]>
Commit | Line | Data |
---|---|---|
c5be0f71 | 1 | /* Copyright (C) 2003,2004,2006,2007,2011 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 | |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
a88c9263 UD |
18 | |
19 | #include <endian.h> | |
20 | #include <errno.h> | |
21 | #include <sysdep.h> | |
22 | #include <lowlevellock.h> | |
23 | #include <pthread.h> | |
24 | #include <pthreadP.h> | |
25 | ||
26 | #include <shlib-compat.h> | |
27 | ||
28 | ||
7ce5c164 UD |
29 | struct _condvar_cleanup_buffer |
30 | { | |
31 | int oldtype; | |
32 | pthread_cond_t *cond; | |
33 | pthread_mutex_t *mutex; | |
893a3511 | 34 | unsigned int bc_seq; |
7ce5c164 UD |
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; | |
73f7c32c | 44 | unsigned int destroying; |
5bd8a249 UD |
45 | int pshared = (cbuffer->cond->__data.__mutex == (void *) ~0l) |
46 | ? LLL_SHARED : LLL_PRIVATE; | |
a88c9263 UD |
47 | |
48 | /* We are going to modify shared data. */ | |
5bd8a249 | 49 | lll_lock (cbuffer->cond->__data.__lock, pshared); |
a88c9263 | 50 | |
893a3511 UD |
51 | if (cbuffer->bc_seq == cbuffer->cond->__data.__broadcast_seq) |
52 | { | |
53 | /* This thread is not waiting anymore. Adjust the sequence counters | |
346e6ad4 | 54 | appropriately. We do not increment WAKEUP_SEQ if this would |
2b6a801e | 55 | bump it over the value of TOTAL_SEQ. This can happen if a thread |
346e6ad4 UD |
56 | was woken and then canceled. */ |
57 | if (cbuffer->cond->__data.__wakeup_seq | |
58 | < cbuffer->cond->__data.__total_seq) | |
2b6a801e UD |
59 | { |
60 | ++cbuffer->cond->__data.__wakeup_seq; | |
61 | ++cbuffer->cond->__data.__futex; | |
62 | } | |
893a3511 UD |
63 | ++cbuffer->cond->__data.__woken_seq; |
64 | } | |
a88c9263 | 65 | |
ee5d5755 | 66 | cbuffer->cond->__data.__nwaiters -= 1 << COND_NWAITERS_SHIFT; |
73f7c32c UD |
67 | |
68 | /* If pthread_cond_destroy was called on this variable already, | |
69 | notify the pthread_cond_destroy caller all waiters have left | |
70 | and it can be successfully destroyed. */ | |
71 | destroying = 0; | |
72 | if (cbuffer->cond->__data.__total_seq == -1ULL | |
ee5d5755 | 73 | && cbuffer->cond->__data.__nwaiters < (1 << COND_NWAITERS_SHIFT)) |
73f7c32c | 74 | { |
5bd8a249 | 75 | lll_futex_wake (&cbuffer->cond->__data.__nwaiters, 1, pshared); |
73f7c32c UD |
76 | destroying = 1; |
77 | } | |
78 | ||
24a49f38 | 79 | /* We are done. */ |
5bd8a249 | 80 | lll_unlock (cbuffer->cond->__data.__lock, pshared); |
24a49f38 | 81 | |
3e976b96 | 82 | /* Wake everybody to make sure no condvar signal gets lost. */ |
73f7c32c | 83 | if (! destroying) |
5bd8a249 | 84 | lll_futex_wake (&cbuffer->cond->__data.__futex, INT_MAX, pshared); |
3e976b96 | 85 | |
7ce5c164 UD |
86 | /* Get the mutex before returning unless asynchronous cancellation |
87 | is in effect. */ | |
69431c9a | 88 | __pthread_mutex_cond_lock (cbuffer->mutex); |
a88c9263 UD |
89 | } |
90 | ||
91 | ||
92 | int | |
93 | __pthread_cond_wait (cond, mutex) | |
94 | pthread_cond_t *cond; | |
95 | pthread_mutex_t *mutex; | |
96 | { | |
97 | struct _pthread_cleanup_buffer buffer; | |
7ce5c164 UD |
98 | struct _condvar_cleanup_buffer cbuffer; |
99 | int err; | |
5bd8a249 UD |
100 | int pshared = (cond->__data.__mutex == (void *) ~0l) |
101 | ? LLL_SHARED : LLL_PRIVATE; | |
a88c9263 | 102 | |
c5be0f71 | 103 | /* Make sure we are alone. */ |
5bd8a249 | 104 | lll_lock (cond->__data.__lock, pshared); |
a88c9263 UD |
105 | |
106 | /* Now we can release the mutex. */ | |
61623643 | 107 | err = __pthread_mutex_unlock_usercnt (mutex, 0); |
b078c591 | 108 | if (__builtin_expect (err, 0)) |
7ce5c164 | 109 | { |
5bd8a249 | 110 | lll_unlock (cond->__data.__lock, pshared); |
7ce5c164 UD |
111 | return err; |
112 | } | |
a88c9263 UD |
113 | |
