1 files changed, 119 insertions, 60 deletions

diff --git a/drivers/misc/mic/scif/scif_peer_bus.c b/drivers/misc/mic/scif/scif_peer_bus.c
index 589ae9ad2501..6ffa3bdbd45b 100644
--- a/drivers/misc/mic/scif/scif_peer_bus.c
+++ b/drivers/misc/mic/scif/scif_peer_bus.c
@@ -24,93 +24,152 @@ dev_to_scif_peer(struct device *dev)
 	return container_of(dev, struct scif_peer_dev, dev);
 }
 
-static inline struct scif_peer_driver *
-drv_to_scif_peer(struct device_driver *drv)
-{
-	return container_of(drv, struct scif_peer_driver, driver);
-}
+struct bus_type scif_peer_bus = {
+	.name  = "scif_peer_bus",
+};
 
-static int scif_peer_dev_match(struct device *dv, struct device_driver *dr)
+static void scif_peer_release_dev(struct device *d)
 {
-	return !strncmp(dev_name(dv), dr->name, 4);
+	struct scif_peer_dev *sdev = dev_to_scif_peer(d);
+	struct scif_dev *scifdev = &scif_dev[sdev->dnode];
+
+	scif_cleanup_scifdev(scifdev);
+	kfree(sdev);
 }
 
-static int scif_peer_dev_probe(struct device *d)
+static int scif_peer_initialize_device(struct scif_dev *scifdev)
 {
-	struct scif_peer_dev *dev = dev_to_scif_peer(d);
-	struct scif_peer_driver *drv = drv_to_scif_peer(dev->dev.driver);
+	struct scif_peer_dev *spdev;
+	int ret;
 
-	return drv->probe(dev);
-}
+	spdev = kzalloc(sizeof(*spdev), GFP_KERNEL);
+	if (!spdev) {
+		ret = -ENOMEM;
+		goto err;
+	}
 
-static int scif_peer_dev_remove(struct device *d)
-{
-	struct scif_peer_dev *dev = dev_to_scif_peer(d);
-	struct scif_peer_driver *drv = drv_to_scif_peer(dev->dev.driver);
+	spdev->dev.parent = scifdev->sdev->dev.parent;
+	spdev->dev.release = scif_peer_release_dev;
+	spdev->dnode = scifdev->node;
+	spdev->dev.bus = &scif_peer_bus;
+	dev_set_name(&spdev->dev, "scif_peer-dev%u", spdev->dnode);
+
+	device_initialize(&spdev->dev);
+	get_device(&spdev->dev);
+	rcu_assign_pointer(scifdev->spdev, spdev);
 
-	drv->remove(dev);
+	mutex_lock(&scif_info.conflock);
+	scif_info.total++;
+	scif_info.maxid = max_t(u32, spdev->dnode, scif_info.maxid);
+	mutex_unlock(&scif_info.conflock);
 	return 0;
+err:
+	dev_err(&scifdev->sdev->dev,
+		"dnode %d: initialize_device rc %d\n", scifdev->node, ret);
+	return ret;
 }
 
-static struct bus_type scif_peer_bus = {
-	.name  = "scif_peer_bus",
-	.match = scif_peer_dev_match,
-	.probe = scif_peer_dev_probe,
-	.remove = scif_peer_dev_remove,
-};
-
-int scif_peer_register_driver(struct scif_peer_driver *driver)
+static int scif_peer_add_device(struct scif_dev *scifdev)
 {
-	driver->driver.bus = &scif_peer_bus;
-	return driver_register(&driver->driver);
+	struct scif_peer_dev *spdev = rcu_dereference(scifdev->spdev);
+	char pool_name[16];
+	int ret;
+
+	ret = device_add(&spdev->dev);
+	put_device(&spdev->dev);
+	if (ret) {
+		dev_err(&scifdev->sdev->dev,
+			"dnode %d: peer device_add failed\n", scifdev->node);
+		goto put_spdev;
+	}
+
+	scnprintf(pool_name, sizeof(pool_name), "scif-%d", spdev->dnode);
+	scifdev->signal_pool = dmam_pool_create(pool_name, &scifdev->sdev->dev,
+						sizeof(struct scif_status), 1,
+						0);
+	if (!scifdev->signal_pool) {
+		dev_err(&scifdev->sdev->dev,
+			"dnode %d: dmam_pool_create failed\n", scifdev->node);
+		ret = -ENOMEM;
+		goto del_spdev;
+	}
+	dev_dbg(&spdev->dev, "Added peer dnode %d\n", spdev->dnode);
+	return 0;
+del_spdev:
+	device_del(&spdev->dev);
+put_spdev:
+	RCU_INIT_POINTER(scifdev->spdev, NULL);
+	synchronize_rcu();
+	put_device(&spdev->dev);
+
+	mutex_lock(&scif_info.conflock);
+	scif_info.total--;
+	mutex_unlock(&scif_info.conflock);
+	return ret;
 }
 
