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Subject: Re: gluebi problems on 2.6.28 backport
From: Holger Brunck <holger.brunck@keymile.com>
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Date: Fri, 10 Jul 2009 14:50:29 +0200
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Hi, 

> The problem is that the mtd_blkdevs module does not open MTD devices
> before working with them. Gluebi changes revealed this problem. Below
> is the patch which should fix the issue. Please, try and let me know
> if it helps.
> 
> ======================================================================
> 
> From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
> Subject: [PATCH] mtd: blkdevs: do not for get to get MTD devices
> 
> Nowadays MTD devices have to be "get" before they can be
> used. This has to be done with 'put_mtd_device()'. The
> 'blktrans_open()' function did not do this and instead
> used 'try_module_get()'. Fixe this.
> 
> Since 'put_mtd_device()' already gets the module, extra
> 'try_module_get()' is not needed.
> 
> This fixes oops when one tries to use mtdbloc on tope of
> gluebi.
> 
> Reported-by: Holger Brunck <holger.brunck@keymile.com>
> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
> ---
>  drivers/mtd/mtd_blkdevs.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
> index 1409f01..2f55242 100644
> --- a/drivers/mtd/mtd_blkdevs.c
> +++ b/drivers/mtd/mtd_blkdevs.c
> @@ -139,7 +139,7 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
>  	struct mtd_blktrans_ops *tr = dev->tr;
>  	int ret = -ENODEV;
>  
> -	if (!try_module_get(dev->mtd->owner))
> +	if (!get_mtd_device(NULL, dev->mtd->index))
>  		goto out;
>  
>  	if (!try_module_get(tr->owner))
> @@ -153,7 +153,7 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
>  	ret = 0;
>  	if (tr->open && (ret = tr->open(dev))) {
>  		dev->mtd->usecount--;
> -		module_put(dev->mtd->owner);
> +		put_mtd_device(dev->mtd);
>  	out_tr:
>  		module_put(tr->owner);
>  	}
> @@ -172,7 +172,7 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode)
>  
>  	if (!ret) {
>  		dev->mtd->usecount--;
> -		module_put(dev->mtd->owner);
> +		put_mtd_device(dev->mtd);
>  		module_put(tr->owner);
>  	}
>  
> -- 
> 1.6.0.6
> 
yes this patch solves my problem. 

Thanks a lot.

Regards 
Holger Brunck