[PATCH v3 1/3] MdeModulePkg/Dhcp4Dxe: Remove unnecessary NULL pointer check.

[Jiaxin Wu <Jiaxin.wu@intel.com>]

v3: Add the instance token check.

v2: The DHCP Instance might be destroyed in PxeDhcpDone. So,
we need safe-delete.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1469

Since the value of Instance is retrieved from the list Entry,
it can't be the NULL pointer, so just remove the unnecessary
check.

Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Wu Hao A <hao.a.wu@intel.com>
Cc: Gao Liming <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Wu Jiaxin <jiaxin.wu@intel.com>
---
 MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c b/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c
index 98a22a77b4..360365ecc3 100644
--- a/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c
+++ b/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c
@@ -1,9 +1,9 @@
 /** @file
   EFI DHCP protocol implementation.
 
-Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php
 
@@ -1646,16 +1646,13 @@ ON_EXIT:
   //
   // Iterate through all the DhcpSb Children.
   //
   NET_LIST_FOR_EACH_SAFE (Entry, Next, &DhcpSb->Children) {
     Instance = NET_LIST_USER_STRUCT (Entry, DHCP_PROTOCOL, Link);
-
-    if ((Instance != NULL) && (Instance->Token != NULL)) {
-      Instance->Timeout--;
-      if (Instance->Timeout == 0) {
-        PxeDhcpDone (Instance);
-      }
+    Instance->Timeout--;
+    if (Instance->Timeout == 0 && Instance->Token != NULL) {
+      PxeDhcpDone (Instance);
     }
   }
 
   return ;
 
-- 
2.17.1.windows.2