rtworkq: Avoid possible scenarios that an async callback could be called twice.

Consider a thread A running waiting_item_cancelable_callback() and a thread B running queue_cancel_item(),
which is the scenario from canceling a work item right after it gets submitted by RtwqPutWaitingWorkItem().
When the invoke_async_callback() call in queue_cancel_item() for item key with WAIT_ITEM_KEY_MASK in
thread B runs before the queue_release_pending_item() in waiting_item_cancelable_callback() in thread
A, the async callback is called the first time in queue_cancel_item() with RTWQ_E_OPERATION_CANCELLED,
then a second time in waiting_item_cancelable_callback(). We should check in queue_release_pending_item()
whether an item is already removed by queue_cancel_item() before calling async callbacks.

A different scenario could happen for scheduled_item_cancelable_callback() with the function ends
up calling its async callback even after it has been canceled by queue_cancel_item().
This commit is contained in:
Zhiyi Zhang 2024-02-23 17:12:04 +08:00 committed by Alexandre Julliard
parent f3bab6c5b7
commit 7865026f53

View file

@ -730,16 +730,22 @@ static HRESULT invoke_async_callback(IRtwqAsyncResult *result)
return hr;
}
static void queue_release_pending_item(struct work_item *item)
/* Return TRUE when the item is actually released by this function. The item could have been already
* removed from pending items when it got canceled. */
static BOOL queue_release_pending_item(struct work_item *item)
{
BOOL ret = FALSE;
EnterCriticalSection(&item->queue->cs);
if (item->key)
{
list_remove(&item->entry);
ret = TRUE;
item->key = 0;
IUnknown_Release(&item->IUnknown_iface);
}
LeaveCriticalSection(&item->queue->cs);
return ret;
}
static void CALLBACK waiting_item_callback(TP_CALLBACK_INSTANCE *instance, void *context, TP_WAIT *wait,
@ -761,9 +767,8 @@ static void CALLBACK waiting_item_cancelable_callback(TP_CALLBACK_INSTANCE *inst
TRACE("result object %p.\n", item->result);
queue_release_pending_item(item);
invoke_async_callback(item->result);
if (queue_release_pending_item(item))
invoke_async_callback(item->result);
IUnknown_Release(&item->IUnknown_iface);
}
@ -785,9 +790,8 @@ static void CALLBACK scheduled_item_cancelable_callback(TP_CALLBACK_INSTANCE *in
TRACE("result object %p.\n", item->result);
queue_release_pending_item(item);
invoke_async_callback(item->result);
if (queue_release_pending_item(item))
invoke_async_callback(item->result);
IUnknown_Release(&item->IUnknown_iface);
}