Log waits for backend state changes.

In addition to preceding changes to ring disconnects, and
associated logging, we also add some logging to check
whether state change notifications are being sent in a timely
manner between frontend and backend. Also a great assistance
to customer debugging.

Signed-off-by: Martin Harvey <martin.harvey@citrix.com>

diff --git a/src/xenvif/frontend.c b/src/xenvif/frontend.c
index 5940e16bccb298f4f11c64f0fe8f14aace6e49fc..72f448db0c055972a5a17678521a76c3a1787cba 100644 (file)
--- a/src/xenvif/frontend.c
+++ b/src/xenvif/frontend.c
@@ -1346,6 +1346,7 @@ FrontendWaitForBackendXenbusStateChange(
     LARGE_INTEGER               Timeout;
     XenbusState                 Old = *State;
     NTSTATUS                    status;
+    const ULONGLONG             TotalTimeout = 120000;
 
     Trace("%s: ====> %s\n",
           __FrontendGetBackendPath(Frontend),
@@ -1369,7 +1370,7 @@ FrontendWaitForBackendXenbusStateChange(
 
     Timeout.QuadPart = 0;
 
-    while (*State == Old && TimeDelta < 120000) {
+    while (*State == Old && TimeDelta < TotalTimeout) {
         PCHAR           Buffer;
         LARGE_INTEGER   Now;
 
@@ -1417,6 +1418,9 @@ FrontendWaitForBackendXenbusStateChange(
         TimeDelta = (Now.QuadPart - Start.QuadPart) / 10000ull;
     }
 
+    if (TimeDelta >= TotalTimeout)
+        Error("%s timed out waiting for backend state change\n", __FrontendGetBackendPath(Frontend));
+
     if (Watch != NULL)
         (VOID) XENBUS_STORE(WatchRemove,
                             &Frontend->StoreInterface,