove_card(adapter);
-
-	usb_put_dev(interface_to_usbdev(intf));
 }
 
 static void mwifiex_usb_coredump(struct device *dev)
-- 
2.52.0

Re: [PATCH 04/13] wifi: mwifiex: drop redundant device reference

[Francesco Dolcini]

On Thu, Mar 05, 2026 at 12:07:04PM +0100, Johan Hovold wrote:
> Driver core holds a reference to the USB interface and its parent USB
> device while the interface is bound to a driver and there is no need to
> take additional references unless the structures are needed after
> disconnect.
> 
> Drop the redundant device reference to reduce cargo culting, make it
> easier to spot drivers where an extra reference is needed, and reduce
> the risk of memory leaks when drivers fail to release it.
> 
> Signed-off-by: Johan Hovold <johan@kernel.org>

Acked-by: Francesco Dolcini <francesco.dolcini@toradex.com>

[PATCH 05/13] wifi: mt76: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7615/usb.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/usb.c b/drivers/net/wireless/mediatek/mt76/mt7615/usb.c
index d91feffadda9..bab7b91f14be 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/usb.c
@@ -151,7 +151,6 @@ static int mt7663u_probe(struct usb_interface *usb_intf,
 		return -ENOMEM;
 
 	dev = container_of(mdev, struct mt7615_dev, mt76);
-	udev = usb_get_dev(udev);
 	usb_reset_device(udev);
 
 	usb_set_intfdata(usb_intf, dev);
@@ -193,7 +192,6 @@ static int mt7663u_probe(struct usb_interface *usb_intf,
 error:
 	mt76u_queues_deinit(&dev->mt76);
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 
 	mt76_free_device(&dev->mt76);
 
@@ -211,7 +209,6 @@ static void mt7663u_disconnect(struct usb_interface *usb_intf)
 	mt7663u_cleanup(dev);
 
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 
 	mt76_free_device(&dev->mt76);
 }
-- 
2.52.0

[PATCH 06/13] wifi: mt76x0u: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt76x0/usb.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76x0/usb.c b/drivers/net/wireless/mediatek/mt76/mt76x0/usb.c
index 90e5666c0857..2acce121fb14 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x0/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x0/usb.c
@@ -245,7 +245,6 @@ static int mt76x0u_probe(struct usb_interface *usb_intf,
 	if (id->driver_info)
 		dev->no_2ghz = true;
 
-	usb_dev = usb_get_dev(usb_dev);
 	usb_reset_device(usb_dev);
 
 	usb_set_intfdata(usb_intf, dev);
@@ -284,7 +283,6 @@ static int mt76x0u_probe(struct usb_interface *usb_intf,
 
 err:
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 	mt76u_queues_deinit(&dev->mt76);
 	mt76_free_device(&dev->mt76);
 
@@ -303,7 +301,6 @@ static void mt76x0_disconnect(struct usb_interface *usb_intf)
 	mt76x0u_cleanup(dev);
 
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 
 	mt76_free_device(&dev->mt76);
 }
-- 
2.52.0

[PATCH 07/13] wifi: mt76x2u: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt76x2/usb.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c b/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c
index 01cb3b2830f3..8af360bca643 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c
@@ -57,7 +57,6 @@ static int mt76x2u_probe(struct usb_interface *intf,
 
 	dev = container_of(mdev, struct mt76x02_dev, mt76);
 
-	udev = usb_get_dev(udev);
 	usb_reset_device(udev);
 
 	usb_set_intfdata(intf, dev);
@@ -84,14 +83,12 @@ static int mt76x2u_probe(struct usb_interface *intf,
 	mt76u_queues_deinit(&dev->mt76);
 	mt76_free_device(&dev->mt76);
 	usb_set_intfdata(intf, NULL);
-	usb_put_dev(udev);
 
 	return err;
 }
 
 static void mt76x2u_disconnect(struct usb_interface *intf)
 {
-	struct usb_device *udev = interface_to_usbdev(intf);
 	struct mt76x02_dev *dev = usb_get_intfdata(intf);
 	struct ieee80211_hw *hw = mt76_hw(dev);
 
