1 files changed, 170 insertions, 0 deletions
diff --git a/network/trans/stmedit/sys/LwQueue.c b/network/trans/stmedit/sys/LwQueue.c
new file mode 100644
index 00000000..a88186c7
--- /dev/null
+++ b/network/trans/stmedit/sys/LwQueue.c
@@ -0,0 +1,170 @@
+/*++
+Copyright (c) Microsoft Corporation. All rights reserved
+
+Abstract:
+	Stream Edit Callout Driver Sample.
+	This file implements Light Weight queues using Worker Item routines.
+
+Environment:
+	Kernel mode
+
+--*/
+
+#include "LwQueue.h"
+
+IO_WORKITEM_ROUTINE     LwWorker;
+
+NTSTATUS
+LwInitializeQueue(
+    _In_  PVOID IoObject,
+    _Out_ PLW_QUEUE Queue,
+    _In_  PIO_WORKITEM_ROUTINE WorkerRoutine
+    )
+/*
+    Initializes Light Weight Queue data structures!
+*/
+{
+    RtlZeroMemory(Queue, sizeof(Queue[0]));
+
+    Queue->Head = &Queue->Dummy;
+    Queue->Tail = &Queue->Dummy;
+    Queue->WorkerScheduled = FALSE;
+
+    Queue->WorkerRoutine = WorkerRoutine;
+    Queue->IoObject = IoObject;
+
+    KeInitializeSpinLock(&Queue->Lock);
+
+    Queue->WorkItem =
+        ExAllocatePoolWithTag(
+        NonPagedPool, IoSizeofWorkItem(), STMEDIT_TAG_LQWI);
+
+    if (Queue->WorkItem == NULL) 
+	{
+        return STATUS_INSUFFICIENT_RESOURCES;
+    }
+
+    IoInitializeWorkItem(IoObject, Queue->WorkItem);
+    Queue->Initialized = TRUE;
+    return STATUS_SUCCESS;
+}
+
+VOID
+LwUninitializeQueue(
+    _Inout_ PLW_QUEUE Queue
+    )
+/*
+    De-Initializes the Light Weight Queue!
+*/
+{
+    if (Queue->Initialized == FALSE)
+	{
+        return;
+    }
+    
+    Queue->Initialized = FALSE;
+
+    IoUninitializeWorkItem(Queue->WorkItem);
+    ExFreePoolWithTag(Queue->WorkItem, STMEDIT_TAG_LQWI);
+    Queue->WorkItem = NULL;
+}
+
+__drv_functionClass(IO_WORKITEM_ROUTINE)
+__drv_requiresIRQL(PASSIVE_LEVEL)
+__drv_sameIRQL
+VOID
+LwWorker(
+    _In_ PDEVICE_OBJECT DeviceObject,
+    _In_opt_ PVOID Context
+    )
+/*
+    Queue processing workitem routine.
+    Drains the task queue and invokes OOB Workitem to process the tasks.
+*/
+{
+    PLW_ENTRY Entry;
+    PLW_QUEUE Queue = (PLW_QUEUE)Context;
+
+    UNREFERENCED_PARAMETER(DeviceObject);
+
+    NT_ASSERT(Queue != NULL);
+    Entry = LwDequeueAll(Queue);
+
+    //
+    // Why were we scheduled if there are no entries?
+    //
+    NT_ASSERT(Entry != NULL);
+
+    while (Entry != NULL)
+    {
+        //
+        // Invoke the caller's worker routine.
+        //
+        Queue->WorkerRoutine(DeviceObject, Entry);
+
+        //
+        // Check if any other entries were added while we were
+        // working.
+        //
+        Entry = LwDequeueAll(Queue);
+    }
+}
+
+VOID
+LwEnqueue(
+    _In_ PLW_QUEUE Queue,
+    _In_ PLW_ENTRY Entry
+    )
+/*
+    Queue a task into the task queue.
+*/
+{
+    KLOCK_QUEUE_HANDLE LockHandle;
+
+    NT_ASSERT(Entry != NULL);
+    NT_ASSERT(Queue != NULL);
+
+    KeAcquireInStackQueuedSpinLock(&Queue->Lock, &LockHandle);
+
+    Entry->Next = NULL;
+    Queue->Tail->Next = Entry;
+    Queue->Tail = Entry;
+
+    if (!Queue->WorkerScheduled) 
+	{
+        Queue->WorkerScheduled = TRUE;
+
+        IoQueueWorkItem(
+            Queue->WorkItem, LwWorker, DelayedWorkQueue, Queue);
+    }
+
+    KeReleaseInStackQueuedSpinLock(&LockHandle);
+}
+
+PLW_ENTRY
+LwDequeueAll(
+    _In_ PLW_QUEUE Queue
+    )
+{
+    KLOCK_QUEUE_HANDLE LockHandle;
+    PLW_ENTRY Entry = NULL;
+
+    KeAcquireInStackQueuedSpinLock(&Queue->Lock, &LockHandle);
+
+    NT_ASSERT(Queue->Head == &Queue->Dummy);
+
+    //
+    // Snap and return the entire queue contents.
+    //
+    Entry = Queue->Head->Next;
+    Queue->Head->Next = NULL;
+    Queue->Tail = Queue->Head;
+
+    if (Entry == NULL) 
+	{
+        Queue->WorkerScheduled = FALSE;
+    }
+
+    KeReleaseInStackQueuedSpinLock(&LockHandle);
+    return Entry;
+}