Add test program for round robin in userland.

5 files changed, 630 insertions, 0 deletions

diff --git a/tools/KSE/rr/Makefile b/tools/KSE/rr/Makefile
new file mode 100644
index 0000000..b97d263
--- /dev/null
+++ b/tools/KSE/rr/Makefile
@@ -0,0 +1,8 @@
+# $FreeBSD$
+
+PROG=		rr	
+NOMAN=
+CFLAGS+=	-g -Wall
+SRCS=		kse_asm.S rr.c 
+
+.include <bsd.prog.mk>
diff --git a/tools/KSE/rr/kse_asm.S b/tools/KSE/rr/kse_asm.S
new file mode 100644
index 0000000..20dc1db
--- /dev/null
+++ b/tools/KSE/rr/kse_asm.S
@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2002 Jonathan Mini <mini@freebsd.org>.
+ * Copyright (c) 2001 Daniel Eischen <deischen@freebsd.org>.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Neither the name of the author nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY DANIEL EISCHEN AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <machine/asm.h>
+__FBSDID("$FreeBSD$");
+
+/*
+ * Where do we define these?
+ */
+#define	MC_SIZE			640	/* sizeof mcontext_t */
+#define	UC_MC_OFFSET		16	/* offset to mcontext from ucontext */
+#define	UC_MC_LEN_OFFSET	96	/* offset to mc_len from mcontext */
+#define	MC_LEN_OFFSET		80	/* offset to mc_len from mcontext */
+#define	MC_FP_REGS_OFFSET	96	/* offset to FP regs from mcontext */
+#define	MC_FP_CW_OFFSET		96	/* offset to FP control word */
+#define	MC_OWNEDFP_OFFSET	88	/* offset to mc_ownedfp from mcontext */
+#define	KM_STACK_SP_OFFSET	36	/* offset to km_stack.ss_sp */
+#define	KM_STACK_SIZE_OFFSET	40	/* offset to km_stack.ss_sp */
+#define	KM_FUNC_OFFSET		32	/* offset to km_func */
+ 
+/*
+ * int uts_to_thread(struct kse_thr_mailbox *tdp,
+ *	struct kse_thr_mailbox **curthreadp);
+ *
+ * Does not return on success, returns -1 otherwise.
+ */
+ENTRY(uts_to_thread)
+	movl	4(%esp), %edx		/* get address of kse_thr_mailbox */
+					/* .. ucontext_t is at offset 0 */
+	cmpl	$0, %edx		/* check for null pointer */
+	jne	1f
+	movl	$-1, %eax
+	jmp	5f
+1:	cmpl	$MC_SIZE, UC_MC_LEN_OFFSET(%edx) /* is context valid? */
+	je	2f
+	movl	$-1, %eax		/* bzzzt, invalid context */
+	jmp	5f
+2:	movl	8(%esp), %ecx		/* get address of curthreadp */
+	movl	%edx, %ebx		/* save the pointer for later */
+	/*
+	 * From here on, we don't touch the old stack.
+	 */
+	addl	$UC_MC_OFFSET, %edx	/* add offset to mcontext */
+	movl	4(%edx), %gs
+	movl	8(%edx), %fs
+	movl	12(%edx), %es
+	movl	16(%edx), %ds
+	movl	76(%edx), %ss
+	movl	20(%edx), %edi
+	movl	24(%edx), %esi
+	movl	28(%edx), %ebp
+	movl	72(%edx), %esp		/* switch to context defined stack */
+	subl	$4, %esp		/* leave space for the return address */
+	movl	60(%edx), %eax		/* put return address at top of stack */
+	movl	%eax, (%esp)
+	cmpl	$0, MC_OWNEDFP_OFFSET(%edx) /* are FP regs valid? */
+	jz	3f
+	frstor	MC_FP_REGS_OFFSET(%edx) /* restore FP regs */
+	jmp	4f
+3:	fninit
+	fldcw	MC_FP_CW_OFFSET(%edx)
+4:	movl	48(%edx), %eax		/* restore ax, bx, cx, dx */
+	pushl	68(%edx)		/* flags on stack */
+	pushl	36(%edx)		/* %ebx on stack */
+	pushl	44(%edx)		/* %ecx on stack */
+	movl	40(%edx), %edx		/* %edx */
+	/* 
+	 * all registers are now moved out of mailbox, 
+	 * it's safe to set current thread pointer
+	 */
+	movl	%ebx,(%ecx)
+	popl	%ecx			/* %ecx off stack */
+	pop	%ebx			/* %ebx off stack */
+	popf				/* flags off stack */
+5:	ret				/* %eip off stack */
+
+/*
+ * int thread_to_uts(struct kse_thr_mailbox *tm, struct kse_mailbox *km);
+ *
+ * Does not return on success, returns -1 otherwise.