@@ -100,7 +97,6 @@ static void mt76x2u_disconnect(struct usb_interface *intf)
 	mt76x2u_cleanup(dev);
 	mt76_free_device(&dev->mt76);
 	usb_set_intfdata(intf, NULL);
-	usb_put_dev(udev);
 }
 
 static int __maybe_unused mt76x2u_suspend(struct usb_interface *intf,
-- 
2.52.0

[PATCH 08/13] wifi: mt76: mt792xu: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7921/usb.c | 2 --
 drivers/net/wireless/mediatek/mt76/mt7925/usb.c | 2 --
 drivers/net/wireless/mediatek/mt76/mt792x_usb.c | 1 -
 3 files changed, 5 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/usb.c b/drivers/net/wireless/mediatek/mt76/mt7921/usb.c
index 17057e68bf21..9bfc234f306f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/usb.c
@@ -197,7 +197,6 @@ static int mt7921u_probe(struct usb_interface *usb_intf,
 	dev->fw_features = features;
 	dev->hif_ops = &hif_ops;
 
-	udev = usb_get_dev(udev);
 	usb_reset_device(udev);
 
 	usb_set_intfdata(usb_intf, dev);
@@ -246,7 +245,6 @@ static int mt7921u_probe(struct usb_interface *usb_intf,
 	mt76u_queues_deinit(&dev->mt76);
 
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 
 	mt76_free_device(&dev->mt76);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/usb.c b/drivers/net/wireless/mediatek/mt76/mt7925/usb.c
index d9968f03856d..84bcebbf009a 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/usb.c
@@ -185,7 +185,6 @@ static int mt7925u_probe(struct usb_interface *usb_intf,
 	dev->fw_features = features;
 	dev->hif_ops = &hif_ops;
 
-	udev = usb_get_dev(udev);
 	usb_reset_device(udev);
 
 	usb_set_intfdata(usb_intf, dev);
@@ -234,7 +233,6 @@ static int mt7925u_probe(struct usb_interface *usb_intf,
 	mt76u_queues_deinit(&dev->mt76);
 
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 
 	mt76_free_device(&dev->mt76);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt792x_usb.c b/drivers/net/wireless/mediatek/mt76/mt792x_usb.c
index 552808458138..f827e8a56a18 100644
--- a/drivers/net/wireless/mediatek/mt76/mt792x_usb.c
+++ b/drivers/net/wireless/mediatek/mt76/mt792x_usb.c
@@ -306,7 +306,6 @@ void mt792xu_disconnect(struct usb_interface *usb_intf)
 	mt792xu_cleanup(dev);
 
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 
 	mt76_free_device(&dev->mt76);
 }
-- 
2.52.0

[PATCH 09/13] wifi: mt7601u: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/mediatek/mt7601u/usb.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt7601u/usb.c b/drivers/net/wireless/mediatek/mt7601u/usb.c
index c41ae251cb95..9306870cbc91 100644
--- a/drivers/net/wireless/mediatek/mt7601u/usb.c
+++ b/drivers/net/wireless/mediatek/mt7601u/usb.c
@@ -274,7 +274,6 @@ static int mt7601u_probe(struct usb_interface *usb_intf,
 	if (!dev)
 		return -ENOMEM;
 
-	usb_dev = usb_get_dev(usb_dev);
 	usb_reset_device(usb_dev);
 
 	usb_set_intfdata(usb_intf, dev);
@@ -319,7 +318,6 @@ static int mt7601u_probe(struct usb_interface *usb_intf,
 	mt7601u_cleanup(dev);
 err:
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 
 	destroy_workqueue(dev->stat_wq);
 	ieee80211_free_hw(dev->hw);
@@ -334,7 +332,6 @@ static void mt7601u_disconnect(struct usb_interface *usb_intf)
 	mt7601u_cleanup(dev);
 
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 
 	destroy_workqueue(dev->stat_wq);
 	ieee80211_free_hw(dev->hw);
-- 
2.52.0

[PATCH 10/13] wifi: rt2x00: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/ralink/rt2x00/rt2x00usb.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
index 54599cad78f9..83d00b6baf64 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
@@ -802,14 +802,12 @@ int rt2x00usb_probe(struct usb_interface *usb_intf,
 	struct rt2x00_dev *rt2x00dev;
 	int retval;
 
