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 MD |
33 | |
34 | static pthread_mutex_t compat_futex_lock = PTHREAD_MUTEX_INITIALIZER; | |
35 | static pthread_cond_t compat_futex_cond = PTHREAD_COND_INITIALIZER; | |
36 | ||
37 | /* | |
38 | * _NOT SIGNAL-SAFE_. pthread_cond is not signal-safe anyway. Though. | |
39 | * For now, timeout, uaddr2 and val3 are unused. | |
40 | * Waiter will relinquish the CPU until woken up. | |
41 | */ | |
42 | ||
6d841bc2 MD |
43 | int compat_futex_noasync(int32_t *uaddr, int op, int32_t val, |
44 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
49617de1 MD |
45 | { |
46 | int ret, i, gret = 0; | |
47 | ||
48 | /* | |
49 | * Check if NULL. Don't let users expect that they are taken into | |
50 | * account. | |
51 | */ | |
52 | assert(!timeout); | |
53 | assert(!uaddr2); | |
54 | assert(!val3); | |
55 | ||
56 | /* | |
57 | * memory barriers to serialize with the previous uaddr modification. | |
58 | */ | |
5481ddb3 | 59 | cmm_smp_mb(); |
49617de1 MD |
60 | |
61 | ret = pthread_mutex_lock(&compat_futex_lock); | |
62 | assert(!ret); | |
63 | switch (op) { | |
64 | case FUTEX_WAIT: | |
65 | if (*uaddr != val) | |
66 | goto end; | |
67 | pthread_cond_wait(&compat_futex_cond, &compat_futex_lock); | |
68 | break; | |
69 | case FUTEX_WAKE: | |
70 | for (i = 0; i < val; i++) | |
71 | pthread_cond_signal(&compat_futex_cond); | |
72 | break; | |
73 | default: | |
74 | gret = -EINVAL; | |
75 | } | |
76 | end: | |
77 | ret = pthread_mutex_unlock(&compat_futex_lock); | |
78 | assert(!ret); | |
79 | return gret; | |
80 | } | |
81 | ||
82 | /* | |
83 | * _ASYNC SIGNAL-SAFE_. | |
84 | * For now, timeout, uaddr2 and val3 are unused. | |
85 | * Waiter will busy-loop trying to read the condition. | |
86 | */ | |
87 | ||
6d841bc2 MD |
88 | int compat_futex_async(int32_t *uaddr, int op, int32_t val, |
89 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
49617de1 | 90 | { |
49617de1 MD |
91 | /* |
92 | * Check if NULL. Don't let users expect that they are taken into | |
93 | * account. | |
94 | */ | |
95 | assert(!timeout); | |
96 | assert(!uaddr2); | |
97 | assert(!val3); | |
98 | ||
99 | /* | |
100 | * Ensure previous memory operations on uaddr have completed. | |
101 | */ | |
5481ddb3 | 102 | cmm_smp_mb(); |
49617de1 MD |
103 | |
104 | switch (op) { | |
105 | case FUTEX_WAIT: | |
106 | while (*uaddr == val) | |
107 | poll(NULL, 0, 10); | |
108 | break; | |
109 | case FUTEX_WAKE: | |
110 | break; | |
111 | default: | |
112 | return -EINVAL; | |
113 | } | |
1494da88 | 114 | return 0; |
49617de1 | 115 | } |