oobavail size calculation error in nand_base.c

oobavail size calculation error in nand_base.c

[Jinyoung Park]

Hello.

I found error in nand_base.c.
In nand_scan_tail() function, oobavail size calculation result is
wrong as follow circumstances.
    - Define nand_ecclayout using full oobfree array like below.
	.oobfree = { {2, 6}, {11, 2}, {16, 8}, {27, 2}, {32, 8}, {43, 2},{48,
8}, {59, 2} }
    - Using ARM EABI cross compiler when kernel compile also enable
"Use the ARM EABI to compile the kernl" feature in kernel menuconfig.
      I using ARM EABI compiler that codesourcery release arm-2008q3-51.

In this case, right oobavail size is 38 but result is too much
value(e.g. 2703572308...). It's random.
I think sometimes happen that after beyond oobfree array(oobfree[8])
is not 0 when ARM EABI compilation.
Below codes are my modified code. Please check...

Thanks.

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 3d7ed43..abb5998 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2756,9 +2756,12 @@ int nand_scan_tail(struct mtd_info *mtd)
	* the out of band area
	*/
	chip->ecc.layout->oobavail = 0;
-	for (i = 0; chip->ecc.layout->oobfree[i].length; i++)
+	for (i = 0; i < MTD_MAX_OOBFREE_ENTRIES; i++) {
+	if (chip->ecc.layout->oobfree[i].length == 0)
+		break;
	chip->ecc.layout->oobavail +=
		chip->ecc.layout->oobfree[i].length;
+	}
	mtd->oobavail = chip->ecc.layout->oobavail;

RE: oobavail size calculation error in nand_base.c

[Park Jinyoung]

I didn't realize that problem was patched, sorry.
And thanks for your reply.

Jinyoung Park

-----Original Message-----
From: vimal singh [mailto:vimalsingh@ti.com] 
Sent: Friday, May 15, 2009 2:37 PM
To: Park Jinyoung
Cc: tglx@linutronix.de; linux-mtd@lists.infradead.org
Subject: Re: oobavail size calculation error in nand_base.c

This issue is already noticed by Snehaprabha Narnakaje. And a patch is
already
sent to fix this by David Brownell.

http://lists.infradead.org/pipermail/linux-mtd/2009-April/025205.html


Sorry, last time I replied on wrong subject line... :)

---
Vimal

On Thu, May 14, 2009 at 1:58 PM, Jinyoung Park <parkjy@mtekvision.com>
wrote:
> Hello.
>
> I found error in nand_base.c.
> In nand_scan_tail() function, oobavail size calculation result is
> wrong as follow circumstances.
>    - Define nand_ecclayout using full oobfree array like below.
>        .oobfree = { {2, 6}, {11, 2}, {16, 8}, {27, 2}, {32, 8}, {43,
2},{48,
> 8}, {59, 2} }
>    - Using ARM EABI cross compiler when kernel compile also enable
> "Use the ARM EABI to compile the kernl" feature in kernel menuconfig.
>      I using ARM EABI compiler that codesourcery release
arm-2008q3-51.
>
> In this case, right oobavail size is 38 but result is too much
> value(e.g. 2703572308...). It's random.
> I think sometimes happen that after beyond oobfree array(oobfree[8])
> is not 0 when ARM EABI compilation.
> Below codes are my modified code. Please check...
>
> Thanks.
>
> diff --git a/drivers/mtd/nand/nand_base.c
b/drivers/mtd/nand/nand_base.c
> index 3d7ed43..abb5998 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -2756,9 +2756,12 @@ int nand_scan_tail(struct mtd_info *mtd)
>        * the out of band area
>        */
>        chip->ecc.layout->oobavail = 0;
> -       for (i = 0; chip->ecc.layout->oobfree[i].length; i++)
> +       for (i = 0; i < MTD_MAX_OOBFREE_ENTRIES; i++) {
> +       if (chip->ecc.layout->oobfree[i].length == 0)
> +               break;
>        chip->ecc.layout->oobavail +=
>                chip->ecc.layout->oobfree[i].length;
> +       }
>        mtd->oobavail = chip->ecc.layout->oobavail;
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>

Re: oobavail size calculation error in nand_base.c

[Artem Bityutskiy]

On Thu, 2009-05-14 at 17:28 +0900, Jinyoung Park wrote:
> Hello.
> 
> I found error in nand_base.c.
> In nand_scan_tail() function, oobavail size calculation result is
> wrong as follow circumstances.
>     - Define nand_ecclayout using full oobfree array like below.
> 	.oobfree = { {2, 6}, {11, 2}, {16, 8}, {27, 2}, {32, 8}, {43, 2},{48,
> 8}, {59, 2} }
>     - Using ARM EABI cross compiler when kernel compile also enable
> "Use the ARM EABI to compile the kernl" feature in kernel menuconfig.
>       I using ARM EABI compiler that codesourcery release arm-2008q3-51.
> 
> In this case, right oobavail size is 38 but result is too much
> value(e.g. 2703572308...). It's random.
> I think sometimes happen that after beyond oobfree array(oobfree[8])
> is not 0 when ARM EABI compilation.
> Below codes are my modified code. Please check...

It seems the following patch which sits in my l2-mtd-2.6.git fixes
this as well: http://git.infradead.org/users/dedekind/l2-mtd-2.6.git

Author: David Brownell <dbrownell@users.sourceforge.net>
Date:   Tue Apr 21 19:51:20 2009 -0700

    MTD: NAND: don't walk past end of oobfree[]

    Resolve issue noted by Sneha:  when computing oobavail from
    the list of free areas in the OOB, don't assume there will
    always be an unused slot at the end.  With ECC_HW_SYNDROME
    and 4KB page chips, it's fairly likely there *won't* be one.

    Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
    Cc: "Narnakaje, Snehaprabha" <nsnehaprabha@ti.com>"
    Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)