[PATCH 6.18 087/314] usb: gadget: u_ether: Add auto-cleanup helper for freeing net_device

Sasha Levin
2026-03-10T11:26:03Z

From: Kuen-Han Tsai <khtsai@google.com>

[ Upstream commit 0c0981126b99288ed354d3d414c8a5fd42ac9e25 ]

The net_device in the u_ether framework currently requires explicit
calls to unregister and free the device.

Introduce gether_unregister_free_netdev() and the corresponding
auto-cleanup macro. This ensures that if a net_device is registered, it
is properly unregistered and the associated work queue is flushed before
the memory is freed.

This is a preparatory patch to simplify error handling paths in gadget
drivers by removing the need for explicit goto labels for net_device
cleanup.

Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://patch.msgid.link/20251230-ncm-refactor-v1-2-793e347bc7a7@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 56a512a9b410 ("usb: gadget: f_ncm: align net_device lifecycle with bind/unbind")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/usb/gadget/function/u_ether.c | 15 +++++++++++++++
drivers/usb/gadget/function/u_ether.h | 2 ++
2 files changed, 17 insertions(+)

diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
index 745ed2c212e3a..6c32665538cc0 100644
--- a/drivers/usb/gadget/function/u_ether.c
+++ b/drivers/usb/gadget/function/u_ether.c
@@ -1125,6 +1125,21 @@ void gether_cleanup(struct eth_dev *dev)
}
EXPORT_SYMBOL_GPL(gether_cleanup);

+void gether_unregister_free_netdev(struct net_device *net)
+{
+ if (!net)
+ return;
+
+ struct eth_dev *dev = netdev_priv(net);
+
+ if (net->reg_state == NETREG_REGISTERED) {
+ unregister_netdev(net);
+ flush_work(&dev->work);
+ }
+ free_netdev(net);
+}
+EXPORT_SYMBOL_GPL(gether_unregister_free_netdev);
+
/**
* gether_connect - notify network layer that USB link is active
* @link: the USB link, set up with endpoints, descriptors matching
diff --git a/drivers/usb/gadget/function/u_ether.h b/drivers/usb/gadget/function/u_ether.h
index 63a0240df4d74..a212a8ec5eb1b 100644
--- a/drivers/usb/gadget/function/u_ether.h
+++ b/drivers/usb/gadget/function/u_ether.h
@@ -283,6 +283,8 @@ int gether_get_ifname(struct net_device *net, char *name, int len);
int gether_set_ifname(struct net_device *net, const char *name, int len);

void gether_cleanup(struct eth_dev *dev);
+void gether_unregister_free_netdev(struct net_device *net);
+DEFINE_FREE(free_gether_netdev, struct net_device *, gether_unregister_free_netdev(_T));

void gether_setup_opts_default(struct gether_opts *opts, const char *name);
void gether_apply_opts(struct net_device *net, struct gether_opts *opts);
--
2.51.0