From: Tu Dinh <ngoc-tu.dinh@vates.tech>
Date: Mon, 2 Dec 2024 09:37:55 +0000 (+0000)
Subject: Invalidate FDOs when no devices are present
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=HEAD;p=pvdrivers%2Fwin%2Fxenvif.git

Invalidate FDOs when no devices are present

In cases where the entire xenstore device key is removed, FdoScan()
currently skips reenumeration entirely. This causes it to not pass the
removal event to xennet. Fix the issue by reenumerating devices even if
xenstore key does not exist.

Signed-off-by: Tu Dinh <ngoc-tu.dinh@vates.tech>
---

diff --git a/src/xenvif/fdo.c b/src/xenvif/fdo.c
index d181184..2499563 100644
--- a/src/xenvif/fdo.c
+++ b/src/xenvif/fdo.c
@@ -758,18 +758,20 @@ __FdoEnumerate(
             Name = PdoGetName(Pdo);
             Missing = TRUE;
 
-            // If the PDO already exists and its name is in the device list
-            // then we don't want to remove it.
-            for (Index = 0; Devices[Index].Buffer != NULL; Index++) {
-                PANSI_STRING Device = &Devices[Index];
-
-                if (Device->Length == 0)
-                    continue;
-
-                if (strcmp(Name, Device->Buffer) == 0) {
-                    Missing = FALSE;
-                    Device->Length = 0;  // avoid duplication
-                    break;
+            if (Devices != NULL) {
+                // If the PDO already exists and its name is in the device list
+                // then we don't want to remove it.
+                for (Index = 0; Devices[Index].Buffer != NULL; Index++) {
+                    PANSI_STRING Device = &Devices[Index];
+
+                    if (Device->Length == 0)
+                        continue;
+
+                    if (strcmp(Name, Device->Buffer) == 0) {
+                        Missing = FALSE;
+                        Device->Length = 0;  // avoid duplication
+                        break;
+                    }
                 }
             }
 
@@ -797,40 +799,42 @@ __FdoEnumerate(
     }
 
     // Walk the class list and create PDOs for any new device
-    for (Index = 0; Devices[Index].Buffer != NULL; Index++) {
-        PANSI_STRING Device = &Devices[Index];
+    if (Devices != NULL) {
+        for (Index = 0; Devices[Index].Buffer != NULL; Index++) {
+            PANSI_STRING Device = &Devices[Index];
 
-        if (Device->Length != 0) {
-            ULONG   Number;
-            CHAR    Prefix[sizeof ("device/vif/XXXXXXXXXX")];
-            PCHAR   Address;
+            if (Device->Length != 0) {
+                ULONG   Number;
+                CHAR    Prefix[sizeof ("device/vif/XXXXXXXXXX")];
+                PCHAR   Address;
 
-            Number = strtol(Device->Buffer, NULL, 10);
+                Number = strtol(Device->Buffer, NULL, 10);
 
-            status = RtlStringCbPrintfA(Prefix,
-                                        sizeof (Prefix),
-                                        "device/vif/%u",
-                                        Number);
-            ASSERT(NT_SUCCESS(status));
-            if (!NT_SUCCESS(status))
-                continue;
-
-            status = XENBUS_STORE(Read,
-                                  &Fdo->StoreInterface,
-                                  NULL,
-                                  Prefix,
-                                  "mac",
-                                  &Address);
-            if (!NT_SUCCESS(status))
-                continue;
+                status = RtlStringCbPrintfA(Prefix,
+                                            sizeof (Prefix),
+                                            "device/vif/%u",
+                                            Number);
+                ASSERT(NT_SUCCESS(status));
+                if (!NT_SUCCESS(status))
+                    continue;
 
-            status = PdoCreate(Fdo, Number, Address);
-            if (NT_SUCCESS(status))
-                NeedInvalidate = TRUE;
+                status = XENBUS_STORE(Read,
+                                      &Fdo->StoreInterface,
+                                      NULL,
+                                      Prefix,
+                                      "mac",
+                                      &Address);
+                if (!NT_SUCCESS(status))
+                    continue;
 
-            XENBUS_STORE(Free,
-                         &Fdo->StoreInterface,
-                         Address);
+                status = PdoCreate(Fdo, Number, Address);
+                if (NT_SUCCESS(status))
+                    NeedInvalidate = TRUE;
+
+                XENBUS_STORE(Free,
+                            &Fdo->StoreInterface,
+                            Address);
+            }
         }
     }
 
@@ -978,8 +982,12 @@ FdoScan(
             Devices = NULL;
         }
 
-        if (Devices == NULL)
-            goto loop;
+        if (Devices == NULL) {
+            if (status == STATUS_OBJECT_PATH_NOT_FOUND)
+                goto invalidate;
+            else
+                goto loop;
+        }
 
         if (ParametersKey != NULL) {
             status = RegistryQuerySzValue(ParametersKey,
@@ -1019,9 +1027,11 @@ FdoScan(
         if (UnsupportedDevices != NULL)
             RegistryFreeSzValue(UnsupportedDevices);
 
+invalidate:
         NeedInvalidate = __FdoEnumerate(Fdo, Devices);
 
-        __FdoFreeAnsi(Devices);
+        if (Devices != NULL)
+            __FdoFreeAnsi(Devices);
 
         if (NeedInvalidate) {
             NeedInvalidate = FALSE;