netbsd/sys/rump/librump/rumpkern/threads.c

/*	$NetBSD: threads.c,v 1.21 2013/05/02 19:15:01 pooka Exp $	*/

/*
 * Copyright (c) 2007-2009 Antti Kantee.  All Rights Reserved.
 *
 * Development of this software was supported by
 * The Finnish Cultural Foundation.
 *
 * 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 ``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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: threads.c,v 1.21 2013/05/02 19:15:01 pooka Exp $");

#include <sys/param.h>
#include <sys/atomic.h>
#include <sys/kmem.h>
#include <sys/kthread.h>
#include <sys/malloc.h>
#include <sys/systm.h>

#include <rump/rumpuser.h>

#include "rump_private.h"

struct kthdesc {
	void (*f)(void *);
	void *arg;
	struct lwp *mylwp;
};

static bool threads_are_go;
static struct rumpuser_mtx *thrmtx;
static struct rumpuser_cv *thrcv;

static void *
threadbouncer(void *arg)
{
	struct kthdesc *k = arg;
	struct lwp *l = k->mylwp;
	void (*f)(void *);
	void *thrarg;

	f = k->f;
	thrarg = k->arg;

	/* don't allow threads to run before all CPUs have fully attached */
	if (!threads_are_go) {
		rumpuser_mutex_enter_nowrap(thrmtx);
		while (!threads_are_go) {
			rumpuser_cv_wait_nowrap(thrcv, thrmtx);
		}
		rumpuser_mutex_exit(thrmtx);
	}

	/* schedule ourselves */
	rumpuser_curlwpop(RUMPUSER_LWP_SET, l);
	rump_schedule();

	/* free dance struct */
	free(k, M_TEMP);

	if ((curlwp->l_pflag & LP_MPSAFE) == 0)
		KERNEL_LOCK(1, NULL);

	f(thrarg);

	panic("unreachable, should kthread_exit()");
}

void
rump_thread_init(void)
{

	rumpuser_mutex_init(&thrmtx, RUMPUSER_MTX_SPIN);
	rumpuser_cv_init(&thrcv);
}

void
rump_thread_allow(void)
{

	rumpuser_mutex_enter(thrmtx);
	threads_are_go = true;
	rumpuser_cv_broadcast(thrcv);
	rumpuser_mutex_exit(thrmtx);

}

static struct {
	const char *t_name;
	bool t_ncmp;
} nothreads[] = {
	{ "vrele", false },
	{ "vdrain", false },
	{ "cachegc", false },
	{ "nfssilly", false },
	{ "unpgc", false },
	{ "pmf", true },
	{ "xcall", true },
};

int
kthread_create(pri_t pri, int flags, struct cpu_info *ci,
	void (*func)(void *), void *arg, lwp_t **newlp, const char *fmt, ...)
{
	char thrstore[MAXCOMLEN];
	const char *thrname = NULL;
	va_list ap;
	struct kthdesc *k;
	struct lwp *l;
	int rv;

	thrstore[0] = '\0';
	if (fmt) {
		va_start(ap, fmt);
		vsnprintf(thrstore, sizeof(thrstore), fmt, ap);
		va_end(ap);
		thrname = thrstore;
	}

	/*
	 * We don't want a module unload thread.
	 * (XXX: yes, this is a kludge too, and the kernel should
	 * have a more flexible method for configuring which threads
	 * we want).
	 */
	if (strcmp(thrstore, "modunload") == 0) {
		return 0;
	}

	if (!rump_threads) {
		bool matched;
		int i;

		/* do we want to fake it? */
		for (i = 0; i < __arraycount(nothreads); i++) {
			if (nothreads[i].t_ncmp) {
				matched = strncmp(thrstore, nothreads[i].t_name,
				    strlen(nothreads[i].t_name)) == 0;
			} else {
				matched = strcmp(thrstore,
				    nothreads[i].t_name) == 0;
			}
			if (matched) {
				aprint_error("rump kernel threads not enabled, "
				    "%s not functional\n", nothreads[i].t_name);
				return 0;
			}
		}
		panic("threads not available");
	}
	KASSERT(fmt != NULL);

	k = malloc(sizeof(*k), M_TEMP, M_WAITOK);
	k->f = func;
	k->arg = arg;
	k->mylwp = l = rump__lwproc_alloclwp(&proc0);
	l->l_flag |= LW_SYSTEM;
	if (flags & KTHREAD_MPSAFE)
		l->l_pflag |= LP_MPSAFE;
	if (flags & KTHREAD_INTR)
		l->l_pflag |= LP_INTR;
	if (ci) {
		l->l_pflag |= LP_BOUND;
		l->l_target_cpu = ci;
	}
	if (thrname) {
		l->l_name = kmem_alloc(MAXCOMLEN, KM_SLEEP);
		strlcpy(l->l_name, thrname, MAXCOMLEN);
	}
		
	rv = rumpuser_thread_create(threadbouncer, k, thrname,
	    (flags & KTHREAD_MUSTJOIN) == KTHREAD_MUSTJOIN,
	    pri, ci ? ci->ci_index : -1, &l->l_ctxlink);
	if (rv)
		return rv;

	if (newlp) {
		*newlp = l;
	} else {
		KASSERT((flags & KTHREAD_MUSTJOIN) == 0);
	}

	return 0;
}

void
kthread_exit(int ecode)
{

	if ((curlwp->l_pflag & LP_MPSAFE) == 0)
		KERNEL_UNLOCK_LAST(NULL);
	rump_lwproc_releaselwp();
	/* unschedule includes membar */
	rump_unschedule();
	rumpuser_thread_exit();
}

int
kthread_join(struct lwp *l)
{
	int rv;

	KASSERT(l->l_ctxlink != NULL);
	rv = rumpuser_thread_join(l->l_ctxlink);
	membar_consumer();

	return rv;
}