greybus: operation: use per-connection work queues

Replace the global operation work queue with per-connection work queues.

There is no need to keep operations strictly ordered across connections,
something which only adds unnecessary latency.
Tested-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/connection.c

@@ -7,6 +7,8 @@
  * Released under the GPLv2 only.
  */
 
+#include <linux/workqueue.h>
+
 #include "greybus.h"
 
 static DEFINE_SPINLOCK(gb_connections_lock);
@@ -99,6 +101,7 @@ static void gb_connection_release(struct device *dev)
 {
 	struct gb_connection *connection = to_gb_connection(dev);
 
+	destroy_workqueue(connection->wq);
 	kfree(connection);
 }
 
@@ -190,6 +193,11 @@ gb_connection_create_range(struct greybus_host_device *hd,
 	spin_lock_init(&connection->lock);
 	INIT_LIST_HEAD(&connection->operations);
 
+	connection->wq = alloc_workqueue("%s:%d", WQ_UNBOUND, 1,
+					 dev_name(parent), cport_id);
+	if (!connection->wq)
+		goto err_free_connection;
+
 	connection->dev.parent = parent;
 	connection->dev.bus = &greybus_bus_type;
 	connection->dev.type = &greybus_connection_type;
@@ -227,6 +235,8 @@ gb_connection_create_range(struct greybus_host_device *hd,
 
 	return connection;
 
+err_free_connection:
+	kfree(connection);
 err_remove_ida:
 	ida_simple_remove(id_map, hd_cport_id);
 

drivers/staging/greybus/connection.h

@@ -39,6 +39,8 @@ struct gb_connection {
 	enum gb_connection_state	state;
 	struct list_head		operations;
 
+	struct workqueue_struct		*wq;
+
 	atomic_t			op_cycle;
 
 	void				*private;

drivers/staging/greybus/operation.c

@@ -19,9 +19,6 @@
 static struct kmem_cache *gb_operation_cache;
 static struct kmem_cache *gb_message_cache;
 
-/* Workqueue to handle Greybus operation completions. */
-static struct workqueue_struct *gb_operation_workqueue;
-
 /* Wait queue for synchronous cancellations. */
 static DECLARE_WAIT_QUEUE_HEAD(gb_operation_cancellation_queue);
 
@@ -800,7 +797,7 @@ void greybus_message_sent(struct greybus_host_device *hd,
 		gb_operation_put(operation);
 	} else if (status) {
 		if (gb_operation_result_set(operation, status))
-			queue_work(gb_operation_workqueue, &operation->work);
+			queue_work(connection->wq, &operation->work);
 	}
 }
 EXPORT_SYMBOL_GPL(greybus_message_sent);
@@ -837,7 +834,7 @@ static void gb_connection_recv_request(struct gb_connection *connection,
 	 * request handler returns.
 	 */
 	if (gb_operation_result_set(operation, -EINPROGRESS))
-		queue_work(gb_operation_workqueue, &operation->work);
+		queue_work(connection->wq, &operation->work);
 }
 
 /*
@@ -877,7 +874,7 @@ static void gb_connection_recv_response(struct gb_connection *connection,
 	/* The rest will be handled in work queue context */
 	if (gb_operation_result_set(operation, errno)) {
 		memcpy(message->header, data, size);
-		queue_work(gb_operation_workqueue, &operation->work);
+		queue_work(connection->wq, &operation->work);
 	}
 
 	gb_operation_put(operation);
@@ -931,12 +928,14 @@ void gb_connection_recv(struct gb_connection *connection,
  */
 void gb_operation_cancel(struct gb_operation *operation, int errno)
 {
+	struct gb_connection *connection = operation->connection;
+
 	if (WARN_ON(gb_operation_is_incoming(operation)))
 		return;
 
 	if (gb_operation_result_set(operation, errno)) {
 		gb_message_cancel(operation->request);
-		queue_work(gb_operation_workqueue, &operation->work);
+		queue_work(connection->wq, &operation->work);
 	}
 
 	atomic_inc(&operation->waiters);
@@ -1043,15 +1042,8 @@ int __init gb_operation_init(void)
 	if (!gb_operation_cache)
 		goto err_destroy_message_cache;
 
-	gb_operation_workqueue = alloc_workqueue("greybus_operation",
-				WQ_UNBOUND, 1);
-	if (!gb_operation_workqueue)
-		goto err_operation;
-
 	return 0;
-err_operation:
-	kmem_cache_destroy(gb_operation_cache);
-	gb_operation_cache = NULL;
+
 err_destroy_message_cache:
 	kmem_cache_destroy(gb_message_cache);
 	gb_message_cache = NULL;
@@ -1061,8 +1053,6 @@ int __init gb_operation_init(void)
 
 void gb_operation_exit(void)
 {
-	destroy_workqueue(gb_operation_workqueue);
-	gb_operation_workqueue = NULL;
 	kmem_cache_destroy(gb_operation_cache);
 	gb_operation_cache = NULL;
 	kmem_cache_destroy(gb_message_cache);