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* [PATCH] libmtd: avoid divide by zero
@ 2020-11-26 22:41 Chris Packham
  2020-11-26 23:43 ` Richard Weinberger
  0 siblings, 1 reply; 2+ messages in thread
From: Chris Packham @ 2020-11-26 22:41 UTC (permalink / raw)
  To: david.oberhollenzer, miquel.raynal, richard, vigneshr
  Cc: Chris Packham, linux-mtd

Some mtd-ram devices report 0 for the erase block size. Avoid a divide
by zero when calculating the erase block count for such devices.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
 lib/libmtd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/libmtd.c b/lib/libmtd.c
index 9d8d0e8..8aa1cb1 100644
--- a/lib/libmtd.c
+++ b/lib/libmtd.c
@@ -791,7 +791,8 @@ int mtd_get_dev_info1(libmtd_t desc, int mtd_num, struct mtd_dev_info *mtd)
 		return -1;
 	mtd->writable = !!(ret & MTD_WRITEABLE);
 
-	mtd->eb_cnt = mtd->size / mtd->eb_size;
+	if (mtd->eb_size)
+		mtd->eb_cnt = mtd->size / mtd->eb_size;
 	mtd->type = type_str2int(mtd->type_str);
 	mtd->bb_allowed = !!(mtd->type == MTD_NANDFLASH ||
 				mtd->type == MTD_MLCNANDFLASH);
-- 
2.29.2


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^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] libmtd: avoid divide by zero
  2020-11-26 22:41 [PATCH] libmtd: avoid divide by zero Chris Packham
@ 2020-11-26 23:43 ` Richard Weinberger
  0 siblings, 0 replies; 2+ messages in thread
From: Richard Weinberger @ 2020-11-26 23:43 UTC (permalink / raw)
  To: Chris Packham
  Cc: Vignesh Raghavendra, Richard Weinberger, linux-mtd,
	David Oberhollenzer, Miquel Raynal

On Thu, Nov 26, 2020 at 11:48 PM Chris Packham
<chris.packham@alliedtelesis.co.nz> wrote:
> Some mtd-ram devices report 0 for the erase block size. Avoid a divide
> by zero when calculating the erase block count for such devices.
>
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
>  lib/libmtd.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/libmtd.c b/lib/libmtd.c
> index 9d8d0e8..8aa1cb1 100644
> --- a/lib/libmtd.c
> +++ b/lib/libmtd.c
> @@ -791,7 +791,8 @@ int mtd_get_dev_info1(libmtd_t desc, int mtd_num, struct mtd_dev_info *mtd)
>                 return -1;
>         mtd->writable = !!(ret & MTD_WRITEABLE);
>
> -       mtd->eb_cnt = mtd->size / mtd->eb_size;
> +       if (mtd->eb_size)
> +               mtd->eb_cnt = mtd->size / mtd->eb_size;

I think it is better to check for MTD_NO_ERASE.
->eb_size is only allowed to be zero if MTD_NO_ERASE is set.
In that case we can configure mtd->eb_cnt to 1.

-- 
Thanks,
//richard

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