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@xxxxxxx> --- --- 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); -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel