linux-kernel - Re: [PATCH] md: check the return of mddev

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Message-ID: <20120515163353.5ab9c084@notabene.brown>
Date:	Tue, 15 May 2012 16:33:53 +1000
From:	NeilBrown <neilb@...e.de>
To:	Yuanhan Liu <yuanhan.liu@...ux.intel.com>
Cc:	linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] md: check the return of mddev_find()

On Tue, 15 May 2012 14:26:40 +0800 Yuanhan Liu <yuanhan.liu@...ux.intel.com>
wrote:

> Check the return of mddev_find(), since it may fail due to out of
> memeory or out of usable minor number.
> 
> The reason I chose -ENODEV instead of -ENOMEM or something else is
> md_alloc() function chose that ;)
> 
> Signed-off-by: Yuanhan Liu <yuanhan.liu@...ux.intel.com>
> ---
>  drivers/md/md.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 477eb2e..0bd44e3 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -6371,6 +6371,9 @@ static int md_open(struct block_device *bdev, fmode_t mode)
>  	struct mddev *mddev = mddev_find(bdev->bd_dev);
>  	int err;
>  
> +	if (!mddev)
> +		return -ENODEV;
> +
>  	if (mddev->gendisk != bdev->bd_disk) {
>  		/* we are racing with mddev_put which is discarding this
>  		 * bd_disk.

Hi,
 thanks for the patch.

 I'm fairly sure that we won't actually get to md_open unless md_probe has
 succeeded and called add_disk, in which case there *must* be a matching
 mddev.

 However it doesn't hurt and looks safer so I have applied it.

Thanks,
NeilBrown

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