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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>
This commit is contained in:
Johan Hovold 2015-03-27 12:41:12 +01:00 committed by Greg Kroah-Hartman
parent d506283491
commit 37754030b0
1 changed files with 14 additions and 19 deletions
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33
drivers/staging/greybus/operation.c
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@ -244,10 +244,9 @@ static void gb_operation_work(struct work_struct *work)
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 @@ gb_operation_create_common(struct gb_connection *connection, u8 type,
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 @@ static void gb_operation_sync_callback(struct gb_operation *operation)
}
/*
* 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 @@ int gb_operation_request_send(struct gb_operation *operation,
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 @@ static void gb_connection_recv_request(struct gb_connection *connection,
* 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))