Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220821000737.328590235@goodmis.org> <20220821000844.510643400@goodmis.org>
 <CAHk-=wjsxu782N0P+oMu35N7rJAOeh3buQFWJaZHZTNmVSB=3Q@mail.gmail.com>
 <5700ac75-f6a9-877e-4011-9b314f12b5ab@acm.org> <CAHk-=wjqkWEr0MRO5hWuBoTDgNUj4qQK8V_Y36et=61mdPztJw@mail.gmail.com>
 <02daa3d6-2847-d7e0-e23e-411076c6d4db@rasmusvillemoes.dk> <0163b361-14bf-7b4c-751a-14f1a004b1a9@acm.org>
 <CAHk-=wjMLb30d0WT_RyKBCX+JBkg3QQU6pCYkrV8f58Ya4Rgzw@mail.gmail.com> <b79c83af-e9fc-9fa0-dff7-f3a8a39887ff@acm.org>
In-Reply-To: <b79c83af-e9fc-9fa0-dff7-f3a8a39887ff@acm.org>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue, 23 Aug 2022 18:49:25 -0700
Message-ID: <CAHk-=wgV1F7_ErXkXT2wd+07LJd_3Vp-yVUKLROPiEgijeoTrQ@mail.gmail.com>
Subject: Re: [for-linus][PATCH 01/10] tracing: Suppress sparse warnings
 triggered by is_signed_type()
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Hellwig <hch@lst.de>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        Jens Axboe <axboe@kernel.dk>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Aug 23, 2022 at 5:09 PM Bart Van Assche <bvanassche@acm.org> wrote:
>
> I'm probably doing something wrong but even with sparse commit 658ee8e0f631
> ("unrestricted values are unrestricted even after a cast") I see warnings
> being triggered by users of the is_signed_type() macro, warnings that
> disappear if I change the definition of the is_signed_type() macro into 0:

That's the

> It does require that kernel change to make
>
>   #define is_signed_type(type)   (((type)(-1)) <= (type)0)

part I was talking about.

So your kernel side patch looks fine, except I don't think you need
the '__force' - the sparse patches in my tree should make sparse happy
about casting '-1'.

But I didn't do very much testing.

                     Linus