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b078c591 | 1 | /* Copyright (C) 2003, 2004 Free Software Foundation, Inc. |
a88c9263 UD |
2 | This file is part of the GNU C Library. |
3 | Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003. | |
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, write to the Free | |
17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
18 | 02111-1307 USA. */ | |
19 | ||
20 | #include <endian.h> | |
21 | #include <errno.h> | |
22 | #include <sysdep.h> | |
23 | #include <lowlevellock.h> | |
24 | #include <pthread.h> | |
25 | #include <pthreadP.h> | |
26 | ||
27 | #include <shlib-compat.h> | |
28 | ||
29 | ||
7ce5c164 UD |
30 | struct _condvar_cleanup_buffer |
31 | { | |
32 | int oldtype; | |
33 | pthread_cond_t *cond; | |
34 | pthread_mutex_t *mutex; | |
35 | }; | |
36 | ||
3e976b96 | 37 | |
a88c9263 UD |
38 | void |
39 | __attribute__ ((visibility ("hidden"))) | |
40 | __condvar_cleanup (void *arg) | |
41 | { | |
7ce5c164 UD |
42 | struct _condvar_cleanup_buffer *cbuffer = |
43 | (struct _condvar_cleanup_buffer *) arg; | |
a88c9263 UD |
44 | |
45 | /* We are going to modify shared data. */ | |
7ce5c164 | 46 | lll_mutex_lock (cbuffer->cond->__data.__lock); |
a88c9263 UD |
47 | |
48 | /* This thread is not waiting anymore. Adjust the sequence counters | |
49 | appropriately. */ | |
7ce5c164 UD |
50 | ++cbuffer->cond->__data.__wakeup_seq; |
51 | ++cbuffer->cond->__data.__woken_seq; | |
a88c9263 | 52 | |
24a49f38 UD |
53 | /* We are done. */ |
54 | lll_mutex_unlock (cbuffer->cond->__data.__lock); | |
55 | ||
3e976b96 UD |
56 | /* Wake everybody to make sure no condvar signal gets lost. */ |
57 | #if BYTE_ORDER == LITTLE_ENDIAN | |
58 | int *futex = ((int *) (&cbuffer->cond->__data.__wakeup_seq)); | |
59 | #elif BYTE_ORDER == BIG_ENDIAN | |
60 | int *futex = ((int *) (&cbuffer->cond->__data.__wakeup_seq)) + 1; | |
61 | #else | |
62 | # error "No valid byte order" | |
63 | #endif | |
64 | lll_futex_wake (futex, INT_MAX); | |
65 | ||
7ce5c164 UD |
66 | /* Get the mutex before returning unless asynchronous cancellation |
67 | is in effect. */ | |
69431c9a | 68 | __pthread_mutex_cond_lock (cbuffer->mutex); |
a88c9263 UD |
69 | } |
70 | ||
71 | ||
72 | int | |
73 | __pthread_cond_wait (cond, mutex) | |
74 | pthread_cond_t *cond; | |
75 | pthread_mutex_t *mutex; | |
76 | { | |
77 | struct _pthread_cleanup_buffer buffer; | |
7ce5c164 UD |
78 | struct _condvar_cleanup_buffer cbuffer; |
79 | int err; | |
a88c9263 UD |
80 | |
81 | /* Make sure we are along. */ | |
82 | lll_mutex_lock (cond->__data.__lock); | |
83 | ||
84 | /* Now we can release the mutex. */ | |
61623643 | 85 | err = __pthread_mutex_unlock_usercnt (mutex, 0); |
b078c591 | 86 | if (__builtin_expect (err, 0)) |
7ce5c164 UD |
87 | { |
88 | lll_mutex_unlock (cond->__data.__lock); | |
89 | return err; | |
90 | } | |
a88c9263 UD |
91 | |
92 | /* We have one new user of the condvar. */ | |
93 | ++cond->__data.__total_seq; | |
94 | ||
69431c9a | 95 | /* Remember the mutex we are using here. If there is already a |
e42a990e UD |
96 | different address store this is a bad user bug. Do not store |
97 | anything for pshared condvars. */ | |
98 | if (cond->__data.__mutex != (void *) ~0l) | |
99 | cond->__data.__mutex = mutex; | |
69431c9a | 100 | |
7ce5c164 UD |
101 | /* Prepare structure passed to cancellation handler. */ |
102 | cbuffer.cond = cond; | |
103 | cbuffer.mutex = mutex; | |
104 | ||
a88c9263 UD |
105 | /* Before we block we enable cancellation. Therefore we have to |
106 | install a cancellation handler. */ | |
7ce5c164 | 107 | __pthread_cleanup_push (&buffer, __condvar_cleanup, &cbuffer); |
a88c9263 UD |
108 | |
109 | /* The current values of the wakeup counter. The "woken" counter | |
110 | must exceed this value. */ | |
111 | unsigned long long int val; | |
112 | unsigned long long int seq; | |
113 | val = seq = cond->__data.__wakeup_seq; | |
114 | ||
115 | /* The futex syscall operates on a 32-bit word. That is fine, we | |
116 | just use the low 32 bits of the sequence counter. */ | |
117 | #if BYTE_ORDER == LITTLE_ENDIAN | |
118 | int *futex = ((int *) (&cond->__data.__wakeup_seq)); | |
119 | #elif BYTE_ORDER == BIG_ENDIAN | |
120 | int *futex = ((int *) (&cond->__data.__wakeup_seq)) + 1; | |
121 | #else | |
122 | # error "No valid byte order" | |
123 | #endif | |
124 | ||
46a32546 | 125 | do |
a88c9263 UD |
126 | { |
127 | /* Prepare to wait. Release the condvar futex. */ | |
128 | lll_mutex_unlock (cond->__data.__lock); | |
129 | ||
130 | /* Enable asynchronous cancellation. Required by the standard. */ | |
69431c9a | 131 | cbuffer.oldtype = __pthread_enable_asynccancel (); |
a88c9263 UD |
132 | |
133 | /* Wait until woken by signal or broadcast. Note that we | |
134 | truncate the 'val' value to 32 bits. */ | |
135 | lll_futex_wait (futex, (unsigned int) val); | |
136 | ||
137 | /* Disable asynchronous cancellation. */ | |
7ce5c164 | 138 | __pthread_disable_asynccancel (cbuffer.oldtype); |
a88c9263 UD |
139 | |
140 | /* We are going to look at shared data again, so get the lock. */ | |
32a589b1 | 141 | lll_mutex_lock (cond->__data.__lock); |
a88c9263 UD |
142 | |
143 | /* Check whether we are eligible for wakeup. */ | |
144 | val = cond->__data.__wakeup_seq; | |
a88c9263 | 145 | } |
cff08c81 | 146 | while (val == seq || cond->__data.__woken_seq == val); |
a88c9263 UD |
147 | |
148 | /* Another thread woken up. */ | |
149 | ++cond->__data.__woken_seq; | |
150 | ||
151 | /* We are done with the condvar. */ | |
152 | lll_mutex_unlock (cond->__data.__lock); | |
153 | ||
154 | /* The cancellation handling is back to normal, remove the handler. */ | |
155 | __pthread_cleanup_pop (&buffer, 0); | |
156 | ||
157 | /* Get the mutex before returning. */ | |
69431c9a | 158 | return __pthread_mutex_cond_lock (mutex); |
a88c9263 UD |
159 | } |
160 | ||
161 | versioned_symbol (libpthread, __pthread_cond_wait, pthread_cond_wait, | |
162 | GLIBC_2_3_2); |