greybus: operation: fix callback handling and documentation
Fix up obsolete comments referring to null callback pointers for
synchronous operations, and make sure a callback is always provided when
sending a request.
Also document that the callback is responsible for dropping the initial
(and not necessarily final) reference to the operation.
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
diff --git a/drivers/staging/greybus/operation.c b/drivers/staging/greybus/operation.c
index 41a3deb..c64b2bf 100644
--- a/drivers/staging/greybus/operation.c
+++ b/drivers/staging/greybus/operation.c
@@ -244,10 +244,9 @@
struct gb_operation *operation;
operation = container_of(work, struct gb_operation, work);
- if (operation->callback) {
- operation->callback(operation);
- operation->callback = NULL;
- }
+
+ operation->callback(operation);
+
gb_operation_put(operation);
}
@@ -526,7 +525,6 @@
operation->errno = -EBADR; /* Initial value--means "never set" */
INIT_WORK(&operation->work, gb_operation_work);
- operation->callback = NULL; /* set at submit time */
init_completion(&operation->completion);
kref_init(&operation->kref);
@@ -632,16 +630,12 @@
}
/*
- * Send an operation request message. The caller has filled in
- * any payload so the request message is ready to go. If non-null,
- * the callback function supplied will be called when the response
- * message has arrived indicating the operation is complete. In
- * that case, the callback function is responsible for fetching the
- * result of the operation using gb_operation_result() if desired,
- * and dropping the final reference to (i.e., destroying) the
- * operation. A null callback function is used for a synchronous
- * request; in that case return from this function won't occur until
- * the operation is complete.
+ * Send an operation request message. The caller has filled in any payload so
+ * the request message is ready to go. The callback function supplied will be
+ * called when the response message has arrived indicating the operation is
+ * complete. In that case, the callback function is responsible for fetching
+ * the result of the operation using gb_operation_result() if desired, and
+ * dropping the initial reference to the operation.
*/
int gb_operation_request_send(struct gb_operation *operation,
gb_operation_callback callback)
@@ -650,6 +644,9 @@
struct gb_operation_msg_hdr *header;
unsigned int cycle;
+ if (!callback)
+ return -EINVAL;
+
if (connection->state != GB_CONNECTION_STATE_ENABLED)
return -ENOTCONN;
@@ -805,10 +802,8 @@
* request handler to be the operation's callback function.
*
* The last thing the handler does is send a response
- * message. The callback function is then cleared (in
- * gb_operation_work()). The original reference to the
- * operation will be dropped when the response has been
- * sent.
+ * message. The original reference to the operation will be
+ * dropped when the response has been sent.
*/
operation->callback = gb_operation_request_handle;
if (gb_operation_result_set(operation, -EINPROGRESS))