Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <20180205182039.GA7891@linux.intel.com>
References: <20180205140852.14110-1-colin.king@canonical.com> <20180205182039.GA7891@linux.intel.com>
From:   Dan Williams <dan.j.williams@intel.com>
Date:   Mon, 5 Feb 2018 10:44:07 -0800
Message-ID: <CAPcyv4geaysZ803Xtd27YGh0udww+95VaGP6r1Hdxx8SHxfX9w@mail.gmail.com>
Subject: Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
To:     Ross Zwisler <ross.zwisler@linux.intel.com>
Cc:     Colin King <colin.king@canonical.com>, linux-nvdimm@lists.01.org,
        kernel-janitors@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Pointer dev is being assigned a value that is never read, it is being
>> re-assigned the same value later on, hence the initialization is redundant
>> and can be removed.
>>
>> Cleans up clang warning:
>> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
>> its initialization is never read
>>
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>
> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>
> More importantly this fixes a potential NULL pointer dereference.  nd_pfn
> is checked for NULL a few lines down, but we would have crashed here trying to
> get nd_pfn->dev.
>

No we wouldn't crash. We're just calculating the address, not
de-referencing a NULL pointer.