greybus: op_cycle doesn't need to be atomic

We can update a connection's operation id counter under spinlock,
and thereby avoid the need to maintain it in an atomic variable.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/connection.c

@@ -210,7 +210,6 @@ struct gb_connection *gb_connection_create(struct gb_interface *interface,
 
 	INIT_LIST_HEAD(&connection->operations);
 	INIT_LIST_HEAD(&connection->pending);
-	atomic_set(&connection->op_cycle, 0);
 
 	return connection;
 }
@@ -244,11 +243,6 @@ void gb_connection_destroy(struct gb_connection *connection)
 	device_del(&connection->dev);
 }
 
-u16 gb_connection_operation_id(struct gb_connection *connection)
-{
-	return (u16)(atomic_inc_return(&connection->op_cycle) & (int)U16_MAX);
-}
-
 void gb_connection_err(struct gb_connection *connection, const char *fmt, ...)
 {
 	struct va_format vaf;

drivers/staging/greybus/connection.h

@@ -35,9 +35,9 @@ struct gb_connection {
 
 	enum gb_connection_state	state;
 
+	u16				op_cycle;
 	struct list_head		operations;
 	struct list_head		pending;	/* awaiting reponse */
-	atomic_t			op_cycle;
 
 	void				*private;
 };
@@ -53,8 +53,6 @@ void gb_connection_exit(struct gb_connection *connection);
 struct gb_connection *gb_hd_connection_find(struct greybus_host_device *hd,
 				u16 cport_id);
 
-u16 gb_connection_operation_id(struct gb_connection *connection);
-
 __printf(2, 3)
 void gb_connection_err(struct gb_connection *connection, const char *fmt, ...);
 

drivers/staging/greybus/operation.c

@@ -61,17 +61,18 @@ static void gb_pending_operation_insert(struct gb_operation *operation)
 	struct gb_connection *connection = operation->connection;
 	struct gb_operation_msg_hdr *header;
 
-	/* Assign the operation's id, and store it in the header of
-	 * the request message header.
+	/*
+	 * Assign the operation's id and move it into its
+	 * connection's pending list.
 	 */
-	operation->id = gb_connection_operation_id(connection);
-	header = operation->request->transfer_buffer;
-	header->id = cpu_to_le16(operation->id);
-
-	/* Insert the operation into its connection's pending list */
 	spin_lock_irq(&gb_operations_lock);
+	operation->id = ++connection->op_cycle;
 	list_move_tail(&operation->links, &connection->pending);
 	spin_unlock_irq(&gb_operations_lock);
+
+	/* Store the operation id in the request header */
+	header = operation->request->transfer_buffer;
+	header->id = cpu_to_le16(operation->id);
 }
 
 static void gb_pending_operation_remove(struct gb_operation *operation)