Move non-transactional and non-idempotent code out of

xenstore transaction retry loops in our device drivers.
Otherwise things get very smelly if a transaction fails and
is retried.

Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c

@@ -80,6 +80,15 @@ static void frontend_changed(struct xenbus_watch *watch, const char *node)
 		return;
 	}
 
+	/* Map the shared frame, irq etc. */
+	err = blkif_map(be->blkif, ring_ref, evtchn);
+	if (err) {
+		xenbus_dev_error(be->dev, err, "mapping ring-ref %lu port %u",
+				 ring_ref, evtchn);
+		return;
+	}
+	/* XXX From here on should 'blkif_unmap' on error. */
+
 again:
 	/* Supply the information about the device the frontend needs */
 	err = xenbus_transaction_start();
@@ -112,14 +121,6 @@ again:
 		goto abort;
 	}
 
-	/* Map the shared frame, irq etc. */
-	err = blkif_map(be->blkif, ring_ref, evtchn);
-	if (err) {
-		xenbus_dev_error(be->dev, err, "mapping ring-ref %lu port %u",
-				 ring_ref, evtchn);
-		goto abort;
-	}
-
 	err = xenbus_transaction_end(0);
 	if (err == -EAGAIN)
 		goto again;

linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c

@@ -591,17 +591,6 @@ again:
 		goto abort_transaction;
 	}
 
-	info->backend = backend;
-	backend = NULL;
-
-	info->watch.node = info->backend;
-	info->watch.callback = watch_for_status;
-	err = register_xenbus_watch(&info->watch);
-	if (err) {
-		message = "registering watch on backend";
-		goto abort_transaction;
-	}
-
 	err = xenbus_transaction_end(0);
 	if (err) {
 		if (err == -EAGAIN)
@@ -610,10 +599,17 @@ again:
 		goto destroy_blkring;
 	}
 
- out:
-	if (backend)
-		kfree(backend);
-	return err;
+	info->watch.node = backend;
+	info->watch.callback = watch_for_status;
+	err = register_xenbus_watch(&info->watch);
+	if (err) {
+		message = "registering watch on backend";
+		goto destroy_blkring;
+	}
+
+	info->backend = backend;
+
+	return 0;
 
  abort_transaction:
 	xenbus_transaction_end(1);
@@ -621,7 +617,10 @@ again:
 	xenbus_dev_error(dev, err, "%s", message);
  destroy_blkring:
 	blkif_free(info);
-	goto out;
+ out:
+	if (backend)
+		kfree(backend);
+	return err;
 }
 
 /* Setup supplies the backend dir, virtual device.

linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c

@@ -1148,17 +1148,6 @@ again:
 		goto abort_transaction;
 	}
 
-	info->backend = backend;
-	backend = NULL;
-
-	info->watch.node = info->backend;
-	info->watch.callback = watch_for_status;
-	err = register_xenbus_watch(&info->watch);
-	if (err) {
-		message = "registering watch on backend";
-		goto abort_transaction;
-	}
-
 	err = xenbus_transaction_end(0);
 	if (err) {
 		if (err == -EAGAIN)
@@ -1167,12 +1156,19 @@ again:
 		goto destroy_ring;
 	}
 
+	info->watch.node = backend;
+	info->watch.callback = watch_for_status;
+	err = register_xenbus_watch(&info->watch);
+	if (err) {
+		message = "registering watch on backend";
+		goto destroy_ring;
+	}
+
+	info->backend = backend;
+
 	netif_state = NETIF_STATE_CONNECTED;
 
- out:
-	if (backend)
-		kfree(backend);
-	return err;
+	return 0;
 
  abort_transaction:
 	xenbus_transaction_end(1);
@@ -1180,7 +1176,10 @@ again:
 	xenbus_dev_error(dev, err, "%s", message);
  destroy_ring:
 	shutdown_device(info);
-	goto out;
+ out:
+	if (backend)
+		kfree(backend);
+	return err;
 }
 
 /* Setup supplies the backend dir, virtual device.

linux-2.6-xen-sparse/drivers/xen/tpmback/xenbus.c

@@ -88,6 +88,26 @@ static void frontend_changed(struct xenbus_watch *watch, const char *node)
 		return;
 	}
 
+	err = tpmif_map(be->tpmif, ringref, evtchn);
+	if (err) {
+		xenbus_dev_error(be->dev, err,
+				 "mapping shared-frame %lu port %u",
+				 ringref, evtchn);
+		return;
+	}
+
+	err = tpmif_vtpm_open(be->tpmif,
+	                      be->frontend_id,
+	                      be->instance);
+	if (err) {
+		xenbus_dev_error(be->dev, err,
+		                 "queueing vtpm open packet");
+		/*
+		 * Should close down this device and notify FE
+		 * about closure.
+		 */
+		return;
+	}
 
 	/*
 	 * Tell the front-end that we are ready to go -
@@ -107,27 +127,6 @@ again:
 		goto abort;
 	}
 
-	err = tpmif_map(be->tpmif, ringref, evtchn);
-	if (err) {
-		xenbus_dev_error(be->dev, err,
-				 "mapping shared-frame %lu port %u",
-				 ringref, evtchn);
-		goto abort;
-	}
-
-	err = tpmif_vtpm_open(be->tpmif,
-	                      be->frontend_id,
-	                      be->instance);
-	if (err) {
-		xenbus_dev_error(be->dev, err,
-		                 "queueing vtpm open packet");
-		/*
-		 * Should close down this device and notify FE
-		 * about closure.
-		 */
-		goto abort;
-	}
-
 	err = xenbus_transaction_end(0);
 	if (err == -EAGAIN)
 		goto again;

linux-2.6-xen-sparse/drivers/xen/tpmfront/tpmfront.c

@@ -352,17 +352,6 @@ again:
 		goto abort_transaction;
 	}
 
-	info->backend = backend;
-	backend = NULL;
-
-	info->watch.node = info->backend;
-	info->watch.callback = watch_for_status;
-	err = register_xenbus_watch(&info->watch);
-	if (err) {
-		message = "registering watch on backend";
-		goto abort_transaction;
-	}
-
 	err = xenbus_transaction_end(0);
 	if (err == -EAGAIN)
 		goto again;
@@ -371,10 +360,17 @@ again:
 		goto destroy_tpmring;
 	}
 
-out:
-	if (backend)
-		kfree(backend);
-	return err;
+	info->watch.node = backend;
+	info->watch.callback = watch_for_status;
+	err = register_xenbus_watch(&info->watch);
+	if (err) {
+		message = "registering watch on backend";
+		goto destroy_tpmring;
+	}
+
+	info->backend = backend;
+
+	return 0;
 
 abort_transaction:
 	xenbus_transaction_end(1);
@@ -382,7 +378,10 @@ abort_transaction:
 	xenbus_dev_error(dev, err, "%s", message);
 destroy_tpmring:
 	destroy_tpmring(info, &my_private);
-	goto out;
+out:
+	if (backend)
+		kfree(backend);
+	return err;
 }