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Date:   Fri, 19 May 2023 21:04:39 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Min-Hua Chen <minhuadotchen@gmail.com>
Cc:     alexandre.torgue@foss.st.com, davem@davemloft.net,
        edumazet@google.com, joabreu@synopsys.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        mcoquelin.stm32@gmail.com, netdev@vger.kernel.org,
        pabeni@redhat.com, peppe.cavallaro@st.com,
        simon.horman@corigine.com
Subject: Re: [PATCH v3] net: stmmac: compare p->des0 and p->des1 with __le32
 type values
Message-ID: <20230519210439.4a3bb326@kernel.org>
In-Reply-To: <20230520015527.215952-1-minhuadotchen@gmail.com>
References: <20230519152715.7d1c3a49@kernel.org>
        <20230520015527.215952-1-minhuadotchen@gmail.com>
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On Sat, 20 May 2023 09:55:27 +0800 Min-Hua Chen wrote:
> >Can you try to fix the sparse tool instead? I believe it already
> >ignores such errors for the constant of 0, maybe it can be taught=20
> >to ignore all "isomorphic" values?
> > =20
>=20
> I downloaded the source code of sparse and I'm afraid that I cannot make
> 0xFFFFFFFF ignored easily. I've tried ~0 instead of 0xFFFFFF,
> but it did not work with current sparse.
>=20
> 0 is a special case mentioned in [1].
>=20
> """
> One small note: the constant integer =E2=80=9C0=E2=80=9D is special.=20
> You can use a constant zero as a bitwise integer type without
> sparse ever complaining. This is because =E2=80=9Cbitwise=E2=80=9D (as th=
e name
> implies) was designed for making sure that bitwise types don=E2=80=99t
> get mixed up (little-endian vs big-endian vs cpu-endian vs whatever),
> and there the constant =E2=80=9C0=E2=80=9D really _is_ special.
> """
>=20
> For 0xFFFFFFFF, it may look like a false alarm, but we can silence the
> sparse warning by taking a fix like mine and people can keep working on
> other sparse warnings easier.

We can make working with sparse easier by making sure it doesn't
generate false positive warnings :\

> (There are around 7000 sparse warning in ARCH=3Darm64 defconfig build and
> sometimes it is hard to remember all the false alarm cases)
>=20
> Could you consider taking this patch, please?

No. We don't take patches to address false positive static=20
checker warnings.