linux-kernel - Re: [PATCH 1/2] drivers: usb: gadget: udc: add missing break in switch

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Date:   Wed, 08 Feb 2017 15:13:25 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     "Gustavo A. R. Silva" <garsilva@...eddedor.com>,
        bhumirks@...il.com, mina86@...a86.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] drivers: usb: gadget: udc: add missing break in switch


Hi,

Greg KH <gregkh@...uxfoundation.org> writes:
> On Wed, Feb 08, 2017 at 02:05:35PM +0200, Felipe Balbi wrote:
>> 
>> Hi,
>> 
>> "Gustavo A. R. Silva" <garsilva@...eddedor.com> writes:
>> >> "Gustavo A. R. Silva" <garsilva@...eddedor.com> writes:
>> >>> Add missing break in switch.
>> >>>
>> >>> Addresses-Coverity-ID: 201385
>> >>> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
>> >>> ---
>> >>>  drivers/usb/gadget/udc/mv_udc_core.c | 1 +
>> >>>  1 file changed, 1 insertion(+)
>> >>>
>> >>> diff --git a/drivers/usb/gadget/udc/mv_udc_core.c  
>> >>> b/drivers/usb/gadget/udc/mv_udc_core.c
>> >>> index 27ebb0d..56b3574 100644
>> >>> --- a/drivers/usb/gadget/udc/mv_udc_core.c
>> >>> +++ b/drivers/usb/gadget/udc/mv_udc_core.c
>> >>> @@ -489,6 +489,7 @@ static int mv_ep_enable(struct usb_ep *_ep,
>> >>>  		break;
>> >>>  	case USB_ENDPOINT_XFER_CONTROL:
>> >>>  		ios = 1;
>> >>> +		break;
>> >>
>> >> are you SURE this is supposed to have this break statement? What if we
>> >> want to initialize mult to 0 *also* for control endpoints? How did you
>> >> test this? Do you have access to Marvel's documentation for this
>> >> controller?
>> >>
>> >
>> > Certainly I wasn't sure, but I also think this is kind of obscure  
>> > code. If that is the case that we also want to initialize mult to 0,  
>> > wouldn't it be clearer (for maintenance purposes) to add mult = 0 and  
>> > the break statement after ios = 1?
>> >
>> > What do you think if I modify that piece of code as follows:
>> 
>> I think you need to test it, or get someone to test it for you :-)
>
> For crap code like this where it's "obvious" that something is wrong?
> That's really hard.

heh :-)

> How about a nice comment instead:
> 	/* Code path falls through, is it correct or not, who knows??? */
> which will make the static code checkers stop complaining about it, and
> if someone actually has the hardware, then they can test it.

works for me

-- 
balbi

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