-	usb_dev = usb_get_dev(usb_dev);
 	usb_reset_device(usb_dev);
 
 	hw = ieee80211_alloc_hw(sizeof(struct rt2x00_dev), ops->hw);
 	if (!hw) {
 		rt2x00_probe_err("Failed to allocate hardware\n");
-		retval = -ENOMEM;
-		goto exit_put_device;
+		return -ENOMEM;
 	}
 
 	usb_set_intfdata(usb_intf, hw);
@@ -851,10 +849,6 @@ int rt2x00usb_probe(struct usb_interface *usb_intf,
 
 exit_free_device:
 	ieee80211_free_hw(hw);
-
-exit_put_device:
-	usb_put_dev(usb_dev);
-
 	usb_set_intfdata(usb_intf, NULL);
 
 	return retval;
@@ -873,11 +867,7 @@ void rt2x00usb_disconnect(struct usb_interface *usb_intf)
 	rt2x00usb_free_reg(rt2x00dev);
 	ieee80211_free_hw(hw);
 
-	/*
-	 * Free the USB device data.
-	 */
 	usb_set_intfdata(usb_intf, NULL);
-	usb_put_dev(interface_to_usbdev(usb_intf));
 }
 EXPORT_SYMBOL_GPL(rt2x00usb_disconnect);
 
-- 
2.52.0

Re: [PATCH 10/13] wifi: rt2x00: drop redundant device reference

[Stanislaw Gruszka]

On Thu, Mar 05, 2026 at 12:07:10PM +0100, Johan Hovold wrote:
> Driver core holds a reference to the USB interface and its parent USB
> device while the interface is bound to a driver and there is no need to
> take additional references unless the structures are needed after
> disconnect.
> 
> Drop the redundant device reference to reduce cargo culting, make it

Getting the reference in probe() and drop it in disconnect() was not a cargo cult.
That was requirement from usb_get_dev() comment, that later it was changed
by below commit:

commit f6a9a2d64dd168b7d71076c0e6b2be7db7cb7399
Author: Alan Stern <stern@rowland.harvard.edu>
Date:   Fri Feb 25 09:38:25 2022 -0500

    USB: core: Update kerneldoc for usb_get_dev() and usb_get_intf()

    The kerneldoc for usb_get_dev() and usb_get_intf() says that drivers
    should always refcount the references they hold for the usb_device or
    usb_interface structure, respectively.  But this is an overstatement:
    In many cases drivers do not access these references after they have
    been unbound, and in such cases refcounting is unnecessary.

    This patch updates the kerneldoc for the two routines, explaining when
    a driver does not need to increment and decrement the refcount.  This
    should help dispel misconceptions which might otherwise afflict
    programmers new to the USB subsystem.

    Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
    Link: https://lore.kernel.org/r/Yhjp4Rp9Alipmwtq@rowland.harvard.edu
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Regards
Stanislaw

> easier to spot drivers where an extra reference is needed, and reduce
> the risk of memory leaks when drivers fail to release it.
> 
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/net/wireless/ralink/rt2x00/rt2x00usb.c | 12 +-----------
>  1 file changed, 1 insertion(+), 11 deletions(-)
> 
> diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
> index 54599cad78f9..83d00b6baf64 100644
> --- a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
> +++ b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
> @@ -802,14 +802,12 @@ int rt2x00usb_probe(struct usb_interface *usb_intf,
>  	struct rt2x00_dev *rt2x00dev;
>  	int retval;
>  
> -	usb_dev = usb_get_dev(usb_dev);
>  	usb_reset_device(usb_dev);
>  
>  	hw = ieee80211_alloc_hw(sizeof(struct rt2x00_dev), ops->hw);
>  	if (!hw) {
>  		rt2x00_probe_err("Failed to allocate hardware\n");
> -		retval = -ENOMEM;
> -		goto exit_put_device;
> +		return -ENOMEM;
>  	}
>  
>  	usb_set_intfdata(usb_intf, hw);
> @@ -851,10 +849,6 @@ int rt2x00usb_probe(struct usb_interface *usb_intf,
>  
>  exit_free_device:
>  	ieee80211_free_hw(hw);
> -
> -exit_put_device:
> -	usb_put_dev(usb_dev);
> -
>  	usb_set_intfdata(usb_intf, NULL);
>  
>  	return retval;
> @@ -873,11 +867,7 @@ void rt2x00usb_disconnect(struct usb_interface *usb_intf)
>  	rt2x00usb_free_reg(rt2x00dev);
>  	ieee80211_free_hw(hw);
>  
> -	/*
> -	 * Free the USB device data.
> -	 */
>  	usb_set_intfdata(usb_intf, NULL);
> -	usb_put_dev(interface_to_usbdev(usb_intf));
>  }
>  EXPORT_SYMBOL_GPL(rt2x00usb_disconnect);
>  
> -- 
> 2.52.0
> 

