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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Sat, 1 Dec 2018 12:34:01 +0900
Message-ID: <CAK7LNARZLHaaFNjuFEteY59ybAHTKp3ciwOMgacTXr+Sagk-DQ@mail.gmail.com>
Subject: Re: [PATCH v4 1/3] kernel.h: disable type-checks in container_of()
 for Sparse
To:     Andrew Morton <akpm@linux-foundation.org>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        Kees Cook <keescook@chromium.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        NeilBrown <neilb@suse.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ingo Molnar <mingo@kernel.org>, Crt Mori <cmo@melexis.com>,
        Dan Carpenter <dan.carpenter@oracle.com>
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Hi Andrew,


On Sat, Nov 24, 2018 at 6:06 PM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Fri, Nov 23, 2018 at 10:14 PM Luc Van Oostenryck
> <luc.vanoostenryck@gmail.com> wrote:
> >
> > On Thu, Nov 22, 2018 at 12:14:20PM +0900, Masahiro Yamada wrote:
> > > When I tried to enable BUILD_BUG_ON for Sparse, the kbuild test robot
> > > reported lots of "unknown expression" warnings from container_of(),
> > > which seemed false positive.
> > >
> > > I addressed this in [1], but fixing Sparse is the right thing to do.
> > >
> > > The issue was fixed by Sparse commit 0eb8175d3e9c ("fix expansion of
> > > function designator"), but it will take time until the fixed version
> > > of Sparse is widely available.
> > >
> > > Disable the container_of() type checks for Sparse for now.
> >
> > I would prefer that developers upgrade their version of sparse but ...
> >
> > Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
>
> Indeed. If someone is writing code for the latest kernels, I think it
> is reasonable to assume they are able to use the latest sparse too,
> since it is not required for compilation anyway.


I was reconsidering about this.

I saw other Sparse warnings anyway
unless I use the state-of-the-art version of Sparse.


So, now I think Luc and Miguel were right.


Requiring the latest Sparse is the right solution.
We do not need to take care of old Sparse.


Andrew,
Could you drop this patch please?


-- 
Best Regards
Masahiro Yamada