+ */
+ENTRY(thread_to_uts)
+	movl	4(%esp), %eax		/* get address of context */
+	cmpl	$0, %eax		/* check for null pointer */
+	jne	1f
+	movl	$-1, %eax
+	jmp	2f
+1:	pushl	%edx			/* save value of edx */
+	movl	%eax, %edx		/* get address of context */
+	addl	$UC_MC_OFFSET, %edx	/* add offset to mcontext */
+	movl	%gs, 4(%edx)
+	movl	%fs, 8(%edx)
+	movl	%es, 12(%edx)
+	movl	%ds, 16(%edx)
+	movl	%edi, 20(%edx)
+	movl	%esi, 24(%edx)
+	movl	%ebp, 28(%edx)
+	movl	%ebx, 36(%edx)
+	movl	$0, 48(%edx)		/* store successful return in eax */
+	popl	%eax			/* get saved value of edx */
+	movl	%eax, 40(%edx)		/* save edx */
+	movl	%ecx, 44(%edx)
+	movl	(%esp), %eax		/* get return address */
+	movl	%eax, 60(%edx)		/* save return address */
+	movl	%ss, 76(%edx)
+	/*
+	 * Don't save floating point registers here.
+	 *
+	 * This is an explicit call to get the current context, so
+	 * the caller is done with the floating point registers.
+	 * Contexts formed by involuntary switches, such as signal delivery,
+	 * have floating point registers saved by the kernel.
+	 */
+	fnstcw	MC_FP_CW_OFFSET(%edx)
+	movl	$0, MC_OWNEDFP_OFFSET(%edx) /* no FP */
+	pushfl 				/* get eflags */
+	popl	%eax
+	movl	%eax, 68(%edx)		/* store eflags */
+	movl	%esp, %eax		/* setcontext pushes the return  */
+	addl	$4, %eax		/*   address onto the top of the */
+	movl	%eax, 72(%edx)		/*   stack; account for this     */
+	movl	$MC_SIZE, MC_LEN_OFFSET(%edx) /* context is now valid */
+	movl	8(%esp), %edx		/* get address of mailbox */
+	movl	KM_STACK_SP_OFFSET(%edx), %eax	/* get bottom of stack */
+	addl	KM_STACK_SIZE_OFFSET(%edx), %eax /* add length */
+	movl	%eax, %esp		/* switch to the uts's stack */
+	pushl	%edx			/* push the address of the mailbox */
+	pushl	KM_FUNC_OFFSET(%edx)	/* .. the uts can return to itself */
+	pushl	KM_FUNC_OFFSET(%edx)	/* push the address of the uts func */
+2:	ret
+
diff --git a/tools/KSE/rr/ksetest b/tools/KSE/rr/ksetest
new file mode 100755
index 0000000..1d44d51
--- /dev/null
+++ b/tools/KSE/rr/ksetest
diff --git a/tools/KSE/rr/rr.c b/tools/KSE/rr/rr.c
new file mode 100644
index 0000000..ec887b2
--- /dev/null
+++ b/tools/KSE/rr/rr.c
@@ -0,0 +1,406 @@
+/*-
+ * Copyright (c) 2002 David Xu(davidxu@freebsd.org).
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * Test Userland Thread Scheduler (UTS) suite for KSE.
+ * Test Userland round roubin.
