1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
|
/* Copyright (C) 2002-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <string.h>
#include <kernel-features.h>
#include "pthreadP.h"
#include <atomic.h>
#include <pthread-offsets.h>
#include <futex-internal.h>
#include <stap-probe.h>
static const struct pthread_mutexattr default_mutexattr =
{
/* Default is a normal mutex, not shared between processes. */
.mutexkind = PTHREAD_MUTEX_NORMAL
};
static bool
prio_inherit_missing (void)
{
static int tpi_supported;
if (__glibc_unlikely (atomic_load_relaxed (&tpi_supported) == 0))
{
int e = futex_unlock_pi (&(unsigned int){0}, 0);
atomic_store_relaxed (&tpi_supported, e == ENOSYS ? -1 : 1);
}
return __glibc_unlikely (tpi_supported < 0);
}
int
__pthread_mutex_init (pthread_mutex_t *mutex,
const pthread_mutexattr_t *mutexattr)
{
const struct pthread_mutexattr *imutexattr;
ASSERT_TYPE_SIZE (pthread_mutex_t, __SIZEOF_PTHREAD_MUTEX_T);
/* __kind is the only field where its offset should be checked to
avoid ABI breakage with static initializers. */
ASSERT_PTHREAD_INTERNAL_OFFSET (pthread_mutex_t, __data.__kind,
__PTHREAD_MUTEX_KIND_OFFSET);
ASSERT_PTHREAD_INTERNAL_MEMBER_SIZE (pthread_mutex_t, __data.__kind, int);
imutexattr = ((const struct pthread_mutexattr *) mutexattr
?: &default_mutexattr);
/* Sanity checks. */
switch (__builtin_expect (imutexattr->mutexkind
& PTHREAD_MUTEXATTR_PROTOCOL_MASK,
PTHREAD_PRIO_NONE
<< PTHREAD_MUTEXATTR_PROTOCOL_SHIFT))
{
case PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
break;
case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
if (__glibc_unlikely (prio_inherit_missing ()))
return ENOTSUP;
break;
default:
/* XXX: For now we don't support robust priority protected mutexes. */
if (imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST)
return ENOTSUP;
break;
}
/* Clear the whole variable. */
memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T);
/* Copy the values from the attribute. */
int mutex_kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS;
if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
{
#ifndef __ASSUME_SET_ROBUST_LIST
if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
&& __set_robust_list_avail < 0)
return ENOTSUP;
#endif
mutex_kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP;
}
switch (imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
{
case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
mutex_kind |= PTHREAD_MUTEX_PRIO_INHERIT_NP;
break;
case PTHREAD_PRIO_PROTECT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
mutex_kind |= PTHREAD_MUTEX_PRIO_PROTECT_NP;
int ceiling = (imutexattr->mutexkind
& PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
>> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT;
if (! ceiling)
{
/* See __init_sched_fifo_prio. */
if (atomic_load_relaxed (&__sched_fifo_min_prio) == -1)
__init_sched_fifo_prio ();
if (ceiling < atomic_load_relaxed (&__sched_fifo_min_prio))
ceiling = atomic_load_relaxed (&__sched_fifo_min_prio);
}
mutex->__data.__lock = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
break;
default:
break;
}
/* The kernel when waking robust mutexes on exit never uses
FUTEX_PRIVATE_FLAG FUTEX_WAKE. */
if ((imutexattr->mutexkind & (PTHREAD_MUTEXATTR_FLAG_PSHARED
| PTHREAD_MUTEXATTR_FLAG_ROBUST)) != 0)
mutex_kind |= PTHREAD_MUTEX_PSHARED_BIT;
/* See concurrency notes regarding __kind in struct __pthread_mutex_s
in sysdeps/nptl/bits/thread-shared-types.h. */
atomic_store_relaxed (&(mutex->__data.__kind), mutex_kind);
/* Default values: mutex not used yet. */
// mutex->__count = 0; already done by memset
// mutex->__owner = 0; already done by memset
// mutex->__nusers = 0; already done by memset
// mutex->__spins = 0; already done by memset
// mutex->__next = NULL; already done by memset
LIBC_PROBE (mutex_init, 1, mutex);
return 0;
}
weak_alias (__pthread_mutex_init, pthread_mutex_init)
hidden_def (__pthread_mutex_init)
|
