[win-pv-devel] [PATCH 1/5] Fix target enumeration

[Paul Durrant <pdurrant@xxxxxxxxx>]

From: Owen Smith <owen.smith@xxxxxxxxxx>

Issues were found when enumeration races with plug/unplug. This patch
should fix these problems.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
---
 src/xenvbd/fdo.c | 36 +++++++++++++++++-------------------
 src/xenvbd/pdo.c | 12 ++++++++++--
 2 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/src/xenvbd/fdo.c b/src/xenvbd/fdo.c
index f240a97..b146f7c 100644
--- a/src/xenvbd/fdo.c
+++ b/src/xenvbd/fdo.c
@@ -619,31 +619,29 @@ __FdoEnumerate(
     *NeedReboot = FALSE;
 
     for (TargetId = 0; TargetId < XENVBD_MAX_TARGETS; ++TargetId) {
+        BOOLEAN     Missing = TRUE;
+
         Pdo = __FdoGetPdo(Fdo, TargetId);
         if (Pdo == NULL)
             continue;
 
-        if (!PdoIsMissing(Pdo)) {
-            BOOLEAN Missing = TRUE;
-            for (Device = Devices; *Device; Device = __NextSz(Device)) {
-                ULONG DeviceTargetId = __ParseVbd(Device);
-                if (TargetId == DeviceTargetId) {
-                    Missing = FALSE;
-                    break;
-                }
-            }
-            if (Missing) {
-                PdoSetMissing(Pdo, "Device Dissappeared");
-                if (PdoGetDevicePnpState(Pdo) == Present)
-                    PdoSetDevicePnpState(Pdo, Deleted);
-                else
-                    *NeedInvalidate = TRUE;
+        for (Device = Devices; *Device; Device = __NextSz(Device)) {
+            ULONG DeviceTargetId = __ParseVbd(Device);
+            if (TargetId == DeviceTargetId) {
+                Missing = FALSE;
+                break;
             }
         }
-        
-        if (PdoIsMissing(Pdo) && 
-            PdoGetDevicePnpState(Pdo) == Deleted) {
-            // drop reference count before destroying
+
+        if (Missing && !PdoIsMissing(Pdo)) {
+            PdoSetMissing(Pdo, "Device Disappeared");
+            if (PdoGetDevicePnpState(Pdo) == Present)
+                PdoSetDevicePnpState(Pdo, Deleted);
+            else
+                *NeedInvalidate = TRUE;
+        }
+
+        if (PdoGetDevicePnpState(Pdo) == Deleted) {
             PdoDereference(Pdo);
             PdoDestroy(Pdo);
         } else {
diff --git a/src/xenvbd/pdo.c b/src/xenvbd/pdo.c
index c5ec9b6..89bfc5a 100644
--- a/src/xenvbd/pdo.c
+++ b/src/xenvbd/pdo.c
@@ -415,8 +415,16 @@ PdoSetDevicePnpState(
     __in DEVICE_PNP_STATE        State
     )
 {
-    ASSERT(Pdo->DevicePnpState != Deleted || State == Deleted);
-    Verbose("Target[%d] : PNP %s to %s\n", PdoGetTargetId(Pdo), 
__PnpStateName(Pdo->DevicePnpState), __PnpStateName(State));
+    Verbose("Target[%d] : PNP %s to %s\n",
+            PdoGetTargetId(Pdo),
+            __PnpStateName(Pdo->DevicePnpState),
+            __PnpStateName(State));
+
+    if (Pdo->DevicePnpState == Deleted) {
+        ASSERT(State == Deleted);
+        return;
+    }
+
     Pdo->PrevPnpState = Pdo->DevicePnpState;
     Pdo->DevicePnpState = State;
 }
-- 
2.1.1


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