linux-kernel - Re: [PATCH v3 3/6] staging: r8188eu: add error handling of rtw

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Date:   Thu, 26 Aug 2021 14:08:07 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Pavel Skripkin <paskripkin@...il.com>,
        kernel test robot <lkp@...el.com>, Larry.Finger@...inger.net,
        phil@...lpotter.co.uk, gregkh@...uxfoundation.org,
        straube.linux@...il.com, fmdefrancesco@...il.com,
        clang-built-linux@...glegroups.com, kbuild-all@...ts.01.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/6] staging: r8188eu: add error handling of rtw_read8

On Wed, Aug 25, 2021 at 10:11:45AM -0700, Nick Desaulniers wrote:
> On Wed, Aug 25, 2021 at 6:44 AM Pavel Skripkin <paskripkin@...il.com> wrote:
> >
> > On 8/25/21 4:34 PM, Dan Carpenter wrote:
> > > On Wed, Aug 25, 2021 at 04:02:26PM +0300, Pavel Skripkin wrote:
> > >> > This is not related to your patch.  Ignore it.
> > >> >
> > >> >
> > >> > > > vim +2022 drivers/staging/r8188eu/hal/usb_halinit.c
> > >> > > >
> > >> > >
> > >> > > >    2020                case HW_VAR_BCN_VALID:
> > >> > > >    2021                        /* BCN_VALID, BIT(16) of REG_TDECTRL = BIT(0) of REG_TDECTRL+2, write 1 to clear, Clear by sw */
> > >> > > > > 2022                         u8 tmp;
> > >> > >
> > >> > > Hm, I don't know anything about ARM compilers, so should I wrap this code
> > >> > > block with {}?
> > >> >
> > >> > Yep.
> > >> >
> > >> > >
> > >> > > My local gcc 11.1.1 (x86_64) does not produce any warnings/errors
> > >> > >
> > >> >
> > >> > You should figure out whats up with that because it shouldn't compile
> > >> > with the gcc options that the kernel uses.
> > >> >
> > >>
> > >> AFAIK, at least 2 guys except me in this CC list compiled my series without
> > >> errors/warnings. Maybe, staging tree is missing some Makefile updates?
> > >>
> > >>
> > >> I'll resend series this evening anyway, but this is strange....
> > >
> > > Hm...  In my version of GCC the error is:
> > >
> > > drivers/staging/r8188eu/hal/usb_halinit.c:1870:3: error: a label can only be part of a statement and a declaration is not a statement
> > >
> > > That's a different error from what I was expecting.  It's caused by
> > > having a declaration directly after a case statement.  The warning that
> > > I was expecting was from -Wdeclaration-after-statement and it looks
> > > like this:
> > >
> > > warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
> > >
> > > You really should try investigate why this compiles for you because
> > > something is going wrong.  It should not build without a warning.
> > >
> >
> > Looks like it's bug in gcc 11.1.1. I've rebuilt this module with gcc 10
> > (gcc-10 (SUSE Linux) 10.3.1 20210707 [revision
> > 048117e16c77f82598fca9af585500572d46ad73]) and build fails with error
> > described above
> >
> >
> > My default gcc is
> >
> > gcc (SUSE Linux) 11.1.1 20210721 [revision
> > 076930b9690ac3564638636f6b13bbb6bc608aea]
> >
> >
> > Any idea? :)
> 
> The original report said the build was with clang-14, which is near
> top of tree and unreleased. It's possible that that build had a bug
> that hopefully was reverted.

No, Clang is right to refuse to build the code.  It's GCC 11.1.1 which
is wrong because it allows it.  I'm not C language expert but we're
using the -Wdeclaration-after-statement because we don't want this.

regards,
dan carpenter