+ */
+
+#include <sys/types.h>
+#include <sys/signal.h>
+#include <sys/signalvar.h>
+#include <sys/sysctl.h>
+#include <sys/kse.h>
+#include <sys/ucontext.h>
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <time.h>
+#include <unistd.h>
+#include "simplelock.h"
+
+#undef TRACE_UTS
+
+#ifdef TRACE_UTS
+#define	UPFMT(fmt...)	pfmt(#fmt)
+#define	UPSTR(s)	pstr(s)
+#define	UPCHAR(c)	pchar(c)
+#else
+#define	UPFMT(fmt...)	/* Nothing. */
+#define	UPSTR(s)	/* Nothing. */
+#define	UPCHAR(c)	/* Nothing. */
+#endif
+
+#define MAIN_STACK_SIZE			(1024 * 1024)
+#define THREAD_STACK_SIZE		(32 * 1024)
+
+struct uts_runq {
+	struct kse_thr_mailbox	*head;
+	struct simplelock	lock;
+};
+
+struct uts_data {
+	struct kse_mailbox	mb;
+	struct uts_runq		*runq;
+	struct kse_thr_mailbox	*cur_thread;
+};
+
+static struct uts_runq runq1;
+static struct uts_data data1;
+
+static void	init_uts(struct uts_data *data, struct uts_runq *q);
+static void	start_uts(struct uts_data *data, int newgrp);
+static void	enter_uts(struct uts_data *);
+static void	pchar(char c);
+static void	pfmt(const char *fmt, ...);
+static void	pstr(const char *s);
+static void	runq_init(struct uts_runq *q);
+static void	runq_insert(struct uts_runq *q, struct kse_thr_mailbox *tm);
+static struct	kse_thr_mailbox *runq_remove(struct uts_runq *q);
+static struct	kse_thr_mailbox *runq_remove_nolock(struct uts_runq *q);
+static void	thread_start(struct uts_data *data, const void *func, int arg);
+static void	uts(struct kse_mailbox *km);
+
+/* Functions implemented in assembly */
+extern int	uts_to_thread(struct kse_thr_mailbox *tdp,
+			struct kse_thr_mailbox **curthreadp);
+extern int	thread_to_uts(struct kse_thr_mailbox *tm,
+			struct kse_mailbox *km);
+
+void
+deadloop(int c)
+{
+	for (;;) {
+		;
+	}
+}
+
+int
+main(void)
+{
+	runq_init(&runq1);
+	init_uts(&data1, &runq1);
+	thread_start(&data1, deadloop, 0);
+	thread_start(&data1, deadloop, 0);
+	thread_start(&data1, deadloop, 0);
+	start_uts(&data1, 0);
+	pause();
+	pstr("\n** main() exiting **\n");
+	return (EX_OK);
+}
+
+
+/*
+ * Enter the UTS from a thread.
+ */
+static void
+enter_uts(struct uts_data *data)
+{
+	struct kse_thr_mailbox	*td;
+
+	/* XXX: We should atomically exchange these two. */
+	td = data->mb.km_curthread;
+	data->mb.km_curthread = NULL;
+
+	thread_to_uts(td, &data->mb);
+}
+
+/*
+ * Initialise threading.
+ */
+static void
+init_uts(struct uts_data *data, struct uts_runq *q)
+{
+	struct kse_thr_mailbox *tm;
+	int mib[2];
+	char	*p;
+#if 0
+	size_t len;
+#endif
+
+	/*
+	 * Create initial thread.
+	 */
+	tm = (struct kse_thr_mailbox *)calloc(1, sizeof(struct kse_thr_mailbox));
+
+	/* Throw us into its context. */
+	getcontext(&tm->tm_context);
+
+	/* Find our stack. */
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_USRSTACK;
+#if 0
+	len = sizeof(p);
+	if (sysctl(mib, 2, &p, &len, NULL, 0) == -1)
+		pstr("sysctl(CTL_KER.KERN_USRSTACK) failed.\n");
+#endif
+	p = (char *)malloc(MAIN_STACK_SIZE) + MAIN_STACK_SIZE;
+	pfmt("main() : 0x%x\n", tm);
+	pfmt("eip -> 0x%x\n", tm->tm_context.uc_mcontext.mc_eip);
+	tm->tm_context.uc_stack.ss_sp = p - MAIN_STACK_SIZE;
+	tm->tm_context.uc_stack.ss_size = MAIN_STACK_SIZE;
+
+	/*
+	 * Create KSE mailbox.
