1 /* Copyright (C) 2003, 2004, 2006, 2007 Free Software Foundation, Inc.
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, see
17 <http://www.gnu.org/licenses/>. */
18
19 #include <errno.h>
20 #include <sysdep.h>
21 #include <lowlevellock.h>
22 #include <pthreadP.h>
23
24 /* Wait on barrier. */
25 int
pthread_barrier_wait(pthread_barrier_t * barrier)26 pthread_barrier_wait (
27 pthread_barrier_t *barrier)
28 {
29 union sparc_pthread_barrier *ibarrier
30 = (union sparc_pthread_barrier *) barrier;
31 int result = 0;
32 int private = ibarrier->s.pshared ? LLL_SHARED : LLL_PRIVATE;
33
34 /* Make sure we are alone. */
35 lll_lock (ibarrier->b.lock, private);
36
37 /* One more arrival. */
38 --ibarrier->b.left;
39
40 /* Are these all? */
41 if (ibarrier->b.left == 0)
42 {
43 /* Yes. Increment the event counter to avoid invalid wake-ups and
44 tell the current waiters that it is their turn. */
45 ++ibarrier->b.curr_event;
46
47 /* Wake up everybody. */
48 lll_futex_wake (&ibarrier->b.curr_event, INT_MAX, private);
49
50 /* This is the thread which finished the serialization. */
51 result = PTHREAD_BARRIER_SERIAL_THREAD;
52 }
53 else
54 {
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->b.curr_event;
58
59 /* Before suspending, make the barrier available to others. */
60 lll_unlock (ibarrier->b.lock, private);
61
62 /* Wait for the event counter of the barrier to change. */
63 do
64 lll_futex_wait (&ibarrier->b.curr_event, event, private);
65 while (event == ibarrier->b.curr_event);
66 }
67
68 /* Make sure the init_count is stored locally or in a register. */
69 unsigned int init_count = ibarrier->b.init_count;
70
71 /* If this was the last woken thread, unlock. */
72 if (__atomic_is_v9 || ibarrier->s.pshared == 0)
73 {
74 if (atomic_increment_val (&ibarrier->b.left) == init_count)
75 /* We are done. */
76 lll_unlock (ibarrier->b.lock, private);
77 }
78 else
79 {
80 unsigned int left;
81 /* Slightly more complicated. On pre-v9 CPUs, atomic_increment_val
82 is only atomic for threads within the same process, not for
83 multiple processes. */
84 __sparc32_atomic_do_lock24 (&ibarrier->s.left_lock);
85 left = ++ibarrier->b.left;
86 __sparc32_atomic_do_unlock24 (&ibarrier->s.left_lock);
87 if (left == init_count)
88 /* We are done. */
89 lll_unlock (ibarrier->b.lock, private);
90 }
91
92 return result;
93 }
94