1 /* Copyright (C) 2006, 2007 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Jakub Jelinek <jakub@redhat.com>, 2006.
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 <sys/time.h>
23 #include <pthreadP.h>
24
25
26 int
__lll_robust_lock_wait(int * futex,int private)27 __lll_robust_lock_wait (int *futex, int private)
28 {
29 int oldval = *futex;
30 int tid = THREAD_GETMEM (THREAD_SELF, tid);
31
32 /* If the futex changed meanwhile try locking again. */
33 if (oldval == 0)
34 goto try;
35
36 do
37 {
38 if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
39 return oldval;
40
41 int newval = oldval | FUTEX_WAITERS;
42 if (oldval != newval
43 && atomic_compare_and_exchange_bool_acq (futex, newval, oldval))
44 continue;
45
46 lll_futex_wait (futex, newval, private);
47
48 try:
49 ;
50 }
51 while ((oldval = atomic_compare_and_exchange_val_acq (futex,
52 tid | FUTEX_WAITERS,
53 0)) != 0);
54 return 0;
55 }
56
57
58 int
__lll_robust_timedlock_wait(int * futex,const struct timespec * abstime,int private)59 __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime,
60 int private)
61 {
62 /* Reject invalid timeouts. */
63 if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
64 return EINVAL;
65
66 int tid = THREAD_GETMEM (THREAD_SELF, tid);
67 int oldval = *futex;
68
69 /* If the futex changed meanwhile try locking again. */
70 if (oldval == 0)
71 goto try;
72
73 do
74 {
75 struct timeval tv;
76 struct timespec rt;
77
78 /* Get the current time. */
79 (void) __gettimeofday (&tv, NULL);
80
81 /* Compute relative timeout. */
82 rt.tv_sec = abstime->tv_sec - tv.tv_sec;
83 rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
84 if (rt.tv_nsec < 0)
85 {
86 rt.tv_nsec += 1000000000;
87 --rt.tv_sec;
88 }
89
90 /* Already timed out? */
91 if (rt.tv_sec < 0)
92 return ETIMEDOUT;
93
94 /* Wait. */
95 if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
96 return oldval;
97
98 int newval = oldval | FUTEX_WAITERS;
99 if (oldval != newval
100 && atomic_compare_and_exchange_bool_acq (futex, newval, oldval))
101 continue;
102
103 lll_futex_timed_wait (futex, newval, &rt, private);
104
105 try:
106 ;
107 }
108 while ((oldval = atomic_compare_and_exchange_val_acq (futex,
109 tid | FUTEX_WAITERS,
110 0)) != 0);
111
112 return 0;
113 }
114