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
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
|
/* futex operations for glibc-internal use. Linux version.
Copyright (C) 2014-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<http://www.gnu.org/licenses/>. */
#ifndef FUTEX_INTERNAL_H
#define FUTEX_INTERNAL_H
#include <sysdeps/nptl/futex-internal.h>
#include <errno.h>
#include <lowlevellock-futex.h>
#include <sysdep-cancel.h>
/* See sysdeps/nptl/futex-internal.h for documentation; this file only
contains Linux-specific comments.
The Linux kernel treats provides absolute timeouts based on the
CLOCK_REALTIME clock and relative timeouts measured against the
CLOCK_MONOTONIC clock.
We expect a Linux kernel version of 2.6.22 or more recent (since this
version, EINTR is not returned on spurious wake-ups anymore). */
/* FUTEX_SHARED is always supported by the Linux kernel. */
static __always_inline int
futex_supports_pshared (int pshared)
{
if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
return 0;
else if (pshared == PTHREAD_PROCESS_SHARED)
return 0;
else
return EINVAL;
}
/* The Linux kernel supports relative timeouts measured against the
CLOCK_MONOTONIC clock. */
static __always_inline bool
futex_supports_exact_relative_timeouts (void)
{
return true;
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_wait (unsigned int *futex_word, unsigned int expected, int private)
{
int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
return -err;
case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
int private)
{
int oldtype;
oldtype = __pthread_enable_asynccancel ();
int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
__pthread_disable_asynccancel (oldtype);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
return -err;
case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_reltimed_wait (unsigned int *futex_word, unsigned int expected,
const struct timespec *reltime, int private)
{
int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_reltimed_wait_cancelable (unsigned int *futex_word,
unsigned int expected,
const struct timespec *reltime, int private)
{
int oldtype;
oldtype = LIBC_CANCEL_ASYNC ();
int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
LIBC_CANCEL_RESET (oldtype);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_abstimed_supported_clockid (clockid_t clockid)
{
return lll_futex_supported_clockid (clockid);
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_abstimed_wait (unsigned int *futex_word, unsigned int expected,
clockid_t clockid,
const struct timespec *abstime, int private)
{
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
return ETIMEDOUT;
int err = lll_futex_clock_wait_bitset (futex_word, expected,
clockid, abstime,
private);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment, unsupported
clockid or due to the timeout not being
normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_abstimed_wait_cancelable (unsigned int *futex_word,
unsigned int expected,
clockid_t clockid,
const struct timespec *abstime, int private)
{
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
return ETIMEDOUT;
int oldtype;
oldtype = __pthread_enable_asynccancel ();
int err = lll_futex_clock_wait_bitset (futex_word, expected,
clockid, abstime,
private);
__pthread_disable_asynccancel (oldtype);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline void
futex_wake (unsigned int *futex_word, int processes_to_wake, int private)
{
int res = lll_futex_wake (futex_word, processes_to_wake, private);
/* No error. Ignore the number of woken processes. */
if (res >= 0)
return;
switch (res)
{
case -EFAULT: /* Could have happened due to memory reuse. */
case -EINVAL: /* Could be either due to incorrect alignment (a bug in
glibc or in the application) or due to memory being
reused for a PI futex. We cannot distinguish between the
two causes, and one of them is correct use, so we do not
act in this case. */
return;
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
#endif /* futex-internal.h */
|