Re: [PATCH 10/13] wifi: rt2x00: drop redundant device reference

[Johan Hovold]

On Thu, Mar 05, 2026 at 02:37:55PM +0100, Stanislaw Gruszka wrote:
> On Thu, Mar 05, 2026 at 12:07:10PM +0100, Johan Hovold wrote:
> > Driver core holds a reference to the USB interface and its parent USB
> > device while the interface is bound to a driver and there is no need to
> > take additional references unless the structures are needed after
> > disconnect.
> > 
> > Drop the redundant device reference to reduce cargo culting, make it
> 
> Getting the reference in probe() and drop it in disconnect() was not a cargo cult.
> That was requirement from usb_get_dev() comment, that later it was changed
> by below commit:
> 
> commit f6a9a2d64dd168b7d71076c0e6b2be7db7cb7399
> Author: Alan Stern <stern@rowland.harvard.edu>
> Date:   Fri Feb 25 09:38:25 2022 -0500
> 
>     USB: core: Update kerneldoc for usb_get_dev() and usb_get_intf()
> 
>     The kerneldoc for usb_get_dev() and usb_get_intf() says that drivers
>     should always refcount the references they hold for the usb_device or
>     usb_interface structure, respectively.  But this is an overstatement:
>     In many cases drivers do not access these references after they have
>     been unbound, and in such cases refcounting is unnecessary.
> 
>     This patch updates the kerneldoc for the two routines, explaining when
>     a driver does not need to increment and decrement the refcount.  This
>     should help dispel misconceptions which might otherwise afflict
>     programmers new to the USB subsystem.

Yeah, the documentation indeed was misleading for a very long time. That
reference comment even predates the driver model.

Many authors base their work on existing drivers so we still get new
ones that take such references even after the docs were amended.

Johan

Re: [PATCH 10/13] wifi: rt2x00: drop redundant device reference

[Stanislaw Gruszka]

On Thu, Mar 05, 2026 at 12:07:10PM +0100, Johan Hovold wrote:
> Driver core holds a reference to the USB interface and its parent USB
> device while the interface is bound to a driver and there is no need to
> take additional references unless the structures are needed after
> disconnect.
> 
> Drop the redundant device reference to reduce cargo culting, make it
> easier to spot drivers where an extra reference is needed, and reduce
> the risk of memory leaks when drivers fail to release it.
> 
> Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>

> ---
>  drivers/net/wireless/ralink/rt2x00/rt2x00usb.c | 12 +-----------
>  1 file changed, 1 insertion(+), 11 deletions(-)
> 
> diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
> index 54599cad78f9..83d00b6baf64 100644
> --- a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
> +++ b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
> @@ -802,14 +802,12 @@ int rt2x00usb_probe(struct usb_interface *usb_intf,
>  	struct rt2x00_dev *rt2x00dev;
>  	int retval;
>  
> -	usb_dev = usb_get_dev(usb_dev);
>  	usb_reset_device(usb_dev);
>  
>  	hw = ieee80211_alloc_hw(sizeof(struct rt2x00_dev), ops->hw);
>  	if (!hw) {
>  		rt2x00_probe_err("Failed to allocate hardware\n");
> -		retval = -ENOMEM;
> -		goto exit_put_device;
> +		return -ENOMEM;
>  	}
>  
>  	usb_set_intfdata(usb_intf, hw);
> @@ -851,10 +849,6 @@ int rt2x00usb_probe(struct usb_interface *usb_intf,
>  
>  exit_free_device:
>  	ieee80211_free_hw(hw);
> -
> -exit_put_device:
> -	usb_put_dev(usb_dev);
> -
>  	usb_set_intfdata(usb_intf, NULL);
>  
>  	return retval;
> @@ -873,11 +867,7 @@ void rt2x00usb_disconnect(struct usb_interface *usb_intf)
>  	rt2x00usb_free_reg(rt2x00dev);
>  	ieee80211_free_hw(hw);
>  
> -	/*
> -	 * Free the USB device data.
> -	 */
>  	usb_set_intfdata(usb_intf, NULL);
> -	usb_put_dev(interface_to_usbdev(usb_intf));
>  }
>  EXPORT_SYMBOL_GPL(rt2x00usb_disconnect);
>  
> -- 
> 2.52.0
> 

