kern_kthread.c revision 1.11 
1/*	$NetBSD: kern_kthread.c,v 1.11 2000/07/14 07:15:05 thorpej Exp $	*/
2
3/*-
4 * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 *    must display the following acknowledgement:
21 *	This product includes software developed by the NetBSD
22 *	Foundation, Inc. and its contributors.
23 * 4. Neither the name of The NetBSD Foundation nor the names of its
24 *    contributors may be used to endorse or promote products derived
25 *    from this software without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37 * POSSIBILITY OF SUCH DAMAGE.
38 */
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/kernel.h>
43#include <sys/kthread.h>
44#include <sys/proc.h>
45#include <sys/wait.h>
46#include <sys/malloc.h>
47#include <sys/queue.h>
48
49/*
50 * note that stdarg.h and the ansi style va_start macro is used for both
51 * ansi and traditional c complers.
52 * XXX: this requires that stdarg.h define: va_alist and va_dcl
53 */
54#include <machine/stdarg.h>
55
56int	kthread_create_now;
57
58/*
59 * Fork a kernel thread.  Any process can request this to be done.
60 * The VM space and limits, etc. will be shared with proc0.
61 */
62int
63kthread_create1(void (*func)(void *), void *arg,
64    struct proc **newpp, const char *fmt, ...)
65{
66	struct proc *p2;
67	int error;
68	va_list ap;
69
70	/* First, create the new process. */
71	error = fork1(&proc0, FORK_SHAREVM | FORK_SHARECWD | FORK_SHAREFILES |
72	    FORK_SHARESIGS, SIGCHLD, NULL, 0, func, arg, NULL, &p2);
73	if (__predict_false(error != 0))
74		return (error);
75
76	/*
77	 * Mark it as a system process and not a candidate for
78	 * swapping.  Set P_NOCLDWAIT so that children are reparented
79	 * to init(8) when they exit.  init(8) can easily wait them
80	 * out for us.
81	 */
82	p2->p_flag |= P_INMEM | P_SYSTEM | P_NOCLDWAIT;	/* XXX */
83
84	/* Name it as specified. */
85	va_start(ap, fmt);
86	vsnprintf(p2->p_comm, MAXCOMLEN, fmt, ap);
87	va_end(ap);
88
89	/* All done! */
90	if (newpp != NULL)
91		*newpp = p2;
92	return (0);
93}
94
95/*
96 * Cause a kernel thread to exit.  Assumes the exiting thread is the
97 * current context.
98 */
99void
100kthread_exit(int ecode)
101{
102
103	/*
104	 * XXX What do we do with the exit code?  Should we even bother
105	 * XXX with it?  The parent (proc0) isn't going to do much with
106	 * XXX it.
107	 */
108	if (ecode != 0)
109		printf("WARNING: thread `%s' (%d) exits with status %d\n",
110		    curproc->p_comm, curproc->p_pid, ecode);
111
112	exit1(curproc, W_EXITCODE(ecode, 0));
113
114	/*
115	 * XXX Fool the compiler.  Making exit1() __noreturn__ is a can
116	 * XXX of worms right now.
117	 */
118	for (;;);
119}
120
121struct kthread_q {
122	SIMPLEQ_ENTRY(kthread_q) kq_q;
123	void (*kq_func)(void *);
124	void *kq_arg;
125};
126
127SIMPLEQ_HEAD(, kthread_q) kthread_q = SIMPLEQ_HEAD_INITIALIZER(kthread_q);
128
129/*
130 * Defer the creation of a kernel thread.  Once the standard kernel threads
131 * and processes have been created, this queue will be run to callback to
132 * the caller to create threads for e.g. file systems and device drivers.
133 */
134void
135kthread_create(void (*func)(void *), void *arg)
136{
137	struct kthread_q *kq;
138
139	if (kthread_create_now) {
140		(*func)(arg);
141		return;
142	}
143
144	kq = malloc(sizeof(*kq), M_TEMP, M_NOWAIT);
145	if (kq == NULL)
146		panic("unable to allocate kthread_q");
147	memset(kq, 0, sizeof(*kq));
148
149	kq->kq_func = func;
150	kq->kq_arg = arg;
151
152	SIMPLEQ_INSERT_TAIL(&kthread_q, kq, kq_q);
153}
154
155void
156kthread_run_deferred_queue(void)
157{
158	struct kthread_q *kq;
159
160	/* No longer need to defer kthread creation. */
161	kthread_create_now = 1;
162
163	while ((kq = SIMPLEQ_FIRST(&kthread_q)) != NULL) {
164		SIMPLEQ_REMOVE_HEAD(&kthread_q, kq, kq_q);
165		(*kq->kq_func)(kq->kq_arg);
166		free(kq, M_TEMP);
167	}
168}
169