[SCSI] ch: fix ch_remove oops

The following commit causes ch_remove oops:

commit 24b42566c3fcbb5a9011d1446783d0f5844ccd45
Author: Greg Kroah-Hartman <[e-mail]>
Date: Fri May 16 17:55:12 2008 -0700

SCSI: fix race in device_create

There is a race from when a device is created with device_create() and
then the drvdata is set with a call to dev_set_drvdata() in which a
sysfs file could be open, yet the drvdata will be NULL, causing all
sorts of bad things to happen.

This patch fixes the problem by using the new function,
device_create_drvdata(). It fixes the problem in all of the scsi
drivers that need it.

Cc: Kay Sievers <[e-mail]>
Cc: Doug Gilbert <[e-mail]>
Cc: James E.J. Bottomley <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

The problem is ch_probe stores ch's private data at a wrong place.

We need to store it at scsi_device->sdev_gendev but the above patch
stores it at device struct that device_create_drvdata returns. So we
hit an oops when ch_remove accesses
scsi_device->sdev_gendev->driver_data, which is NULL.

Actually, there wasn't a race because ch doesn't create sysfs files
with device struct that device_create returns. This patch puts back
dev_set_drvdata() to set ch's private data properly.

Signed-off-by: FUJITA Tomonori <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/ch.c

···
 	if (init)
 		ch_init_elem(ch);
 
+	dev_set_drvdata(dev, ch);
 	sdev_printk(KERN_INFO, sd, "Attached scsi changer %s\n", ch->name);
 
 	return 0;