7 * Userspace RCU - sys_futex/compat_futex header.
9 * Copyright 2011-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
11 * This library is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this library; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 #include <urcu/config.h>
31 #ifdef CONFIG_RCU_HAVE_FUTEX
35 #include <urcu/compiler.h>
36 #include <urcu/arch.h>
38 #elif defined(__FreeBSD__)
40 #include <sys/types.h>
53 * sys_futex compatibility header.
54 * Use *only* *either of* futex_noasync OR futex_async on a given address.
56 * futex_noasync cannot be executed in signal handlers, but ensures that
57 * it will be put in a wait queue even in compatibility mode.
59 * futex_async is signal-handler safe for the wakeup. It uses polling
60 * on the wait-side in compatibility mode.
62 * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted
66 extern int compat_futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
67 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
);
68 extern int compat_futex_async(int32_t *uaddr
, int op
, int32_t val
,
69 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
);
71 #ifdef CONFIG_RCU_HAVE_FUTEX
73 static inline int futex(int32_t *uaddr
, int op
, int32_t val
,
74 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
76 return syscall(__NR_futex
, uaddr
, op
, val
, timeout
,
80 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
81 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
85 ret
= futex(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
86 if (caa_unlikely(ret
< 0 && errno
== ENOSYS
)) {
88 * The fallback on ENOSYS is the async-safe version of
89 * the compat futex implementation, because the
90 * async-safe compat implementation allows being used
91 * concurrently with calls to futex(). Indeed, sys_futex
92 * FUTEX_WAIT, on some architectures (mips and parisc),
93 * within a given process, spuriously return ENOSYS due
94 * to signal restart bugs on some kernel versions.
96 return compat_futex_async(uaddr
, op
, val
, timeout
,
103 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
104 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
108 ret
= futex(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
109 if (caa_unlikely(ret
< 0 && errno
== ENOSYS
)) {
110 return compat_futex_async(uaddr
, op
, val
, timeout
,
116 #elif defined(__FreeBSD__)
118 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
119 const struct timespec
*timeout
,
120 int32_t *uaddr2
__attribute__((unused
)),
121 int32_t val3
__attribute__((unused
)))
124 void *umtx_uaddr
= NULL
, *umtx_uaddr2
= NULL
;
125 struct _umtx_time umtx_timeout
= {
126 ._flags
= UMTX_ABSTIME
,
127 ._clockid
= CLOCK_MONOTONIC
,
132 /* On FreeBSD, a "u_int" is a 32-bit integer. */
133 umtx_op
= UMTX_OP_WAIT_UINT
;
134 if (timeout
!= NULL
) {
135 umtx_timeout
._timeout
= *timeout
;
136 umtx_uaddr
= (void *) sizeof(umtx_timeout
);
137 umtx_uaddr2
= (void *) &umtx_timeout
;
141 umtx_op
= UMTX_OP_WAKE
;
148 return _umtx_op(uaddr
, umtx_op
, (uint32_t) val
, umtx_uaddr
,
152 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
153 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
155 return futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
158 #elif defined(__CYGWIN__)
161 * The futex_noasync compat code uses a weak symbol to share state across
162 * different shared object which is not possible on Windows with the
163 * Portable Executable format. Use the async compat code for both cases.
165 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
166 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
168 return compat_futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
171 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
172 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
174 return compat_futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
179 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
180 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
182 return compat_futex_noasync(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
185 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
186 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
188 return compat_futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
197 #endif /* _URCU_FUTEX_H */
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