1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
/*++
Copyright (c) 2005, 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:
Implements FLOCK
Revision History
--*/
#include "EfiShellLib.h"
VOID
InitializeLock (
IN OUT FLOCK *Lock,
IN EFI_TPL Priority
)
/*++
Routine Description:
Initialize a basic mutual exclusion lock. Each lock
provides mutual exclusion access at it's task priority
level. Since there is no-premption (at any TPL) or
multiprocessor support, acquiring the lock only consists
of raising to the locks TPL.
Note on a debug build the lock is acquired and released
to help ensure proper usage.
Arguments:
Lock - The FLOCK structure to initialize
Priority - The task priority level of the lock
Returns:
An initialized F Lock structure.
--*/
{
ASSERT (Lock != NULL);
Lock->Tpl = Priority;
Lock->OwnerTpl = 0;
Lock->Lock = 0;
}
VOID
AcquireLock (
IN FLOCK *Lock
)
/*++
Routine Description:
Raising to the task priority level of the mutual exclusion
lock, and then acquires ownership of the lock.
Arguments:
Lock - The lock to acquire
Returns:
Lock owned
--*/
{
ASSERT (Lock);
if (BS) {
if (BS->RaiseTPL != NULL) {
Lock->OwnerTpl = BS->RaiseTPL (Lock->Tpl);
}
}
Lock->Lock += 1;
ASSERT (Lock->Lock == 1);
}
VOID
ReleaseLock (
IN FLOCK *Lock
)
/*++
Routine Description:
Releases ownership of the mutual exclusion lock, and
restores the previous task priority level.
Arguments:
Lock - The lock to release
Returns:
Lock unowned
--*/
{
EFI_TPL Tpl;
ASSERT (Lock != NULL);
Tpl = Lock->OwnerTpl;
ASSERT (Lock->Lock == 1);
Lock->Lock -= 1;
if (BS) {
if (BS->RestoreTPL != NULL) {
BS->RestoreTPL (Tpl);
}
}
}
|
