From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Zwisler Date: Mon, 05 Feb 2018 21:35:44 +0000 Subject: Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev' Message-Id: <20180205213544.GA30855@linux.intel.com> List-Id: References: <20180205140852.14110-1-colin.king@canonical.com> <20180205182039.GA7891@linux.intel.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Dan Williams Cc: Colin King , kernel-janitors@vger.kernel.org, Linux Kernel Mailing List , linux-nvdimm@lists.01.org On Mon, Feb 05, 2018 at 10:44:07AM -0800, Dan Williams wrote: > On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler > wrote: > > On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote: > >> From: Colin Ian King > >> > >> 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 > > > > Reviewed-by: Ross Zwisler > > > > 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. Ah, yep, you're right of course. This is exactly how offsetof() is implemented in some architectures. Thanks.