[ISAPNP] Allocate the Read Port resources on demand

This will simplify failure paths and reduce memory usage

drivers/bus/isapnp/isapnp.c

@@ -1038,9 +1038,8 @@ IsaForwardOrIgnore(
 }
 
 CODE_SEG("PAGE")
-NTSTATUS
+PIO_RESOURCE_REQUIREMENTS_LIST
 IsaPnpCreateReadPortDORequirements(
-    _In_ PISAPNP_PDO_EXTENSION PdoExt,
     _In_opt_ ULONG SelectedReadPort)
 {
     ULONG ResourceCount, ListSize, i;
@@ -1087,7 +1086,7 @@ IsaPnpCreateReadPortDORequirements(
                sizeof(IO_RESOURCE_DESCRIPTOR) * (ResourceCount - 1);
     RequirementsList = ExAllocatePoolZero(PagedPool, ListSize, TAG_ISAPNP);
     if (!RequirementsList)
-        return STATUS_NO_MEMORY;
+        return NULL;
 
     RequirementsList->ListSize = ListSize;
     RequirementsList->AlternativeLists = 1;
@@ -1182,15 +1181,12 @@ IsaPnpCreateReadPortDORequirements(
         }
     }
 
-    PdoExt->RequirementsList = RequirementsList;
+    return RequirementsList;
-    return STATUS_SUCCESS;
 }
 
-static
 CODE_SEG("PAGE")
-NTSTATUS
+PCM_RESOURCE_LIST
-IsaPnpCreateReadPortDOResources(
+IsaPnpCreateReadPortDOResources(VOID)
-    _In_ PISAPNP_PDO_EXTENSION PdoExt)
 {
     const USHORT Ports[] = { ISAPNP_WRITE_DATA, ISAPNP_ADDRESS };
     ULONG ListSize, i;
@@ -1203,7 +1199,7 @@ IsaPnpCreateReadPortDOResources(
                sizeof(CM_PARTIAL_RESOURCE_DESCRIPTOR) * (RTL_NUMBER_OF(Ports) - 1);
     ResourceList = ExAllocatePoolZero(PagedPool, ListSize, TAG_ISAPNP);
     if (!ResourceList)
-        return STATUS_NO_MEMORY;
+        return NULL;
 
     ResourceList->Count = 1;
     ResourceList->List[0].InterfaceType = Internal;
@@ -1223,9 +1219,7 @@ IsaPnpCreateReadPortDOResources(
         Descriptor++;
     }
 
-    PdoExt->ResourceList = ResourceList;
+    return ResourceList;
-    PdoExt->ResourceListSize = ListSize;
-    return STATUS_SUCCESS;
 }
 
 static
@@ -1259,23 +1253,8 @@ IsaPnpCreateReadPortDO(
     PdoExt->Common.State = dsStopped;
     PdoExt->FdoExt = FdoExt;
 
-    Status = IsaPnpCreateReadPortDORequirements(PdoExt, 0);
-    if (!NT_SUCCESS(Status))
-        goto Failure;
-
-    Status = IsaPnpCreateReadPortDOResources(PdoExt);
-    if (!NT_SUCCESS(Status))
-        goto Failure;
-
     FdoExt->ReadPortPdo->Flags &= ~DO_DEVICE_INITIALIZING;
 
-    return Status;
-
-Failure:
-    IsaPnpRemoveReadPortDO(FdoExt->ReadPortPdo);
-
-    FdoExt->ReadPortPdo = NULL;
-
     return Status;
 }
 
@@ -1284,18 +1263,10 @@ VOID
 IsaPnpRemoveReadPortDO(
     _In_ PDEVICE_OBJECT Pdo)
 {
-    PISAPNP_PDO_EXTENSION ReadPortExt = Pdo->DeviceExtension;
-
     PAGED_CODE();
 
     DPRINT("Removing Read Port\n");
 
-    if (ReadPortExt->RequirementsList)
-        ExFreePoolWithTag(ReadPortExt->RequirementsList, TAG_ISAPNP);
-
-    if (ReadPortExt->ResourceList)
-        ExFreePoolWithTag(ReadPortExt->ResourceList, TAG_ISAPNP);
-
     IoDeleteDevice(Pdo);
 }
 

drivers/bus/isapnp/isapnp.h

@@ -176,12 +176,7 @@ typedef struct _ISAPNP_FDO_EXTENSION
 typedef struct _ISAPNP_PDO_EXTENSION
 {
     ISAPNP_COMMON_EXTENSION Common;
-    PISAPNP_LOGICAL_DEVICE IsaPnpDevice;
     PISAPNP_FDO_EXTENSION FdoExt;
-    PIO_RESOURCE_REQUIREMENTS_LIST RequirementsList;
-
-    PCM_RESOURCE_LIST ResourceList;
-    ULONG ResourceListSize;
 
