From 31cd5ee8c0946b62520795bdbe81f886a8b81559 Mon Sep 17 00:00:00 2001
From: Zhiguang Liu <zhiguang.liu@intel.com>
Date: Fri, 8 Mar 2024 13:46:14 +0800
Subject: Revert 2ec8f0c6407f062441b205b900038933865c7b3c

This reverts commit "StandaloneMmPkg: Disallow unregister MMI
handler in other MMI handler" for better design later.

Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
---
 StandaloneMmPkg/Core/Mmi.c | 32 +++++++++-----------------------
 1 file changed, 9 insertions(+), 23 deletions(-)

diff --git a/StandaloneMmPkg/Core/Mmi.c b/StandaloneMmPkg/Core/Mmi.c
index 9e52072bf7..c1a1d76e85 100644
--- a/StandaloneMmPkg/Core/Mmi.c
+++ b/StandaloneMmPkg/Core/Mmi.c
@@ -36,9 +36,8 @@ typedef struct {
   MMI_ENTRY                     *MmiEntry;
 } MMI_HANDLER;
 
-LIST_ENTRY   mRootMmiHandlerList = INITIALIZE_LIST_HEAD_VARIABLE (mRootMmiHandlerList);
-LIST_ENTRY   mMmiEntryList       = INITIALIZE_LIST_HEAD_VARIABLE (mMmiEntryList);
-MMI_HANDLER  *mCurrentMmiHandler = NULL;
+LIST_ENTRY  mRootMmiHandlerList = INITIALIZE_LIST_HEAD_VARIABLE (mRootMmiHandlerList);
+LIST_ENTRY  mMmiEntryList       = INITIALIZE_LIST_HEAD_VARIABLE (mMmiEntryList);
 
 /**
   Finds the MMI entry for the requested handler type.
@@ -162,19 +161,13 @@ MmiManage (
     // get next node before handler is executed, since LIST_ENTRY that
     // Link points to may be freed if unregister MMI handler.
     //
-    Link = Link->ForwardLink;
-    //
-    // Assign gCurrentMmiHandle before calling the MMI handler and
-    // set to NULL when it returns.
-    //
-    mCurrentMmiHandler = MmiHandler;
-    Status             = MmiHandler->Handler (
-                                       (EFI_HANDLE)MmiHandler,
-                                       Context,
-                                       CommBuffer,
-                                       CommBufferSize
-                                       );
-    mCurrentMmiHandler = NULL;
+    Link   = Link->ForwardLink;
+    Status = MmiHandler->Handler (
+                           (EFI_HANDLE)MmiHandler,
+                           Context,
+                           CommBuffer,
+                           CommBufferSize
+                           );
 
     switch (Status) {
       case EFI_INTERRUPT_PENDING:
@@ -321,13 +314,6 @@ MmiHandlerUnRegister (
     return EFI_INVALID_PARAMETER;
   }
 
-  //
-  // Do not allow to unregister MMI Handler inside other MMI Handler
-  //
-  if ((mCurrentMmiHandler != NULL) && (mCurrentMmiHandler != MmiHandler)) {
-    return EFI_INVALID_PARAMETER;
-  }
-
   MmiEntry = MmiHandler->MmiEntry;
 
   RemoveEntryList (&MmiHandler->Link);
-- 
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