[win-pv-devel] [PATCH 4/4] Rework BlkifRingDisable

[Owen Smith <owen.smith@xxxxxxxxxx>]

Clean up all prepared and submitted requests when the ring is disabled,
so that outstanding SRBs are returned to storport for queueing. This is
especially important on the return from suspend path, as the ring is no
longer valid, and any submitted requests would be lost and trigger a
storport target reset.

Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
---
 src/xenvbd/ring.c | 62 +++++++++++++++++++++----------------------------------
 1 file changed, 23 insertions(+), 39 deletions(-)

diff --git a/src/xenvbd/ring.c b/src/xenvbd/ring.c
index d5db1da..5323243 100644
--- a/src/xenvbd/ring.c
+++ b/src/xenvbd/ring.c
@@ -1242,16 +1242,17 @@ BlkifRingPoll(
 
             rsp = RING_GET_RESPONSE(&BlkifRing->Front, rsp_cons);
             rsp_cons++;
-            BlkifRing->ResponsesProcessed++;
 
             BlkifRing->Stopped = FALSE;
 
             Request = __BlkifRingGetSubmittedRequest(BlkifRing,
                                                      rsp->id);
-            if (Request != NULL)
+            if (Request != NULL) {
+                BlkifRing->ResponsesProcessed++;
                 __BlkifRingCompleteResponse(BlkifRing,
                                             Request,
                                             rsp->status);
+            }
 
             if (rsp_cons - BlkifRing->Front.rsp_cons > XENVBD_BATCH(BlkifRing))
                 Retry = TRUE;
@@ -2043,58 +2044,41 @@ BlkifRingDisable(
     IN  PXENVBD_BLKIF_RING  BlkifRing
     )
 {
-    PXENVBD_RING            Ring = BlkifRing->Ring;
-    ULONG                   Attempt;
-
     Trace("====> %u\n", BlkifRing->Index);
 
     __BlkifRingAcquireLock(BlkifRing);
     ASSERT(BlkifRing->Enabled);
 
-    // Discard any pending requests
+    BlkifRing->Enabled = FALSE;
+
     for (;;) {
-        PLIST_ENTRY         ListEntry;
-        PXENVBD_REQUEST     Request;
-        PXENVBD_SRBEXT      SrbExt;
-        PSCSI_REQUEST_BLOCK Srb;
+        PLIST_ENTRY ListEntry;
+        PXENVBD_REQUEST Request;
 
-        ListEntry = RemoveHeadList(&BlkifRing->PreparedQueue);
-        if (ListEntry  == &BlkifRing->PreparedQueue)
+        ListEntry = RemoveHeadList(&BlkifRing->SubmittedList);
+        if (ListEntry == &BlkifRing->SubmittedList)
             break;
 
-        Request = CONTAINING_RECORD(ListEntry,
-                                    XENVBD_REQUEST,
-                                    ListEntry);
-        SrbExt = Request->SrbExt;
-        Srb = SrbExt->Srb;
-        Srb->SrbStatus = SRB_STATUS_ABORTED;
-        Srb->ScsiStatus = 0x40; // SCSI_ABORTED
-
-        BlkifRingPutRequest(BlkifRing, Request);
-
-        if (InterlockedDecrement(&SrbExt->RequestCount) == 0)
-            __BlkifRingCompleteSrb(BlkifRing, SrbExt);
+        Request = CONTAINING_RECORD(ListEntry, XENVBD_REQUEST, ListEntry);
+        BlkifRing->ResponsesProcessed++;
+        __BlkifRingCompleteResponse(BlkifRing, Request, BLKIF_RSP_ERROR);
     }
 
-    Attempt = 0;
-    ASSERT3U(BlkifRing->RequestsPushed, == , BlkifRing->RequestsPosted);
-    while (BlkifRing->ResponsesProcessed != BlkifRing->RequestsPushed) {
-        Attempt++;
-        ASSERT(Attempt < 100);
-
-        // Try to move things along
-        __BlkifRingSend(BlkifRing);
-        (VOID)BlkifRingPoll(BlkifRing);
+    for (;;) {
+        PLIST_ENTRY ListEntry;
+        PXENVBD_REQUEST Request;
 
-        // 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);
+        ListEntry = RemoveHeadList(&BlkifRing->PreparedQueue);
+        if (ListEntry == &BlkifRing->PreparedQueue)
+            break;
 
-        KeStallExecutionProcessor(1000);    // 1ms
+        Request = CONTAINING_RECORD(ListEntry, XENVBD_REQUEST, ListEntry);
+        // Dont increment ResponsesProcessed, as this is a faked response
+        __BlkifRingCompleteResponse(BlkifRing, Request, BLKIF_RSP_ERROR);
     }
 
-    BlkifRing->Enabled = FALSE;
+    BlkifRing->Stopped = FALSE;
+
     __BlkifRingReleaseLock(BlkifRing);
 
     Trace("<==== %u\n", BlkifRing->Index);
-- 
2.16.2.windows.1


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