+	 */
+	p = (char *)malloc(THREAD_STACK_SIZE);
+	bzero(&data->mb, sizeof(struct kse_mailbox));
+	data->mb.km_stack.ss_sp = p;
+	data->mb.km_stack.ss_size = THREAD_STACK_SIZE;
+	data->mb.km_func = (void *)uts;
+	data->mb.km_udata = data;
+	data->cur_thread = tm;
+	data->runq = q;
+	pfmt("uts() at : 0x%x\n", uts);
+	pfmt("uts stack at : 0x%x - 0x%x\n", p, p + THREAD_STACK_SIZE);
+}
+
+static void
+start_uts(struct uts_data *data, int newgrp)
+{
+	/*
+	 * Start KSE scheduling.
+	 */
+	pfmt("kse_create() -> %d\n", kse_create(&data->mb, newgrp));
+	data->mb.km_curthread = data->cur_thread;
+}
+
+/*
+ * Write a single character to stdout, in a thread-safe manner.
+ */
+static void
+pchar(char c)
+{
+
+	write(STDOUT_FILENO, &c, 1);
+}
+
+/*
+ * Write formatted output to stdout, in a thread-safe manner.
+ *
+ * Recognises the following conversions:
+ *	%c	-> char
+ *	%d	-> signed int (base 10)
+ *	%s	-> string
+ *	%u	-> unsigned int (base 10)
+ *	%x	-> unsigned int (base 16)
+ */
+static void
+pfmt(const char *fmt, ...)
+{
+	static const char digits[16] = "0123456789abcdef";
+	va_list	 ap;
+	char buf[10];
+	char *s;
+	unsigned r, u;
+	int c, d;
+
+	va_start(ap, fmt);
+	while ((c = *fmt++)) {
+		if (c == '%') {
+			c = *fmt++;
+			switch (c) {
+			case 'c':
+				pchar(va_arg(ap, int));
+				continue;
+			case 's':
+				pstr(va_arg(ap, char *));
+				continue;
+			case 'd':
+			case 'u':
+			case 'x':
+				r = ((c == 'u') || (c == 'd')) ? 10 : 16;
+				if (c == 'd') {
+					d = va_arg(ap, unsigned);
+					if (d < 0) {
+						pchar('-');
+						u = (unsigned)(d * -1);
+					} else
+						u = (unsigned)d;
+				} else
+					u = va_arg(ap, unsigned);
+				s = buf;
+				do {
+					*s++ = digits[u % r];
+				} while (u /= r);
+				while (--s >= buf)
+					pchar(*s);
+				continue;
+			}
+		}
+		pchar(c);
+	}
+	va_end(ap);
+}
+
+static void
+pstr(const char *s)
+{
+
+	write(STDOUT_FILENO, s, strlen(s));
+}
+
+static void
+runq_init(struct uts_runq *q)
+{
+	q->head = NULL;
+	simplelock_init(&q->lock);
+}
+
+/*
+ * Insert a thread into the run queue.
+ */
+static void
+runq_insert(struct uts_runq *q, struct kse_thr_mailbox *tm)
+{
+	simplelock_lock(&q->lock);
+	tm->tm_next = q->head;
+	q->head = tm;
+	simplelock_unlock(&q->lock);
+}
+
+/*
+ * Select and remove a thread from the run queue.
+ */
+static struct kse_thr_mailbox *
+runq_remove(struct uts_runq *q)
+{
+	struct kse_thr_mailbox *tm;
+
+	simplelock_lock(&q->lock);
+	tm = runq_remove_nolock(q);
+	simplelock_unlock(&q->lock);
+	return tm;
+}
+
+static struct kse_thr_mailbox *
+runq_remove_nolock(struct uts_runq *q)
+{
+	struct kse_thr_mailbox *p, *p1;
+	
+	if (q->head == NULL)
+		return (NULL);
+	p1 = NULL;
+	for (p = q->head; p->tm_next != NULL; p = p->tm_next)
+		p1 = p;
+	if (p1 == NULL)
+		q->head = NULL;
+	else
+		p1->tm_next = NULL;
+	return (p);
+}
+
+/*
+ * Userland thread scheduler.
