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>
37 * sys_futex compatibility header.
38 * Use *only* *either of* futex_noasync OR futex_async on a given address.
40 * futex_noasync cannot be executed in signal handlers, but ensures that
41 * it will be put in a wait queue even in compatibility mode.
43 * futex_async is signal-handler safe for the wakeup. It uses polling
44 * on the wait-side in compatibility mode.
46 * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted
50 extern int compat_futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
51 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
);
52 extern int compat_futex_async(int32_t *uaddr
, int op
, int32_t val
,
53 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
);
55 #ifdef CONFIG_RCU_HAVE_FUTEX
59 #include <urcu/compiler.h>
60 #include <urcu/arch.h>
62 static inline int futex(int32_t *uaddr
, int op
, int32_t val
,
63 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
65 return syscall(__NR_futex
, uaddr
, op
, val
, timeout
,
69 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
70 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
74 ret
= futex(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
75 if (caa_unlikely(ret
< 0 && errno
== ENOSYS
)) {
77 * The fallback on ENOSYS is the async-safe version of
78 * the compat futex implementation, because the
79 * async-safe compat implementation allows being used
80 * concurrently with calls to futex(). Indeed, sys_futex
81 * FUTEX_WAIT, on some architectures (mips and parisc),
82 * within a given process, spuriously return ENOSYS due
83 * to signal restart bugs on some kernel versions.
85 return compat_futex_async(uaddr
, op
, val
, timeout
,
92 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
93 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
97 ret
= futex(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
98 if (caa_unlikely(ret
< 0 && errno
== ENOSYS
)) {
99 return compat_futex_async(uaddr
, op
, val
, timeout
,
107 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
108 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
110 return compat_futex_noasync(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
113 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
114 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
116 return compat_futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
125 #endif /* _URCU_FUTEX_H */
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