[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [dm-devel] [PATCH 2/6] scsi_dh : increment the refcounts while calling activate



On 07/28/2010 06:59 PM, Moger, Babu wrote:
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);
Why not kref_put here instead of in the device handler.. It is easier to associate the ref counts..

Also, you are removing the put_device here and adding them to the device handler which can be avoided ..
-	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 redhat com
https://www.redhat.com/mailman/listinfo/dm-devel

-Shyam Iyer


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]