linux-kernel - Re: [PATCH v4 7/7] mtd: spi-nor: add read loop

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Date:	Fri, 14 Aug 2015 11:02:07 +0100
From:	Andrew Murray <amurray@...edded-bits.co.uk>
To:	Michal Suchanek <hramrach@...il.com>
Cc:	Hou Zhiqiang <B48286@...escale.com>, shijie.huang@...el.com,
	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	Han Xu <han.xu@...escale.com>,
	Rafał Miłecki <zajec5@...il.com>,
	Huang Shijie <b32955@...escale.com>,
	Ben Hutchings <ben@...adent.org.uk>,
	Marek Vasut <marex@...x.de>, Gabor Juhos <juhosg@...nwrt.org>,
	Bean Huo 霍斌斌, <beanhuo@...ron.com>,
	MTD Maling List <linux-mtd@...ts.infradead.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 7/7] mtd: spi-nor: add read loop

On 14 August 2015 at 10:23, Michal Suchanek <hramrach@...il.com> wrote:
> mtdblock and ubi do not handle the situation when read returns less data
> than requested. Loop in spi-nor until buffer is filled or an error is
> returned.
>
> Signed-off-by: Michal Suchanek <hramrach@...il.com>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index e0ae9cf..246fac7 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -738,14 +738,22 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
>         if (ret)
>                 return ret;
>
> -       ret = nor->read(nor, from, len, buf);
> +       while (len) {
> +               ret = nor->read(nor, from, len, buf);
> +               if (ret <= 0)
> +                       goto read_err;
> +
> +               BUG_ON(ret > len);
> +               *retlen += ret;

Is *retlen initialized to 0 anywhere?

Andrew Murray

> +               buf += ret;
> +               from += ret;
> +               len -= ret;
> +       }
> +       ret = 0;
>
> +read_err:
>         spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
> -       if (ret < 0)
> -               return ret;
> -
> -       *retlen += ret;
> -       return 0;
> +       return ret;
>  }
>
>  static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
> --
> 2.1.4
>
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
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