linux-kernel - Re: [PATCH v2 1/2] IB/qib: remove superfluous fallthrough statements

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Message-ID: <20200827104020.jfp5kju56duu4sh4@lenovo-laptop>
Date:   Thu, 27 Aug 2020 11:40:20 +0100
From:   Alex Dewar <alex.dewar90@...il.com>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc:     Jason Gunthorpe <jgg@...pe.ca>,
        Alex Dewar <alex.dewar90@...il.com>,
        dennis.dalessandro@...el.com, dledford@...hat.com,
        gustavo@...eddedor.com, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, mike.marciniszyn@...el.com,
        roland@...estorage.com
Subject: Re: [PATCH v2 1/2] IB/qib: remove superfluous fallthrough statements

On Wed, Aug 26, 2020 at 08:41:20PM -0500, Gustavo A. R. Silva wrote:
> On Wed, Aug 26, 2020 at 09:11:49PM -0300, Jason Gunthorpe wrote:
> > On Wed, Aug 26, 2020 at 02:18:59PM -0500, Gustavo A. R. Silva wrote:
> > > Hi,
> > > 
> > > On Tue, Aug 25, 2020 at 02:33:27PM -0500, Gustavo A. R. Silva wrote:
> > > > On Tue, Aug 25, 2020 at 06:12:42PM +0100, Alex Dewar wrote:
> > > > > Commit 36a8f01cd24b ("IB/qib: Add congestion control agent implementation")
> > > > > erroneously marked a couple of switch cases as /* FALLTHROUGH */, which
> > > > > were later converted to fallthrough statements by commit df561f6688fe
> > > > > ("treewide: Use fallthrough pseudo-keyword"). This triggered a Coverity
> > > > > warning about unreachable code.
> > > > >
> > > > 
> > > > It's worth mentioning that this warning is triggered only by compilers
> > > > that don't support __attribute__((__fallthrough__)), which has been
> > > > supported since GCC 7.1.
> > > > 
> > > > > Remove the fallthrough statements.
> > > > > 
> > > > > Addresses-Coverity: ("Unreachable code")
> > > > > Fixes: 36a8f01cd24b ("IB/qib: Add congestion control agent implementation")
> > > > > Signed-off-by: Alex Dewar <alex.dewar90@...il.com>
> > > > 
> > > > Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> > > > 
> > > 
> > > I can take this in my tree for 5.9-rc3.
> > 
> > That would make conflicts for the 2nd patch, lets just send them all
> > through the rdma tree please.
> 
> OK.
> 
> > Is there a reason this is -rc material?
> 
> It's just that this warning is currently in mainline.

FYI this issue was found with Coverity, not a compiler. I just built the
unfixed version from mainline (with gcc 10.2.0) and didn't get any
warnings.

> 
> Thanks
> --
> Gustavo