Re: fs/dlm/midcomms.c:913:22: sparse: sparse: restricted __le32 degrades to integer

From: Alexander Aring <aahringo@redhat.com>
To: Randy Dunlap <rdunlap@infradead.org>
Cc: kernel test robot <lkp@intel.com>,
	kbuild-all@lists.01.org, linux-kernel@vger.kernel.org,
	David Teigland <teigland@redhat.com>,
	cluster-devel <cluster-devel@redhat.com>,
	linux-sparse@vger.kernel.org, rcu@vger.kernel.org
Subject: Re: fs/dlm/midcomms.c:913:22: sparse: sparse: restricted __le32 degrades to integer
Date: Sun, 23 Jan 2022 13:41:52 -0500	[thread overview]
Message-ID: <CAK-6q+j2jc3pBmbvQ-DCmxveC-UMV75SFc2nC1zwXKe9wm4YPg@mail.gmail.com> (raw)
In-Reply-To: <91901e7b-7d82-116c-aaf2-c74c6a6b999c@infradead.org>

Hi Randy,

On Sat, Jan 22, 2022 at 2:19 PM Randy Dunlap <rdunlap@infradead.org> wrote:
>
>
>
> On 1/22/22 10:28, Alexander Aring wrote:
> > Hi,
> >
> > On Fri, Jan 21, 2022 at 9:45 PM kernel test robot <lkp@intel.com> wrote:
> >>
> >> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> >> head:   9b57f458985742bd1c585f4c7f36d04634ce1143
> >> commit: 658bd576f95ed597e519cdadf1c86ac87c17aea5 fs: dlm: move version conversion to compile time
> >> date:   3 months ago
> >> config: x86_64-rhel-8.3-kselftests (https://download.01.org/0day-ci/archive/20220122/202201221028.YKA8kSdm-lkp@intel.com/config)
> >> compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
> >> reproduce:
> >>         # apt-get install sparse
> >>         # sparse version: v0.6.4-dirty
> >>         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=658bd576f95ed597e519cdadf1c86ac87c17aea5
> >>         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> >>         git fetch --no-tags linus master
> >>         git checkout 658bd576f95ed597e519cdadf1c86ac87c17aea5
> >>         # save the config file to linux build tree
> >>         mkdir build_dir
> >>         make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=x86_64 SHELL=/bin/bash
> >>
> >> If you fix the issue, kindly add following tag as appropriate
> >
> > I have it on my list but it isn't easy to make sparse happy here...
> > this is the second time the robot reported this issue. Is there a way
> > to turn the robot off in that case?
> >
> > Maybe some human who reads that knows the answer?
>
> Hi Alex,
>
> In the source file, you can surround the "offending" line(s) with
>
> #ifndef __CHECKER__
>  ...
> #endif
>
> to prevent sparse from checking those lines.
> Sometimes there needs to be an "#else" branch also.
>
> 'git grep __CHECKER__' will show you quite a few other examples.
>

Thanks, I will try that to stop the false positives and endianness
warnings (temporarily).

I see also:

fs/dlm/midcomms.c:213:1: sparse: sparse: symbol
'__srcu_struct_nodes_srcu' was not declared. Should it be static?

For a macro which contains the "static" keyword, it's
"DEFINE_STATIC_SRCU()". Either sparse should be teached to deal with
that or everybody should use "static DEFINE_SRCU()" instead of using
"DEFINE_STATIC_SRCU()".
I would like to see the second way because everybody can see "static"
is being used, that means maybe we should remove
"DEFINE_STATIC_SRCU()"? The alternative by doing nothing would be to
use "#ifndef __CHECKER__".

I cc here rcu@vger.kernel.org and linux-sparse@vger.kernel.org, maybe
this can be discussed?

- Alex