[VIDEOPRT] Use a spinlock instead of mutex

Author: DarkFire01

win32ss/drivers/videoprt/resource.c

@@ -993,9 +993,18 @@ VideoPortVerifyAccessRanges(
     PCM_PARTIAL_RESOURCE_DESCRIPTOR PartialDescriptor;
     ULONG i;
     NTSTATUS Status;
+    KIRQL OldIrql;
 
     TRACE_(VIDEOPRT, "VideoPortVerifyAccessRanges\n");
 
+    /* This function requires PASSIVE_LEVEL for IoReportResourceUsage and PagedPool allocations */
+    if (KeGetCurrentIrql() != PASSIVE_LEVEL)
+    {
+        ERR_(VIDEOPRT, "VideoPortVerifyAccessRanges called at IRQL %d (requires PASSIVE_LEVEL)\n",
+             KeGetCurrentIrql());
+        return ERROR_INVALID_PARAMETER;
+    }
+
     /* Verify parameters */
     if (NumAccessRanges && !AccessRanges)
         return ERROR_INVALID_PARAMETER;
@@ -1009,25 +1018,15 @@ VideoPortVerifyAccessRanges(
         /* If releasing VGA device resources, clear tracked ranges */
         if (DeviceExtension->IsVgaDriver)
         {
-            /* Mutexes can only be acquired at PASSIVE_LEVEL */
-            if (KeGetCurrentIrql() == PASSIVE_LEVEL)
-            {
-                KeWaitForMutexObject(&VgaSyncLock, Executive, KernelMode, FALSE, NULL);
-                if (VgaRanges)
-                {
-                    ExFreePoolWithTag(VgaRanges, TAG_VIDEO_PORT);
-                    VgaRanges = NULL;
-                }
-                NumOfVgaRanges = 0;
-                VgaDeviceExtension = NULL;
-                KeReleaseMutex(&VgaSyncLock, FALSE);
-            }
-            else
+            KeAcquireSpinLock(&VgaSyncLock, &OldIrql);
+            if (VgaRanges)
             {
-                /* Can't acquire mutex at elevated IRQL; skip VGA tracking cleanup */
-                WARN_(VIDEOPRT, "VideoPortVerifyAccessRanges: Cannot release VGA resources at IRQL %d\n",
-                      KeGetCurrentIrql());
+                ExFreePoolWithTag(VgaRanges, TAG_VIDEO_PORT);
+                VgaRanges = NULL;
             }
+            NumOfVgaRanges = 0;
+            VgaDeviceExtension = NULL;
+            KeReleaseSpinLock(&VgaSyncLock, OldIrql);
         }
         return NO_ERROR;
     }
@@ -1198,28 +1197,26 @@ VideoPortVerifyAccessRanges(
         /* Track VGA access ranges on success for fallback handling */
         if (DeviceExtension->IsVgaDriver)
         {
-            if (KeGetCurrentIrql() == PASSIVE_LEVEL)
+            KeAcquireSpinLock(&VgaSyncLock, &OldIrql);
+            if (VgaRanges)
+            {
+                ExFreePoolWithTag(VgaRanges, TAG_VIDEO_PORT);
+                VgaRanges = NULL;
+                NumOfVgaRanges = 0;
+            }
+            if (NumAccessRanges)
             {
-                KeWaitForMutexObject(&VgaSyncLock, Executive, KernelMode, FALSE, NULL);
+                SIZE_T sz = NumAccessRanges * sizeof(VIDEO_ACCESS_RANGE);
+                /* Note: We're at PASSIVE_LEVEL, so PagedPool allocation is safe */
+                VgaRanges = ExAllocatePoolWithTag(PagedPool, sz, TAG_VIDEO_PORT);
                 if (VgaRanges)
                 {
-                    ExFreePoolWithTag(VgaRanges, TAG_VIDEO_PORT);
-                    VgaRanges = NULL;
-                    NumOfVgaRanges = 0;
-                }
-                if (NumAccessRanges)
-                {
-                    SIZE_T sz = NumAccessRanges * sizeof(VIDEO_ACCESS_RANGE);
-                    VgaRanges = ExAllocatePoolWithTag(PagedPool, sz, TAG_VIDEO_PORT);
-                    if (VgaRanges)
-                    {
-                        RtlCopyMemory(VgaRanges, AccessRanges, sz);
-                        NumOfVgaRanges = NumAccessRanges;
-                        VgaDeviceExtension = DeviceExtension;
-                    }
+                    RtlCopyMemory(VgaRanges, AccessRanges, sz);
+                    NumOfVgaRanges = NumAccessRanges;
+                    VgaDeviceExtension = DeviceExtension;
                 }
-                KeReleaseMutex(&VgaSyncLock, FALSE);
             }
+            KeReleaseSpinLock(&VgaSyncLock, OldIrql);
         }
         /* Leave VGA detect phase after first successful claim */
         DeviceExtension->IsVgaDetect = FALSE;

win32ss/drivers/videoprt/videoprt.c

@@ -42,7 +42,7 @@ BOOLEAN VideoPortUseNewKey = FALSE;
 
