usb: gadget: dummy_hcd: remove usage of list iterator past the loop body

[ Upstream commit 7975f08 ]

To move the list iterator variable into the list_for_each_entry_*()
macro in the future it should be avoided to use the list iterator
variable after the loop body.

To *never* use the list iterator variable after the loop it was
concluded to use a separate iterator variable [1].

Link: https://lore.kernel.org/all/YhdfEIwI4EdtHdym@kroah.com/
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
Link: https://lore.kernel.org/r/20220308171818.384491-26-jakobkoschel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 8d63c83 ("USB: gadget: dummy-hcd: Fix locking bug in RT-enabled kernels")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Jakob-Koschel

drivers/usb/gadget/udc/dummy_hcd.c

@@ -748,7 +748,7 @@ static int dummy_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 	struct dummy		*dum;
 	int			retval = -EINVAL;
 	unsigned long		flags;
-	struct dummy_request	*req = NULL;
+	struct dummy_request	*req = NULL, *iter;
 
 	if (!_ep || !_req)
 		return retval;
@@ -760,13 +760,14 @@ static int dummy_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 
 	local_irq_save(flags);
 	spin_lock(&dum->lock);
-	list_for_each_entry(req, &ep->queue, queue) {
-		if (&req->req == _req) {
-			list_del_init(&req->queue);
-			_req->status = -ECONNRESET;
-			retval = 0;
-			break;
-		}
+	list_for_each_entry(iter, &ep->queue, queue) {
+		if (&iter->req != _req)
+			continue;
+		list_del_init(&iter->queue);
+		_req->status = -ECONNRESET;
+		req = iter;
+		retval = 0;
+		break;
 	}
 	spin_unlock(&dum->lock);