Re: [PATCH] mtd: mtdchar: Exit write loop when hitting end of OTP memory

[Artem Bityutskiy <dedekind1@gmail.com>]

On Fri, 2013-04-26 at 19:56 +0200, Christian Riesch wrote:
> If a write to one time programmable memory (OTP) hits the end
> of this memory area, no more data can be written and count does not
> decrease anymore. We are trapped in the loop forever.
> 
> Therefore drop the remaining data if retlen != len.
> 
> Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
> ---
>  drivers/mtd/mtdchar.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
> index e0e59bf..70c18c2 100644
> --- a/drivers/mtd/mtdchar.c
> +++ b/drivers/mtd/mtdchar.c
> @@ -321,6 +321,10 @@ static ssize_t mtdchar_write(struct file *file, const char __user *buf, size_t c
>  		case MTD_FILE_MODE_OTP_USER:
>  			ret = mtd_write_user_prot_reg(mtd, *ppos, len,
>  						      &retlen, kbuf);
> +
> +			/* if we hit the end of otp memory, drop the rest */
> +			if (retlen != len)
> +				count -= len - retlen;
>  			break;

I think the problem is that 'mtd_write_user_prot_reg()' should return an
error if you try to write more data than it is available. At least this
is the behavior of 'mtd_write()'.

-- 
Best Regards,
Artem Bityutskiy