1 | /* Low-level lock implementation. Mach gsync-based version. |
2 | Copyright (C) 1994-2022 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #ifndef _MACH_LOWLEVELLOCK_H |
20 | #define _MACH_LOWLEVELLOCK_H 1 |
21 | |
22 | #include <mach/gnumach.h> |
23 | #include <atomic.h> |
24 | |
25 | /* Gsync flags. */ |
26 | #ifndef GSYNC_SHARED |
27 | # define GSYNC_SHARED 0x01 |
28 | # define GSYNC_QUAD 0x02 |
29 | # define GSYNC_TIMED 0x04 |
30 | # define GSYNC_BROADCAST 0x08 |
31 | # define GSYNC_MUTATE 0x10 |
32 | #endif |
33 | |
34 | /* Static initializer for low-level locks. */ |
35 | #define LLL_LOCK_INITIALIZER 0 |
36 | |
37 | #define LLL_PRIVATE 0 |
38 | #define LLL_SHARED SYNC_SHARED |
39 | |
40 | /* Interruptible version of __gsync_wait. */ |
41 | extern kern_return_t __gsync_wait_intr |
42 | ( |
43 | mach_port_t task, |
44 | vm_offset_t addr, |
45 | unsigned val1, |
46 | unsigned val2, |
47 | natural_t msec, |
48 | int flags |
49 | ); |
50 | |
51 | /* Wait on address PTR, without blocking if its contents |
52 | * are different from VAL. */ |
53 | #define __lll_wait(ptr, val, flags) \ |
54 | __gsync_wait (__mach_task_self (), \ |
55 | (vm_offset_t)(ptr), (val), 0, 0, (flags)) |
56 | #define lll_wait(var, val, flags) \ |
57 | __lll_wait (&(var), val, flags) |
58 | |
59 | /* Interruptible version. */ |
60 | #define __lll_wait_intr(ptr, val, flags) \ |
61 | __gsync_wait_intr (__mach_task_self (), \ |
62 | (vm_offset_t)(ptr), (val), 0, 0, (flags)) |
63 | #define lll_wait_intr(var, val, flags) \ |
64 | __lll_wait_intr ((&var), val, flags) |
65 | |
66 | /* Wake one or more threads waiting on address PTR. */ |
67 | #define __lll_wake(ptr, flags) \ |
68 | __gsync_wake (__mach_task_self (), (vm_offset_t)(ptr), 0, (flags)) |
69 | #define lll_wake(var, flags) \ |
70 | __lll_wake (&(var), flags) |
71 | |
72 | /* Acquire the lock at PTR. */ |
73 | #define __lll_lock(ptr, flags) \ |
74 | ({ \ |
75 | int *__iptr = (int *)(ptr); \ |
76 | int __flags = (flags); \ |
77 | if (*__iptr != 0 \ |
78 | || atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) != 0) \ |
79 | while (1) \ |
80 | { \ |
81 | if (atomic_exchange_acq (__iptr, 2) == 0) \ |
82 | break; \ |
83 | __lll_wait (__iptr, 2, __flags); \ |
84 | } \ |
85 | (void)0; \ |
86 | }) |
87 | #define lll_lock(var, flags) \ |
88 | __lll_lock (&(var), flags) |
89 | |
90 | /* Try to acquire the lock at PTR, without blocking. |
91 | Evaluates to zero on success. */ |
92 | #define __lll_trylock(ptr) \ |
93 | ({ \ |
94 | int *__iptr = (int *)(ptr); \ |
95 | *__iptr == 0 \ |
96 | && atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) == 0 ? 0 : -1; \ |
97 | }) |
98 | #define lll_trylock(var) \ |
99 | __lll_trylock (&(var)) |
100 | |
101 | /* Release the lock at PTR. */ |
102 | #define __lll_unlock(ptr, flags) \ |
103 | ({ \ |
104 | int *__iptr = (int *)(ptr); \ |
105 | if (atomic_exchange_rel (__iptr, 0) == 2) \ |
106 | __lll_wake (__iptr, (flags)); \ |
107 | (void)0; \ |
108 | }) |
109 | #define lll_unlock(var, flags) \ |
110 | __lll_unlock (&(var), flags) |
111 | |
112 | #endif |
113 | |