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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: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
This commit is contained in:
Alex Elder 2014-11-25 11:33:14 -06:00 committed by Greg Kroah-Hartman
parent ba986b5ab9
commit abe9a3006f
1 changed files with 15 additions and 11 deletions
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16
drivers/staging/greybus/operation.c
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@ -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.