EdkCompatibilityPkg/Foundation/Library/RuntimeDxe/EfiRuntimeLib/Ipf/Lock.c

   1 /*++
   2
   3 Copyright (c) 2004, Intel Corporation. All rights reserved.<BR>
   4 This program and the accompanying materials
   5 are licensed and made available under the terms and conditions of the BSD License
   6 which accompanies this distribution.  The full text of the license may be found at
   7 http://opensource.org/licenses/bsd-license.php
   8
   9 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11
  12 Module Name:
  13
  14   Lock.c
  15
  16 Abstract:
  17
  18   Support for locking lib services. These primitives may be implemented
  19   as Esal calls but since these result in small code that us position
  20   independent, we can use lib functions. ESAL calls have a significant
  21   software overhead and too deep nesting is bad for the stack.
  22
  23 --*/
  24
  25 #include "Tiano.h"
  26 #include "EfiDriverLib.h"
  27
  28 extern
  29 BOOLEAN
  30 EfiAtRuntime (
  31   VOID
  32   );
  33
  34 VOID
  35 EfiInitializeLock (
  36   IN OUT EFI_LOCK *Lock,
  37   IN EFI_TPL      Priority
  38   )
  39 /*++
  40
  41 Routine Description:
  42
  43   Initialize a basic mutual exclusion lock. There is
  44   no concept of TPL at runtime hence priority is
  45   ignored.
  46
  47 Arguments:
  48
  49   Lock        - The EFI_LOCK structure to initialize
  50
  51   Priority    - Ignored
  52
  53
  54 Returns:
  55
  56   An initialized Efi Lock structure.
  57
  58 --*/
  59 {
  60   Lock->Tpl       = Priority;
  61   Lock->OwnerTpl  = 0;
  62   Lock->Lock      = 0;
  63 }
  64
  65 EFI_STATUS
  66 EfiAcquireLockOrFail (
  67   IN EFI_LOCK  *Lock
  68   )
  69 /*++
  70
  71 Routine Description:
  72
  73   Initialize a basic mutual exclusion lock. For now,
  74   only allow one level of nesting.
  75
  76 Arguments:
  77
  78   Lock        - The EFI_LOCK structure to initialize
  79
  80 Returns:
  81
  82   EFI_SUCCESS       - Lock Owned.
  83   EFI_ACCESS_DENIED - Reentrant Lock Acquisition, Lock not Owned.
  84
  85 --*/
  86 {
  87   if (Lock->Lock != 0) {
  88     //
  89     // Lock is already owned, so bail out
  90     //
  91     return EFI_ACCESS_DENIED;
  92   }
  93
  94   if (!EfiAtRuntime ()) {
  95     //
  96     // The check is just debug code for core inplementation. It must
  97     //  always be true in a driver
  98     //
  99     Lock->OwnerTpl = gBS->RaiseTPL (Lock->Tpl);
 100   }
 101
 102   Lock->Lock += 1;
 103   return EFI_SUCCESS;
 104 }
 105
 106 VOID
 107 EfiAcquireLock (
 108   IN EFI_LOCK  *Lock
 109   )
 110 /*++
 111
 112 Routine Description:
 113
 114   Acquires ownership of the lock.
 115
 116 Arguments:
 117
 118   Lock - The lock to acquire
 119
 120 Returns:
 121
 122   Lock owned
 123
 124 --*/
 125 {
 126   EFI_STATUS  Status;
 127
 128   Status = EfiAcquireLockOrFail (Lock);
 129
 130   //
 131   // Lock was already locked.
 132   //
 133   ASSERT_EFI_ERROR (Status);
 134 }
 135
 136 VOID
 137 EfiReleaseLock (
 138   IN EFI_LOCK  *Lock
 139   )
 140 /*++
 141
 142 Routine Description:
 143
 144     Releases ownership of the mutual exclusion lock.
 145
 146 Arguments:
 147
 148     Lock - The lock to release
 149
 150 Returns:
 151
 152     Lock unowned
 153
 154 --*/
 155 {
 156   EFI_TPL Tpl;
 157
 158   Tpl = Lock->OwnerTpl;
 159
 160   ASSERT (Lock->Lock == 1);
 161   Lock->Lock -= 1;
 162
 163   if (!EfiAtRuntime ()) {
 164     //
 165     // The check is just debug code for core inplementation. It must
 166     //  always be true in a driver
 167     //
 168     gBS->RestoreTPL (Tpl);
 169   }
 170 }