Hold the refcounts for device and scsi_dh_data while calling handler's activate. This will make sure that devices and scsi_dh_data are not removed while activate is still in progress. Make sure to call put_device and kref_put in the handler after activate is complete.

Signed-off-by: Babu Moger <babu.moger@lsi.com>
---
--- linux-2.6.35-rc5/drivers/scsi/device_handler/scsi_dh.c.orig 2010-07-23 05:40:11.000000000 -0500
+++ linux-2.6.35-rc5/drivers/scsi/device_handler/scsi_dh.c 2010-07-23 05:48:53.000000000 -0500
@@ -228,7 +228,8 @@ store_dh_state(struct device *dev, struc
* Activate a device handler
*/
if (scsi_dh->activate)
- err = scsi_dh->activate(sdev, NULL, NULL);
+ err = scsi_dh_activate(sdev->request_queue,
+ NULL, NULL);
else
err = 0;
}
@@ -431,6 +432,8 @@ EXPORT_SYMBOL_GPL(scsi_unregister_device
* do not hold the lock in the caller which may be needed in fn.
* @data - data passed to the function fn upon completion.
*
+ * NOTE - Remember to call put_device and kref_put in the handler after
+ * calling the callback function. Otherwise things could become messy.
*/
int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
{
@@ -450,9 +453,12 @@ int scsi_dh_activate(struct request_queu
if (err)
return err;

- if (scsi_dh->activate)
+ if (scsi_dh->activate) {
+ kref_get(&sdev->scsi_dh_data->kref);
err = scsi_dh->activate(sdev, fn, data);
- put_device(&sdev->sdev_gendev);
+ } else
+ put_device(&sdev->sdev_gendev);
+
return err;
}
EXPORT_SYMBOL_GPL(scsi_dh_activate);




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