[userspace-rcu.git] / include / urcu / futex.h

// SPDX-FileCopyrightText: 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
//
// SPDX-License-Identifier: LGPL-2.1-or-later

#ifndef _URCU_FUTEX_H
#define _URCU_FUTEX_H

/*
 * Userspace RCU - sys_futex/compat_futex header.
 */

#include <urcu/config.h>
#include <urcu/syscall-compat.h>

#include <errno.h>
#include <stdint.h>
#include <time.h>

#if (defined(__linux__) && defined(__NR_futex))

/* For backwards compat */
# define CONFIG_RCU_HAVE_FUTEX 1

# include <unistd.h>
# include <errno.h>
# include <urcu/compiler.h>
# include <urcu/arch.h>
# include <urcu/assert.h>

#elif defined(__FreeBSD__)

# include <sys/types.h>
# include <sys/umtx.h>

#elif defined(__OpenBSD__)

# include <sys/time.h>
# include <sys/futex.h>

#endif

#ifdef __cplusplus
extern "C" {
#endif

#ifndef __OpenBSD__
# define FUTEX_WAIT		0
# define FUTEX_WAKE		1
#endif

/*
 * sys_futex compatibility header.
 * Use *only* *either of* futex_noasync OR futex_async on a given address.
 *
 * futex_noasync cannot be executed in signal handlers, but ensures that
 * it will be put in a wait queue even in compatibility mode.
 *
 * futex_async is signal-handler safe for the wakeup. It uses polling
 * on the wait-side in compatibility mode.
 *
 * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted
 * (returns EINTR).
 */

extern int compat_futex_noasync(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3);
extern int compat_futex_async(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3);

#if (defined(__linux__) && defined(__NR_futex))

static inline int futex(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	return syscall(__NR_futex, uaddr, op, val, timeout, uaddr2, val3);
}

static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	int ret;

	ret = futex(uaddr, op, val, timeout, uaddr2, val3);
	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
		/*
		 * The fallback on ENOSYS is the async-safe version of
		 * the compat futex implementation, because the
		 * async-safe compat implementation allows being used
		 * concurrently with calls to futex(). Indeed, sys_futex
		 * FUTEX_WAIT, on some architectures (mips and parisc),
		 * within a given process, spuriously return ENOSYS due
		 * to signal restart bugs on some kernel versions.
		 */
		return compat_futex_async(uaddr, op, val, timeout,
				uaddr2, val3);
	}
	return ret;

}

static inline int futex_async(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	int ret;

	ret = futex(uaddr, op, val, timeout, uaddr2, val3);
	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
		return compat_futex_async(uaddr, op, val, timeout,
				uaddr2, val3);
	}
	return ret;
}

#elif defined(__FreeBSD__)

static inline int futex_async(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	int umtx_op;
	void *umtx_uaddr = NULL, *umtx_uaddr2 = NULL;
	struct _umtx_time umtx_timeout = {
		._flags = UMTX_ABSTIME,
		._clockid = CLOCK_MONOTONIC,
	};

	/*
	 * Check if NULL or zero. Don't let users expect that they are
	 * taken into account.
	 */
	urcu_posix_assert(!uaddr2);
	urcu_posix_assert(!val3);

	switch (op) {
	case FUTEX_WAIT:
		/* On FreeBSD, a "u_int" is a 32-bit integer. */
		umtx_op = UMTX_OP_WAIT_UINT;
		if (timeout != NULL) {
			umtx_timeout._timeout = *timeout;
			umtx_uaddr = (void *) sizeof(umtx_timeout);
			umtx_uaddr2 = (void *) &umtx_timeout;
		}
		break;
	case FUTEX_WAKE:
		umtx_op = UMTX_OP_WAKE;
		break;
	default:
		errno = EINVAL;
		return -1;
	}

	return _umtx_op(uaddr, umtx_op, (uint32_t) val, umtx_uaddr,
			umtx_uaddr2);
}

static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	return futex_async(uaddr, op, val, timeout, uaddr2, val3);
}

#elif defined(__OpenBSD__)

static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	int ret;

	/*
	 * Check that val3 is zero. Don't let users expect that it is
	 * taken into account.
	 */
	urcu_posix_assert(!val3);

	ret = futex((volatile uint32_t *) uaddr, op, val, timeout,
		(volatile uint32_t *) uaddr2);
	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
		return compat_futex_noasync(uaddr, op, val, timeout,
				uaddr2, val3);
	}
	return ret;
}

static inline int futex_async(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	int ret;

	/*
	 * Check that val3 is zero. Don't let users expect that it is
	 * taken into account.
	 */
	urcu_posix_assert(!val3);

	ret = futex((volatile uint32_t *) uaddr, op, val, timeout,
		(volatile uint32_t *) uaddr2);
	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
		return compat_futex_async(uaddr, op, val, timeout,
				uaddr2, val3);
	}
	return ret;
}