[PATCH 11/13] wifi: rtl818x: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
index f7e0f6573180..1d21c468a236 100644
--- a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
+++ b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
@@ -1475,8 +1475,6 @@ static int rtl8187_probe(struct usb_interface *intf,
 	usb_set_intfdata(intf, dev);
 	priv->udev = udev;
 
-	usb_get_dev(udev);
-
 	skb_queue_head_init(&priv->rx_queue);
 
 	BUILD_BUG_ON(sizeof(priv->channels) != sizeof(rtl818x_channels));
@@ -1663,7 +1661,6 @@ static int rtl8187_probe(struct usb_interface *intf,
  err_free_dmabuf:
 	kfree(priv->io_dmabuf);
 	usb_set_intfdata(intf, NULL);
-	usb_put_dev(udev);
  err_free_dev:
 	ieee80211_free_hw(dev);
 	return err;
@@ -1685,7 +1682,6 @@ static void rtl8187_disconnect(struct usb_interface *intf)
 
 	priv = dev->priv;
 	usb_reset_device(priv->udev);
-	usb_put_dev(interface_to_usbdev(intf));
 	kfree(priv->io_dmabuf);
 	ieee80211_free_hw(dev);
 }
-- 
2.52.0

[PATCH 12/13] wifi: rtl8xxxu: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/realtek/rtl8xxxu/core.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtl8xxxu/core.c b/drivers/net/wireless/realtek/rtl8xxxu/core.c
index 794187d28caa..f131ca09ae43 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/core.c
@@ -7698,7 +7698,7 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
 	int ret;
 	int untested = 1;
 
-	udev = usb_get_dev(interface_to_usbdev(interface));
+	udev = interface_to_usbdev(interface);
 
 	switch (id->idVendor) {
 	case USB_VENDOR_ID_REALTEK:
@@ -7756,10 +7756,8 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
 	}
 
 	hw = ieee80211_alloc_hw(sizeof(struct rtl8xxxu_priv), &rtl8xxxu_ops);
-	if (!hw) {
-		ret = -ENOMEM;
-		goto err_put_dev;
-	}
+	if (!hw)
+		return -ENOMEM;
 
 	priv = hw->priv;
 	priv->hw = hw;
@@ -7901,8 +7899,6 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
 	mutex_destroy(&priv->h2c_mutex);
 
 	ieee80211_free_hw(hw);
-err_put_dev:
-	usb_put_dev(udev);
 
 	return ret;
 }
@@ -7935,7 +7931,6 @@ static void rtl8xxxu_disconnect(struct usb_interface *interface)
 			 "Device still attached, trying to reset\n");
 		usb_reset_device(priv->udev);
 	}
-	usb_put_dev(priv->udev);
 	ieee80211_free_hw(hw);
 }
 
-- 
2.52.0

[PATCH 13/13] wifi: rtlwifi: usb: drop redundant device reference

[Johan Hovold]

Driver core holds a reference to the USB interface and its parent USB
device while the interface is bound to a driver and there is no need to
take additional references unless the structures are needed after
disconnect.

Drop the redundant device reference to reduce cargo culting, make it
easier to spot drivers where an extra reference is needed, and reduce
the risk of memory leaks when drivers fail to release it.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/wireless/realtek/rtlwifi/usb.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/usb.c b/drivers/net/wireless/realtek/rtlwifi/usb.c
index d35ed56d6db9..9a64df9eed39 100644
--- a/drivers/net/wireless/realtek/rtlwifi/usb.c
+++ b/drivers/net/wireless/realtek/rtlwifi/usb.c
@@ -986,7 +986,6 @@ int rtl_usb_probe(struct usb_interface *intf,
 	init_completion(&rtlpriv->firmware_loading_complete);
 	SET_IEEE80211_DEV(hw, &intf->dev);
 	udev = interface_to_usbdev(intf);
-	usb_get_dev(udev);
 	usb_priv = rtl_usbpriv(hw);
 	memset(usb_priv, 0, sizeof(*usb_priv));
 	usb_priv->dev.intf = intf;
@@ -1038,7 +1037,6 @@ int rtl_usb_probe(struct usb_interface *intf,
 	rtl_deinit_core(hw);
 error_out2:
 	_rtl_usb_io_handler_release(hw);
-	usb_put_dev(udev);
 	kfree(rtlpriv->usb_data);
 	ieee80211_free_hw(hw);
 	return -ENODEV;
@@ -1050,7 +1048,6 @@ void rtl_usb_disconnect(struct usb_interface *intf)
 	struct ieee80211_hw *hw = usb_get_intfdata(intf);
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
 	struct rtl_mac *rtlmac = rtl_mac(rtl_priv(hw));
-	struct rtl_usb *rtlusb = rtl_usbdev(rtl_usbpriv(hw));
 
