1 /* Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007
2 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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 <assert.h>
21 #include <errno.h>
22 #include <string.h>
23 #include <bits/kernel-features.h>
24 #include "pthreadP.h"
25
26 static const struct pthread_mutexattr default_attr =
27 {
28 /* Default is a normal mutex, not shared between processes. */
29 .mutexkind = PTHREAD_MUTEX_NORMAL
30 };
31
32
33 #ifndef __ASSUME_FUTEX_LOCK_PI
34 static int tpi_supported;
35 #endif
36
37
38 int
39 attribute_protected
__pthread_mutex_init(pthread_mutex_t * mutex,const pthread_mutexattr_t * mutexattr)40 __pthread_mutex_init (
41 pthread_mutex_t *mutex,
42 const pthread_mutexattr_t *mutexattr)
43 {
44 const struct pthread_mutexattr *imutexattr;
45
46 assert (sizeof (pthread_mutex_t) <= __SIZEOF_PTHREAD_MUTEX_T);
47
48 imutexattr = (const struct pthread_mutexattr *) mutexattr ?: &default_attr;
49
50 /* Sanity checks. */
51 switch (__builtin_expect (imutexattr->mutexkind
52 & PTHREAD_MUTEXATTR_PROTOCOL_MASK,
53 PTHREAD_PRIO_NONE
54 << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT))
55 {
56 case PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
57 break;
58
59 case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
60 #ifndef __ASSUME_FUTEX_LOCK_PI
61 if (__builtin_expect (tpi_supported == 0, 0))
62 {
63 int lock = 0;
64 INTERNAL_SYSCALL_DECL (err);
65 #if defined(__UCLIBC_USE_TIME64__) && defined(__NR_futex_time64)
66 int ret = INTERNAL_SYSCALL (futex_time64, err, 4, &lock, FUTEX_UNLOCK_PI,
67 0, 0);
68 #else
69 int ret = INTERNAL_SYSCALL (futex, err, 4, &lock, FUTEX_UNLOCK_PI,
70 0, 0);
71 #endif
72 assert (INTERNAL_SYSCALL_ERROR_P (ret, err));
73 tpi_supported = INTERNAL_SYSCALL_ERRNO (ret, err) == ENOSYS ? -1 : 1;
74 }
75 if (__builtin_expect (tpi_supported < 0, 0))
76 return ENOTSUP;
77 #endif
78 break;
79
80 default:
81 /* XXX: For now we don't support robust priority protected mutexes. */
82 if (imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST)
83 return ENOTSUP;
84 break;
85 }
86
87 /* Clear the whole variable. */
88 memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T);
89
90 /* Copy the values from the attribute. */
91 mutex->__data.__kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS;
92
93 if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
94 {
95 #ifndef __ASSUME_SET_ROBUST_LIST
96 if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
97 && __set_robust_list_avail < 0)
98 return ENOTSUP;
99 #endif
100
101 mutex->__data.__kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP;
102 }
103
104 switch (imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
105 {
106 case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
107 mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_INHERIT_NP;
108 break;
109
110 case PTHREAD_PRIO_PROTECT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
111 mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_PROTECT_NP;
112
113 int ceiling = (imutexattr->mutexkind
114 & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
115 >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT;
116 if (! ceiling)
117 {
118 if (__sched_fifo_min_prio == -1)
119 __init_sched_fifo_prio ();
120 if (ceiling < __sched_fifo_min_prio)
121 ceiling = __sched_fifo_min_prio;
122 }
123 mutex->__data.__lock = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
124 break;
125
126 default:
127 break;
128 }
129
130 /* The kernel when waking robust mutexes on exit never uses
131 FUTEX_PRIVATE_FLAG FUTEX_WAKE. */
132 if ((imutexattr->mutexkind & (PTHREAD_MUTEXATTR_FLAG_PSHARED
133 | PTHREAD_MUTEXATTR_FLAG_ROBUST)) != 0)
134 mutex->__data.__kind |= PTHREAD_MUTEX_PSHARED_BIT;
135
136 /* Default values: mutex not used yet. */
137 // mutex->__count = 0; already done by memset
138 // mutex->__owner = 0; already done by memset
139 // mutex->__nusers = 0; already done by memset
140 // mutex->__spins = 0; already done by memset
141 // mutex->__next = NULL; already done by memset
142
143 return 0;
144 }
145 strong_alias (__pthread_mutex_init, pthread_mutex_init)
146 INTDEF(__pthread_mutex_init)
147