1 /* Copyright (C) 2002-2012 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/>. */
22 #include <kernel-features.h>
25 #include <stap-probe.h>
27 static const struct pthread_mutexattr default_attr
=
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
;
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
?: &default_attr
;
51 switch (__builtin_expect (imutexattr
->mutexkind
52 & PTHREAD_MUTEXATTR_PROTOCOL_MASK
,
54 << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT
))
56 case PTHREAD_PRIO_NONE
<< PTHREAD_MUTEXATTR_PROTOCOL_SHIFT
:
59 case PTHREAD_PRIO_INHERIT
<< PTHREAD_MUTEXATTR_PROTOCOL_SHIFT
:
60 #ifndef __ASSUME_FUTEX_LOCK_PI
61 if (__builtin_expect (tpi_supported
== 0, 0))
64 INTERNAL_SYSCALL_DECL (err
);
65 int ret
= INTERNAL_SYSCALL (futex
, err
, 4, &lock
, FUTEX_UNLOCK_PI
,
67 assert (INTERNAL_SYSCALL_ERROR_P (ret
, err
));
68 tpi_supported
= INTERNAL_SYSCALL_ERRNO (ret
, err
) == ENOSYS
? -1 : 1;
70 if (__builtin_expect (tpi_supported
< 0, 0))
76 /* XXX: For now we don't support robust priority protected mutexes. */
77 if (imutexattr
->mutexkind
& PTHREAD_MUTEXATTR_FLAG_ROBUST
)
82 /* Clear the whole variable. */
83 memset (mutex
, '\0', __SIZEOF_PTHREAD_MUTEX_T
);
85 /* Copy the values from the attribute. */
86 mutex
->__data
.__kind
= imutexattr
->mutexkind
& ~PTHREAD_MUTEXATTR_FLAG_BITS
;
88 if ((imutexattr
->mutexkind
& PTHREAD_MUTEXATTR_FLAG_ROBUST
) != 0)
90 #ifndef __ASSUME_SET_ROBUST_LIST
91 if ((imutexattr
->mutexkind
& PTHREAD_MUTEXATTR_FLAG_PSHARED
) != 0
92 && __set_robust_list_avail
< 0)
96 mutex
->__data
.__kind
|= PTHREAD_MUTEX_ROBUST_NORMAL_NP
;
99 switch (imutexattr
->mutexkind
& PTHREAD_MUTEXATTR_PROTOCOL_MASK
)
101 case PTHREAD_PRIO_INHERIT
<< PTHREAD_MUTEXATTR_PROTOCOL_SHIFT
:
102 mutex
->__data
.__kind
|= PTHREAD_MUTEX_PRIO_INHERIT_NP
;
105 case PTHREAD_PRIO_PROTECT
<< PTHREAD_MUTEXATTR_PROTOCOL_SHIFT
:
106 mutex
->__data
.__kind
|= PTHREAD_MUTEX_PRIO_PROTECT_NP
;
108 int ceiling
= (imutexattr
->mutexkind
109 & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK
)
110 >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT
;
113 if (__sched_fifo_min_prio
== -1)
114 __init_sched_fifo_prio ();
115 if (ceiling
< __sched_fifo_min_prio
)
116 ceiling
= __sched_fifo_min_prio
;
118 mutex
->__data
.__lock
= ceiling
<< PTHREAD_MUTEX_PRIO_CEILING_SHIFT
;
125 /* The kernel when waking robust mutexes on exit never uses
126 FUTEX_PRIVATE_FLAG FUTEX_WAKE. */
127 if ((imutexattr
->mutexkind
& (PTHREAD_MUTEXATTR_FLAG_PSHARED
128 | PTHREAD_MUTEXATTR_FLAG_ROBUST
)) != 0)
129 mutex
->__data
.__kind
|= PTHREAD_MUTEX_PSHARED_BIT
;
131 /* Default values: mutex not used yet. */
132 // mutex->__count = 0; already done by memset
133 // mutex->__owner = 0; already done by memset
134 // mutex->__nusers = 0; already done by memset
135 // mutex->__spins = 0; already done by memset
136 // mutex->__next = NULL; already done by memset
138 LIBC_PROBE (mutex_init
, 1, mutex
);
142 strong_alias (__pthread_mutex_init
, pthread_mutex_init
)
143 hidden_def (__pthread_mutex_init
)