From 1f041b444485c5e6b302df49293ba1607075fe76 Mon Sep 17 00:00:00 2001
From: Dibyamartanda Samanta <dibyaxp@noreply.codingworkshop.git>
Date: Sat, 25 May 2024 10:15:26 +0200
Subject: [PATCH] Update NTOSKRNL/CC/cclazywriter.cpp

---
 NTOSKRNL/CC/cclazywriter.cpp | 89 +++++++++++++++++++++++++++++-------
 1 file changed, 73 insertions(+), 16 deletions(-)

diff --git a/NTOSKRNL/CC/cclazywriter.cpp b/NTOSKRNL/CC/cclazywriter.cpp
index 33035ab..bfd7c0c 100644
--- a/NTOSKRNL/CC/cclazywriter.cpp
+++ b/NTOSKRNL/CC/cclazywriter.cpp
@@ -1019,7 +1019,74 @@ NTSTATUS CcWaitForCurrentLazyWriterActivity()
 
     return result;
 }
+VOID VECTORCALL CcReEngageWorkerThreads(
+    ULONG NormalThreadsToActivate, 
+    ULONG ExtraWriteBehindThreadsToActivate
+)
+{
+    ULONG i;
+    PLIST_ENTRY currentThreadEntry;
+    PLIST_ENTRY nextThreadEntry;
+	ULONG j;
+    PLIST_ENTRY currentExtraThreadEntry;
+    PLIST_ENTRY nextExtraThreadEntry;
 
+    /*Activate the required number of normal worker threads*/
+    for (i = 0; i < NormalThreadsToActivate; ++i)
+    {
+        
+        currentThreadEntry = CcIdleWorkerThreadList.Flink;
+     
+        if (IsListEmpty(&CcIdleWorkerThreadList))
+            break;
+        nextThreadEntry = currentThreadEntry->Flink;
+
+        /*Check if List is corrupt*/
+        if (currentThreadEntry->Blink != &CcIdleWorkerThreadList || 
+            nextThreadEntry->Blink != currentThreadEntry)
+        {
+            __fastfail(3u);
+        }
+
+        /* Move to the next thread in the idle list*/
+        ++CcNumberActiveWorkerThreads;
+        CcIdleWorkerThreadList.Flink = nextThreadEntry;
+        nextThreadEntry->Blink = &CcIdleWorkerThreadList;
+        /* Detach the current = thread from the list and schedule it for work*/
+        currentThreadEntry->Flink = NULL;
+        ExQueueWorkItem(currentThreadEntry, CriticalWorkQueue);
+    }
+
+    
+
+    for (j = 0; j < ExtraWriteBehindThreadsToActivate; ++j)
+    {
+        /*first thread in the idle extra write-behind list*/
+        currentExtraThreadEntry = CcIdleExtraWriteBehindThreadList.Flink;
+        
+        
+        if (IsListEmpty(&CcIdleExtraWriteBehindThreadList))
+            break;
+        
+        nextExtraThreadEntry = currentExtraThreadEntry->Flink;
+
+        /*Consistency check to prevent corrupt list operations*/
+        if (currentExtraThreadEntry->Blink != &CcIdleExtraWriteBehindThreadList || 
+            nextExtraThreadEntry->Blink != currentExtraThreadEntry)
+        {
+            __fastfail(3u);
+        }
+
+        /* Move to the next thread in the idle extra list*/
+        ++CcActiveExtraWriteBehindThreads;
+        CcIdleExtraWriteBehindThreadList.Flink = nextExtraThreadEntry;
+        nextExtraThreadEntry->Blink = &CcIdleExtraWriteBehindThreadList;
+        
+        /* Detach the current extra thread from the list and schedule it for work*/
+        currentExtraThreadEntry->Flink = NULL;
+        ExQueueWorkItem(currentExtraThreadEntry, CriticalWorkQueue);
+    }
+}
 VOID 
 NTAPI 
 CcWorkerThread(PVOID Parameter)
@@ -1037,8 +1104,7 @@ CcWorkerThread(PVOID Parameter)
 
     DPRINT("CcWorkerThread: WorkItem");
 
-    IoStatus.Status = STATUS_SUCCESS;
-    IoStatus.Information = 0;
+    
 
     /* Loop till we have jobs */
     while (TRUE)
@@ -1051,6 +1117,7 @@ CcWorkerThread(PVOID Parameter)
         {
             CcQueueThrottle = FALSE;
             DropThrottle = FALSE;
+            CcReEngageWorkerThreads(CcThreadsActiveBeforeThrottle, CcExtraThreadsActiveBeforeThrottle);
         }
 
         if (IoStatus.Information == 0x8A5E)
@@ -1090,10 +1157,7 @@ CcWorkerThread(PVOID Parameter)
             break;
         }
 
-        /* Get our work item, if someone is waiting for us to finish
-           and we're not the only thread in queue then, quit running to let the others do
-           and throttle so that noone starts till current activity is over
-        */
+        
         WorkEntry = CONTAINING_RECORD(Entry->Flink, WORK_QUEUE_ENTRY, WorkQueueLinks);
 
         if (WorkEntry->Function == SetDone && CcNumberActiveWorkerThreads > 1)
@@ -1108,10 +1172,8 @@ CcWorkerThread(PVOID Parameter)
         /* Remove current entry */
         RemoveHeadList(Entry);
 
-        /* Unlock queues */
         KeReleaseQueuedSpinLock(LockQueueWorkQueueLock, OldIrql);
 
-        /* And handle it */
         __try
         {
             switch (WorkEntry->Function)
@@ -1149,11 +1211,9 @@ CcWorkerThread(PVOID Parameter)
                 PsGetCurrentThread()->MemoryMaker = 0;
         }
 
-        /* Handle for WriteBehind */
         if (IoStatus.Information == 0x8A5E)
             continue;
 
-        /* Release the current element and continue */
 
         LookasideList = Prcb->PPLookasideList[5].P;
         InterlockedIncrement(&LookasideList->TotalFrees); // Use interlocked increment
@@ -1183,21 +1243,18 @@ CcWorkerThread(PVOID Parameter)
         InterlockedIncrement(&LookasideList->FreeMisses);
         LookasideList->Free(WorkEntry);
     }
-    /* Our thread is available again */
+    /* UNlock QUes*/
     InsertTailList(&CcIdleWorkerThreadList, &WorkItem->List);
 
-    /* One less worker */
     CcNumberActiveWorkerThreads--;
 
     /* Unlock queues */
     KeReleaseQueuedSpinLock(LockQueueWorkQueueLock, OldIrql);
 
-    /* If there are pending write openations and we have at least 20 dirty pages */
+    
     if (!IsListEmpty(&CcDeferredWrites) && CcTotalDirtyPages >= 20)
     {
-        /* And if we performed a write operation previously,
-           then stress the system a bit and reschedule a scan to find stuff to write
-        */
+        
         if (WritePerformed)
             CcLazyWriteScan();
     }