kern_kthread.c revision 1.13 
1/*	$NetBSD: kern_kthread.c,v 1.13 2002/06/01 23:51:05 lukem 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/cdefs.h>
41__KERNEL_RCSID(0, "$NetBSD: kern_kthread.c,v 1.13 2002/06/01 23:51:05 lukem Exp $");
42
43#include <sys/param.h>
44#include <sys/systm.h>
45#include <sys/kernel.h>
46#include <sys/kthread.h>
47#include <sys/proc.h>
48#include <sys/wait.h>
49#include <sys/malloc.h>
50#include <sys/queue.h>
51
52/*
53 * note that stdarg.h and the ansi style va_start macro is used for both
54 * ansi and traditional c complers.
55 * XXX: this requires that stdarg.h define: va_alist and va_dcl
56 */
57#include <machine/stdarg.h>
58
59int	kthread_create_now;
60
61/*
62 * Fork a kernel thread.  Any process can request this to be done.
63 * The VM space and limits, etc. will be shared with proc0.
64 */
65int
66kthread_create1(void (*func)(void *), void *arg,
67    struct proc **newpp, const char *fmt, ...)
68{
69	struct proc *p2;
70	int error;
71	va_list ap;
72
73	/* First, create the new process. */
74	error = fork1(&proc0, FORK_SHAREVM | FORK_SHARECWD | FORK_SHAREFILES |
75	    FORK_SHARESIGS, SIGCHLD, NULL, 0, func, arg, NULL, &p2);
76	if (__predict_false(error != 0))
77		return (error);
78
79	/*
80	 * Mark it as a system process and not a candidate for
81	 * swapping.  Set P_NOCLDWAIT so that children are reparented
82	 * to init(8) when they exit.  init(8) can easily wait them
83	 * out for us.
84	 */
85	p2->p_flag |= P_INMEM | P_SYSTEM | P_NOCLDWAIT;	/* XXX */
86
87	/* Name it as specified. */
88	va_start(ap, fmt);
89	vsnprintf(p2->p_comm, MAXCOMLEN, fmt, ap);
90	va_end(ap);
91
92	/* All done! */
93	if (newpp != NULL)
94		*newpp = p2;
95	return (0);
96}
97
98/*
99 * Cause a kernel thread to exit.  Assumes the exiting thread is the
100 * current context.
101 */
102void
103kthread_exit(int ecode)
104{
105
106	/*
107	 * XXX What do we do with the exit code?  Should we even bother
108	 * XXX with it?  The parent (proc0) isn't going to do much with
109	 * XXX it.
110	 */
111	if (ecode != 0)
112		printf("WARNING: thread `%s' (%d) exits with status %d\n",
113		    curproc->p_comm, curproc->p_pid, ecode);
114
115	exit1(curproc, W_EXITCODE(ecode, 0));
116
117	/*
118	 * XXX Fool the compiler.  Making exit1() __noreturn__ is a can
119	 * XXX of worms right now.
120	 */
121	for (;;);
122}
123
124struct kthread_q {
125	SIMPLEQ_ENTRY(kthread_q) kq_q;
126	void (*kq_func)(void *);
127	void *kq_arg;
128};
129
130SIMPLEQ_HEAD(, kthread_q) kthread_q = SIMPLEQ_HEAD_INITIALIZER(kthread_q);
131
132/*
133 * Defer the creation of a kernel thread.  Once the standard kernel threads
134 * and processes have been created, this queue will be run to callback to
135 * the caller to create threads for e.g. file systems and device drivers.
136 */
137void
138kthread_create(void (*func)(void *), void *arg)
139{
140	struct kthread_q *kq;
141
142	if (kthread_create_now) {
143		(*func)(arg);
144		return;
145	}
146
147	kq = malloc(sizeof(*kq), M_TEMP, M_NOWAIT);
148	if (kq == NULL)
149		panic("unable to allocate kthread_q");
150	memset(kq, 0, sizeof(*kq));
151
152	kq->kq_func = func;
153	kq->kq_arg = arg;
154
155	SIMPLEQ_INSERT_TAIL(&kthread_q, kq, kq_q);
156}
157
158void
159kthread_run_deferred_queue(void)
160{
161	struct kthread_q *kq;
162
163	/* No longer need to defer kthread creation. */
164	kthread_create_now = 1;
165
166	while ((kq = SIMPLEQ_FIRST(&kthread_q)) != NULL) {
167		SIMPLEQ_REMOVE_HEAD(&kthread_q, kq_q);
168		(*kq->kq_func)(kq->kq_arg);
169		free(kq, M_TEMP);
170	}
171}
172