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Date: Fri, 16 May 2003 20:49:20 -0700
From: Andrew Morton <akpm@digeo.com>
To: Kevin Brosius <cobra@compuserve.com>
Cc: dmo@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: DAC960 breakage, 2.5 bk current
Message-Id: <20030516204920.25b8e951.akpm@digeo.com>
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Kevin Brosius <cobra@compuserve.com> wrote:
>
> kernel NULL pointer deref - virt 00000019
>  Oops: 0000 [#1]
>  CPU: 0
>  EIP: 0060:[<c02774d3>]  Not tainted
>  EFLAGS: 00010286
>  EIP is at DAC960_ioctl+0x33/0x190
> 
>  Process swapper (pid: 1, ...)
> 
>  Call Trace:
>  ] blkdev_ioctl+0xa5/0x466
>  ] ioctl_by_dev+0x41/0x50

You tricking me.  That's "ioctl_by_bdev".  It passes in a null file*, and
we have to handle it.

Does this fix?

diff -puN drivers/block/DAC960.c~DAC960-oops-fix drivers/block/DAC960.c
--- 25/drivers/block/DAC960.c~DAC960-oops-fix	2003-05-16 20:44:52.000000000 -0700
+++ 25-akpm/drivers/block/DAC960.c	2003-05-16 20:45:16.000000000 -0700
@@ -102,7 +102,7 @@ static int DAC960_ioctl(struct inode *in
 	int drive_nr = (int)disk->private_data;
 	struct hd_geometry g, *loc = (struct hd_geometry *)arg;
 
-	if (file->f_flags & O_NONBLOCK)
+	if (file && file->f_flags & O_NONBLOCK)
 		return DAC960_UserIOCTL(inode, file, cmd, arg);
 
 	if (cmd != HDIO_GETGEO || !loc)

_