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/*++
Copyright (c) 2004, Intel Corporation
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
Module Name:
Lock.c
Abstract:
Support for locking lib services. These primitives may be implemented
as Esal calls but since these result in small code that us position
independent, we can use lib functions. ESAL calls have a significant
software overhead and too deep nesting is bad for the stack.
--*/
#include "Tiano.h"
#include "EfiDriverLib.h"
extern
BOOLEAN
EfiAtRuntime (
VOID
);
VOID
EfiInitializeLock (
IN OUT EFI_LOCK *Lock,
IN EFI_TPL Priority
)
/*++
Routine Description:
Initialize a basic mutual exclusion lock. There is
no concept of TPL at runtime hence priority is
ignored.
Arguments:
Lock - The EFI_LOCK structure to initialize
Priority - Ignored
Returns:
An initialized Efi Lock structure.
--*/
{
Lock->Tpl = Priority;
Lock->OwnerTpl = 0;
Lock->Lock = 0;
}
EFI_STATUS
EfiAcquireLockOrFail (
IN EFI_LOCK *Lock
)
/*++
Routine Description:
Initialize a basic mutual exclusion lock. For now,
only allow one level of nesting.
Arguments:
Lock - The EFI_LOCK structure to initialize
Returns:
EFI_SUCCESS - Lock Owned.
EFI_ACCESS_DENIED - Reentrant Lock Acquisition, Lock not Owned.
--*/
{
if (Lock->Lock != 0) {
//
// Lock is already owned, so bail out
//
return EFI_ACCESS_DENIED;
}
if (!EfiAtRuntime ()) {
//
// The check is just debug code for core inplementation. It must
// always be true in a driver
//
Lock->OwnerTpl = gBS->RaiseTPL (Lock->Tpl);
}
Lock->Lock += 1;
return EFI_SUCCESS;
}
VOID
EfiAcquireLock (
IN EFI_LOCK *Lock
)
/*++
Routine Description:
Acquires ownership of the lock.
Arguments:
Lock - The lock to acquire
Returns:
Lock owned
--*/
{
EFI_STATUS Status;
Status = EfiAcquireLockOrFail (Lock);
//
// Lock was already locked.
//
ASSERT_EFI_ERROR (Status);
}
VOID
EfiReleaseLock (
IN EFI_LOCK *Lock
)
/*++
Routine Description:
Releases ownership of the mutual exclusion lock.
Arguments:
Lock - The lock to release
Returns:
Lock unowned
--*/
{
EFI_TPL Tpl;
Tpl = Lock->OwnerTpl;
ASSERT (Lock->Lock == 1);
Lock->Lock -= 1;
if (!EfiAtRuntime ()) {
//
// The check is just debug code for core inplementation. It must
// always be true in a driver
//
gBS->RestoreTPL (Tpl);
}
}
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