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

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Message-ID: <20180205182039.GA7891@linux.intel.com>
Date:   Mon, 5 Feb 2018 11:20:39 -0700
From:   Ross Zwisler <ross.zwisler@...ux.intel.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Dan Williams <dan.j.williams@...el.com>, linux-nvdimm@...ts.01.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'

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.

We can append the above info to the changelog when we apply.

> ---
>  drivers/nvdimm/pfn_devs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index f5c4e8c6e29d..2f4d18752c97 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -304,7 +304,7 @@ static const struct attribute_group *nd_pfn_attribute_groups[] = {
>  struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
>  		struct nd_namespace_common *ndns)
>  {
> -	struct device *dev = &nd_pfn->dev;
> +	struct device *dev;
>  
>  	if (!nd_pfn)
>  		return NULL;
> -- 
> 2.15.1
> 
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@...ts.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm

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