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
|
/* Copyright (C) 2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by David Bartley <dtbartle@csclub.uwaterloo.ca>, 2008.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <errno.h>
#include <pthreadP.h>
#include <synch.h>
#include <abstime-to-reltime.h>
int __rw_timedrdlock (rwlock, abstime)
rwlock_t *rwlock;
struct timespec *abstime;
{
/* Reject invalid timeouts. */
if (INVALID_TIMESPEC (abstime))
return EINVAL;
struct timespec _reltime;
struct timespec *reltime = abstime_to_reltime (abstime, &_reltime);
if (reltime && reltime->tv_sec < 0)
return ETIME;
int errval = mutex_lock (&rwlock->mutex);
if (errval != 0)
return errval;
/* Check for deadlock. */
if (__builtin_expect (rwlock->owner == (uintptr_t)THREAD_SELF, 0) ||
((rwlock->type & LOCK_SHARED) && __builtin_expect (
rwlock->ownerpid == THREAD_GETMEM (THREAD_SELF, pid), 0)))
{
(void)mutex_unlock (&rwlock->mutex);
return EDEADLK;
}
/* Wait until we can acquire the read lock. */
while ((rwlock->readers & _RWLOCK_WR_LOCK) ||
(__cond_has_waiters (&rwlock->writercv) &&
!PTHREAD_RWLOCK_PREFER_READER_P (rwlock)))
{
/* Wait for writer to wake us up. */
errval = __cond_reltimedwait_internal ((cond_t *)&rwlock->readercv,
(mutex_t *)&rwlock->mutex, reltime, 0);
if (errval != 0 && errval != EINTR)
{
(void)mutex_unlock (&rwlock->mutex);
return errval;
}
}
/* Increment readers (note that no other bits are set). */
if (rwlock->readers == _RWLOCK_RD_MAX)
{
/* XXX: Solaris mutexes have no overflow check and don't know about
EAGAIN; in practice overflow will not occur so we don't care. */
(void)mutex_unlock (&rwlock->mutex);
return EAGAIN;
}
++rwlock->readers;
(void)mutex_unlock (&rwlock->mutex);
return 0;
}
|
