1 /* GLIB - Library of useful routines for C programming
2 *
3 * gthreadprivate.h - GLib internal thread system related declarations.
4 *
5 * Copyright (C) 2003 Sebastian Wilhelmi
6 *
7 * SPDX-License-Identifier: LGPL-2.1-or-later
8 *
9 * This library is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * This library is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public License
20 * along with this library; if not, see <http://www.gnu.org/licenses/>.
21 */
22
23 #ifndef __G_THREADPRIVATE_H__
24 #define __G_THREADPRIVATE_H__
25
26 #include "config.h"
27
28 #include "deprecated/gthread.h"
29
30 typedef struct _GRealThread GRealThread;
31 struct _GRealThread
32 {
33 GThread thread;
34
35 gint ref_count;
36 gboolean ours;
37 gchar *name;
38 gpointer retval;
39 };
40
41 /* system thread implementation (gthread-posix.c, gthread-win32.c) */
42
43 #if defined(HAVE_FUTEX) || defined(HAVE_FUTEX_TIME64)
44 #include <errno.h>
45 #include <linux/futex.h>
46 #include <sys/syscall.h>
47 #include <unistd.h>
48
49 #ifndef FUTEX_WAIT_PRIVATE
50 #define FUTEX_WAIT_PRIVATE FUTEX_WAIT
51 #define FUTEX_WAKE_PRIVATE FUTEX_WAKE
52 #endif
53
54 /* Wrapper macro to call `futex_time64` and/or `futex` with simple
55 * parameters and without returning the return value.
56 *
57 * We expect futex to sometimes return EAGAIN due to the race
58 * between the caller checking the current value and deciding to
59 * do the futex op. To avoid splattering errno on success, we
60 * restore the original errno if EAGAIN is seen. See also:
61 * https://gitlab.gnome.org/GNOME/glib/-/issues/3034
62 *
63 * If the `futex_time64` syscall does not exist (`ENOSYS`), we retry again
64 * with the normal `futex` syscall. This can happen if newer kernel headers
65 * are used than the kernel that is actually running.
66 *
67 * This must not be called with a timeout parameter as that differs
68 * in size between the two syscall variants!
69 */
70 #if defined(__NR_futex) && defined(__NR_futex_time64)
71 #define g_futex_simple(uaddr, futex_op, ...) \
72 G_STMT_START \
73 { \
74 int saved_errno = errno; \
75 int res = syscall (__NR_futex_time64, uaddr, (gsize) futex_op, __VA_ARGS__); \
76 if (res < 0 && errno == ENOSYS) \
77 { \
78 errno = saved_errno; \
79 res = syscall (__NR_futex, uaddr, (gsize) futex_op, __VA_ARGS__); \
80 } \
81 if (res < 0 && errno == EAGAIN) \
82 { \
83 errno = saved_errno; \
84 } \
85 } \
86 G_STMT_END
87 #elif defined(__NR_futex_time64)
88 #define g_futex_simple(uaddr, futex_op, ...) \
89 G_STMT_START \
90 { \
91 int saved_errno = errno; \
92 int res = syscall (__NR_futex_time64, uaddr, (gsize) futex_op, __VA_ARGS__); \
93 if (res < 0 && errno == EAGAIN) \
94 { \
95 errno = saved_errno; \
96 } \
97 } \
98 G_STMT_END
99 #elif defined(__NR_futex)
100 #define g_futex_simple(uaddr, futex_op, ...) \
101 G_STMT_START \
102 { \
103 int saved_errno = errno; \
104 int res = syscall (__NR_futex, uaddr, (gsize) futex_op, __VA_ARGS__); \
105 if (res < 0 && errno == EAGAIN) \
106 { \
107 errno = saved_errno; \
108 } \
109 } \
110 G_STMT_END
111 #else /* !defined(__NR_futex) && !defined(__NR_futex_time64) */
112 #error "Neither __NR_futex nor __NR_futex_time64 are defined but were found by meson"
113 #endif /* defined(__NR_futex) && defined(__NR_futex_time64) */
114
115 #endif
116
117 void g_system_thread_wait (GRealThread *thread);
118
119 GRealThread *g_system_thread_new (GThreadFunc proxy,
120 gulong stack_size,
121 const char *name,
122 GThreadFunc func,
123 gpointer data,
124 GError **error);
125 void g_system_thread_free (GRealThread *thread);
126
127 G_NORETURN void g_system_thread_exit (void);
128 void g_system_thread_set_name (const gchar *name);
129
130 /* gthread.c */
131 GThread *g_thread_new_internal (const gchar *name,
132 GThreadFunc proxy,
133 GThreadFunc func,
134 gpointer data,
135 gsize stack_size,
136 GError **error);
137
138 gpointer g_thread_proxy (gpointer thread);
139
140 guint g_thread_n_created (void);
141
142 gpointer g_private_set_alloc0 (GPrivate *key,
143 gsize size);
144
145 #endif /* __G_THREADPRIVATE_H__ */