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From:   Alexander Aring <aahringo@redhat.com>
Date:   Mon, 24 Jan 2022 16:36:55 -0500
Message-ID: <CAK-6q+gGx68Wx8mBJAdo0ygpBWPoHW+L+HD11U6UQSOjSXVP3w@mail.gmail.com>
Subject: Re: fs/dlm/midcomms.c:913:22: sparse: sparse: restricted __le32
 degrades to integer
To:     paulmck@kernel.org
Cc:     Dan Carpenter <dan.carpenter@oracle.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        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
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Hi,

On Mon, Jan 24, 2022 at 3:23 PM Paul E. McKenney <paulmck@kernel.org> wrote:
>
> On Mon, Jan 24, 2022 at 12:41:04PM -0500, Alexander Aring wrote:
> > Hi,
> >
> > On Mon, Jan 24, 2022 at 12:36 PM Alexander Aring <aahringo@redhat.com> wrote:
> > >
> > > Hi,
> > >
> > > On Mon, Jan 24, 2022 at 12:21 PM Alexander Aring <aahringo@redhat.com> wrote:
> > > >
> > > > Hi,
> > > >
> > > > On Mon, Jan 24, 2022 at 7:46 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > > > >
> > > > > On Sun, Jan 23, 2022 at 01:41:52PM -0500, Alexander Aring wrote:
> > > > > >
> > > > > > I see also:
> > > > > >
> > > > > > fs/dlm/midcomms.c:213:1: sparse: sparse: symbol
> > > > > > '__srcu_struct_nodes_srcu' was not declared. Should it be static?
> > > > > >
> > > > >
> > > > > Why not just do this?  (Untested.  Maybe I don't understand?)
> > > > >
> > > > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
> > > > > index cb1f4351e8ba..a164089abec4 100644
> > > > > --- a/include/linux/srcutree.h
> > > > > +++ b/include/linux/srcutree.h
> > > > > @@ -121,7 +121,7 @@ struct srcu_struct {
> > > > >  #ifdef MODULE
> > > > >  # define __DEFINE_SRCU(name, is_static)                                        \
> > > > >         is_static struct srcu_struct name;                              \
> > > > > -       struct srcu_struct * const __srcu_struct_##name                 \
> > > > > +       is_static struct srcu_struct * const __srcu_struct_##name       \
> > > > >                 __section("___srcu_struct_ptrs") = &name
> > > > >  #else
> > > > >  # define __DEFINE_SRCU(name, is_static)                                        \
> > > > >
> > > >
> > > > I tried it and yes it will fix the issue and introduce another one
> > > > about "is_static struct srcu_struct * const __srcu_struct_##name" is
> > > > unused ("-Wunused-const-variable").
> > > > I added a __maybe_unused after the introduced is_static and it seems
> > > > to fix the introduced issue, now it compiles and sparse is happy. I am
> > > > not sure if this is the right fix?
> > >
> > > it is obviously unused, but it has something to do with
> > > "__section("___srcu_struct_ptrs")" and during module loading it, I
> > > suppose, srcu tries to access it to find whatever needs to be
> > > registered?
> >
> > Sorry, but if this is true then it can't be declared as static... and
> > we are at the beginning again.
>
> Welcome to my world!!!  ;-)
>
> More seriously, thank you for chasing this down.  But would it work to
> add a declaration just before?
>

only if I add an "extern" in front of the declaration before, so it looks like:

extern struct srcu_struct * const __srcu_struct_##name;

(compile and sparse tested only)

- Alex