kern_kthread.c revision 71559 
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 71559 2001-01-24 10:47:50Z jhb $
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/lock.h>
34#include <sys/resourcevar.h>
35#include <sys/signalvar.h>
36#include <sys/unistd.h>
37#include <sys/wait.h>
38
39#include <machine/stdarg.h>
40
41/*
42 * Start a kernel process.  This is called after a fork() call in
43 * mi_startup() in the file kern/init_main.c.
44 *
45 * This function is used to start "internal" daemons and intended
46 * to be called from SYSINIT().
47 */
48void
49kproc_start(udata)
50	const void *udata;
51{
52	const struct kproc_desc	*kp = udata;
53	int error;
54
55	error = kthread_create((void (*)(void *))kp->func, NULL,
56		    kp->global_procpp, 0, kp->arg0);
57	if (error)
58		panic("kproc_start: %s: error %d", kp->arg0, error);
59}
60
61/*
62 * Create a kernel process/thread/whatever.  It shares its address space
63 * with proc0 - ie: kernel only.
64 *
65 * func is the function to start.
66 * arg is the parameter to pass to function on first startup.
67 * newpp is the return value pointing to the thread's struct proc.
68 * flags are flags to fork1 (in unistd.h)
69 * fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
70 */
71int
72kthread_create(void (*func)(void *), void *arg,
73    struct proc **newpp, int flags, const char *fmt, ...)
74{
75	int error;
76	va_list ap;
77	struct proc *p2;
78
79	if (!proc0.p_stats /* || proc0.p_stats->p_start.tv_sec == 0 */)
80		panic("kthread_create called too soon");
81
82	error = fork1(&proc0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags, &p2);
83	if (error)
84		return error;
85
86	/* save a global descriptor, if desired */
87	if (newpp != NULL)
88		*newpp = p2;
89
90	/* this is a non-swapped system process */
91	PROC_LOCK(p2);
92	p2->p_flag |= P_SYSTEM | P_KTHREAD;
93	p2->p_procsig->ps_flag |= PS_NOCLDWAIT;
94	PROC_UNLOCK(p2);
95	PHOLD(p2);
96
97	/* set up arg0 for 'ps', et al */
98	va_start(ap, fmt);
99	vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
100	va_end(ap);
101
102	/* call the processes' main()... */
103	cpu_set_fork_handler(p2, func, arg);
104
105	/* Delay putting it on the run queue until now. */
106	mtx_enter(&sched_lock, MTX_SPIN);
107	p2->p_sflag |= PS_INMEM;
108	if (!(flags & RFSTOPPED)) {
109		p2->p_stat = SRUN;
110		setrunqueue(p2);
111	}
112	mtx_exit(&sched_lock, MTX_SPIN);
113
114	return 0;
115}
116
117void
118kthread_exit(int ecode)
119{
120
121	PROCTREE_LOCK(PT_EXCLUSIVE);
122	proc_reparent(curproc, initproc);
123	PROCTREE_LOCK(PT_RELEASE);
124	exit1(curproc, W_EXITCODE(ecode, 0));
125}
126
127/*
128 * Advise a kernel process to suspend (or resume) in its main loop.
129 * Participation is voluntary.
130 */
131int
132kthread_suspend(struct proc *p, int timo)
133{
134	/*
135	 * Make sure this is indeed a system process and we can safely
136	 * use the p_siglist field.
137	 */
138	if ((p->p_flag & P_SYSTEM) == 0)
139		return (EINVAL);
140	SIGADDSET(p->p_siglist, SIGSTOP);
141	return tsleep((caddr_t)&p->p_siglist, PPAUSE, "suspkt", timo);
142}
143
144int
145kthread_resume(struct proc *p)
146{
147	/*
148	 * Make sure this is indeed a system process and we can safely
149	 * use the p_siglist field.
150	 */
151	if ((p->p_flag & P_SYSTEM) == 0)
152		return (EINVAL);
153	SIGDELSET(p->p_siglist, SIGSTOP);
154	wakeup((caddr_t)&p->p_siglist);
155	return (0);
156}
157
158void
159kthread_suspend_check(struct proc *p)
160{
161	while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
162		wakeup((caddr_t)&p->p_siglist);
163		tsleep((caddr_t)&p->p_siglist, PPAUSE, "ktsusp", 0);
164	}
165}
166