     ULONG Flags;
 #define ISAPNP_ENUMERATED               0x00000001 /**< @brief Whether the device has been reported to the PnP manager. */
@@ -189,6 +184,22 @@ typedef struct _ISAPNP_PDO_EXTENSION
 #define ISAPNP_READ_PORT_ALLOW_FDO_SCAN 0x00000004 /**< @brief Allows the active FDO to scan the bus. */
 #define ISAPNP_READ_PORT_NEED_REBALANCE 0x00000008 /**< @brief The I/O resource requirements have changed. */
 
+    union
+    {
+        /* Data belonging to logical devices */
+        struct
+        {
+            PISAPNP_LOGICAL_DEVICE IsaPnpDevice;
+
+            PIO_RESOURCE_REQUIREMENTS_LIST RequirementsList;
+
+            PCM_RESOURCE_LIST ResourceList;
+            ULONG ResourceListSize;
+        };
+
+        ULONG SelectedPort;
+    };
+
     _Write_guarded_by_(_Global_interlock_)
     volatile LONG SpecialFiles;
 } ISAPNP_PDO_EXTENSION, *PISAPNP_PDO_EXTENSION;
@@ -315,11 +326,14 @@ FindMemoryDescriptor(
     _Out_opt_ PUCHAR WriteOrder);
 
 CODE_SEG("PAGE")
-NTSTATUS
+PIO_RESOURCE_REQUIREMENTS_LIST
 IsaPnpCreateReadPortDORequirements(
-    _In_ PISAPNP_PDO_EXTENSION PdoExt,
     _In_opt_ ULONG SelectedReadPort);
 
+CODE_SEG("PAGE")
+PCM_RESOURCE_LIST
+IsaPnpCreateReadPortDOResources(VOID);
+
 CODE_SEG("PAGE")
 VOID
 IsaPnpRemoveReadPortDO(

drivers/bus/isapnp/pdo.c

@@ -478,8 +478,17 @@ IsaPdoQueryResources(
 
     PAGED_CODE();
 
-    if (PdoExt->Common.Signature == IsaPnpLogicalDevice &&
+    if (PdoExt->Common.Signature == IsaPnpReadDataPort)
-        !(PdoExt->IsaPnpDevice->Flags & ISAPNP_HAS_RESOURCES))
+    {
+        ResourceList = IsaPnpCreateReadPortDOResources();
+        if (!ResourceList)
+            return STATUS_NO_MEMORY;
+
+        Irp->IoStatus.Information = (ULONG_PTR)ResourceList;
+        return STATUS_SUCCESS;
+    }
+
+    if (!(PdoExt->IsaPnpDevice->Flags & ISAPNP_HAS_RESOURCES))
     {
         Irp->IoStatus.Information = 0;
         return STATUS_SUCCESS;
@@ -513,6 +522,16 @@ IsaPdoQueryResourceRequirements(
 
     PAGED_CODE();
 
+    if (PdoExt->Common.Signature == IsaPnpReadDataPort)
+    {
+        RequirementsList = IsaPnpCreateReadPortDORequirements(PdoExt->SelectedPort);
+        if (!RequirementsList)
+            return STATUS_NO_MEMORY;
+
+        Irp->IoStatus.Information = (ULONG_PTR)RequirementsList;
+        return STATUS_SUCCESS;
+    }
+
     if (!PdoExt->RequirementsList)
         return Irp->IoStatus.Status;
 
@@ -593,19 +612,9 @@ IsaPdoStartReadPort(
 
         ASSERT(SelectedPort != 0);
 
-        if (PdoExt->RequirementsList)
-        {
-            ExFreePoolWithTag(PdoExt->RequirementsList, TAG_ISAPNP);
-            PdoExt->RequirementsList = NULL;
-        }
-
         /* Discard the Read Ports at conflicting locations */
-        Status = IsaPnpCreateReadPortDORequirements(PdoExt, SelectedPort);
+        PdoExt->SelectedPort = SelectedPort;
-        if (!NT_SUCCESS(Status))
-            return Status;
-
         PdoExt->Flags |= ISAPNP_READ_PORT_NEED_REBALANCE;
-
         IoInvalidateDeviceState(PdoExt->Common.Self);
 
         return STATUS_SUCCESS;