1 /* low level locking for pthread library. Generic futex-using version.
2 Copyright (C) 2003, 2007 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
19
20 #include <errno.h>
21 #include <sysdep.h>
22 #include <lowlevellock.h>
23 #include <sys/time.h>
24 #include <tls.h>
25
26 void
__lll_lock_wait_private(int * futex)27 __lll_lock_wait_private (int *futex)
28 {
29 if (*futex == 2)
30 lll_futex_wait (futex, 2, LLL_PRIVATE);
31
32 while (atomic_exchange_acq (futex, 2) != 0)
33 lll_futex_wait (futex, 2, LLL_PRIVATE);
34 }
35
36
37 /* These functions don't get included in libc.so */
38 #ifdef IS_IN_libpthread
39 void
__lll_lock_wait(int * futex,int private)40 __lll_lock_wait (int *futex, int private)
41 {
42 if (*futex == 2)
43 lll_futex_wait (futex, 2, private);
44
45 while (atomic_exchange_acq (futex, 2) != 0)
46 lll_futex_wait (futex, 2, private);
47 }
48
49
50 int
__lll_timedlock_wait(int * futex,const struct timespec * abstime,int private)51 __lll_timedlock_wait (int *futex, const struct timespec *abstime, int private)
52 {
53 /* Reject invalid timeouts. */
54 if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
55 return EINVAL;
56
57 /* Try locking. */
58 while (atomic_exchange_acq (futex, 2) != 0)
59 {
60 struct timeval tv;
61
62 /* Get the current time. */
63 (void) gettimeofday (&tv, NULL);
64
65 /* Compute relative timeout. */
66 struct timespec rt;
67 rt.tv_sec = abstime->tv_sec - tv.tv_sec;
68 rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
69 if (rt.tv_nsec < 0)
70 {
71 rt.tv_nsec += 1000000000;
72 --rt.tv_sec;
73 }
74
75 if (rt.tv_sec < 0)
76 return ETIMEDOUT;
77
78 /* Wait. */
79 lll_futex_timed_wait (futex, 2, &rt, private);
80 }
81
82 return 0;
83 }
84
85
86 int
__lll_timedwait_tid(int * tidp,const struct timespec * abstime)87 __lll_timedwait_tid (int *tidp, const struct timespec *abstime)
88 {
89 int tid;
90
91 if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
92 return EINVAL;
93
94 /* Repeat until thread terminated. */
95 while ((tid = *tidp) != 0)
96 {
97 struct timeval tv;
98 struct timespec rt;
99
100 /* Get the current time. */
101 (void) __gettimeofday (&tv, NULL);
102
103 /* Compute relative timeout. */
104 rt.tv_sec = abstime->tv_sec - tv.tv_sec;
105 rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
106 if (rt.tv_nsec < 0)
107 {
108 rt.tv_nsec += 1000000000;
109 --rt.tv_sec;
110 }
111
112 /* Already timed out? */
113 if (rt.tv_sec < 0)
114 return ETIMEDOUT;
115
116 /* Wait until thread terminates. The kernel so far does not use
117 the private futex operations for this. */
118 if (lll_futex_timed_wait (tidp, tid, &rt, LLL_SHARED) == -ETIMEDOUT)
119 return ETIMEDOUT;
120 }
121
122 return 0;
123 }
124 #endif
125