Re: [PATCH] 2.6.0-test4-mm2 drivers/char.c ---> drivers/char/raw.c

[Dave Olien <dmo@osdl.org>]

Mistake in subject line... should refer to drivers/char/raw.c

On Thu, Aug 28, 2003 at 04:18:53PM -0700, Dave Olien wrote:
> 
> The raw.c character device Oopses dereferencing a NULL pointer in bd_claim()
> This problem occurred after bd_claim() in block_dev.c was modified to "claim
> the whole device when a partition is claimed".
> 
> raw_open() made the mistake of calling bd_claim BEFORE calling
> blkdev_get().  At that time, the bdev->bd_contains field. has't been
> initialized yet.  Switching the order allows blkdev_get() to initialize
> those fields before calling bd_claim().
> 
> Also fixed up some error return paths:
> 
> igrab() should never fail under these circumstances since the caller
> already has a reference to that inode through the bdev at that time.
> 
> In the event of blkdev_get() failure or set_blocksize() failure, not
> all the work to unwind from the error was done.
> 
> --- linux-2.6.0-test4-mm2_original/drivers/char/raw.c	2003-08-28 13:16:03.000000000 -0700
> +++ linux-2.6.0-test4-mm2_raw/drivers/char/raw.c	2003-08-28 14:07:44.000000000 -0700
> @@ -60,25 +60,25 @@
>  	bdev = raw_devices[minor].binding;
>  	err = -ENODEV;
>  	if (bdev) {
> -		err = bd_claim(bdev, raw_open);
> +		err = blkdev_get(bdev, filp->f_mode, 0, BDEV_RAW);
>  		if (err)
>  			goto out;
> -		err = -ENODEV;
> -		if (!igrab(bdev->bd_inode))
> +		igrab(bdev->bd_inode);
> +		err = bd_claim(bdev, raw_open);
> +		if (err) {
> +			blkdev_put(bdev, BDEV_RAW);
>  			goto out;
> -		err = blkdev_get(bdev, filp->f_mode, 0, BDEV_RAW);
> +		}
> +		err = set_blocksize(bdev, bdev_hardsect_size(bdev));
>  		if (err) {
>  			bd_release(bdev);
> +			blkdev_put(bdev, BDEV_RAW);
>  			goto out;
> -		} else {
> -			err = set_blocksize(bdev, bdev_hardsect_size(bdev));
> -			if (err == 0) {
> -				filp->f_flags |= O_DIRECT;
> -				if (++raw_devices[minor].inuse == 1)
> -					filp->f_dentry->d_inode->i_mapping =
> -						bdev->bd_inode->i_mapping;
> -			}
>  		}
> +		filp->f_flags |= O_DIRECT;
> +		if (++raw_devices[minor].inuse == 1)
> +			filp->f_dentry->d_inode->i_mapping =
> +				bdev->bd_inode->i_mapping;
>  	}
>  	filp->private_data = bdev;
>  out: