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References: <20210510085339.1857696-4-schnelle@linux.ibm.com> <202105102111.SyGVczHt-lkp@intel.com>
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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Mon, 10 May 2021 15:43:08 +0200
Message-ID: <CAK8P3a0CiVFvgpJJMcutHv6gdfeKWN2=AWYDuAX-ohEg3+L3gQ@mail.gmail.com>
Subject: Re: [PATCH v5 3/3] asm-generic/io.h: warn in inb() and friends with
 undefined PCI_IOBASE
To:     kernel test robot <lkp@intel.com>
Cc:     Niklas Schnelle <schnelle@linux.ibm.com>,
        Vineet Gupta <vgupta@synopsys.com>,
        "David S. Miller" <davem@davemloft.net>, kbuild-all@lists.01.org,
        Networking <netdev@vger.kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-s390 <linux-s390@vger.kernel.org>
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On Mon, May 10, 2021 at 3:30 PM kernel test robot <lkp@intel.com> wrote:
> All warnings (new ones prefixed by >>):
>
>    In file included from include/linux/kernel.h:10,
>                     from include/linux/list.h:9,
>                     from include/linux/module.h:12,
>                     from drivers/net/arcnet/com20020.c:31:
>    drivers/net/arcnet/com20020.c: In function 'com20020_reset':
> >> include/linux/compiler.h:70:32: warning: 'inbyte' is used uninitialized in this function [-Wuninitialized]
>       70 |   (__if_trace.miss_hit[1]++,1) :  \
>          |                                ^
>    drivers/net/arcnet/com20020.c:286:9: note: 'inbyte' was declared here
>      286 |  u_char inbyte;
>          |         ^~~~~~

This looks like a real problem with the patch: the insb()/insw()/insl() helpers
should memset(buffer, 0xff, size) to avoid using random stack data.

        Arnd