Commit | Line | Data |
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49617de1 MD |
1 | /* |
2 | * compat_futex.c | |
3 | * | |
4 | * Userspace RCU library - sys_futex compatibility code | |
5 | * | |
6982d6d7 | 6 | * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
49617de1 MD |
7 | * |
8 | * This library is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with this library; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
23 | #include <stdio.h> | |
24 | #include <pthread.h> | |
25 | #include <signal.h> | |
26 | #include <assert.h> | |
27 | #include <errno.h> | |
28 | #include <poll.h> | |
6d841bc2 | 29 | #include <stdint.h> |
49617de1 MD |
30 | |
31 | #include <urcu/arch.h> | |
41849996 | 32 | #include <urcu/futex.h> |
49617de1 | 33 | |
5c02e37d MD |
34 | /* |
35 | * Using attribute "weak" for __urcu_compat_futex_lock and | |
36 | * __urcu_compat_futex_cond. Those are globally visible by the entire | |
37 | * program, even though many shared objects may have their own version. | |
38 | * The first version that gets loaded will be used by the entire program | |
39 | * (executable and all shared objects). | |
40 | */ | |
41 | ||
42 | __attribute__((weak)) | |
43 | pthread_mutex_t __urcu_compat_futex_lock = PTHREAD_MUTEX_INITIALIZER; | |
44 | __attribute__((weak)) | |
45 | pthread_cond_t __urcu_compat_futex_cond = PTHREAD_COND_INITIALIZER; | |
49617de1 MD |
46 | |
47 | /* | |
48 | * _NOT SIGNAL-SAFE_. pthread_cond is not signal-safe anyway. Though. | |
49 | * For now, timeout, uaddr2 and val3 are unused. | |
50 | * Waiter will relinquish the CPU until woken up. | |
51 | */ | |
52 | ||
6d841bc2 MD |
53 | int compat_futex_noasync(int32_t *uaddr, int op, int32_t val, |
54 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
49617de1 | 55 | { |
5b80127f | 56 | int ret, gret = 0; |
49617de1 MD |
57 | |
58 | /* | |
59 | * Check if NULL. Don't let users expect that they are taken into | |
60 | * account. | |
61 | */ | |
62 | assert(!timeout); | |
63 | assert(!uaddr2); | |
64 | assert(!val3); | |
65 | ||
66 | /* | |
67 | * memory barriers to serialize with the previous uaddr modification. | |
68 | */ | |
5481ddb3 | 69 | cmm_smp_mb(); |
49617de1 | 70 | |
5c02e37d | 71 | ret = pthread_mutex_lock(&__urcu_compat_futex_lock); |
49617de1 MD |
72 | assert(!ret); |
73 | switch (op) { | |
74 | case FUTEX_WAIT: | |
75 | if (*uaddr != val) | |
76 | goto end; | |
5c02e37d | 77 | pthread_cond_wait(&__urcu_compat_futex_cond, &__urcu_compat_futex_lock); |
49617de1 MD |
78 | break; |
79 | case FUTEX_WAKE: | |
5c02e37d | 80 | pthread_cond_broadcast(&__urcu_compat_futex_cond); |
49617de1 MD |
81 | break; |
82 | default: | |
83 | gret = -EINVAL; | |
84 | } | |
85 | end: | |
5c02e37d | 86 | ret = pthread_mutex_unlock(&__urcu_compat_futex_lock); |
49617de1 MD |
87 | assert(!ret); |
88 | return gret; | |
89 | } | |
90 | ||
91 | /* | |
92 | * _ASYNC SIGNAL-SAFE_. | |
93 | * For now, timeout, uaddr2 and val3 are unused. | |
94 | * Waiter will busy-loop trying to read the condition. | |
95 | */ | |
96 | ||
6d841bc2 MD |
97 | int compat_futex_async(int32_t *uaddr, int op, int32_t val, |
98 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
49617de1 | 99 | { |
49617de1 MD |
100 | /* |
101 | * Check if NULL. Don't let users expect that they are taken into | |
102 | * account. | |
103 | */ | |
104 | assert(!timeout); | |
105 | assert(!uaddr2); | |
106 | assert(!val3); | |
107 | ||
108 | /* | |
109 | * Ensure previous memory operations on uaddr have completed. | |
110 | */ | |
5481ddb3 | 111 | cmm_smp_mb(); |
49617de1 MD |
112 | |
113 | switch (op) { | |
114 | case FUTEX_WAIT: | |
115 | while (*uaddr == val) | |
116 | poll(NULL, 0, 10); | |
117 | break; | |
118 | case FUTEX_WAKE: | |
119 | break; | |
120 | default: | |
121 | return -EINVAL; | |
122 | } | |
1494da88 | 123 | return 0; |
49617de1 | 124 | } |