linux-kernel - Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'

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Message-ID: <CAPcyv4geaysZ803Xtd27YGh0udww+95VaGP6r1Hdxx8SHxfX9w@mail.gmail.com>
Date:   Mon, 5 Feb 2018 10:44:07 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc:     Colin King <colin.king@...onical.com>, linux-nvdimm@...ts.01.org,
        kernel-janitors@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'

On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
<ross.zwisler@...ux.intel.com> wrote:
> On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
>> From: Colin Ian King <colin.king@...onical.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@...onical.com>
>
> Reviewed-by: Ross Zwisler <ross.zwisler@...ux.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.