#elif defined(__CYGWIN__)

/*
 * The futex_noasync compat code uses a weak symbol to share state across
 * different shared object which is not possible on Windows with the
 * Portable Executable format. Use the async compat code for both cases.
 */
static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
}

static inline int futex_async(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
}

#else

static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	return compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3);
}

static inline int futex_async(int32_t *uaddr, int op, int32_t val,
		const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
{
	return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
}

#endif

#ifdef __cplusplus
}
#endif

#endif /* _URCU_FUTEX_H */
Commit	Line	Data
d3d3857f MJ	1	// SPDX-FileCopyrightText: 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	2	//
	3	// SPDX-License-Identifier: LGPL-2.1-or-later
	4
49617de1 MD	5	#ifndef _URCU_FUTEX_H
	6	#define _URCU_FUTEX_H
	7
	8	/*
49617de1	9	* Userspace RCU - sys_futex/compat_futex header.
49617de1 MD	10	*/
	11
	12	#include <urcu/config.h>
ca91060e MJ	13	#include <urcu/syscall-compat.h>
ca91060e MJ	14
32146086	15	#include <errno.h>
6d841bc2	16	#include <stdint.h>
6a29bfc1	17	#include <time.h>
49617de1	18
d428afc4 MD	19	#if (defined(__linux__) && defined(__NR_futex))
	20
	21	/* For backwards compat */
8f44fbdc	22	# define CONFIG_RCU_HAVE_FUTEX 1
d428afc4	23
8f44fbdc MD	24	# include <unistd.h>
	25	# include <errno.h>
	26	# include <urcu/compiler.h>
	27	# include <urcu/arch.h>
	28	# include <urcu/assert.h>
d428afc4 MD	29
	30	#elif defined(__FreeBSD__)
	31
8f44fbdc MD	32	# include <sys/types.h>
8f44fbdc MD	33	# include <sys/umtx.h>
d428afc4	34
e9af364c BS	35	#elif defined(__OpenBSD__)
e9af364c BS	36
8f44fbdc MD	37	# include <sys/time.h>
8f44fbdc MD	38	# include <sys/futex.h>
e9af364c	39
d428afc4 MD	40	#endif
d428afc4 MD	41
36bc70a8 MD	42	#ifdef __cplusplus
36bc70a8 MD	43	extern "C" {
67ecffc0	44	#endif
36bc70a8	45
e9af364c	46	#ifndef __OpenBSD__
8f44fbdc MD	47	# define FUTEX_WAIT 0
8f44fbdc MD	48	# define FUTEX_WAKE 1
e9af364c	49	#endif
49617de1 MD	50
	51	/*
	52	* sys_futex compatibility header.
	53	* Use only either of futex_noasync OR futex_async on a given address.
	54	*
	55	* futex_noasync cannot be executed in signal handlers, but ensures that
	56	* it will be put in a wait queue even in compatibility mode.
	57	*
	58	* futex_async is signal-handler safe for the wakeup. It uses polling
	59	* on the wait-side in compatibility mode.
b0a841b4 MD	60	*
	61	* BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted
	62	* (returns EINTR).
49617de1 MD	63	*/
49617de1 MD	64
42dfe454 MD	65	extern int compat_futex_noasync(int32_t *uaddr, int op, int32_t val,
	66	const struct timespec timeout, int32_t uaddr2, int32_t val3);
	67	extern int compat_futex_async(int32_t *uaddr, int op, int32_t val,
	68	const struct timespec timeout, int32_t uaddr2, int32_t val3);
	69
0afb29b2	70	#if (defined(__linux__) && defined(__NR_futex))
ca91060e	71
42dfe454 MD	72	static inline int futex(int32_t *uaddr, int op, int32_t val,
	73	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	74	{
e463c38f	75	return syscall(__NR_futex, uaddr, op, val, timeout, uaddr2, val3);
42dfe454 MD	76	}
	77
	78	static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
	79	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	80	{
	81	int ret;
	82
	83	ret = futex(uaddr, op, val, timeout, uaddr2, val3);
	84	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
b2633d21 MD	85	/*
	86	* The fallback on ENOSYS is the async-safe version of
	87	* the compat futex implementation, because the
	88	* async-safe compat implementation allows being used
	89	* concurrently with calls to futex(). Indeed, sys_futex
	90	* FUTEX_WAIT, on some architectures (mips and parisc),
	91	* within a given process, spuriously return ENOSYS due
	92	* to signal restart bugs on some kernel versions.
	93	*/
	94	return compat_futex_async(uaddr, op, val, timeout,
42dfe454 MD	95	uaddr2, val3);
	96	}
	97	return ret;
	98
	99	}
	100
	101	static inline int futex_async(int32_t *uaddr, int op, int32_t val,
