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Date: Fri, 12 Jan 2018 08:52:25 +0100
From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Miquel Raynal <miquel.raynal@free-electrons.com>
Cc: Richard Weinberger <richard@nod.at>, David Woodhouse
 <dwmw2@infradead.org>, Brian Norris <computersforpeace@gmail.com>, Marek
 Vasut <marek.vasut@gmail.com>, Cyrille Pitchen
 <cyrille.pitchen@wedev4u.fr>, linux-mtd@lists.infradead.org,
 stable@vger.kernel.org
Subject: Re: [PATCH v2] mtd: nand: Fix nand_do_read_oob() return value
Message-ID: <20180112085225.52482fba@bbrezillon>
In-Reply-To: <20180111214202.24531-1-miquel.raynal@free-electrons.com>
References: <20180111214202.24531-1-miquel.raynal@free-electrons.com>
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On Thu, 11 Jan 2018 22:42:02 +0100
Miquel Raynal <miquel.raynal@free-electrons.com> wrote:

> Starting from commit 041e4575f034 ("mtd: nand: handle ECC errors in
> OOB"), nand_do_read_oob() (from the NAND core) did return 0 or a
> negative error, and the MTD layer expected it.
> 
> However, the trend for the NAND layer is now to return an error or a
> positive number of bitflips. Deciding which status to return to the user
> belongs to the MTD layer.
> 
> Commit e47f68587b82 ("mtd: check for max_bitflips in mtd_read_oob()")
> brought this logic to the mtd_read_oob() function while the return value
> coming from nand_do_read_oob() (called by the ->_read_oob() hook) was
> left unchanged.
> 
> Fixes: e47f68587b82 ("mtd: check for max_bitflips in mtd_read_oob()")
> Cc: stable@vger.kernel.org
> Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
> ---
> 
> Changes since v1:
>   - s/->ecc.read_oob() hook/->_read_oob() hook/ in the commit message
>   - Fixed the compilation issue
> 
>  drivers/mtd/nand/nand_base.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 469220065b8b..440d9f5d5b17 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -3876,7 +3876,7 @@ static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
>  	if (mtd->ecc_stats.failed - stats.failed)
>  		return -EBADMSG;
>  
> -	return  mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
> +	return ret;

This is wrong, you're only returning the max number of bitflips of the
last OOB read.

>  }
>  
>  /**