1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
/*
* Berkeley Lab Checkpoint/Restart (BLCR) for Linux is Copyright (c)
* 2008, The Regents of the University of California, through Lawrence
* Berkeley National Laboratory (subject to receipt of any required
* approvals from the U.S. Dept. of Energy). All rights reserved.
*
* Portions may be copyrighted by others, as may be noted in specific
* copyright notices within specific files.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: cr_barrier.c,v 1.16 2008/09/12 18:56:04 phargrov Exp $
*/
#include "cr_module.h"
// Helpers
#define CR_BARRIER_WAIT_COND(b) ((atomic_read(&((b)->count)) <= 0) || (b)->interrupted)
static inline int do_barrier_once(cr_barrier_t *barrier)
{
smp_rmb();
return !test_and_set_bit(0, &barrier->once);
}
// Initializer
void cr_barrier_init(cr_barrier_t *barrier, int count)
{
init_waitqueue_head(&barrier->wait);
atomic_set(&barrier->count, count);
barrier->once = 0;
barrier->interrupted = 0;
}
// Called to signal a barrier, possibly waking any waiters.
// Can be called by a third party if somebody dies unexpectedly.
void __cr_barrier_notify(cr_barrier_t *barrier)
{
smp_wmb();
if (atomic_dec_and_test(&barrier->count)) {
wake_up(&barrier->wait);
}
}
// Called to wait on a barrier
int __cr_barrier_wait(cr_barrier_t *barrier)
{
#if CRI_DEBUG
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(dummy);
const int interval = 60;
int sum = 0;
do {
wait_event_timeout(barrier->wait, CR_BARRIER_WAIT_COND(barrier), interval * HZ);
if (CR_BARRIER_WAIT_COND(barrier)) break;
sum += interval;
CR_ERR("cr_barrier warning: tgid/pid %d/%d still blocked after %d seconds, with signal_pending=%d.", current->tgid, current->pid, sum, signal_pending(current));
} while (1);
smp_rmb();
if (barrier->interrupted) {
CR_ERR("cr_barrier error: interrupt on non-interruptible barrier");
}
#else
wait_event(barrier->wait, CR_BARRIER_WAIT_COND(barrier));
#endif
return do_barrier_once(barrier);
}
// Called to interruptible wait on a barrier
int __cr_barrier_wait_interruptible(cr_barrier_t *barrier)
{
int retval = wait_event_interruptible(barrier->wait, CR_BARRIER_WAIT_COND(barrier));
if (retval != 0) {
/* Interrupted. Wake others. */
barrier->interrupted = 1;
smp_wmb();
wake_up(&barrier->wait);
retval = -EINTR;
} else {
retval = do_barrier_once(barrier);
}
return retval;
}
// Called to signal a barrier, blocking for all others to do so too.
// See cr_barrier.h for more information.
int __cr_barrier_enter(cr_barrier_t *barrier)
{
__cr_barrier_notify(barrier);
return __cr_barrier_wait(barrier);
}
int __cr_barrier_enter_interruptible(cr_barrier_t *barrier)
{
__cr_barrier_notify(barrier);
return __cr_barrier_wait_interruptible(barrier);
}
// Called to test a barrier
int __cr_barrier_test(cr_barrier_t *barrier)
{
return CR_BARRIER_WAIT_COND(barrier) && do_barrier_once(barrier);
}
|