[PATCH v3] greybus: es2: drop redundant device reference

[PATCH v3] greybus: es2: 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>
---

This one needs one more spin... Sorry about the mess up.

Johan


Changes in v3:
 - drop the leftover usb_dev_put() in early error paths

Changes in v2:
 - drop temporary udev variable as reported by the kernel test robot
   (W=1 warning)


 drivers/greybus/es2.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/greybus/es2.c b/drivers/greybus/es2.c
index 6ae0ac828afa..75b889fa21b4 100644
--- a/drivers/greybus/es2.c
+++ b/drivers/greybus/es2.c
@@ -772,7 +772,6 @@ static int check_urb_status(struct urb *urb)
 
 static void es2_destroy(struct es2_ap_dev *es2)
 {
-	struct usb_device *udev;
 	struct urb *urb;
 	int i;
 
@@ -804,10 +803,7 @@ static void es2_destroy(struct es2_ap_dev *es2)
 	gb_hd_cport_release_reserved(es2->hd, ES2_CPORT_CDSI1);
 	gb_hd_cport_release_reserved(es2->hd, ES2_CPORT_CDSI0);
 
-	udev = es2->usb_dev;
 	gb_hd_put(es2->hd);
-
-	usb_put_dev(udev);
 }
 
 static void cport_in_callback(struct urb *urb)
@@ -1257,11 +1253,10 @@ static int ap_probe(struct usb_interface *interface,
 	bool bulk_in_found = false;
 	bool arpc_in_found = false;
 
-	udev = usb_get_dev(interface_to_usbdev(interface));
+	udev = interface_to_usbdev(interface);
 
 	num_cports = apb_get_cport_count(udev);
 	if (num_cports < 0) {
-		usb_put_dev(udev);
 		dev_err(&udev->dev, "Cannot retrieve CPort count: %d\n",
 			num_cports);
 		return num_cports;
@@ -1269,10 +1264,8 @@ static int ap_probe(struct usb_interface *interface,
 
 	hd = gb_hd_create(&es2_driver, &udev->dev, ES2_GBUF_MSG_SIZE_MAX,
 			  num_cports);
-	if (IS_ERR(hd)) {
-		usb_put_dev(udev);
+	if (IS_ERR(hd))
 		return PTR_ERR(hd);
-	}
 
 	es2 = hd_to_es2(hd);
 	es2->hd = hd;
-- 
2.52.0

Re: [PATCH v3] greybus: es2: drop redundant device reference

[Johan Hovold]

On Wed, Mar 11, 2026 at 09:22:26AM +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>
> ---
> 
> This one needs one more spin... Sorry about the mess up.

> Changes in v3:
>  - drop the leftover usb_dev_put() in early error paths
> 
> Changes in v2:
>  - drop temporary udev variable as reported by the kernel test robot
>    (W=1 warning)

Greg, can you pick this one up for 7.1?

Johan