 KSPIN_LOCK HwResetAdaptersLock;
 RTL_STATIC_LIST_HEAD(HwResetAdaptersList);
-KMUTEX VgaSyncLock;
+KSPIN_LOCK VgaSyncLock;
 PVIDEO_PORT_DEVICE_EXTENSION VgaDeviceExtension = NULL;
 PVIDEO_ACCESS_RANGE VgaRanges = NULL;
 ULONG NumOfVgaRanges = 0;
@@ -435,6 +435,7 @@ IntVideoPortFindAdapter(
     UCHAR Again = FALSE;
     BOOL LegacyDetection = FALSE;
     BOOLEAN VgaResourcesReleased = FALSE;
+    KIRQL OldIrql;
 
     DeviceExtension = (PVIDEO_PORT_DEVICE_EXTENSION)DeviceObject->DeviceExtension;
     DeviceExtension->IsVgaDriver = IntIsVgaSaveDriverName(DriverObject);
@@ -489,14 +490,14 @@ IntVideoPortFindAdapter(
      /* If we already have a VGA miniport and are about to probe for additional adapters,
       * release its resources temporarily so conflicts are visible during detection.
       * We'll reclaim them later if no new adapter successfully claims them. */
-    KeWaitForMutexObject(&VgaSyncLock, Executive, KernelMode, FALSE, NULL);
+    KeAcquireSpinLock(&VgaSyncLock, &OldIrql);
     if (VgaDeviceExtension)
     {
         INFO_(VIDEOPRT, "Temporarily releasing VGA resources for adapter probing\n");
         IntVideoPortReleaseResources(VgaDeviceExtension);
         VgaResourcesReleased = TRUE;
     }
-    KeReleaseMutex(&VgaSyncLock, FALSE);
+    KeReleaseSpinLock(&VgaSyncLock, OldIrql);
 
     if (LegacyDetection)
     {
@@ -616,12 +617,12 @@ IntVideoPortFindAdapter(
 
     if (DeviceExtension->IsVgaDriver)
     {
-        KeWaitForMutexObject(&VgaSyncLock, Executive, KernelMode, FALSE, NULL);
+        KeAcquireSpinLock(&VgaSyncLock, &OldIrql);
         if (VgaDeviceExtension == NULL)
         {
             VgaDeviceExtension = DeviceExtension;
         }
-        KeReleaseMutex(&VgaSyncLock, FALSE);
+        KeReleaseSpinLock(&VgaSyncLock, OldIrql);
     }
 
     DeviceExtension->IsVgaDetect = FALSE;
@@ -669,15 +670,12 @@ IntVideoPortFindAdapter(
         {
             /* Another driver has taken VGA resources; drop fallback state */
             WARN_(VIDEOPRT, "VGA reclaim failed (vpStatus=0x%X); releasing fallback state\n", vr);
-            if (KeGetCurrentIrql() == PASSIVE_LEVEL)
-            {
-                KeWaitForMutexObject(&VgaSyncLock, Executive, KernelMode, FALSE, NULL);
-                ExFreePoolWithTag(VgaRanges, TAG_VIDEO_PORT);
-                VgaRanges = NULL;
-                NumOfVgaRanges = 0;
-                VgaDeviceExtension = NULL;
-                KeReleaseMutex(&VgaSyncLock, FALSE);
-            }
+            KeAcquireSpinLock(&VgaSyncLock, &OldIrql);
+            ExFreePoolWithTag(VgaRanges, TAG_VIDEO_PORT);
+            VgaRanges = NULL;
+            NumOfVgaRanges = 0;
+            VgaDeviceExtension = NULL;
+            KeReleaseSpinLock(&VgaSyncLock, OldIrql);
         }
         else
         {
@@ -943,7 +941,7 @@ VideoPortInitialize(
     {
         FirstInitialization = TRUE;
         KeInitializeMutex(&VideoPortInt10Mutex, 0);
-        KeInitializeMutex(&VgaSyncLock, 0);
+        KeInitializeSpinLock(&VgaSyncLock);
         KeInitializeSpinLock(&HwResetAdaptersLock);
         IntLoadRegistryParameters();
     }

win32ss/drivers/videoprt/videoprt.h

@@ -262,7 +262,7 @@ extern BOOLEAN VideoPortUseNewKey;
 
 extern KSPIN_LOCK HwResetAdaptersLock;
 extern LIST_ENTRY HwResetAdaptersList;
-extern KMUTEX VgaSyncLock;
+extern KSPIN_LOCK VgaSyncLock;
 extern PVIDEO_PORT_DEVICE_EXTENSION VgaDeviceExtension;
 extern PVIDEO_ACCESS_RANGE VgaRanges;
 extern ULONG NumOfVgaRanges;