SCSI: add starget_for_each_device

From: 	James.Smart@Emulex.Com

This patch deprecates the use of device_for_each_child() with stargets.
The reasoning behind this is due to issues regarding:
      Semaphores that device_for_each_child() takes
      Implicit assumptions that each child is an sdev device.

The patch adds a new helper function, starget_for_each_device(), and
replaces all previous uses of device_for_each_child().
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi.c

@@ -1082,6 +1082,28 @@ struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
 }
 EXPORT_SYMBOL(__scsi_iterate_devices);
 
+/**
+ * starget_for_each_device  -  helper to walk all devices of a target
+ * @starget:	target whose devices we want to iterate over.
+ *
+ * This traverses over each devices of @shost.  The devices have
+ * a reference that must be released by scsi_host_put when breaking
+ * out of the loop.
+ */
+void starget_for_each_device(struct scsi_target *starget, void * data,
+		     void (*fn)(struct scsi_device *, void *))
+{
+	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+	struct scsi_device *sdev;
+
+	shost_for_each_device(sdev, shost) {
+		if ((sdev->channel == starget->channel) &&
+		    (sdev->id == starget->id))
+			fn(sdev, data);
+	}
+}
+EXPORT_SYMBOL(starget_for_each_device);
+
 /**
  * scsi_device_lookup - find a device given the host (UNLOCKED)
  * @shost:	SCSI host pointer

drivers/scsi/scsi_lib.c

@@ -1782,31 +1782,29 @@ scsi_device_resume(struct scsi_device *sdev)
 }
 EXPORT_SYMBOL(scsi_device_resume);
 
-static int
-device_quiesce_fn(struct device *dev, void *data)
+static void
+device_quiesce_fn(struct scsi_device *sdev, void *data)
 {
-	scsi_device_quiesce(to_scsi_device(dev));
-	return 0;
+	scsi_device_quiesce(sdev);
 }
 
 void
 scsi_target_quiesce(struct scsi_target *starget)
 {
-	device_for_each_child(&starget->dev, NULL, device_quiesce_fn);
+	starget_for_each_device(starget, NULL, device_quiesce_fn);
 }
 EXPORT_SYMBOL(scsi_target_quiesce);
 
-static int
-device_resume_fn(struct device *dev, void *data)
+static void
+device_resume_fn(struct scsi_device *sdev, void *data)
 {
-	scsi_device_resume(to_scsi_device(dev));
-	return 0;
+	scsi_device_resume(sdev);
 }
 
 void
 scsi_target_resume(struct scsi_target *starget)
 {
-	device_for_each_child(&starget->dev, NULL, device_resume_fn);
+	starget_for_each_device(starget, NULL, device_resume_fn);
 }
 EXPORT_SYMBOL(scsi_target_resume);
 

drivers/scsi/scsi_transport_fc.c

@@ -808,10 +808,9 @@ EXPORT_SYMBOL(fc_release_transport);
  * @dev:	scsi device
  * @data:	unused
  **/
-static int fc_device_block(struct device *dev, void *data)
+static void fc_device_block(struct scsi_device *sdev, void *data)
 {
-	scsi_internal_device_block(to_scsi_device(dev));
-	return 0;
+	scsi_internal_device_block(sdev);
 }
 
 /**
@@ -819,10 +818,9 @@ static int fc_device_block(struct device *dev, void *data)
  * @dev:	scsi device
  * @data:	unused
  **/
-static int fc_device_unblock(struct device *dev, void *data)
+static void fc_device_unblock(struct scsi_device *sdev, void *data)
 {
-	scsi_internal_device_unblock(to_scsi_device(dev));
-	return 0;
+	scsi_internal_device_unblock(sdev);
 }
 
 /**
@@ -842,7 +840,7 @@ static void fc_timeout_blocked_tgt(void  *data)
 	 * unblock this device, then IO errors will probably
 	 * result if the host still isn't ready.
 	 */
-	device_for_each_child(&starget->dev, NULL, fc_device_unblock);
+	starget_for_each_device(starget, NULL, fc_device_unblock);
 }
 
 /**
@@ -870,7 +868,7 @@ fc_target_block(struct scsi_target *starget)
 	if (timeout < 0 || timeout > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
 		return -EINVAL;
 
-	device_for_each_child(&starget->dev, NULL, fc_device_block);
+	starget_for_each_device(starget, NULL, fc_device_block);
 
 	/* The scsi lld blocks this target for the timeout period only. */
 	schedule_delayed_work(work, timeout * HZ);
@@ -901,7 +899,7 @@ fc_target_unblock(struct scsi_target *starget)
 	if (cancel_delayed_work(&fc_starget_dev_loss_work(starget)))
 		flush_scheduled_work();
 
-	device_for_each_child(&starget->dev, NULL, fc_device_unblock);
+	starget_for_each_device(starget, NULL, fc_device_unblock);
 }
 EXPORT_SYMBOL(fc_target_unblock);
 

include/scsi/scsi_device.h

@@ -172,6 +172,8 @@ extern struct scsi_device *scsi_device_lookup(struct Scsi_Host *,
 					      uint, uint, uint);
 extern struct scsi_device *__scsi_device_lookup(struct Scsi_Host *,
 						uint, uint, uint);
+extern void starget_for_each_device(struct scsi_target *, void *,
+		     void (*fn)(struct scsi_device *, void *));
 
 /* only exposed to implement shost_for_each_device */
 extern struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *,