MdeModulePkg/Core/Dxe/Library/Library.c

   1 /** @file
   2   DXE Core library services.
   3
   4 Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
   5 SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "DxeMain.h"
  10
  11 //
  12 // Lock Stuff
  13 //
  14
  15 /**
  16   Initialize a basic mutual exclusion lock.   Each lock
  17   provides mutual exclusion access at it's task priority
  18   level.  Since there is no-premption (at any TPL) or
  19   multiprocessor support, acquiring the lock only consists
  20   of raising to the locks TPL.
  21
  22   @param  Lock               The EFI_LOCK structure to initialize
  23
  24   @retval EFI_SUCCESS        Lock Owned.
  25   @retval EFI_ACCESS_DENIED  Reentrant Lock Acquisition, Lock not Owned.
  26
  27 **/
  28 EFI_STATUS
  29 CoreAcquireLockOrFail (
  30   IN EFI_LOCK  *Lock
  31   )
  32 {
  33   ASSERT (Lock != NULL);
  34   ASSERT (Lock->Lock != EfiLockUninitialized);
  35
  36   if (Lock->Lock == EfiLockAcquired) {
  37     //
  38     // Lock is already owned, so bail out
  39     //
  40     return EFI_ACCESS_DENIED;
  41   }
  42
  43   Lock->OwnerTpl = CoreRaiseTpl (Lock->Tpl);
  44
  45   Lock->Lock = EfiLockAcquired;
  46   return EFI_SUCCESS;
  47 }
  48
  49 /**
  50   Raising to the task priority level of the mutual exclusion
  51   lock, and then acquires ownership of the lock.
  52
  53   @param  Lock               The lock to acquire
  54
  55   @return Lock owned
  56
  57 **/
  58 VOID
  59 CoreAcquireLock (
  60   IN EFI_LOCK  *Lock
  61   )
  62 {
  63   ASSERT (Lock != NULL);
  64   ASSERT (Lock->Lock == EfiLockReleased);
  65
  66   Lock->OwnerTpl = CoreRaiseTpl (Lock->Tpl);
  67   Lock->Lock     = EfiLockAcquired;
  68 }
  69
  70 /**
  71   Releases ownership of the mutual exclusion lock, and
  72   restores the previous task priority level.
  73
  74   @param  Lock               The lock to release
  75
  76   @return Lock unowned
  77
  78 **/
  79 VOID
  80 CoreReleaseLock (
  81   IN EFI_LOCK  *Lock
  82   )
  83 {
  84   EFI_TPL  Tpl;
  85
  86   ASSERT (Lock != NULL);
  87   ASSERT (Lock->Lock == EfiLockAcquired);
  88
  89   Tpl = Lock->OwnerTpl;
  90
  91   Lock->Lock = EfiLockReleased;
  92
  93   CoreRestoreTpl (Tpl);
  94 }