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 d1811844126af8fe1a41706288ddf02ab5a6c2b0..249956371c8ed14bed89897f59a5494f5521c5b6 100644 (file)
--- 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;