linux-kernel - Re: [PATCH v2] nvdimm/btt: fix variable 'rc' set but not used

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Date:   Wed, 30 Oct 2019 21:38:10 +0000
From:   "Verma, Vishal L" <vishal.l.verma@...el.com>
To:     "cai@....pw" <cai@....pw>,
        "Williams, Dan J" <dan.j.williams@...el.com>
CC:     "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        "Busch, Keith" <keith.busch@...el.com>,
        "Weiny, Ira" <ira.weiny@...el.com>
Subject: Re: [PATCH v2] nvdimm/btt: fix variable 'rc' set but not used


On Wed, 2019-10-30 at 17:28 -0400, Qian Cai wrote:
> drivers/nvdimm/btt.c: In function 'btt_read_pg':
> drivers/nvdimm/btt.c:1264:8: warning: variable 'rc' set but not used
> [-Wunused-but-set-variable]
>     int rc;
>         ^~
> 
> Add a ratelimited message in case a storm of errors is encountered.
> 
> Fixes: d9b83c756953 ("libnvdimm, btt: rework error clearing")
> Signed-off-by: Qian Cai <cai@....pw>
> ---
> 
> v2: include the block address that is returning an error per Dan.
> 
>  drivers/nvdimm/btt.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index 3e9f45aec8d1..10313be78221 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
> @@ -1266,6 +1266,12 @@ static int btt_read_pg(struct btt *btt, struct bio_integrity_payload *bip,
>  			/* Media error - set the e_flag */
>  			rc = btt_map_write(arena, premap, postmap, 0, 1,
>  				NVDIMM_IO_ATOMIC);
> +
> +			if (rc)
> +				dev_warn_ratelimited(to_dev(arena),
> +					"Error persistently tracking bad blocks at %#x\n",
> +					premap);
> +
>  			goto out_rtt;
>  		}

Good find! Since we're not really using rc later, we should just
simplify this to:

	if (btt_map_write(...))
		dev_warn_ratelimited(...)
	goto out_rtt;