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Message-ID: <0c55a627-69e9-bd1c-8316-4c3e8366e8b8@acm.org>
Date:   Mon, 22 Aug 2022 13:19:39 -0700
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Subject: Re: [for-linus][PATCH 01/10] tracing: Suppress sparse warnings
 triggered by is_signed_type()
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To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     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>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        Jens Axboe <axboe@kernel.dk>
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>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <CAHk-=wjqkWEr0MRO5hWuBoTDgNUj4qQK8V_Y36et=61mdPztJw@mail.gmail.com>
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On 8/22/22 11:45, Linus Torvalds wrote:
> On Mon, Aug 22, 2022 at 11:20 AM Bart Van Assche <bvanassche@acm.org> wrote:
>>
>> I agree that it's better that sparse sees the same code as what is used to
>> build the kernel. However, I do not agree that the patch above is a solution.
>> Sparse reports a warning for the suggested definition above of is_signed_type()
>> because the new definition tries to use the less-than (<) operator to compare
>> two __bitwise types.
> 
> Argh. I forgot that part. It wasn't just the cast that warned, it was
> the compare too.
> 
> But we did have a sparse fix for it, didn't we? That fix required that
> the '< (type)1' cast be changed to '<= (type)0' iirc, and a patch to
> sparse, but it at least avoided the problem.

Hi Linus,

I haven't seen any progress on the plan to modify sparse. Hence my attempt to
modify the is_signed_type() definition in the kernel.

Thanks,

Bart.