	102	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	103	{
	104	int ret;
	105
	106	ret = futex(uaddr, op, val, timeout, uaddr2, val3);
	107	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
	108	return compat_futex_async(uaddr, op, val, timeout,
	109	uaddr2, val3);
	110	}
	111	return ret;
	112	}
	113
32146086 AX	114	#elif defined(__FreeBSD__)
32146086 AX	115
32146086	116	static inline int futex_async(int32_t *uaddr, int op, int32_t val,
e463c38f	117	const struct timespec timeout, int32_t uaddr2, int32_t val3)
32146086 AX	118	{
	119	int umtx_op;
	120	void umtx_uaddr = NULL, umtx_uaddr2 = NULL;
	121	struct _umtx_time umtx_timeout = {
	122	._flags = UMTX_ABSTIME,
	123	._clockid = CLOCK_MONOTONIC,
	124	};
	125
e463c38f MD	126	/*
	127	* Check if NULL or zero. Don't let users expect that they are
	128	* taken into account.
	129	*/
	130	urcu_posix_assert(!uaddr2);
	131	urcu_posix_assert(!val3);
	132
32146086 AX	133	switch (op) {
	134	case FUTEX_WAIT:
	135	/* On FreeBSD, a "u_int" is a 32-bit integer. */
	136	umtx_op = UMTX_OP_WAIT_UINT;
	137	if (timeout != NULL) {
	138	umtx_timeout._timeout = *timeout;
	139	umtx_uaddr = (void *) sizeof(umtx_timeout);
	140	umtx_uaddr2 = (void *) &umtx_timeout;
	141	}
	142	break;
	143	case FUTEX_WAKE:
	144	umtx_op = UMTX_OP_WAKE;
	145	break;
	146	default:
	147	errno = EINVAL;
	148	return -1;
	149	}
	150
	151	return _umtx_op(uaddr, umtx_op, (uint32_t) val, umtx_uaddr,
	152	umtx_uaddr2);
	153	}
	154
	155	static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
	156	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	157	{
	158	return futex_async(uaddr, op, val, timeout, uaddr2, val3);
	159	}
	160
e9af364c BS	161	#elif defined(__OpenBSD__)
	162
	163	static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
	164	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	165	{
	166	int ret;
	167
e463c38f MD	168	/*
	169	* Check that val3 is zero. Don't let users expect that it is
	170	* taken into account.
	171	*/
	172	urcu_posix_assert(!val3);
	173
e9af364c BS	174	ret = futex((volatile uint32_t *) uaddr, op, val, timeout,
	175	(volatile uint32_t *) uaddr2);
	176	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
	177	return compat_futex_noasync(uaddr, op, val, timeout,
	178	uaddr2, val3);
	179	}
	180	return ret;
	181	}
	182
	183	static inline int futex_async(int32_t *uaddr, int op, int32_t val,
	184	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	185	{
	186	int ret;
	187
e463c38f MD	188	/*
	189	* Check that val3 is zero. Don't let users expect that it is
	190	* taken into account.
	191	*/
	192	urcu_posix_assert(!val3);
	193
e9af364c BS	194	ret = futex((volatile uint32_t *) uaddr, op, val, timeout,
	195	(volatile uint32_t *) uaddr2);
	196	if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
	197	return compat_futex_async(uaddr, op, val, timeout,
	198	uaddr2, val3);
	199	}
	200	return ret;
	201	}
	202
bb109fb6 MJ	203	#elif defined(__CYGWIN__)
	204
	205	/*
	206	* The futex_noasync compat code uses a weak symbol to share state across
	207	* different shared object which is not possible on Windows with the
	208	* Portable Executable format. Use the async compat code for both cases.
	209	*/
	210	static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
	211	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	212	{
	213	return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
	214	}
	215
	216	static inline int futex_async(int32_t *uaddr, int op, int32_t val,
	217	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	218	{
	219	return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
	220	}
	221
49617de1	222	#else
42dfe454 MD	223
	224	static inline int futex_noasync(int32_t *uaddr, int op, int32_t val,
	225	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	226	{
	227	return compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3);
	228	}
	229
	230	static inline int futex_async(int32_t *uaddr, int op, int32_t val,
	231	const struct timespec timeout, int32_t uaddr2, int32_t val3)
	232	{
	233	return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
	234	}
	235
49617de1 MD	236	#endif
49617de1 MD	237
67ecffc0	238	#ifdef __cplusplus
36bc70a8 MD	239	}
	240	#endif
	241
49617de1	242	#endif /* _URCU_FUTEX_H */