From 47585511b0c60c62f107472711ee05ed4c56b1a8 Mon Sep 17 00:00:00 2001
From: Michael Friesen <3517159+mtfriesen@users.noreply.github.com>
Date: Tue, 11 Apr 2023 13:44:17 -0400
Subject: [PATCH] assert MDL reuse correctness in generic XDP

---
 src/xdplwf/send.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/xdplwf/send.c b/src/xdplwf/send.c
index 21a9c5ae..0bdc3d1c 100644
--- a/src/xdplwf/send.c
+++ b/src/xdplwf/send.c
@@ -220,6 +220,17 @@ XdpGenericCompleteTx(
             *CompletionContext = NblTxContext(Nbl)->CompletionContext;
         }
 
+        //
+        // In lieu of calling MmPrepareMdlForReuse, assert our MDL did not get
+        // mapped by the memory manager: the original MDL should have been
+        // mapped by XDP itself, and the partial MDL inherited that mapping,
+        // precluding the need for it to be mapped by itself.
+        //
+        ASSERT(Nbl->FirstNetBuffer->Next == NULL);
+        ASSERT(Nbl->FirstNetBuffer->MdlChain->Next == NULL);
+        ASSERT(Nbl->FirstNetBuffer->MdlChain->MdlFlags & MDL_PARTIAL);
+        ASSERT((Nbl->FirstNetBuffer->MdlChain->MdlFlags & MDL_PARTIAL_HAS_BEEN_MAPPED) == 0);
+
         // Return the NBL to the TX free list.
         NT_VERIFY(TxQueue->OutstandingCount-- > 0);
         Nbl->Next = TxQueue->FreeNbls;