[SCSI] scsi_sysfs: restore prep_fn when ULD is removed

A recent bug report:

http://bugzilla.kernel.org/show_bug.cgi?id=9674

Was caused because the ULDs now set their own prep functions, but
don't necessarily reset the prep function back to the SCSI default
when they are removed.  This leads to panics if commands are sent to
the device after the module is removed because the prep_fn is still
pointing to the old module code.  The fix for this is to implement a
bus remove method that resets the prep_fn pointer correctly before
calling the ULD specific driver remove method.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index f374fdcb6815..00b386677392 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -373,12 +373,29 @@ static int scsi_bus_resume(struct device * dev)
 	return err;
 }
 
+static int scsi_bus_remove(struct device *dev)
+{
+	struct device_driver *drv = dev->driver;
+	struct scsi_device *sdev = to_scsi_device(dev);
+	int err = 0;
+
+	/* reset the prep_fn back to the default since the
+	 * driver may have altered it and it's being removed */
+	blk_queue_prep_rq(sdev->request_queue, scsi_prep_fn);
+
+	if (drv && drv->remove)
+		err = drv->remove(dev);
+
+	return 0;
+}
+
 struct bus_type scsi_bus_type = {
         .name		= "scsi",
         .match		= scsi_bus_match,
 	.uevent		= scsi_bus_uevent,
 	.suspend	= scsi_bus_suspend,
 	.resume		= scsi_bus_resume,
+	.remove		= scsi_bus_remove,
 };
 
 int scsi_sysfs_register(void)