usb: gadget: Store endpoint pointer in usb_request

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

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index d709e24c1fd4228c47f877d097faf987975ac392..e3d63b8fa0f4c17c6d59ab9d2f2c529e98f20d45 100644 (file)
--- 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(struct usb_ep *ep,
 
        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;

diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 0f28c5512fcb6ccd7a854ae8a66c21aec194c3c7..0f20794760887314d81a070755c8908c6ac4ed90 100644 (file)
--- 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
@@ -98,6 +99,7 @@ struct usb_ep;
  */
 
 struct usb_request {
+       struct usb_ep           *ep;
        void                    *buf;
        unsigned                length;
        dma_addr_t              dma;