ARM: Convert fork.c to arch-fork.h
[glibc.git] / nptl / pthread_mutex_init.c
blob2b3468835c2f773f7ae61c5bf460eee98c541007
1 /* Copyright (C) 2002-2014 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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.
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.
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/>. */
19 #include <assert.h>
20 #include <errno.h>
21 #include <string.h>
22 #include <kernel-features.h>
23 #include "pthreadP.h"
25 #include <stap-probe.h>
27 static const struct pthread_mutexattr default_mutexattr =
29 /* Default is a normal mutex, not shared between processes. */
30 .mutexkind = PTHREAD_MUTEX_NORMAL
34 #ifndef __ASSUME_FUTEX_LOCK_PI
35 static int tpi_supported;
36 #endif
39 int
40 __pthread_mutex_init (mutex, mutexattr)
41 pthread_mutex_t *mutex;
42 const pthread_mutexattr_t *mutexattr;
44 const struct pthread_mutexattr *imutexattr;
46 assert (sizeof (pthread_mutex_t) <= __SIZEOF_PTHREAD_MUTEX_T);
48 imutexattr = ((const struct pthread_mutexattr *) mutexattr
49 ?: &default_mutexattr);
51 /* Sanity checks. */
52 switch (__builtin_expect (imutexattr->mutexkind
53 & PTHREAD_MUTEXATTR_PROTOCOL_MASK,
54 PTHREAD_PRIO_NONE
55 << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT))
57 case PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
58 break;
60 case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
61 #ifndef __ASSUME_FUTEX_LOCK_PI
62 if (__glibc_unlikely (tpi_supported == 0))
64 int lock = 0;
65 INTERNAL_SYSCALL_DECL (err);
66 int ret = INTERNAL_SYSCALL (futex, err, 4, &lock, FUTEX_UNLOCK_PI,
67 0, 0);
68 assert (INTERNAL_SYSCALL_ERROR_P (ret, err));
69 tpi_supported = INTERNAL_SYSCALL_ERRNO (ret, err) == ENOSYS ? -1 : 1;
71 if (__glibc_unlikely (tpi_supported < 0))
72 return ENOTSUP;
73 #endif
74 break;
76 default:
77 /* XXX: For now we don't support robust priority protected mutexes. */
78 if (imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST)
79 return ENOTSUP;
80 break;
83 /* Clear the whole variable. */
84 memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T);
86 /* Copy the values from the attribute. */
87 mutex->__data.__kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS;
89 if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
91 #ifndef __ASSUME_SET_ROBUST_LIST
92 if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
93 && __set_robust_list_avail < 0)
94 return ENOTSUP;
95 #endif
97 mutex->__data.__kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP;
100 switch (imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
102 case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
103 mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_INHERIT_NP;
104 break;
106 case PTHREAD_PRIO_PROTECT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
107 mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_PROTECT_NP;
109 int ceiling = (imutexattr->mutexkind
110 & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
111 >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT;
112 if (! ceiling)
114 if (__sched_fifo_min_prio == -1)
115 __init_sched_fifo_prio ();
116 if (ceiling < __sched_fifo_min_prio)
117 ceiling = __sched_fifo_min_prio;
119 mutex->__data.__lock = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
120 break;
122 default:
123 break;
126 /* The kernel when waking robust mutexes on exit never uses
127 FUTEX_PRIVATE_FLAG FUTEX_WAKE. */
128 if ((imutexattr->mutexkind & (PTHREAD_MUTEXATTR_FLAG_PSHARED
129 | PTHREAD_MUTEXATTR_FLAG_ROBUST)) != 0)
130 mutex->__data.__kind |= PTHREAD_MUTEX_PSHARED_BIT;
132 /* Default values: mutex not used yet. */
133 // mutex->__count = 0; already done by memset
134 // mutex->__owner = 0; already done by memset
135 // mutex->__nusers = 0; already done by memset
136 // mutex->__spins = 0; already done by memset
137 // mutex->__next = NULL; already done by memset
139 LIBC_PROBE (mutex_init, 1, mutex);
141 return 0;
143 strong_alias (__pthread_mutex_init, pthread_mutex_init)
144 hidden_def (__pthread_mutex_init)