kern_kthread.c revision 64529 
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 64529 2000-08-11 09:05:12Z peter $
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/resourcevar.h>
34#include <sys/signalvar.h>
35#include <sys/unistd.h>
36#include <sys/wait.h>
37
38#include <machine/stdarg.h>
39
40/*
41 * Start a kernel process.  This is called after a fork() call in
42 * mi_startup() in the file kern/init_main.c.
43 *
44 * This function is used to start "internal" daemons and intended
45 * to be called from SYSINIT().
46 */
47void
48kproc_start(udata)
49	const void *udata;
50{
51	const struct kproc_desc	*kp = udata;
52	int error;
53
54	error = kthread_create((void (*)(void *))kp->func, NULL,
55		    kp->global_procpp, kp->arg0);
56	if (error)
57		panic("kproc_start: %s: error %d", kp->arg0, error);
58}
59
60/*
61 * Create a kernel process/thread/whatever.  It shares it's address space
62 * with proc0 - ie: kernel only.
63 */
64int
65kthread_create(void (*func)(void *), void *arg,
66    struct proc **newpp, const char *fmt, ...)
67{
68	int error;
69	va_list ap;
70	struct proc *p2;
71
72	error = fork1(&proc0, RFMEM | RFFDG | RFPROC, &p2);
73	if (error)
74		return error;
75
76	/* save a global descriptor, if desired */
77	if (newpp != NULL)
78		*newpp = p2;
79
80	/* this is a non-swapped system process */
81	p2->p_flag |= P_INMEM | P_SYSTEM;
82	p2->p_procsig->ps_flag |= PS_NOCLDWAIT;
83	PHOLD(p2);
84
85	/* set up arg0 for 'ps', et al */
86	va_start(ap, fmt);
87	vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
88	va_end(ap);
89
90	/* call the processes' main()... */
91	cpu_set_fork_handler(p2, func, arg);
92
93	return 0;
94}
95
96void
97kthread_exit(int ecode)
98{
99	exit1(curproc, W_EXITCODE(ecode, 0));
100}
101
102/*
103 * Advise a kernel process to suspend (or resume) in its main loop.
104 * Participation is voluntary.
105 */
106int
107suspend_kproc(struct proc *p, int timo)
108{
109	/*
110	 * Make sure this is indeed a system process and we can safely
111	 * use the p_siglist field.
112	 */
113	if ((p->p_flag & P_SYSTEM) == 0)
114		return (EINVAL);
115	SIGADDSET(p->p_siglist, SIGSTOP);
116	return tsleep((caddr_t)&p->p_siglist, PPAUSE, "suspkp", timo);
117}
118
119int
120resume_kproc(struct proc *p)
121{
122	/*
123	 * Make sure this is indeed a system process and we can safely
124	 * use the p_siglist field.
125	 */
126	if ((p->p_flag & P_SYSTEM) == 0)
127		return (EINVAL);
128	SIGDELSET(p->p_siglist, SIGSTOP);
129	wakeup((caddr_t)&p->p_siglist);
130	return (0);
131}
132
133void
134kproc_suspend_loop(struct proc *p)
135{
136	while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
137		wakeup((caddr_t)&p->p_siglist);
138		tsleep((caddr_t)&p->p_siglist, PPAUSE, "kpsusp", 0);
139	}
140}
141