 	if (unlikely(!rtlpriv))
 		return;
@@ -1072,7 +1069,6 @@ void rtl_usb_disconnect(struct usb_interface *intf)
 	kfree(rtlpriv->usb_data);
 	rtlpriv->cfg->ops->deinit_sw_vars(hw);
 	_rtl_usb_io_handler_release(hw);
-	usb_put_dev(rtlusb->udev);
 	usb_set_intfdata(intf, NULL);
 	ieee80211_free_hw(hw);
 }
-- 
2.52.0

RE: [PATCH 00/13] wifi: drop redundant USB device references

[Ping-Ke Shih]

// +Cc Greg

Hi Johan,

Johan Hovold <johan@kernel.org> wrote:

[...]

>  drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c |  4 ----
>  drivers/net/wireless/realtek/rtl8xxxu/core.c       | 11 +++--------
>  drivers/net/wireless/realtek/rtlwifi/usb.c         |  4 ----

Acked to changes of these Realtek WiFi drivers. But I'd like to know why
rtw88/rtw89 aren't included in this patchset? Greg sent a patch [1] to
correct error path of USB probe for rtw88. In the discussion, he also
mentioned the simplest way is to drop usb_get_dev()/usb_put_dev() like
this patchset does. Will you share patches for rtw88/rtw89? I so, I'd
drop Greg's patch and apply yours.

[1] https://lore.kernel.org/linux-wireless/2026022333-periscope-unusual-f0a0@gregkh/

Ping-Ke

Re: [PATCH 00/13] wifi: drop redundant USB device references

[Johan Hovold]

On Fri, Mar 06, 2026 at 01:40:31AM +0000, Ping-Ke Shih wrote:
> // +Cc Greg
> 
> Hi Johan,
> 
> Johan Hovold <johan@kernel.org> wrote:
> 
> [...]
> 
> >  drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c |  4 ----
> >  drivers/net/wireless/realtek/rtl8xxxu/core.c       | 11 +++--------
> >  drivers/net/wireless/realtek/rtlwifi/usb.c         |  4 ----
> 
> Acked to changes of these Realtek WiFi drivers. But I'd like to know why
> rtw88/rtw89 aren't included in this patchset?

I used a more specific grep pattern to catch driver releasing references
in disconnect() and therefore missed a few that dropped the reference in
helper functions (or used non-standard names for their disconnect
function such as ath10k, I see now).

> Greg sent a patch [1] to
> correct error path of USB probe for rtw88. In the discussion, he also
> mentioned the simplest way is to drop usb_get_dev()/usb_put_dev() like
> this patchset does. Will you share patches for rtw88/rtw89? I so, I'd
> drop Greg's patch and apply yours.
> 
> [1] https://lore.kernel.org/linux-wireless/2026022333-periscope-unusual-f0a0@gregkh/

Sure, I can include rtw88 (and ath10k and ath6kl) in a v2.

Do you really prefer replacing Greg's fix or shall I send an incremental
patch on top?

Johan

RE: [PATCH 00/13] wifi: drop redundant USB device references

[Ping-Ke Shih]

Johan Hovold <johan@kernel.org> wrote:
> On Fri, Mar 06, 2026 at 01:40:31AM +0000, Ping-Ke Shih wrote:
> > // +Cc Greg
> >
> > Hi Johan,
> >
> > Johan Hovold <johan@kernel.org> wrote:
> >
> > [...]
> >
> > >  drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c |  4 ----
> > >  drivers/net/wireless/realtek/rtl8xxxu/core.c       | 11 +++--------
> > >  drivers/net/wireless/realtek/rtlwifi/usb.c         |  4 ----
> >
> > Acked to changes of these Realtek WiFi drivers. But I'd like to know why
> > rtw88/rtw89 aren't included in this patchset?
> 
> I used a more specific grep pattern to catch driver releasing references
> in disconnect() and therefore missed a few that dropped the reference in
> helper functions (or used non-standard names for their disconnect
> function such as ath10k, I see now).
> 
> > Greg sent a patch [1] to
> > correct error path of USB probe for rtw88. In the discussion, he also
> > mentioned the simplest way is to drop usb_get_dev()/usb_put_dev() like
> > this patchset does. Will you share patches for rtw88/rtw89? I so, I'd
> > drop Greg's patch and apply yours.
> >
> > [1] https://lore.kernel.org/linux-wireless/2026022333-periscope-unusual-f0a0@gregkh/
> 
> Sure, I can include rtw88 (and ath10k and ath6kl) in a v2.

