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Subject: Re: [PATCHv2 7/7] mtd: Raise limit on block device minor numbers
From: Ben Hutchings <bhutchings@solarflare.com>
To: David Woodhouse <dwmw2@infradead.org>
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Date: Thu, 14 Jan 2010 19:19:29 +0000
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On Tue, 2010-01-12 at 23:10 +0000, Ben Hutchings wrote:
> add_mtd_blktrans_dev() imposes a maximum of 257 devices per block
> translator.  This was presumably meant to prevent overflow back in the
> days of 8-bit minor numbers.  Since we now have 20-bit minor numbers
> and can have more than 32 MTDs, change the maximum to MINORMASK.
> 
> Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
> ---
>  drivers/mtd/mtd_blkdevs.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
> index 85a52b3..5e88b49 100644
> --- a/drivers/mtd/mtd_blkdevs.c
> +++ b/drivers/mtd/mtd_blkdevs.c
> @@ -242,7 +242,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
>  	if (new->devnum == -1)
>  		new->devnum = last_devnum+1;
>  
> -	if ((new->devnum << tr->part_bits) > 256) {
> +	if ((new->devnum << tr->part_bits) > MINORMASK) {

Actually this still has a boundary error.  I think the correct condition
is:

	new->devnum > (MINORMASK >> tr->part_bits)

Ben.

>  		return -EBUSY;
>  	}
>  
> -- 
> 1.5.5
> 

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.