Attempt to process responses on the ring

When Disabling the ring, outstanding responses need to be completed.
Poll the ring to complete outstanding responses if the backend is still
connected and valid.

Signed-off-by: Owen Smith <owen.smith@citrix.com>

diff --git a/src/xenvbd/ring.c b/src/xenvbd/ring.c
index 8dcdee38cc819c2d03b65d6ef15e0957b6db8961..4bb7475ddc3ad09c0b3957ec682fc69c0ca2bf2c 100644 (file)
--- a/src/xenvbd/ring.c
+++ b/src/xenvbd/ring.c
@@ -2044,11 +2044,57 @@ BlkifRingDisable(
     IN  PXENVBD_BLKIF_RING  BlkifRing
     )
 {
+    PXENVBD_RING            Ring;
+    PCHAR                   Buffer;
+    XenbusState             State;
+    NTSTATUS                status;
+
+    Ring = BlkifRing->Ring;
+
     Trace("====> %u\n", BlkifRing->Index);
 
     __BlkifRingAcquireLock(BlkifRing);
     ASSERT(BlkifRing->Enabled);
 
+    status = XENBUS_STORE(Read,
+                          &Ring->StoreInterface,
+                          NULL,
+                          FrontendGetBackendPath(Ring->Frontend),
+                          "state",
+                          &Buffer);
+    if (!NT_SUCCESS(status)) {
+        State = XenbusStateUnknown;
+    } else {
+        State = (XenbusState) strtol(Buffer, NULL, 10);
+
+        XENBUS_STORE(Free,
+                     &Ring->StoreInterface,
+                     Buffer);
+    }
+
+    if (State == XenbusStateConnected) {
+        ULONG               Attempt;
+
+        Attempt = 0;
+        ASSERT3U(BlkifRing->RequestsPushed, ==, BlkifRing->RequestsPosted);
+        while (BlkifRing->ResponsesProcessed != BlkifRing->RequestsPushed) {
+            Attempt++;
+            if (Attempt > 100)
+                break;
+
+            // Try to move things along
+            __BlkifRingSend(BlkifRing);
+            (VOID) BlkifRingPoll(BlkifRing);
+
+            // We are waiting for a watch event at DISPATCH_LEVEL so
+            // it is our responsibility to poll the store ring.
+            XENBUS_STORE(Poll,
+                         &Ring->StoreInterface);
+
+            KeStallExecutionProcessor(1000);    // 1ms
+        }
+    }
+
     BlkifRing->Enabled = FALSE;
 
     while (!IsListEmpty(&BlkifRing->SubmittedList)) {