[reactos] 01/01: [NTOS:PNP] Avoid recursion when walking the device tree.

[Thomas Faber]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=c0e7eaf4036fd23cf4fb79...

commit c0e7eaf4036fd23cf4fb79d15d82150e3fd0e689
Author:     Thomas Faber [e-mail]
AuthorDate: Sat Jan 14 17:40:14 2023 -0500
Commit:     Thomas Faber [e-mail]
CommitDate: Sun Jan 22 09:42:08 2023 -0500

[NTOS:PNP] Avoid recursion when walking the device tree.
---
 ntoskrnl/io/pnpmgr/plugplay.c | 55 +++++++++++++++++++++++++------------------
 1 file changed, 32 insertions(+), 23 deletions(-)

diff --git a/ntoskrnl/io/pnpmgr/plugplay.c b/ntoskrnl/io/pnpmgr/plugplay.c
index 192612c66a2..46585458b84 100644
--- a/ntoskrnl/io/pnpmgr/plugplay.c
+++ b/ntoskrnl/io/pnpmgr/plugplay.c
@@ -18,6 +18,12 @@ typedef struct _PNP_EVENT_ENTRY
     PLUGPLAY_EVENT_BLOCK Event;
 } PNP_EVENT_ENTRY, *PPNP_EVENT_ENTRY;

+typedef struct _IOP_FIND_DEVICE_INSTANCE_TRAVERSE_CONTEXT
+{
+    PCUNICODE_STRING InstancePath;
+    PDEVICE_OBJECT DeviceObject;
+} IOP_FIND_DEVICE_INSTANCE_TRAVERSE_CONTEXT, *PIOP_FIND_DEVICE_INSTANCE_TRAVERSE_CONTEXT;
+

/* GLOBALS *******************************************************************/

@@ -88,39 +94,32 @@ IopQueueTargetDeviceEvent(const GUID *Guid,
     return STATUS_SUCCESS;
 }

-
-static PDEVICE_OBJECT
-IopTraverseDeviceNode(PDEVICE_NODE Node, PUNICODE_STRING DeviceInstance)
+NTSTATUS
+IopFindDeviceInstanceTraverse(
+    _In_ PDEVICE_NODE DeviceNode,
+    _Inout_ PVOID Context)
 {
-    PDEVICE_OBJECT DeviceObject;
-    PDEVICE_NODE ChildNode;
+    PIOP_FIND_DEVICE_INSTANCE_TRAVERSE_CONTEXT DeviceInstanceContext = Context;

-    if (RtlEqualUnicodeString(&Node->InstancePath,
-                              DeviceInstance, TRUE))
+    if (RtlEqualUnicodeString(&DeviceNode->InstancePath,
+                              DeviceInstanceContext->InstancePath, TRUE))
     {
-        ObReferenceObject(Node->PhysicalDeviceObject);
-        return Node->PhysicalDeviceObject;
-    }
+        ObReferenceObject(DeviceNode->PhysicalDeviceObject);
+        DeviceInstanceContext->DeviceObject = DeviceNode->PhysicalDeviceObject;

-    /* Traversal of all children nodes */
-    for (ChildNode = Node->Child;
-         ChildNode != NULL;
-         ChildNode = ChildNode->Sibling)
-    {
-        DeviceObject = IopTraverseDeviceNode(ChildNode, DeviceInstance);
-        if (DeviceObject != NULL)
-        {
-            return DeviceObject;
-        }
+        /* Stop enumeration */
+        return STATUS_UNSUCCESSFUL;
     }

-    return NULL;
+    return STATUS_SUCCESS;
 }

-
 PDEVICE_OBJECT
 IopGetDeviceObjectFromDeviceInstance(PUNICODE_STRING DeviceInstance)
 {
+    DEVICETREE_TRAVERSE_CONTEXT Context;
+    IOP_FIND_DEVICE_INSTANCE_TRAVERSE_CONTEXT DeviceInstanceContext;
+
     if (IopRootDeviceNode == NULL)
         return NULL;

@@ -136,7 +135,17 @@ IopGetDeviceObjectFromDeviceInstance(PUNICODE_STRING DeviceInstance)
             return NULL;
     }

-    return IopTraverseDeviceNode(IopRootDeviceNode, DeviceInstance);
+    /* Traverse the device tree to find the matching device node */
+    DeviceInstanceContext.InstancePath = DeviceInstance;
+    DeviceInstanceContext.DeviceObject = NULL;
+    IopInitDeviceTreeTraverseContext(&Context,
+                                     IopRootDeviceNode,
+                                     IopFindDeviceInstanceTraverse,
+                                     &DeviceInstanceContext);
+    (void)IopTraverseDeviceTree(&Context);
+
+    /* In case of error or instance not found, this will still be NULL from above. */
+    return DeviceInstanceContext.DeviceObject;
 }

static NTSTATUS