[edk2-devel] [PATCH v2 6/6] StandaloneMmPkg: Support to unregister MMI handler in MMI handlers

["Zhiguang Liu" <zhiguang.liu@intel.com>]

Unregistering MMI handler will free the MMI_HANDLER. However, the
MmiManage() may be using the link node from MMI_HANDLER for loop if
the unregistering happens in MMI handlers.
To avoid that, the idea is to inform MmiHandlerUnRegister() whether
it's running or not running on the stack of MmiManage(), and to
postpone MMI_HANDLER deletion until after the loop finishes.

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>
Cc: 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 | 149 +++++++++++++++++++++++++++++++------
 1 file changed, 126 insertions(+), 23 deletions(-)

diff --git a/StandaloneMmPkg/Core/Mmi.c b/StandaloneMmPkg/Core/Mmi.c
index 0de6fd17fc..b13c7a3bc6 100644
--- a/StandaloneMmPkg/Core/Mmi.c
+++ b/StandaloneMmPkg/Core/Mmi.c
@@ -34,11 +34,50 @@ typedef struct {
   LIST_ENTRY                    Link;        // Link on MMI_ENTRY.MmiHandlers
   EFI_MM_HANDLER_ENTRY_POINT    Handler;     // The mm handler's entry point
   MMI_ENTRY                     *MmiEntry;
+  BOOLEAN                       ToDelete;    // To delete this MMI_HANDLER later
 } MMI_HANDLER;
 
+//
+// mMmiManageCallingDepth is used to track the depth of recursive calls of MmiManage.
+//
+UINTN  mMmiManageCallingDepth = 0;
+
 LIST_ENTRY  mRootMmiHandlerList = INITIALIZE_LIST_HEAD_VARIABLE (mRootMmiHandlerList);
 LIST_ENTRY  mMmiEntryList       = INITIALIZE_LIST_HEAD_VARIABLE (mMmiEntryList);
 
+/**
+  Remove MmiHandler and free the memory it used.
+  If MmiEntry is empty, remove MmiEntry and free the memory it used.
+
+  @param  MmiHandler  Points to MMI handler.
+  @param  MmiEntry    Points to MMI Entry or NULL for root MMI handlers.
+
+  @retval TRUE        MmiEntry is removed.
+  @retval FALSE       MmiEntry is not removed.
+**/
+BOOLEAN
+RemoveMmiHandler (
+  IN MMI_HANDLER  *MmiHandler,
+  IN MMI_ENTRY    *MmiEntry
+  )
+{
+  RemoveEntryList (&MmiHandler->Link);
+  FreePool (MmiHandler);
+
+  if (MmiEntry != NULL) {
+    if (IsListEmpty (&MmiEntry->MmiHandlers)) {
+      //
+      // No handler registered for this MMI_ENTRY, remove the MMI_ENTRY
+      //
+      RemoveEntryList (&MmiEntry->AllEntries);
+      FreePool (MmiEntry);
+      return TRUE;
+    }
+  }
+
+  return FALSE;
+}
+
 /**
   Finds the MMI entry for the requested handler type.
 
@@ -126,13 +165,16 @@ MmiManage (
 {
   LIST_ENTRY   *Link;
   LIST_ENTRY   *Head;
+  LIST_ENTRY   *EntryLink;
   MMI_ENTRY    *MmiEntry;
   MMI_HANDLER  *MmiHandler;
-  BOOLEAN      SuccessReturn;
+  EFI_STATUS   ReturnStatus;
+  BOOLEAN      WillReturn;
   EFI_STATUS   Status;
 
-  Status        = EFI_NOT_FOUND;
-  SuccessReturn = FALSE;
+  mMmiManageCallingDepth++;
+  Status       = EFI_NOT_FOUND;
+  ReturnStatus = Status;
   if (HandlerType == NULL) {
     //
     // Root MMI handler
@@ -171,7 +213,16 @@ MmiManage (
         // no additional handlers will be processed and EFI_INTERRUPT_PENDING will be returned.
         //
         if (HandlerType != NULL) {
-          return EFI_INTERRUPT_PENDING;
+          ReturnStatus = EFI_INTERRUPT_PENDING;
+          WillReturn   = TRUE;
+        } else {
+          //
+          // If any other handler's result sets ReturnStatus as EFI_SUCCESS, the return status
+          // will be EFI_SUCCESS.
+          //
+          if (ReturnStatus != EFI_SUCCESS) {
+            ReturnStatus = Status;
+          }
         }
 
         break;
@@ -183,10 +234,10 @@ MmiManage (
         // additional handlers will be processed.
         //
         if (HandlerType != NULL) {
-          return EFI_SUCCESS;
+          WillReturn = TRUE;
         }
 
