Re: [PATCH][next] USB: gadget: Fix return of -EBUSY

Alan Stern
2022-05-04T14:06:17Z

On Wed, May 04, 2022 at 02:58:40PM +0100, Colin Ian King wrote:
> Currently when driver->match_existing_only is true, the error return is
> set to -EBUSY however ret is then set to 0 at the end of the if/else
> statement. I believe the ret = 0 statement should be set in the else
> part of the if statement and not at the end to ensure -EBUSY is being
> returned correctly.
>
> Detected by clang scan:
> drivers/usb/gadget/udc/core.c:1558:4: warning: Value stored to 'ret' is
> never read [deadcode.DeadStores]
>
> Fixes: fc274c1e9973 ("USB: gadget: Add a new bus for gadgets")
> Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
> ---

Acked-by: Alan Stern <stern@rowland.harvard.edu>

Don't know how I missed that. Thanks for fixing it.

In fact, since it's guaranteed that ret is already 0 before the
driver->match_existing_only test, you could eliminate the assignment
entirely. But moving it into the second branch of the "if" statement is
probably more clear.

Alan Stern

> drivers/usb/gadget/udc/core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 61790592b2c8..3281d8a3dae7 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -1559,8 +1559,8 @@ int usb_gadget_register_driver_owner(struct usb_gadget_driver *driver,
> } else {
> pr_info("%s: couldn't find an available UDC\n",
> driver->function);
> + ret = 0;
> }
> - ret = 0;
> }
> mutex_unlock(&udc_lock);
>
> --
> 2.35.1
>