kern_kthread.c revision 55539 
1/*
2 * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/kern/kern_kthread.c 55539 2000-01-07 08:36:44Z luoqi $
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/proc.h>
32#include <sys/kthread.h>
33#include <sys/signalvar.h>
34#include <sys/unistd.h>
35#include <sys/wait.h>
36
37#include <machine/stdarg.h>
38
39/*
40 * Start a kernel process.  This is called after a fork() call in
41 * mi_startup() in the file kern/init_main.c.
42 *
43 * This function is used to start "internal" daemons and intended
44 * to be called from SYSINIT().
45 */
46void
47kproc_start(udata)
48	const void *udata;
49{
50	const struct kproc_desc	*kp = udata;
51	int error;
52
53	error = kthread_create((void (*)(void *))kp->func, NULL,
54		    kp->global_procpp, kp->arg0);
55	if (error)
56		panic("kproc_start: %s: error %d", kp->arg0, error);
57}
58
59/*
60 * Create a kernel process/thread/whatever.  It shares it's address space
61 * with proc0 - ie: kernel only.
62 */
63int
64kthread_create(void (*func)(void *), void *arg,
65    struct proc **newpp, const char *fmt, ...)
66{
67	int error;
68	va_list ap;
69	struct proc *p2;
70
71	error = fork1(&proc0, RFMEM | RFFDG | RFPROC, &p2);
72	if (error)
73		return error;
74
75	/* save a global descriptor, if desired */
76	if (newpp != NULL)
77		*newpp = p2;
78
79	/* this is a non-swapped system process */
80	p2->p_flag |= P_INMEM | P_SYSTEM;
81	p2->p_procsig->ps_flag |= PS_NOCLDWAIT;
82	PHOLD(p2);
83
84	/* set up arg0 for 'ps', et al */
85	va_start(ap, fmt);
86	vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
87	va_end(ap);
88
89	/* call the processes' main()... */
90	cpu_set_fork_handler(p2, func, arg);
91
92	return 0;
93}
94
95void
96kthread_exit(int ecode)
97{
98	exit1(curproc, W_EXITCODE(ecode, 0));
99}
100
101/*
102 * Advise a kernel process to suspend (or resume) in its main loop.
103 * Participation is voluntary.
104 */
105int
106suspend_kproc(struct proc *p, int timo)
107{
108	/*
109	 * Make sure this is indeed a system process and we can safely
110	 * use the p_siglist field.
111	 */
112	if ((p->p_flag & P_SYSTEM) == 0)
113		return (EINVAL);
114	SIGADDSET(p->p_siglist, SIGSTOP);
115	return tsleep((caddr_t)&p->p_siglist, PPAUSE, "suspkp", timo);
116}
117
118int
119resume_kproc(struct proc *p)
120{
121	/*
122	 * Make sure this is indeed a system process and we can safely
123	 * use the p_siglist field.
124	 */
125	if ((p->p_flag & P_SYSTEM) == 0)
126		return (EINVAL);
127	SIGDELSET(p->p_siglist, SIGSTOP);
128	wakeup((caddr_t)&p->p_siglist);
129	return (0);
130}
131
132void
133kproc_suspend_loop(struct proc *p)
134{
135	while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
136		wakeup((caddr_t)&p->p_siglist);
137		tsleep((caddr_t)&p->p_siglist, PPAUSE, "kpsusp", 0);
138	}
139}
140