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From:   Sven Eckelmann <sven@narfation.org>
To:     Al Viro <viro@zeniv.linux.org.uk>, Arnd Bergmann <arnd@arndb.de>
Cc:     Arnd Bergmann <arnd@arndb.de>, b.a.t.m.a.n@lists.open-mesh.org,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] asm-generic: avoid sparse {get,put}_unaligned warning
Date:   Mon, 26 Jul 2021 17:04:46 +0200
Message-ID: <3234493.RMHOAZ7QyG@ripper>
In-Reply-To: <CAK8P3a2MVQMFFBUzudy+yrcp4Md8mm=NcvX7YzGVz4C8W61sgQ@mail.gmail.com>
References: <20210724162429.394792-1-sven@narfation.org> <YPxHYW/HPI/LLMXx@zeniv-ca.linux.org.uk> <CAK8P3a2MVQMFFBUzudy+yrcp4Md8mm=NcvX7YzGVz4C8W61sgQ@mail.gmail.com>
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From: Sven Eckelmann <sven@narfation.org>
To: Al Viro <viro@zeniv.linux.org.uk>, Arnd Bergmann <arnd@arndb.de>
Cc: Arnd Bergmann <arnd@arndb.de>, b.a.t.m.a.n@lists.open-mesh.org, linux-arch <linux-arch@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] asm-generic: avoid sparse {get,put}_unaligned warning
Date: Mon, 26 Jul 2021 17:04:46 +0200
Message-ID: <3234493.RMHOAZ7QyG@ripper>
In-Reply-To: <CAK8P3a2MVQMFFBUzudy+yrcp4Md8mm=NcvX7YzGVz4C8W61sgQ@mail.gmail.com>
References: <20210724162429.394792-1-sven@narfation.org> <YPxHYW/HPI/LLMXx@zeniv-ca.linux.org.uk> <CAK8P3a2MVQMFFBUzudy+yrcp4Md8mm=NcvX7YzGVz4C8W61sgQ@mail.gmail.com>

On Monday, 26 July 2021 14:57:31 CEST Arnd Bergmann wrote:
> >
> > > The special attribute force must be used in such statements when the cast
> > > is known to be safe to avoid these warnings.
> 
> I can see why this would warn, but I'm having trouble reproducing the
> warning on linux-next.

I have sparse 0.6.3 on an Debian bullseye amd64 system. Sources are from 
linux-next next-20210723

    make allnoconfig
    cat >> .config << "EOF"
    CONFIG_NET=y
    CONFIG_INET=y
    CONFIG_BATMAN_ADV=y
    CONFIG_BATMAN_ADV_DAT=y
    EOF
    make olddefconfig
    make CHECK="sparse -Wbitwise-pointer" C=1

I should maybe have made this clearer in the last sentence of the first 
paragraph: "This is also true for pointers to variables with this type when
-Wbitwise-pointer is activated."

Kind regards,
	Sven

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