[PATCH v2] mtd: nand: Fix nand_do_read_oob() return value

[PATCH v2] mtd: nand: Fix nand_do_read_oob() return value

[Miquel Raynal]

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;
 }
 
 /**
-- 
2.11.0

Re: [PATCH v2] mtd: nand: Fix nand_do_read_oob() return value

[Boris Brezillon]

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.

>  }
>  
>  /**

Re: [PATCH v2] mtd: nand: Fix nand_do_read_oob() return value

[Miquel Raynal]

Hi Boris,

On Fri, 12 Jan 2018 08:52:25 +0100
Boris Brezillon <boris.brezillon@free-electrons.com> wrote:

> 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.

I forgot about the while loop, that's right.

There will be a v3 :)

Thanks,
Miquèl