Re: [PATCH] usb: host: fhci-hcd: annotate PIPE_CONTROL switch case with fallthrough - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Timur Tabi <timur@kernel.org>, Li Yang <leoyang.li@nxp.com>,
	Anton Vorontsov <avorontsov@ru.mvista.com>,
	kbuild test robot <lkp@intel.com>,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	Joe Perches <joe@perches.com>
Subject: Re: [PATCH] usb: host: fhci-hcd: annotate PIPE_CONTROL switch case with fallthrough
Date: Mon, 17 Feb 2020 17:29:45 +0100	[thread overview]
Message-ID: <20200217162945.GC1502885@kroah.com> (raw)
In-Reply-To: <298629e3-40bb-9530-8292-7e2a9432cd4a@embeddedor.com>

On Mon, Feb 17, 2020 at 10:15:09AM -0600, Gustavo A. R. Silva wrote:
> Hi!
> 
> Sorry for the late reply. I wasn't aware of this thread until now.
> 
> Please, see my comments below...
> 
> On 2/17/20 08:18, Greg Kroah-Hartman wrote:
> > On Mon, Feb 17, 2020 at 03:12:21PM +0100, Rasmus Villemoes wrote:
> >> On 17/02/2020 10.38, Greg Kroah-Hartman wrote:
> >>> On Thu, Feb 13, 2020 at 02:35:18PM +0100, Rasmus Villemoes wrote:
> >>>> On 13/02/2020 13.56, Greg Kroah-Hartman wrote:
> >>>>
> >>>>> Shouldn't this be /* fall through */ instead?
> >>>>>
> >>>>> Gustavo, what's the best practice here, I count only a few
> >>>>> "fallthrough;" instances in the kernel, although one is in our coding
> >>>>> style document, and thousands of the /* */ version.
> >>>>
> >>>> Yes, I went with the attribute/macro due to that, and the history is
> >>>> that Linus applied Joe's patches directly
> >>>> (https://lore.kernel.org/lkml/CAHk-=whOF8heTGz5tfzYUBp_UQQzSWNJ_50M7-ECXkfFRDQWFA@mail.gmail.com/),
> >>>> so I assumed that meant the Penguin decided that the attribute/macro is
> >>>> the right thing to do for new code, while existing comment annotations
> >>>> can be left alone or changed piecemeal as code gets refactored anyway.
> >>>
> >>> But, to be fair, Gustavo went and fixed up thousands of these, with the
> >>> /* */ version, not the attribute.
> >>>
> >>> Gustavo, can coverity notice the "fallthrough;" attribute properly?  I
> >>> don't want to start adding things that end up triggering
> >>> false-positives.
> >>
> >> I'm not Gustavo, and I don't know the answer, but 1.5 years ago some guy
> >> named greg k-h suggested that coverity does grok the fallthrough attribute:
> >>
> >> https://patchwork.kernel.org/cover/10651357/#22279095
> > 
> > I wouldn't trust anything that bum says :)
> > 
> > Ok, I don't remember saying that at all, but I'll wait a day or two to
> > get Gustavo's opinion befor applying the patch.
> > 
> 
> We are good to go with the 'fallthrough' pseudo keyword. Linus is OK with
> that.
> 
> The comment annotations will eventually be transformed to "fallthrough;"

Ok, thanks for the confirmation, will queue this up.

greg k-h