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37c054c7 | 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 <errno.h> | |
21 | #include <sysdep.h> | |
22 | #include <lowlevellock.h> | |
23 | #include <pthreadP.h> | |
24 | ||
25 | ||
26 | /* Wait on barrier. */ | |
27 | int | |
28 | pthread_barrier_wait (barrier) | |
29 | pthread_barrier_t *barrier; | |
30 | { | |
31 | struct pthread_barrier *ibarrier = (struct pthread_barrier *) barrier; | |
37c054c7 | 32 | int result = 0; |
a88c9263 UD |
33 | |
34 | /* Make sure we are alone. */ | |
35 | lll_lock (ibarrier->lock); | |
36 | ||
37 | /* One more arrival. */ | |
38 | --ibarrier->left; | |
39 | ||
40 | /* Are these all? */ | |
41 | if (ibarrier->left == 0) | |
42 | { | |
37c054c7 | 43 | /* Yes. Increment the event counter to avoid invalid wake-ups and |
a88c9263 UD |
44 | tell the current waiters that it is their turn. */ |
45 | ++ibarrier->curr_event; | |
46 | ||
47 | /* Wake up everybody. */ | |
48 | lll_futex_wake (&ibarrier->curr_event, INT_MAX); | |
49 | ||
a88c9263 | 50 | /* This is the thread which finished the serialization. */ |
37c054c7 | 51 | result = PTHREAD_BARRIER_SERIAL_THREAD; |
a88c9263 | 52 | } |
37c054c7 | 53 | else |
a88c9263 | 54 | { |
37c054c7 UD |
55 | /* The number of the event we are waiting for. The barrier's event |
56 | number must be bumped before we continue. */ | |
57 | unsigned int event = ibarrier->curr_event; | |
37c054c7 | 58 | |
33ab3b66 UD |
59 | /* Before suspending, make the barrier available to others. */ |
60 | lll_unlock (ibarrier->lock); | |
37c054c7 | 61 | |
33ab3b66 UD |
62 | /* Wait for the event counter of the barrier to change. */ |
63 | do | |
64 | lll_futex_wait (&ibarrier->curr_event, event); | |
37c054c7 | 65 | while (event == ibarrier->curr_event); |
a88c9263 | 66 | } |
a88c9263 | 67 | |
37c054c7 UD |
68 | /* Make sure the init_count is stored locally or in a register. */ |
69 | unsigned int init_count = ibarrier->init_count; | |
70 | ||
71 | /* If this was the last woken thread, unlock. */ | |
11986c68 | 72 | if (atomic_exchange_and_add (&ibarrier->left, 1) == init_count - 1) |
37c054c7 UD |
73 | /* We are done. */ |
74 | lll_unlock (ibarrier->lock); | |
a88c9263 | 75 | |
37c054c7 | 76 | return result; |
a88c9263 | 77 | } |