firewire: cdev: always wait for outbound transactions to complete

We must not use fw_cancel_transaction() because it cannot correctly
abort still-active transactions.  The only place in core-cdev where this
matters is when the file is released.  Instead of trying to abort the
transactions, we wait for them to complete normally, i.e., until all
outbound transaction resources have been removed from the IDR tree.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: "Stefan Richter" <stefanr@s5r6.in-berlin.de>

drivers/firewire/core-cdev.c

@@ -64,6 +64,7 @@ struct client {
 	struct idr resource_idr;
 	struct list_head event_list;
 	wait_queue_head_t wait;
+	wait_queue_head_t tx_flush_wait;
 	u64 bus_reset_closure;
 
 	struct fw_iso_context *iso_context;
@@ -251,6 +252,7 @@ static int fw_device_op_open(struct inode *inode, struct file *file)
 	idr_init(&client->resource_idr);
 	INIT_LIST_HEAD(&client->event_list);
 	init_waitqueue_head(&client->wait);
+	init_waitqueue_head(&client->tx_flush_wait);
 	INIT_LIST_HEAD(&client->phy_receiver_link);
 	kref_init(&client->kref);
 
@@ -520,10 +522,6 @@ static int release_client_resource(struct client *client, u32 handle,
 static void release_transaction(struct client *client,
 				struct client_resource *resource)
 {
-	struct outbound_transaction_resource *r = container_of(resource,
-			struct outbound_transaction_resource, resource);
-
-	fw_cancel_transaction(client->device->card, &r->transaction);
 }
 
 static void complete_transaction(struct fw_card *card, int rcode,
@@ -540,16 +538,9 @@ static void complete_transaction(struct fw_card *card, int rcode,
 		memcpy(rsp->data, payload, rsp->length);
 
 	spin_lock_irqsave(&client->lock, flags);
-	/*
-	 * 1. If called while in shutdown, the idr tree must be left untouched.
-	 *    The idr handle will be removed and the client reference will be
-	 *    dropped later.
-	 */
-	if (!client->in_shutdown) {
-		idr_remove(&client->resource_idr, e->r.resource.handle);
-		/* Drop the idr's reference */
-		client_put(client);
-	}
+	idr_remove(&client->resource_idr, e->r.resource.handle);
+	if (client->in_shutdown)
+		wake_up(&client->tx_flush_wait);
 	spin_unlock_irqrestore(&client->lock, flags);
 
 	rsp->type = FW_CDEV_EVENT_RESPONSE;
@@ -569,6 +560,8 @@ static void complete_transaction(struct fw_card *card, int rcode,
 		queue_event(client, &e->event, rsp, sizeof(*rsp) + rsp->length,
 			    NULL, 0);
 
+	/* Drop the idr's reference */
+	client_put(client);
 	/* Drop the transaction callback's reference */
 	client_put(client);
 }
@@ -1672,6 +1665,25 @@ static int fw_device_op_mmap(struct file *file, struct vm_area_struct *vma)
 	return ret;
 }
 
+static int is_outbound_transaction_resource(int id, void *p, void *data)
+{
+	struct client_resource *resource = p;
+
+	return resource->release == release_transaction;
+}
+
+static int has_outbound_transactions(struct client *client)
+{
+	int ret;
+
+	spin_lock_irq(&client->lock);
+	ret = idr_for_each(&client->resource_idr,
+			   is_outbound_transaction_resource, NULL);
+	spin_unlock_irq(&client->lock);
+
+	return ret;
+}
+
 static int shutdown_resource(int id, void *p, void *data)
 {
 	struct client_resource *resource = p;
@@ -1707,6 +1719,8 @@ static int fw_device_op_release(struct inode *inode, struct file *file)
 	client->in_shutdown = true;
 	spin_unlock_irq(&client->lock);
 
+	wait_event(client->tx_flush_wait, !has_outbound_transactions(client));
+
 	idr_for_each(&client->resource_idr, shutdown_resource, client);
 	idr_remove_all(&client->resource_idr);
 	idr_destroy(&client->resource_idr);