linux-kernel - Re: [PATCH] mtd: change len type from signed to unsigned type

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Date:   Wed, 31 Oct 2018 15:02:25 +0100
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Huijin Park <huijin.park@...sung.com>
Cc:     Marek Vasut <marek.vasut@...il.com>, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, bbanghj.park@...il.com
Subject: Re: [PATCH] mtd: change len type from signed to unsigned type

Hi Huijin,

On Thu, 23 Aug 2018 04:43:39 -0400
Huijin Park <huijin.park@...sung.com> wrote:

> From: "huijin.park" <huijin.park@...sung.com>
> 
> assign of a signed value which has type 'int' to a variable of
> a bigger unsigned integer type 'uint64_t'.

Why are you mentioning u64? AFAICT, the len passed to erase_write() is
always an unsigned int.

> this is ok most of the time, but can lead to unexpectedly large
> resulting value if the original signed value is negative.
> in addtion, the callers of the erase_write() pass the len parameter

  ^In addition,

> as unsigned type.
> 
> Signed-off-by: huijin.park <huijin.park@...sung.com>
> ---
>  drivers/mtd/mtdblock.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c
> index a5b1933..b2d5ed1 100644
> --- a/drivers/mtd/mtdblock.c
> +++ b/drivers/mtd/mtdblock.c
> @@ -56,7 +56,7 @@ struct mtdblk_dev {
>   */
>  
>  static int erase_write (struct mtd_info *mtd, unsigned long pos,
> -			int len, const char *buf)
> +			unsigned int len, const char *buf)

The diff looks good, but the commit message is not clear at all. Can
you reword it?

Thanks,

Boris

>  {
>  	struct erase_info erase;
>  	size_t retlen;