-void scif_peer_unregister_driver(struct scif_peer_driver *driver)
+void scif_add_peer_device(struct work_struct *work)
 {
-	driver_unregister(&driver->driver);
+	struct scif_dev *scifdev = container_of(work, struct scif_dev,
+						peer_add_work);
+
+	scif_peer_add_device(scifdev);
 }
 
-static void scif_peer_release_dev(struct device *d)
+/*
+ * Peer device registration is split into a device_initialize and a device_add.
+ * The reason for doing this is as follows: First, peer device registration
+ * itself cannot be done in the message processing thread and must be delegated
+ * to another workqueue, otherwise if SCIF client probe, called during peer
+ * device registration, calls scif_connect(..), it will block the message
+ * processing thread causing a deadlock. Next, device_initialize is done in the
+ * "top-half" message processing thread and device_add in the "bottom-half"
+ * workqueue. If this is not done, SCIF_CNCT_REQ message processing executing
+ * concurrently with SCIF_INIT message processing is unable to get a reference
+ * on the peer device, thereby failing the connect request.
+ */
+void scif_peer_register_device(struct scif_dev *scifdev)
 {
-	struct scif_peer_dev *sdev = dev_to_scif_peer(d);
-	struct scif_dev *scifdev = &scif_dev[sdev->dnode];
+	int ret;
 
-	scif_cleanup_scifdev(scifdev);
-	kfree(sdev);
+	mutex_lock(&scifdev->lock);
+	ret = scif_peer_initialize_device(scifdev);
+	if (ret)
+		goto exit;
+	schedule_work(&scifdev->peer_add_work);
+exit:
+	mutex_unlock(&scifdev->lock);
 }
 
-struct scif_peer_dev *
-scif_peer_register_device(struct scif_dev *scifdev)
+int scif_peer_unregister_device(struct scif_dev *scifdev)
 {
-	int ret;
 	struct scif_peer_dev *spdev;
 
-	spdev = kzalloc(sizeof(*spdev), GFP_KERNEL);
-	if (!spdev)
-		return ERR_PTR(-ENOMEM);
-
-	spdev->dev.parent = scifdev->sdev->dev.parent;
-	spdev->dev.release = scif_peer_release_dev;
-	spdev->dnode = scifdev->node;
-	spdev->dev.bus = &scif_peer_bus;
+	mutex_lock(&scifdev->lock);
+	/* Flush work to ensure device register is complete */
+	flush_work(&scifdev->peer_add_work);
 
-	dev_set_name(&spdev->dev, "scif_peer-dev%u", spdev->dnode);
 	/*
-	 * device_register() causes the bus infrastructure to look for a
-	 * matching driver.
+	 * Continue holding scifdev->lock since theoretically unregister_device
+	 * can be called simultaneously from multiple threads
 	 */
-	ret = device_register(&spdev->dev);
-	if (ret)
-		goto free_spdev;
-	return spdev;
-free_spdev:
-	kfree(spdev);
-	return ERR_PTR(ret);
-}
-
-void scif_peer_unregister_device(struct scif_peer_dev *sdev)
-{
-	device_unregister(&sdev->dev);
+	spdev = rcu_dereference(scifdev->spdev);
+	if (!spdev) {
+		mutex_unlock(&scifdev->lock);
+		return -ENODEV;
+	}
+
+	RCU_INIT_POINTER(scifdev->spdev, NULL);
+	synchronize_rcu();
+	mutex_unlock(&scifdev->lock);
+
+	dev_dbg(&spdev->dev, "Removing peer dnode %d\n", spdev->dnode);
+	device_unregister(&spdev->dev);
+
+	mutex_lock(&scif_info.conflock);
+	scif_info.total--;
+	mutex_unlock(&scif_info.conflock);
+	return 0;
 }
 
 int scif_peer_bus_init(void)