Commit abe9a300 authored by Alex Elder's avatar Alex Elder Committed by Greg Kroah-Hartman
Browse files

greybus: first operation error prevails 



If an operation already has an error result recorded, don't
overwrite it with a new error code.

In order to ensure a request completes exactly once, return a
Boolean indicating whether setting the result was successful.  If
two threads are racing to complete an operation (for example if a
slow-but-normal response message arrives at the same time timeout
processing commences) only the one that sets the final result
will finish its activity.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <greg@kroah.com>
parent ba986b5a

drivers/staging/greybus/operation.c

+15 −11
Original line number Diff line number Diff line
@@ -66,9 +66,12 @@ struct gb_operation_msg_hdr { 
/* XXX Could be per-host device, per-module, or even per-connection */

static DEFINE_SPINLOCK(gb_operations_lock);



static void gb_operation_result_set(struct gb_operation *operation, int result)

static bool gb_operation_result_set(struct gb_operation *operation, int result)

{

	if (operation->errno)

		return false;

	operation->errno = result;

	return true;

}



int gb_operation_result(struct gb_operation *operation)
@@ -174,7 +177,7 @@ static void gb_operation_request_handle(struct gb_operation *operation) 


	gb_connection_err(operation->connection,

		"unexpected incoming request type 0x%02hhx\n", header->type);

	gb_operation_result_set(operation, -EPROTONOSUPPORT);

	(void)gb_operation_result_set(operation, -EPROTONOSUPPORT);

}

#endif
@@ -512,7 +515,7 @@ greybus_data_sent(struct greybus_host_device *hd, void *header, int status) 
	/* XXX Right now we assume we're an outgoing request */

	message = gb_hd_message_find(hd, header);

	operation = message->operation;

	gb_operation_result_set(operation, status);

	if (gb_operation_result_set(operation, status))

		queue_work(gb_operation_workqueue, &operation->work);

}

EXPORT_SYMBOL_GPL(greybus_data_sent);
@@ -538,7 +541,7 @@ void gb_connection_recv_request(struct gb_connection *connection, 
	memcpy(operation->request->header, data, size);



	/* XXX Right now this will just complete the operation */

	gb_operation_result_set(operation, -ENOSYS);

	if (gb_operation_result_set(operation, -ENOSYS))

		queue_work(gb_operation_workqueue, &operation->work);

}
@@ -582,7 +585,7 @@ static void gb_connection_recv_response(struct gb_connection *connection, 
		memcpy(message->header, data, size);



	/* The rest will be handled in work queue context */

	gb_operation_result_set(operation, result);

	if (gb_operation_result_set(operation, result))

		queue_work(gb_operation_workqueue, &operation->work);

}
@@ -630,10 +633,11 @@ void gb_connection_recv(struct gb_connection *connection, 
 */

void gb_operation_cancel(struct gb_operation *operation, int errno)

{

	gb_operation_result_set(operation, errno);

	if (gb_operation_result_set(operation, errno)) {

		gb_message_cancel(operation->request);

		gb_message_cancel(operation->response);

	}

}



/**

 * gb_operation_sync: implement a "simple" synchronous gb operation.