MdePkg/BaseSynchronizationLib: Do not check timeout if lock released

[mirror_edk2.git] / MdePkg / Library / BaseSynchronizationLib / SynchronizationMsc.c

diff --git a/MdePkg/Library/BaseSynchronizationLib/SynchronizationMsc.c b/MdePkg/Library/BaseSynchronizationLib/SynchronizationMsc.c
index 895acdc39fac47012e599f25b2c9cd667c857075..821c79812110aee044e6627e7a6d98c5dbf18f42 100644 (file)
--- a/MdePkg/Library/BaseSynchronizationLib/SynchronizationMsc.c
+++ b/MdePkg/Library/BaseSynchronizationLib/SynchronizationMsc.c
@@ -1,7 +1,7 @@
 /** @file\r
   Implementation of synchronization functions.\r
 \r
-  Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>\r
+  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>\r
   This program and the accompanying materials\r
   are licensed and made available under the terms and conditions of the BSD License\r
   which accompanies this distribution.  The full text of the license may be found at\r
@@ -30,8 +30,8 @@ void    _ReadWriteBarrier (void);
   optimal spin lock performance.\r
 \r
   This function retrieves the spin lock alignment requirements for optimal\r
-  performance on a given CPU architecture. The spin lock alignment must be a\r
-  power of two and is returned by this function. If there are no alignment\r
+  performance on a given CPU architecture. The spin lock alignment is byte alignment. \r
+  It must be a power of two and is returned by this function. If there are no alignment\r
   requirements, then 1 must be returned. The spin lock synchronization\r
   functions must function correctly if the spin lock size and alignment values\r
   returned by this function are not used at all. These values are hints to the\r
@@ -116,7 +116,11 @@ AcquireSpinLock (
   INT64   Cycle;\r
   INT64   Delta;\r
 \r
-  if (PcdGet32 (PcdSpinLockTimeout) > 0) {\r
+  if (PcdGet32 (PcdSpinLockTimeout) == 0) {\r
+    while (!AcquireSpinLockOrFail (SpinLock)) {\r
+      CpuPause ();\r
+    }\r
+  } else if (!AcquireSpinLockOrFail (SpinLock)) {\r
     //\r
     // Get the current timer value\r
     //\r
@@ -160,10 +164,6 @@ AcquireSpinLock (
       Total += Delta;\r
       ASSERT (Total < Timeout);\r
     }\r
-  } else {\r
-    while (!AcquireSpinLockOrFail (SpinLock)) {\r
-      CpuPause ();\r
-    }\r
   }\r
   return SpinLock;\r
 }\r
@@ -294,6 +294,37 @@ InterlockedDecrement (
   return InternalSyncDecrement (Value);\r
 }\r
 \r
+/**\r
+  Performs an atomic compare exchange operation on a 16-bit unsigned integer.\r
+\r
+  Performs an atomic compare exchange operation on the 16-bit unsigned integer\r
+  specified by Value.  If Value is equal to CompareValue, then Value is set to\r
+  ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,\r
+  then Value is returned.  The compare exchange operation must be performed using\r
+  MP safe mechanisms.\r
+\r
+  If Value is NULL, then ASSERT().\r
+\r
+  @param  Value         A pointer to the 16-bit value for the compare exchange\r
+                        operation.\r
+  @param  CompareValue  A 16-bit value used in a compare operation.\r
+  @param  ExchangeValue A 16-bit value used in an exchange operation.\r
+\r
+  @return The original *Value before exchange.\r
+\r
+**/\r
+UINT16\r
+EFIAPI\r
+InterlockedCompareExchange16 (\r
+  IN OUT  UINT16                    *Value,\r
+  IN      UINT16                    CompareValue,\r
+  IN      UINT16                    ExchangeValue\r
+  )\r
+{\r
+  ASSERT (Value != NULL);\r
+  return InternalSyncCompareExchange16 (Value, CompareValue, ExchangeValue);\r
+}\r
+\r
 /**\r
   Performs an atomic compare exchange operation on a 32-bit unsigned integer.\r
 \r