+ */
+static void
+uts(struct kse_mailbox *km)
+{
+	struct kse_thr_mailbox *tm, *p;
+	struct uts_data *data;
+
+	UPSTR("\n--uts() start--\n");
+	UPFMT("mailbox -> %x\n", km);
+
+	/*
+	 * Insert any processes back from being blocked
+	 * in the kernel into the run queue.
+	 */
+	data = km->km_udata;
+	p = km->km_completed;
+	km->km_completed = NULL;
+	UPFMT("km_completed -> 0x%x", p);
+	while ((tm = p) != NULL) {
+		p = tm->tm_next;
+		UPFMT(" 0x%x", p);
+		if (tm->tm_slices <= 0) {
+			tm->tm_slices = 10;
+			pfmt("thread %x exhausted its time slice, reassign it 10 statclock ticks\n", tm);
+		}
+		runq_insert(data->runq, tm);
+	}
+	UPCHAR('\n');
+
+	/*
+	 * Pull a thread off the run queue.
+	 */
+	simplelock_lock(&data->runq->lock);
+	p = runq_remove_nolock(data->runq);
+	simplelock_unlock(&data->runq->lock);
+
+	/*
+	 * Either schedule a thread, or idle if none ready to run.
+	 */
+	if (p != NULL) {
+		UPFMT("\n-- uts() scheduling 0x%x--\n", p);
+		UPFMT("eip -> 0x%x progress -> %d\n",
+		    p->tm_context.uc_mcontext.mc_eip, progress);
+		UPSTR("curthread set\n");
+		uts_to_thread(p, &km->km_curthread);
+		UPSTR("\n-- uts_to_thread() failed --\n");
+	}
+	kse_release(NULL);
+	pstr("** uts() exiting **\n");
+	exit(EX_SOFTWARE);
+}
+
+/*
+ * Start a thread.
+ */
+static struct kse_thr_mailbox *
+thread_create(const void *func, int arg)
+{
+	struct kse_thr_mailbox *tm;
+	char *p;
+
+	tm = (struct kse_thr_mailbox *)calloc(1, sizeof(struct kse_thr_mailbox));
+	getcontext(&tm->tm_context);
+	p = (char *)malloc(THREAD_STACK_SIZE);
+	tm->tm_context.uc_stack.ss_sp = p;
+	tm->tm_context.uc_stack.ss_size = THREAD_STACK_SIZE;
+	makecontext(&tm->tm_context, func, 1, arg);
+	// setcontext(&tm->tm_context);
+	return tm;
+}
+
+static void
+thread_start(struct uts_data *data, const void *func, int arg)
+{
+	struct kse_thr_mailbox *tm;
+	struct kse_thr_mailbox *tm2;
+
+	tm = thread_create(func, arg);
+	tm->tm_slices = 10;
+	tm2 = thread_create(enter_uts, (int)data);
+	tm->tm_context.uc_link = &tm2->tm_context;
+	runq_insert(data->runq, tm);
+	pfmt("thread_start() : 0x%x\n", tm);
+}
diff --git a/tools/KSE/rr/simplelock.h b/tools/KSE/rr/simplelock.h
new file mode 100644
index 0000000..2dae6ab
--- /dev/null
+++ b/tools/KSE/rr/simplelock.h
@@ -0,0 +1,59 @@
+/*-
+ * Copyright (c) 2002 David Xu (davidxu@freebsd.org).
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _SIMPLELOCK_H
+#define _SIMPLELOCK_H
+
+#include <machine/asmacros.h>
+#include <machine/atomic.h>
+
+struct simplelock {
+	int s_lock;
+};
+
+static inline void
+simplelock_init(struct simplelock *lock)
+{
+	lock->s_lock = 0;
+}
+
+static inline void
+simplelock_lock(struct simplelock *lock)
+{
+	while (!atomic_cmpset_int(&lock->s_lock, 0, 1))
+		;
+}
+
+static inline void
+simplelock_unlock(struct simplelock *lock)
+{
+	atomic_store_rel_int(&lock->s_lock, 0);
+}
+
+#endif
+