Windows Driver: Optimize spinlock usage in CompleteIrpWorkItemRoutine

Reduce the critical section protected by spinlock to only cover the list manipulation operation. Move the ActiveWorkItems counter decrement outside the spinlock using InterlockedDecrement, and separate event signaling from the locked section.
This change minimizes time spent at raised IRQL (DISPATCH_LEVEL) and reduces potential for lock contention.

src/Driver/EncryptedIoQueue.c

@@ -271,6 +271,7 @@ static VOID CompleteIrpWorkItemRoutine(PDEVICE_OBJECT DeviceObject, PVOID Contex
 	PCOMPLETE_IRP_WORK_ITEM workItem = (PCOMPLETE_IRP_WORK_ITEM)Context;
 	EncryptedIoQueueItem* item = (EncryptedIoQueueItem * ) workItem->Item;
 	EncryptedIoQueue* queue = item->Queue;
+	KIRQL oldIrql;
 	UNREFERENCED_PARAMETER(DeviceObject);
 
 	__try
@@ -283,19 +284,14 @@ static VOID CompleteIrpWorkItemRoutine(PDEVICE_OBJECT DeviceObject, PVOID Contex
 	}
 	__finally
 	{
-		// Return the work item to the free list
-		KIRQL oldIrql;
-		KeAcquireSpinLock(&queue->WorkItemLock, &oldIrql);
-
-		// Decrement ActiveWorkItems
-		LONG activeWorkItems = InterlockedDecrement(&queue->ActiveWorkItems);
-
 		// If no active work items remain, signal the event
-		if (activeWorkItems == 0)
+		if (InterlockedDecrement(&queue->ActiveWorkItems) == 0)
 		{
 			KeSetEvent(&queue->NoActiveWorkItemsEvent, IO_NO_INCREMENT, FALSE);
 		}
 
+		// Return the work item to the free list
+		KeAcquireSpinLock(&queue->WorkItemLock, &oldIrql);
 		InsertTailList(&queue->FreeWorkItemsList, &workItem->ListEntry);
 		KeReleaseSpinLock(&queue->WorkItemLock, oldIrql);