Can you please also include rtw89? (I saw you have sent v2 though)

> 
> Do you really prefer replacing Greg's fix or shall I send an incremental
> patch on top?

No. I'd drop Gerg's fix from my tree.

Ping-Ke

Re: [PATCH 00/13] wifi: drop redundant USB device references

[Johan Hovold]

On Fri, Mar 06, 2026 at 09:04:22AM +0000, Ping-Ke Shih wrote:
> Johan Hovold <johan@kernel.org> wrote:

> > Sure, I can include rtw88 (and ath10k and ath6kl) in a v2.
> 
> Can you please also include rtw89? (I saw you have sent v2 though)

Ah, sorry about that. I was sure I had grepped for usb_get_dev in
wireless before sending v2 but apparently I did not.

I just sent a separate follow-up for rtw89 here:

	https://lore.kernel.org/r/20260306093206.21081-1-johan@kernel.org

Johan

RE: [PATCH 00/13] wifi: drop redundant USB device references

[Ping-Ke Shih]

Johan Hovold <johan@kernel.org> wrote:
> On Fri, Mar 06, 2026 at 09:04:22AM +0000, Ping-Ke Shih wrote:
> > Johan Hovold <johan@kernel.org> wrote:
> 
> > > Sure, I can include rtw88 (and ath10k and ath6kl) in a v2.
> >
> > Can you please also include rtw89? (I saw you have sent v2 though)
> 
> Ah, sorry about that. I was sure I had grepped for usb_get_dev in
> wireless before sending v2 but apparently I did not.
> 
> I just sent a separate follow-up for rtw89 here:
> 
>         https://lore.kernel.org/r/20260306093206.21081-1-johan@kernel.org

Got it & thank you. :)

Ping-Ke

Re: [PATCH 00/13] wifi: drop redundant USB device references

[Greg Kroah-Hartman]

On Fri, Mar 06, 2026 at 09:04:22AM +0000, Ping-Ke Shih wrote:
> Johan Hovold <johan@kernel.org> wrote:
> > On Fri, Mar 06, 2026 at 01:40:31AM +0000, Ping-Ke Shih wrote:
> > > // +Cc Greg
> > >
> > > Hi Johan,
> > >
> > > Johan Hovold <johan@kernel.org> wrote:
> > >
> > > [...]
> > >
> > > >  drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c |  4 ----
> > > >  drivers/net/wireless/realtek/rtl8xxxu/core.c       | 11 +++--------
> > > >  drivers/net/wireless/realtek/rtlwifi/usb.c         |  4 ----
> > >
> > > Acked to changes of these Realtek WiFi drivers. But I'd like to know why
> > > rtw88/rtw89 aren't included in this patchset?
> > 
> > I used a more specific grep pattern to catch driver releasing references
> > in disconnect() and therefore missed a few that dropped the reference in
> > helper functions (or used non-standard names for their disconnect
> > function such as ath10k, I see now).
> > 
> > > Greg sent a patch [1] to
> > > correct error path of USB probe for rtw88. In the discussion, he also
> > > mentioned the simplest way is to drop usb_get_dev()/usb_put_dev() like
> > > this patchset does. Will you share patches for rtw88/rtw89? I so, I'd
> > > drop Greg's patch and apply yours.
> > >
> > > [1] https://lore.kernel.org/linux-wireless/2026022333-periscope-unusual-f0a0@gregkh/
> > 
> > Sure, I can include rtw88 (and ath10k and ath6kl) in a v2.
> 
> Can you please also include rtw89? (I saw you have sent v2 though)
> 
> > 
> > Do you really prefer replacing Greg's fix or shall I send an incremental
> > patch on top?
> 
> No. I'd drop Gerg's fix from my tree.

I have no objection for my changes being dropped, thanks for making
these changes.

greg k-h