From 7e8e22056b721203f29b3ee982a64e98b0cbc22a Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Fri, 6 Mar 2015 02:55:35 +0000
Subject: [PATCH] MdeModulePkg: use index to traverse free pool pages

In preparation of making the pool code capable of serving allocations
from higher-up bins, update the free path to traverse a candidate page
by following the index of POOL_FREE header instead of duplicating the
carving logic that was used at page allocation time. This allows chunks
to be split into smaller ones, where one can be returned to serve the
allocation, and the other stored in a smaller bin for later use.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17013 6f19259b-4bc3-4df7-8a09-765794883524
---
 MdeModulePkg/Core/Dxe/Mem/Pool.c | 30 +++++++++---------------------
 1 file changed, 9 insertions(+), 21 deletions(-)

diff --git a/MdeModulePkg/Core/Dxe/Mem/Pool.c b/MdeModulePkg/Core/Dxe/Mem/Pool.c
index c7998e80cc..0c5cf3d284 100644
--- a/MdeModulePkg/Core/Dxe/Mem/Pool.c
+++ b/MdeModulePkg/Core/Dxe/Mem/Pool.c
@@ -495,7 +495,6 @@ CoreFreePoolI (
   UINTN       NoPages;
   UINTN       Size;
   CHAR8       *NewPage;
-  UINTN       FSize;
   UINTN       Offset;
   BOOLEAN     AllFree;
   UINTN       Granularity;
@@ -589,22 +588,16 @@ CoreFreePoolI (
 
     if (Free->Signature == POOL_FREE_SIGNATURE) {
 
-      Index = Free->Index;
-
       AllFree = TRUE;
       Offset = 0;
 
       while ((Offset < Granularity) && (AllFree)) {
-        FSize = LIST_TO_SIZE(Index);
-        while (Offset + FSize <= Granularity) {
-          Free = (POOL_FREE *) &NewPage[Offset];
-          ASSERT(Free != NULL);
-          if (Free->Signature != POOL_FREE_SIGNATURE) {
-            AllFree = FALSE;
-          }
-          Offset += FSize;
+        Free = (POOL_FREE *) &NewPage[Offset];
+        ASSERT(Free != NULL);
+        if (Free->Signature != POOL_FREE_SIGNATURE) {
+          AllFree = FALSE;
         }
-        Index -= 1;
+        Offset += LIST_TO_SIZE(Free->Index);
       }
 
       if (AllFree) {
@@ -616,18 +609,13 @@ CoreFreePoolI (
         //
         Free = (POOL_FREE *) &NewPage[0];
         ASSERT(Free != NULL);
-        Index = Free->Index;
         Offset = 0;
 
         while (Offset < Granularity) {
-          FSize = LIST_TO_SIZE(Index);
-          while (Offset + FSize <= Granularity) {
-            Free = (POOL_FREE *) &NewPage[Offset];
-            ASSERT(Free != NULL);
-            RemoveEntryList (&Free->Link);
-            Offset += FSize;
-          }
-          Index -= 1;
+          Free = (POOL_FREE *) &NewPage[Offset];
+          ASSERT(Free != NULL);
+          RemoveEntryList (&Free->Link);
+          Offset += LIST_TO_SIZE(Free->Index);
         }
 
         //