[PATCH v2 1/2] MdeModulePkg: Do not free memory during ExitBootServices ().

["Marvin Häuser" <Marvin.Haeuser@outlook.com>]

During exiting Boot Services, there should be no changes made to the
Memory Map. This patch eliminates explicit and implicit calls to the
Memory Allocation Services and, where applicable, zeros the memory
instead.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Marvin Haeuser <Marvin.Haeuser@outlook.com>
---
 MdeModulePkg/Universal/Network/IScsiDxe/IScsiMisc.c | 11 +++++++++--
 MdeModulePkg/Universal/Network/SnpDxe/Snp.c         | 12 ++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Universal/Network/IScsiDxe/IScsiMisc.c b/MdeModulePkg/Universal/Network/IScsiDxe/IScsiMisc.c
index ae202c3fe24a..b5e36b8bec06 100644
--- a/MdeModulePkg/Universal/Network/IScsiDxe/IScsiMisc.c
+++ b/MdeModulePkg/Universal/Network/IScsiDxe/IScsiMisc.c
@@ -872,9 +872,16 @@ IScsiOnExitBootService (
   ISCSI_DRIVER_DATA *Private;
 
   Private = (ISCSI_DRIVER_DATA *) Context;
-  gBS->CloseEvent (Private->ExitBootServiceEvent);
 
-  IScsiSessionAbort (&Private->Session);
+  if (Private->Session.Signature != 0) {
+    IScsiSessionAbort (&Private->Session);
+
+    //
+    // Empty Session as it will not be freed.
+    // This will also prevent this code from being re-run.
+    //
+    ZeroMem (&Private->Session, sizeof (Private->Session));
+  }
 }
 
 /**
diff --git a/MdeModulePkg/Universal/Network/SnpDxe/Snp.c b/MdeModulePkg/Universal/Network/SnpDxe/Snp.c
index 9f61aee05773..e15e79c7065f 100644
--- a/MdeModulePkg/Universal/Network/SnpDxe/Snp.c
+++ b/MdeModulePkg/Universal/Network/SnpDxe/Snp.c
@@ -32,6 +32,18 @@ SnpNotifyExitBootServices (
 
   Snp  = (SNP_DRIVER *)Context;
 
+  if (Snp->TxRxBuffer != NULL) {
+    //
+    // Empty TxRxBuffer as it will not be freed.
+    //
+    ZeroMem (Snp->TxRxBuffer, Snp->TxRxBufferSize);
+
+    //
+    // Set TxRxBuffer to NULL so FreeBuffer () will not be called.
+    //
+    Snp->TxRxBuffer = NULL;
+  }
+
   //
   // Shutdown and stop UNDI driver
   //
-- 
2.10.1.windows.1