Patchwork nftl: fix offset alignments

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Submitter dimitri.gorokhovik@free.fr
Date Aug. 18, 2009, 10:06 p.m.
Message ID <785022442.3397251250633188592.JavaMail.root@zimbra3-e1.priv.proxad.net>
Download mbox | patch
Permalink /patch/31603/
State New, archived
Headers show

Comments

dimitri.gorokhovik@free.fr - Aug. 18, 2009, 10:06 p.m.
Arithmetic conversion in the mask computation makes the upper word 
of the second argument passed down to mtd->read_oob(), be always 0
(assuming 'offs' being a 64-bit signed long long type, and 
'mtd->writesize' being a 32-bit unsigned int type). 

This patch applies over the other one adding masking in nftl_write,
"nftl: write support is broken".

Signed-off-by: <dimitri.gorokhovik@free.fr>
---
Andrew Morton - Aug. 19, 2009, 11:34 p.m.
On Wed, 19 Aug 2009 00:06:28 +0200 (CEST) dimitri.gorokhovik@free.fr wrote:

> Arithmetic conversion in the mask computation makes the upper word 
> of the second argument passed down to mtd->read_oob(), be always 0
> (assuming 'offs' being a 64-bit signed long long type, and 
> 'mtd->writesize' being a 32-bit unsigned int type). 
> 
> This patch applies over the other one adding masking in nftl_write,
> "nftl: write support is broken".
> 
> Signed-off-by: <dimitri.gorokhovik@free.fr>
> ---
>  
> diff --git a/drivers/mtd/nftlcore.c b/drivers/mtd/nftlcore.c
> index 665d3eb..d2fd066 100644
> --- a/drivers/mtd/nftlcore.c
> +++ b/drivers/mtd/nftlcore.c
> @@ -135,16 +135,17 @@ static void nftl_remove_dev(struct mtd_blktrans_dev *dev)
>  int nftl_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
>  		  size_t *retlen, uint8_t *buf)
>  {
> +	typeof(offs) mask = mtd->writesize - 1;

I see no reason to use typeof here.  Plain old

	loff_t mask = mtd->writesize - 1;

would be more conventional.

>  	struct mtd_oob_ops ops;
>  	int res;
>  
>  	ops.mode = MTD_OOB_PLACE;
> -	ops.ooboffs = offs & (mtd->writesize - 1);
> +	ops.ooboffs = offs & mask;
>  	ops.ooblen = len;
>  	ops.oobbuf = buf;
>  	ops.datbuf = NULL;
>  
> -	res = mtd->read_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
> +	res = mtd->read_oob(mtd, offs & ~mask, &ops);

yup.

Patch

diff --git a/drivers/mtd/nftlcore.c b/drivers/mtd/nftlcore.c
index 665d3eb..d2fd066 100644
--- a/drivers/mtd/nftlcore.c
+++ b/drivers/mtd/nftlcore.c
@@ -135,16 +135,17 @@  static void nftl_remove_dev(struct mtd_blktrans_dev *dev)
 int nftl_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 		  size_t *retlen, uint8_t *buf)
 {
+	typeof(offs) mask = mtd->writesize - 1;
 	struct mtd_oob_ops ops;
 	int res;
 
 	ops.mode = MTD_OOB_PLACE;
-	ops.ooboffs = offs & (mtd->writesize - 1);
+	ops.ooboffs = offs & mask;
 	ops.ooblen = len;
 	ops.oobbuf = buf;
 	ops.datbuf = NULL;
 
-	res = mtd->read_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	res = mtd->read_oob(mtd, offs & ~mask, &ops);
 	*retlen = ops.oobretlen;
 	return res;
 }
@@ -155,16 +156,17 @@  int nftl_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 int nftl_write_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 		   size_t *retlen, uint8_t *buf)
 {
+	typeof(offs) mask = mtd->writesize - 1;
 	struct mtd_oob_ops ops;
 	int res;
 
 	ops.mode = MTD_OOB_PLACE;
-	ops.ooboffs = offs & (mtd->writesize - 1);
+	ops.ooboffs = offs & mask;
 	ops.ooblen = len;
 	ops.oobbuf = buf;
 	ops.datbuf = NULL;
 
-	res = mtd->write_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	res = mtd->write_oob(mtd, offs & ~mask, &ops);
 	*retlen = ops.oobretlen;
 	return res;
 }
@@ -177,17 +179,18 @@  int nftl_write_oob(struct mtd_info *mtd, loff_t offs, size_t len,
 static int nftl_write(struct mtd_info *mtd, loff_t offs, size_t len,
 		      size_t *retlen, uint8_t *buf, uint8_t *oob)
 {
+	typeof(offs) mask = mtd->writesize - 1;
 	struct mtd_oob_ops ops;
 	int res;
 
 	ops.mode = MTD_OOB_PLACE;
-	ops.ooboffs = offs & (mtd->writesize - 1);
+	ops.ooboffs = offs & mask;
 	ops.ooblen = mtd->oobsize;
 	ops.oobbuf = oob;
 	ops.datbuf = buf;
 	ops.len = len;
 
-	res = mtd->write_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	res = mtd->write_oob(mtd, offs & ~mask, &ops);
 	*retlen = ops.retlen;
 	return res;
 }