-        SuccessReturn = TRUE;
+        ReturnStatus = EFI_SUCCESS;
         break;
 
       case EFI_WARN_INTERRUPT_SOURCE_QUIESCED:
@@ -194,7 +245,7 @@ MmiManage (
         // If at least one of the handlers returns EFI_WARN_INTERRUPT_SOURCE_QUIESCED
         // then the function will return EFI_SUCCESS.
         //
-        SuccessReturn = TRUE;
+        ReturnStatus = EFI_SUCCESS;
         break;
 
       case EFI_WARN_INTERRUPT_SOURCE_PENDING:
@@ -202,6 +253,10 @@ MmiManage (
         // If all the handlers returned EFI_WARN_INTERRUPT_SOURCE_PENDING
         // then EFI_WARN_INTERRUPT_SOURCE_PENDING will be returned.
         //
+        if (ReturnStatus != EFI_SUCCESS) {
+          ReturnStatus = Status;
+        }
+
         break;
 
       default:
@@ -211,13 +266,67 @@ MmiManage (
         ASSERT_EFI_ERROR (Status);
         break;
     }
+
+    if (WillReturn) {
+      break;
+    }
   }
 
-  if (SuccessReturn) {
-    Status = EFI_SUCCESS;
+  ASSERT (mMmiManageCallingDepth > 0);
+  mMmiManageCallingDepth--;
+
+  //
+  // The MmiHandlerUnRegister won't take effect inside MmiManage.
+  // Before returned from MmiManage, delete the MmiHandler which is
+  // marked as ToDelete.
+  // Note that MmiManage can be called recursively.
+  //
+  if (mMmiManageCallingDepth == 0) {
+    //
+    // Go through all MmiHandler in root Mmi handlers
+    //
+    for ( Link = GetFirstNode (&mRootMmiHandlerList)
+          ; !IsNull (&mRootMmiHandlerList, Link);
+          )
+    {
+      MmiHandler = CR (Link, MMI_HANDLER, Link, MMI_HANDLER_SIGNATURE);
+      Link       = GetNextNode (&mRootMmiHandlerList, Link);
+      if (MmiHandler->ToDelete) {
+        //
+        // Remove MmiHandler if the ToDelete is set.
+        //
+        RemoveMmiHandler (MmiHandler, NULL);
+      }
+    }
+
+    //
+    // Go through all MmiHandler in non-root MMI handlers
+    //
+    for ( EntryLink = GetFirstNode (&mMmiEntryList)
+          ; !IsNull (&mMmiEntryList, EntryLink);
+          )
+    {
+      MmiEntry  = CR (EntryLink, MMI_ENTRY, AllEntries, MMI_ENTRY_SIGNATURE);
+      EntryLink = GetNextNode (&mMmiEntryList, EntryLink);
+      for ( Link = GetFirstNode (&MmiEntry->MmiHandlers)
+            ; !IsNull (&MmiEntry->MmiHandlers, Link);
+            )
+      {
+        MmiHandler = CR (Link, MMI_HANDLER, Link, MMI_HANDLER_SIGNATURE);
+        Link       = GetNextNode (&MmiEntry->MmiHandlers, Link);
+        if (MmiHandler->ToDelete) {
+          //
+          // Remove MmiHandler if the ToDelete is set.
+          //
+          if (RemoveMmiHandler (MmiHandler, MmiEntry)) {
+            break;
+          }
+        }
+      }
+    }
   }
 
-  return Status;
+  return ReturnStatus;
 }
 
 /**
@@ -254,6 +363,7 @@ MmiHandlerRegister (
 
   MmiHandler->Signature = MMI_HANDLER_SIGNATURE;
   MmiHandler->Handler   = Handler;
+  MmiHandler->ToDelete  = FALSE;
 
   if (HandlerType == NULL) {
     //
@@ -311,24 +421,17 @@ MmiHandlerUnRegister (
 
   MmiEntry = MmiHandler->MmiEntry;
 
-  RemoveEntryList (&MmiHandler->Link);
-  FreePool (MmiHandler);
-
-  if (MmiEntry == NULL) {
+  if (mMmiManageCallingDepth > 0) {
     //
-    // This is root MMI handler
+    // This function is called from MmiManage()
+    // Do not delete or remove MmiHandler or MmiEntry now.
+    // Set the ToDelete field in MmiHandler so that MmiManage will delete it later
     //
+    MmiHandler->ToDelete = TRUE;
     return EFI_SUCCESS;
   }
 
-  if (IsListEmpty (&MmiEntry->MmiHandlers)) {
-    //
-    // No handler registered for this interrupt now, remove the MMI_ENTRY
-    //
-    RemoveEntryList (&MmiEntry->AllEntries);
-
-    FreePool (MmiEntry);
-  }
+  RemoveMmiHandler (MmiHandler, MmiEntry);
 
   return EFI_SUCCESS;
 }
-- 
2.31.1.windows.1



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