114 | /* We have one new user of the condvar. */ | |
115 | ++cond->__data.__total_seq; | |
75fccede | 116 | ++cond->__data.__futex; |
ee5d5755 | 117 | cond->__data.__nwaiters += 1 << COND_NWAITERS_SHIFT; |
a88c9263 | 118 | |
69431c9a | 119 | /* Remember the mutex we are using here. If there is already a |
e42a990e UD |
120 | different address store this is a bad user bug. Do not store |
121 | anything for pshared condvars. */ | |
122 | if (cond->__data.__mutex != (void *) ~0l) | |
123 | cond->__data.__mutex = mutex; | |
69431c9a | 124 | |
7ce5c164 UD |
125 | /* Prepare structure passed to cancellation handler. */ |
126 | cbuffer.cond = cond; | |
127 | cbuffer.mutex = mutex; | |
128 | ||
a88c9263 UD |
129 | /* Before we block we enable cancellation. Therefore we have to |
130 | install a cancellation handler. */ | |
7ce5c164 | 131 | __pthread_cleanup_push (&buffer, __condvar_cleanup, &cbuffer); |
a88c9263 UD |
132 | |
133 | /* The current values of the wakeup counter. The "woken" counter | |
134 | must exceed this value. */ | |
135 | unsigned long long int val; | |
136 | unsigned long long int seq; | |
137 | val = seq = cond->__data.__wakeup_seq; | |
893a3511 UD |
138 | /* Remember the broadcast counter. */ |
139 | cbuffer.bc_seq = cond->__data.__broadcast_seq; | |
a88c9263 | 140 | |
46a32546 | 141 | do |
a88c9263 | 142 | { |
75fccede UD |
143 | unsigned int futex_val = cond->__data.__futex; |
144 | ||
a88c9263 | 145 | /* Prepare to wait. Release the condvar futex. */ |
5bd8a249 | 146 | lll_unlock (cond->__data.__lock, pshared); |
a88c9263 UD |
147 | |
148 | /* Enable asynchronous cancellation. Required by the standard. */ | |
69431c9a | 149 | cbuffer.oldtype = __pthread_enable_asynccancel (); |
a88c9263 | 150 | |
75fccede | 151 | /* Wait until woken by signal or broadcast. */ |
5bd8a249 | 152 | lll_futex_wait (&cond->__data.__futex, futex_val, pshared); |
a88c9263 UD |
153 | |
154 | /* Disable asynchronous cancellation. */ | |
7ce5c164 | 155 | __pthread_disable_asynccancel (cbuffer.oldtype); |
a88c9263 | 156 | |
3abc82c8 | 157 | /* We are going to look at shared data again, so get the lock. */ |
5bd8a249 | 158 | lll_lock (cond->__data.__lock, pshared); |
3abc82c8 | 159 | |
893a3511 UD |
160 | /* If a broadcast happened, we are done. */ |
161 | if (cbuffer.bc_seq != cond->__data.__broadcast_seq) | |
162 | goto bc_out; | |
163 | ||
a88c9263 UD |
164 | /* Check whether we are eligible for wakeup. */ |
165 | val = cond->__data.__wakeup_seq; | |
a88c9263 | 166 | } |
cff08c81 | 167 | while (val == seq || cond->__data.__woken_seq == val); |
a88c9263 UD |
168 | |
169 | /* Another thread woken up. */ | |
170 | ++cond->__data.__woken_seq; | |
171 | ||
893a3511 | 172 | bc_out: |
73f7c32c | 173 | |
ee5d5755 | 174 | cond->__data.__nwaiters -= 1 << COND_NWAITERS_SHIFT; |
73f7c32c UD |
175 | |
176 | /* If pthread_cond_destroy was called on this varaible already, | |
177 | notify the pthread_cond_destroy caller all waiters have left | |
178 | and it can be successfully destroyed. */ | |
179 | if (cond->__data.__total_seq == -1ULL | |
ee5d5755 | 180 | && cond->__data.__nwaiters < (1 << COND_NWAITERS_SHIFT)) |
5bd8a249 | 181 | lll_futex_wake (&cond->__data.__nwaiters, 1, pshared); |
73f7c32c | 182 | |
a88c9263 | 183 | /* We are done with the condvar. */ |
5bd8a249 | 184 | lll_unlock (cond->__data.__lock, pshared); |
a88c9263 UD |
185 | |
186 | /* The cancellation handling is back to normal, remove the handler. */ | |
187 | __pthread_cleanup_pop (&buffer, 0); | |
188 | ||
189 | /* Get the mutex before returning. */ | |
69431c9a | 190 | return __pthread_mutex_cond_lock (mutex); |
a88c9263 UD |
191 | } |
192 | ||
193 | versioned_symbol (libpthread, __pthread_cond_wait, pthread_cond_wait, | |
194 | GLIBC_2_3_2); |