[PATCH 6.6 028/105] usb: gadget: Store endpoint pointer in usb_request

Greg Kroah-Hartman
2025-10-21T19:53:38Z

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

[ Upstream commit bfb1d99d969fe3b892db30848aeebfa19d21f57f ]

Gadget function drivers often have goto-based error handling in their
bind paths, which can be bug-prone. Refactoring these paths to use
__free() scope-based cleanup is desirable, but currently blocked.

The blocker is that usb_ep_free_request(ep, req) requires two
parameters, while the __free() mechanism can only pass a pointer to the
request itself.

Store an endpoint pointer in the struct usb_request. The pointer is
populated centrally in usb_ep_alloc_request() on every successful
allocation, making the request object self-contained.

Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://lore.kernel.org/r/20250916-ready-v1-1-4997bf277548@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250916-ready-v1-1-4997bf277548@google.com
Stable-dep-of: 75a5b8d4ddd4 ("usb: gadget: f_ncm: Refactor bind path to use __free()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/gadget/udc/core.c | 3 +++
include/linux/usb/gadget.h | 2 ++
2 files changed, 5 insertions(+)

--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -194,6 +194,9 @@ struct usb_request *usb_ep_alloc_request

req = ep->ops->alloc_request(ep, gfp_flags);

+ if (req)
+ req->ep = ep;
+
trace_usb_ep_alloc_request(ep, req, req ? 0 : -ENOMEM);

return req;
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -32,6 +32,7 @@ struct usb_ep;

/**
* struct usb_request - describes one i/o request
+ * @ep: The associated endpoint set by usb_ep_alloc_request().
* @buf: Buffer used for data. Always provide this; some controllers
* only use PIO, or don't use DMA for some endpoints.
* @dma: DMA address corresponding to 'buf'. If you don't set this
@@ -97,6 +98,7 @@ struct usb_ep;
*/

struct usb_request {
+ struct usb_ep *ep;
void *buf;
unsigned length;
dma_addr_t dma;