[PATCH] usb: remove res2 argument from gadget code completions

[Jens Axboe <axboe@kernel.dk>]

The USB gadget code is the only code that every tried to utilize the
2nd argument of the aio completions, but there are strong suspicions
that it was never actually used by anything on the userspace side.

Out of the 3 cases that touch it, two of them just pass in the same
as res, and the last one passes in error/transfer in res like any
other normal use case.

Remove the 2nd argument, pass 0 like the rest of the in-kernel users
of kiocb based IO.

Link: https://lore.kernel.org/linux-block/20211021174021.273c82b1.john@metanate.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

Greg/John - if you guys are fine with this patch, let me know. I've got
the ->ki_complete() argument removal sitting on top of this.

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 8260f38025b7..7bd22398d52f 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -831,7 +831,7 @@ static void ffs_user_copy_worker(struct work_struct *work)
 		kthread_unuse_mm(io_data->mm);
 	}
 
-	io_data->kiocb->ki_complete(io_data->kiocb, ret, ret);
+	io_data->kiocb->ki_complete(io_data->kiocb, ret, 0);
 
 	if (io_data->ffs->ffs_eventfd && !kiocb_has_eventfd)
 		eventfd_signal(io_data->ffs->ffs_eventfd, 1);
diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index 539220d7f5b6..28d3d4e71182 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -469,7 +469,7 @@ static void ep_user_copy_worker(struct work_struct *work)
 		ret = -EFAULT;
 
 	/* completing the iocb can drop the ctx and mm, don't touch mm after */
-	iocb->ki_complete(iocb, ret, ret);
+	iocb->ki_complete(iocb, ret, 0);
 
 	kfree(priv->buf);
 	kfree(priv->to_free);
@@ -496,11 +496,9 @@ static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
 		kfree(priv->to_free);
 		kfree(priv);
 		iocb->private = NULL;
-		/* aio_complete() reports bytes-transferred _and_ faults */
-
 		iocb->ki_complete(iocb,
 				req->actual ? req->actual : (long)req->status,
-				req->status);
+				0);
 	} else {
 		/* ep_copy_to_user() won't report both; we hide some faults */
 		if (unlikely(0 != req->status))
-- 
Jens Axboe