linux-kernel - Re: [PATCH][mtd-next] mtd: nand: remove redundant check of len

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Date:   Wed, 13 Dec 2017 21:24:25 +0100
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        linux-mtd@...ts.infradead.org, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH][mtd-next] mtd: nand: remove redundant check of len

On Wed, 13 Dec 2017 20:17:43 +0000
Colin King <colin.king@...onical.com> wrote:

> From: Colin Ian King <colin.king@...onical.com>
> 
> The check of len being zero is redundant as it has already been
> sanity checked for this value at the start of the function. Hence
> it is impossible for this test to be true and so the redundant
> code can be removed.

Nope, it's not the same test, the initial test is

	if (len && !buf)

not

	if (len)

So this test is not redundant.

> 
> Detected by CoverityScan, CID#1462748 ("Logically dead code")
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/mtd/nand/nand_base.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index afd5e18db81c..9daaa23db943 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -1507,10 +1507,6 @@ static int nand_read_param_page_op(struct nand_chip *chip, u8 page, void *buf,
>  		};
>  		struct nand_operation op = NAND_OPERATION(instrs);
>  
> -		/* Drop the DATA_IN instruction if len is set to 0. */
> -		if (!len)
> -			op.ninstrs--;
> -
>  		return nand_exec_op(chip, &op);
>  	}
>